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Raji F, Nguyen NN, Nguyen CV, Nguyen AV. Lead (II) ions enable the ion-specific effects of monovalent anions on the molecular structure and interactions at silica/aqueous interfaces. J Colloid Interface Sci 2024; 662:653-662. [PMID: 38367582 DOI: 10.1016/j.jcis.2024.02.094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/07/2024] [Accepted: 02/11/2024] [Indexed: 02/19/2024]
Abstract
HYPOTHESIS The adsorption of heavy metal ions such as Pb(II) onto negatively charged minerals such as silica is expected to alter the structure and the interactions at the silica/aqueous interfaces. Besides the solution pH, the inner-sphere sorption of Pb(II) is expected to regulate the surface charge/potential, hypothesized to control the actions of monovalent anions in the aqueous environment. These complex pictures can be probed directly using surface-sensitive sum-frequency generation (SFG) spectroscopy. EXPERIMENTS The pH-dependent water structure within the double layer at silica/aqueous interfaces under the influence of different ions was examined using SFG. The recorded SFG spectra were deconvoluted into the Stern layer (SL) and diffuse layer (DL) using the maximum entropy method in conjunction with the electrical double-layer theory. FINDINGS Standalone monovalent sodium salts do not exhibit ion-specific effects on the silica/aqueous interfaces. However, the mixture of Pb(II) species and each of these salts display profound ion-specific effects on the structure of silica/aqueous interfaces, indicating the role of Pb(II) as an enabler of the ion-specificity of the investigated monovalent anions. The interesting effect arises from a complex interplay between the physical processes (i.e., electrostatic interactions, screening effects, etc.) and chemical processes such as the hydrolysis of Pb(II) ions, ion complexation, protonation and deprotonation of the surface silanol group.
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Affiliation(s)
- Foad Raji
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia.
| | - Ngoc N Nguyen
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Cuong V Nguyen
- Department of Water and Environmental Regulation, Joondalup, WA 6027, Australia
| | - Anh V Nguyen
- School of Chemical Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
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2
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Basu T, Das S, Majumdar S. Elucidating the influence of electrostatic force on the re-arrangement of H-bonds of protein polymers in the presence of salts. SOFT MATTER 2024; 20:2361-2373. [PMID: 38372459 DOI: 10.1039/d3sm01440a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Polyampholytes/proteins have an intriguing network of hydrogen bonds (H-bonds), especially their secondary structure, which plays a crucial role in determining the conformational stability of the polymer. The changes in protein secondary structure in the protein-salt system have been extensively deciphered by researchers, yet their pathways for breakage and recreation are unknown. Understanding the mechanism of protein conformational changes towards their biological activities, like protein folding, remains one of the main challenges and requires multiscale analysis of this strongly correlated system. Herein, salts have been used to reveal the re-arrangement behavior in the H-bond network of proteins under the influence of electrostatic interactions, as the strength of electrostatic forces is much stronger than that of H-bonds. At lower salt concentrations, there are negligible changes in the secondary structures as the electrostatic forces induced by the salt ions are less. Later, the existing H-bonds break and reconstruct new H-bonds at higher salt concentrations due to the influence of the stronger electrostatic interaction induced by the large number of salt ions. Molecular dynamics (MD) simulations and FTIR studies have been used rigorously to decipher the reason behind the re-arrangement of the H-bonds within gelatin (protein). The re-arrangement in the H-bond has also been observed with time from simulations and experiments. Thus, this study could provide a fresh perspective on the conformational changes of polyampholytes/proteins and will also influence the studies of protein folding-unfolding interaction in the presence of salt ions.
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Affiliation(s)
- Tithi Basu
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Telangana, 502285, India.
| | - Sougat Das
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Telangana, 502285, India.
| | - Saptarshi Majumdar
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Telangana, 502285, India.
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3
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Gresham IJ, Johnson EC, Robertson H, Willott JD, Webber GB, Wanless EJ, Nelson ARJ, Prescott SW. Comparing polymer-surfactant complexes to polyelectrolytes. J Colloid Interface Sci 2024; 655:262-272. [PMID: 37944374 DOI: 10.1016/j.jcis.2023.10.101] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/12/2023] [Accepted: 10/19/2023] [Indexed: 11/12/2023]
Abstract
HYPOTHESIS Understanding the complex interactions between polymers and surfactants is required to optimise commercially relevant systems such as paint, toothpaste and detergent. Neutral polymers complex with surfactants, forming 'pearl necklace' structures that are often conceptualised as pseudo-polyelectrolytes. Here we pose two questions to test the limits of this analogy: Firstly, in the presence of salt, do these polymer-surfactant systems behave like polyelectrolytes? Secondly, do polymer-surfactant complexes resist geometric confinement like polyelectrolytes? EXPERIMENTS We test the limits of the pseudo-polyelectrolyte analogy through studying a poly(N-isopropylacrylamide) (PNIPAM) brush in the presence of sodium dodecylsulfate (SDS). Brushes are ideal for interrogating pseudo-polyelectrolytes, as neutral and polyelectrolyte brushes exhibit distinct and well understood behaviours. Spectroscopic ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D), and neutron reflectometry (NR) were used to monitor the behaviour and structure of the PNIPAM-SDS system as a function of NaCl concentration. The ability of the PNIPAM-SDS complex to resist geometric confinement was probed with NR. FINDINGS At a fixed SDS concentration below the zero-salt CMC, increasing NaCl concentration <100 mM promoted brush swelling due to an increase in osmotic pressure, not dissimilar to a weak polyelectrolyte. At these salt concentrations, the swelling of the brush could be described by a single parameter: the effective CMC. However, at high NaCl concentrations (e.g., 500 mM) no brush collapse was observed at all (non-zero) concentrations of SDS studied, contrary to what is seen for many polyelectrolytes. Study of the polymer-surfactant system under confinement revealed that the physical volume of surfactant dominates the structure of the strongly confined system, which further differentiates it from the polyelectrolyte case.
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Affiliation(s)
- Isaac J Gresham
- School of Chemical Engineering, UNSW Sydney, Sydney, 2052, NSW, Australia
| | - Edwin C Johnson
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, 2308, NSW, Australia
| | - Hayden Robertson
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, 2308, NSW, Australia
| | - Joshua D Willott
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, 2308, NSW, Australia
| | - Grant B Webber
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, 2308, NSW, Australia
| | - Erica J Wanless
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, 2308, NSW, Australia
| | | | - Stuart W Prescott
- School of Chemical Engineering, UNSW Sydney, Sydney, 2052, NSW, Australia.
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4
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Robertson H, Willott JD, Gregory KP, Johnson EC, Gresham IJ, Nelson ARJ, Craig VSJ, Prescott SW, Chapman R, Webber GB, Wanless EJ. From Hofmeister to hydrotrope: Effect of anion hydrocarbon chain length on a polymer brush. J Colloid Interface Sci 2023; 634:983-994. [PMID: 36571860 DOI: 10.1016/j.jcis.2022.12.114] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/07/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022]
Abstract
HYPOTHESIS Specific ion effects govern myriad biological phenomena, including protein-ligand interactions and enzyme activity. Despite recent advances, detailed understanding of the role of ion hydrophobicity in specific ion effects, and the intersection with hydrotropic effects, remains elusive. Short chain fatty acid sodium salts are simple amphiphiles which play an integral role in our gastrointestinal health. We hypothesise that increasing a fatty acid's hydrophobicity will manifest stronger salting-out behaviour. EXPERIMENTS Here we study the effect of these amphiphiles on an exemplar thermoresponsive polymer brush system, conserving the carboxylate anion identity while varying anion hydrophobicity via the carbon chain length. Ellipsometry and quartz crystal microbalance with dissipation monitoring were used to characterise the thermoresponse and viscoelasticity of the brush, respectively, whilst neutron reflectometry was used to reveal the internal structure of the brush. Diffusion-ordered nuclear magnetic resonance spectroscopy and computational investigations provide insight into polymer-ion interactions. FINDINGS Surface sensitive techniques unveiled a non-monotonic trend in salting-out ability with increasing anion hydrophobicity, revealing the bundle-like morphology of the ion-collapsed system. An intersection between ion-specific and hydrotropic effects was observed both experimentally and computationally; trending from good anti-hydrotrope towards hydrotropic behaviour with increasing anion hydrophobicity, accompanying a change in hydrophobic hydration.
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Affiliation(s)
- Hayden Robertson
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Joshua D Willott
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Kasimir P Gregory
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia; Department of Materials Physics, Research School of Physics, Australian National University, Canberra, ACT 0200, Australia
| | - Edwin C Johnson
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia; Department of Chemistry, The University of Sheffield, Sheffield, UK
| | - Isaac J Gresham
- School of Chemical Engineering, UNSW Sydney, Sydney, NSW 2052, Australia; School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Andrew R J Nelson
- Australian Centre for Neutron Scattering, ANSTO, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Vincent S J Craig
- Department of Materials Physics, Research School of Physics, Australian National University, Canberra, ACT 0200, Australia
| | - Stuart W Prescott
- School of Chemical Engineering, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Robert Chapman
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Grant B Webber
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Erica J Wanless
- College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia.
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Thambi T, Jung JM, Lee DS. Recent strategies to develop pH-sensitive injectable hydrogels. Biomater Sci 2023; 11:1948-1961. [PMID: 36723174 DOI: 10.1039/d2bm01519f] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
"Smart" biomaterials that are responsive to pathological abnormalities are an appealing class of therapeutic platforms for the development of personalized medications. The development of such therapeutic platforms requires novel techniques that could precisely deliver therapeutic agents to the diseased tissues, resulting in enhanced therapeutic effects without harming normal tissues. Among various therapeutic platforms, injectable pH-responsive biomaterials are promising biomaterials that respond to the change in environmental pH. Aqueous solutions of injectable pH-responsive biomaterials exhibit a phase transition from sol-to-gel in response to environmental pH changes. The injectable pH-responsive hydrogel depot can provide spatially and temporally controlled release of various bioactive agents including chemotherapeutic drugs, peptides, and proteins. Therapeutic agents are imbibed into hydrogels by simple mixing without the use of toxic solvents and used for long-term storage or in situ injection using a syringe or catheter that could form a stable gel and acts as a controlled release depot in a minimally invasive manner. Tunable physicochemical properties of the hydrogels, such as biodegradability, ability to interact with drugs and mechanical properties, can control the release of the therapeutic agent. This review highlights the advances in the design and development of biodegradable and in situ forming injectable pH-responsive biomaterials that respond to the physiological conditions. Special attention has been paid to the development of amphoteric pH-responsive biomaterials and their utilization in biomedical applications. We also highlight key challenges and future directions of pH-responsive biomaterials in clinical translation.
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Affiliation(s)
- Thavasyappan Thambi
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.
| | - Jae Min Jung
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.
| | - Doo Sung Lee
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea.
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6
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Hofmeister series: An insight into its application on gelatin and alginate-based dual-drug biomaterial design. Eur Polym J 2023. [DOI: 10.1016/j.eurpolymj.2023.111961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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7
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Organo-Montmorillonite Modified by Gemini Quaternary Ammonium Surfactants with Different Counterions for Adsorption toward Phenol. Molecules 2023; 28:molecules28052021. [PMID: 36903268 PMCID: PMC10004245 DOI: 10.3390/molecules28052021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 02/07/2023] [Accepted: 02/15/2023] [Indexed: 02/24/2023] Open
Abstract
The discharge of industrial phenol pollutants causes great harm to the natural environment and human health. In this study, phenol removal from water was studied via the adsorption of Na-montmorillonite (Na-Mt) modified by a series of Gemini quaternary ammonium surfactants with different counterions [(C11H23CONH(CH2)2N+ (CH3)2(CH2)2 N+(CH3)2 (CH2)2NHCOC11H23·2Y-, Y = CH3CO3-, C6H5COO- and Br-, 12-2-12·2Y-]. The results of the phenol adsorption indicated that MMt-12-2-12·2Br-, MMt-12-2-12·2CH3CO3- and MMt-12-2-12·2C6H5COO- reached the optimum adsorption capacity, which was 115.110 mg/g, 100.834 mg/g and 99.985 mg/g, respectively, under the conditions of the saturated intercalation concentration at 2.0 times that of the cation exchange capacity (CEC) of the original Na-Mt, 0.04 g of adsorbent and a pH = 10. The adsorption kinetics of all adsorption processes were in good agreement with the pseudo-second-order kinetics model, and the adsorption isotherm was better modeled by Freundlich isotherm. Thermodynamic parameters revealed that the adsorption of phenol was a physical, spontaneous and exothermic process. The results also showed that the counterions of the surfactant had a certain influence on the adsorption performance of MMt for phenol, especially the rigid structure, hydrophobicity, and hydration of the counterions.
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8
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Ehtiati K, Moghaddam SZ, Klok HA, Daugaard AE, Thormann E. Specific Counterion Effects on the Swelling Behavior of Strong Polyelectrolyte Brushes. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Koosha Ehtiati
- Department of Chemistry, Technical University of Denmark, 2800 Kgs Lyngby, Denmark
| | - Saeed Z. Moghaddam
- Department of Chemistry, Technical University of Denmark, 2800 Kgs Lyngby, Denmark
| | - Harm-Anton Klok
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire des Polyméres, Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Bâtiment MXD, Station 12, CH-1015 Lausanne, Switzerland
| | - Anders E. Daugaard
- Danish Polymer Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Esben Thormann
- Department of Chemistry, Technical University of Denmark, 2800 Kgs Lyngby, Denmark
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9
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Abstract
I review experimental developments in the growth and application of surface-grafted weak polyelectrolytes (brushes), concentrating on their surface, tribological, and adhesive and bioadhesive properties, and their role as actuators.
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Affiliation(s)
- Mark Geoghegan
- School of Engineering, Newcastle University, Merz Court, Newcastle-upon-Tyne NE1 7RU, UK.
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10
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4D-printed pH sensing claw. Anal Chim Acta 2022; 1204:339733. [DOI: 10.1016/j.aca.2022.339733] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 02/10/2022] [Accepted: 03/14/2022] [Indexed: 01/30/2023]
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11
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The Anion Binding Affinity Determines the Strength of Anion Specificities of Thermosensitive Polymers. CHINESE JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1007/s10118-021-2633-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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Gresham IJ, Murdoch TJ, Johnson EC, Robertson H, Webber GB, Wanless EJ, Prescott SW, Nelson ARJ. Quantifying the robustness of the neutron reflectometry technique for structural characterization of polymer brushes. J Appl Crystallogr 2021. [DOI: 10.1107/s160057672100251x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Neutron reflectometry is the foremost technique for in situ determination of the volume fraction profiles of polymer brushes at planar interfaces. However, the subtle features in the reflectometry data produced by these diffuse interfaces challenge data interpretation. Historically, data analyses have used least-squares approaches that do not adequately quantify the uncertainty of the modeled profile and ignore the possibility of other structures that also match the collected data (multimodality). Here, a Bayesian statistical approach is used that permits the structural uncertainty and multimodality to be quantified for polymer brush systems. A free-form model is used to describe the volume fraction profile, minimizing assumptions regarding brush structure, while only allowing physically reasonable profiles to be produced. The model allows the total volume of polymer and the profile monotonicity to be constrained. The rigor of the approach is demonstrated via a round-trip analysis of a simulated system, before it is applied to real data examining the well characterized collapse of a thermoresponsive brush. It is shown that, while failure to constrain the interfacial volume and consider multimodality may result in erroneous structures being derived, carefully constraining the model allows for robust determination of polymer brush compositional profiles. This work highlights that an appropriate combination of flexibility and constraint must be used with polymer brush systems to ensure the veracity of the analysis. The code used in this analysis is provided, enabling the reproduction of the results and the application of the method to similar problems.
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Ehtiati K, Z. Moghaddam S, Daugaard AE, Thormann E. Crucial Nonelectrostatic Effects on Polyelectrolyte Brush Behavior. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Koosha Ehtiati
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Saeed Z. Moghaddam
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Anders E. Daugaard
- Danish Polymer Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Esben Thormann
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
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Johnson EC, Gresham IJ, Prescott SW, Nelson A, Wanless EJ, Webber GB. The direction of influence of specific ion effects on a pH and temperature responsive copolymer brush is dependent on polymer charge. POLYMER 2021. [DOI: 10.1016/j.polymer.2020.123287] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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Kent EW, Lewoczko EM, Zhao B. Effect of Buffer Anions on Pearl-Necklace Morphology of Tertiary Amine-Containing Binary Heterografted Linear Molecular Bottlebrushes in Acidic Aqueous Buffers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13320-13330. [PMID: 33135416 DOI: 10.1021/acs.langmuir.0c02435] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Molecular bottlebrushes can exhibit a multitude of distinct conformations under different conditions, and precise control of their morphology can facilitate better use of such materials in potential applications. Herein, we report a study on the effect of buffer anions on the pearl-necklace morphology of linear binary heterografted molecular brushes consisting of pH-responsive poly(2-N,N-diethylamino)ethyl methacrylate) (PDEAEMA) with a pKa of 7.40 and thermoresponsive poly(ethoxydi(ethylene glycol) acrylate) (PDEGEA) with a lower critical solution temperature of 9 °C as side chains in various acidic aqueous buffers at 0 °C. The molecular brushes, denotated as BMB, were prepared by a grafting-to approach using copper(I)-catalyzed azide-alkyne cycloaddition reaction. Dynamic light scattering studies showed that the apparent hydrodynamic size of BMB in aqueous buffers with a pH of 6.50 at 1 °C decreased with increasing valency of buffer anions, from acetate anions with a charge of 1-, to phosphate anions carrying charges of 2- and 1- and citrate anions bearing charges of 3- and 2- at pH = 6.50. Atomic force microscopy revealed that BMB exhibited a pearl-necklace morphology from all three aqueous buffers with a pH of 6.50 when spin-cast at 0 °C. Analysis of AFM images showed that the average length of BMB and the number of beads per brush molecule decreased with increasing valency of buffer anions while the size and height of the beads increased. The pearl-necklace morphology of BMB was believed to be the result of microphase separation of the neutral PDEGEA and the charged PDEAEMA side chains along the brush backbone. Multivalent kosmotropic buffer anions formed bridging linkages between protonated tertiary amine moieties and thus "crosslinked" the charged PDEAEMA side chains, resulting in the shrinkage of BMB and enhanced microphase separation of two side chain polymers.
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Affiliation(s)
- Ethan W Kent
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Evan M Lewoczko
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Bin Zhao
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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16
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Johnson EC, Willott JD, Gresham IJ, Murdoch TJ, Humphreys BA, Prescott SW, Nelson A, de Vos WM, Webber GB, Wanless EJ. Enrichment of Charged Monomers Explains Non-monotonic Polymer Volume Fraction Profiles of Multi-stimulus Responsive Copolymer Brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:12460-12472. [PMID: 33105998 DOI: 10.1021/acs.langmuir.0c01502] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Multi-stimulus responsive poly(2-(2-methoxyethoxy)ethyl methacrylate-co-2-(diethylamino)ethyl methacrylate) [P(MEO2MA-co-DEA)] 80:20 mol % copolymer brushes were synthesized on planar silica substrates via surface-initiated activators continuously regenerated via electron transfer atom transfer radical polymerization. Brush thickness was sensitive to changes in pH and temperature as monitored with ellipsometry. At low pH, the brush is charged and swollen, while at high pH, the brush is uncharged and more collapsed. Clear thermoresponsive behavior is also observed with the brush more swollen at low temperatures compared to high temperatures at both high and low pH. Neutron reflectometry was used to determine the polymer volume fraction profiles (VFPs) at various pH values and temperatures. A region of lower polymer content, or a depletion region, near the substrate is present in all of the experimental polymer VFPs, and it is more pronounced at low pH (high charge) and less so at high pH (low charge). Polymer VFPs calculated through numerical self-consistent field theory suggest that enrichment of DEA monomers near the substrate results in the experimentally observed non-monotonic VFPs. Adsorption of DEA monomers to the substrate prior to initiation of polymerization could give rise to DEA segment-enriched region proximal to the substrate.
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Affiliation(s)
- Edwin C Johnson
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Joshua D Willott
- Membrane Surface Science (MSuS), Membrane Science and Technology cluster, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Isaac J Gresham
- School of Chemical Engineering, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Timothy J Murdoch
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Ben A Humphreys
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Stuart W Prescott
- School of Chemical Engineering, UNSW Sydney, Sydney, New South Wales 2052, Australia
| | - Andrew Nelson
- ANSTO, Locked bag 2001, Kirrawee DC, Sydney, New South Wales 2232, Australia
| | - Wiebe M de Vos
- Membrane Surface Science (MSuS), Membrane Science and Technology cluster, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Grant B Webber
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Erica J Wanless
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, New South Wales 2308, Australia
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17
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Competitive specific ion effects in mixed salt solutions on a thermoresponsive polymer brush. J Colloid Interface Sci 2020; 586:292-304. [PMID: 33189318 DOI: 10.1016/j.jcis.2020.10.092] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/21/2020] [Accepted: 10/22/2020] [Indexed: 11/22/2022]
Abstract
HYPOTHESIS Grafted poly(ethylene glycol) methyl ether methacrylate (POEGMA) copolymer brushes change conformation in response to temperature ('thermoresponse'). In the presence of different ions the thermoresponse of these coatings is dramatically altered. These effects are complex and poorly understood with no all-inclusive predictive theory of specific ion effects. As natural environments are composed of mixed electrolytes, it is imperative we understand the interplay of different ions for future applications. We hypothesise anion mixtures from the same end of the Hofmeister series (same-type anions) will exhibit non-additive and competitive behaviour. EXPERIMENTS The behaviour of POEGMA brushes, synthesised via surface-initiated ARGET-ATRP, in both single and mixed aqueous electrolyte solutions was characterised with ellipsometry and neutron reflectometry as a function of temperature. FINDINGS In mixed fluoride and chloride aqueous electrolytes (salting-out ions), or mixed thiocyanate and iodide aqueous electrolytes (salting-in ions), a non-monotonic concentration-dependent influence of the two anions on the thermoresponse of the brush was observed. A new term, δ, has been defined to quantitively describe synergistic or antagonistic behaviour. This study determined the specific ion effects imparted by salting-out ions are dependent on available solvent molecules, whereas the influence of salting-in ions is dependent on the interactions of the anions and polymer chains.
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18
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Higaki Y, Kobayashi M, Takahara A. Hydration State Variation of Polyzwitterion Brushes through Interplay with Ions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9015-9024. [PMID: 32677837 DOI: 10.1021/acs.langmuir.0c01672] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Polyzwitterions have emerged as a new class of antifouling materials alternating poly(ethylene glycol). The exemplary biopassivation and lubrication behaviors are often attributed to the particular chemical structure of zwitterions, which involve a large dipole moment of the charged groups and a neutral net charge, while the hydration state and dynamics also associate with these characteristics. Polymer brushes composed of surface-tethered polyzwitterion chains produced by surface-initiated controlled radical polymerization have been developed as thin films which exhibit excellent antifouling and lubrication properties. In past decades, numerous studies have been devoted to examining the structure and dynamics of polyzwitterion brush chains in aqueous solutions. This feature article provides an overview of recent studies exploring the hydration state of polyzwitterion brushes with specular neutron reflectivity, highlights some newly published work on the nonuniform equilibrium structure, ion concentration dependence, ion specificity, and the effects of charge spacer length in the zwitterions, and discusses future perspective in this field.
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Affiliation(s)
- Yuji Higaki
- Department of Integrated Science and Technology, Faculty of Science and Technology, Oita University, 700 Dannoharu, Oita 870-1192, Japan
| | - Motoyasu Kobayashi
- School of Advanced Engineering, Kogakuin University, Tokyo 192-0015, Japan
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Johnson EC, Willott JD, de Vos WM, Wanless EJ, Webber GB. Interplay of Composition, pH, and Temperature on the Conformation of Multi-stimulus-responsive Copolymer Brushes: Comparison of Experiment and Theory. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:5765-5777. [PMID: 32364745 DOI: 10.1021/acs.langmuir.0c00424] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO2MA), a thermoresponsive polymer with a lower critical solution temperature of ∼28 °C, and poly(2-(diethylamino)ethyl methacrylate) (PDEA), a weak polybase with an apparent pKa of ∼7.5, have been statistically copolymerized using activators continuously regenerated via electron transfer atom transfer radical polymerization to form multi-stimulus-responsive polymer brushes. The stimulus-responsive behavior of these brushes has been investigated with ellipsometry and numerical self-consistent field (nSCF) theory. The pH- and thermoresponsive behaviors of a PDEA homopolymer brush were investigated experimentally in order to benchmark the nSCF theory calculations. nSCF theory was able to reproduce the responsive behavior of PDEA and PMEO2MA homopolymer brushes. Three copolymer compositions (90:10, 70:30, and 50:50 mol % MEO2MA:DEA) were investigated experimentally with pH ramps performed at low and high temperatures and temperature ramps performed at low and high pH. A broader range of compositions were investigated with nSCF theory and compared to the experimental results, with the nSCF calculations able to capture the general behavior of the homopolymer and copolymer brushes. The responsive behavior of each brush to a given stimulus (temperature or pH) was dependent on both the polymer composition and environment (temperature or pH). The influence of pH on the brush increased with higher DEA mol % with a copolymer brush response transitioning from temperature-dominant to pH-dominant. The temperature response of PMEO2MA was completely masked at low and high pH values by the presence of at least 30 mol % polybase in the copolymer.
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Affiliation(s)
- Edwin C Johnson
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Joshua D Willott
- Membrane Surface Science (MSuS), Membrane Science and Technology Cluster, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7522 NB, The Netherlands
| | - Wiebe M de Vos
- Membrane Surface Science (MSuS), Membrane Science and Technology Cluster, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7522 NB, The Netherlands
| | - Erica J Wanless
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Grant B Webber
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, New South Wales 2308, Australia
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20
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Yuan H, Liu G. Ionic effects on synthetic polymers: from solutions to brushes and gels. SOFT MATTER 2020; 16:4087-4104. [PMID: 32292998 DOI: 10.1039/d0sm00199f] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The ionic effects on synthetic polymers have attracted extensive attention due to the crucial role of ions in the determination of the properties of synthetic polymers. This review places the focus on specific ion effects, multivalent ion effects, and ionic hydrophilicity/hydrophobicity effects in synthetic polymer systems from solutions to brushes and gels. The specific ion effects on neutral polymers are determined by both the direct and indirect specific ion-polymer interactions, whereas the ion specificities of charged polymers are mainly dominated by the specific ion-pairing interactions. The ionic cross-linking effect exerted by the multivalent ions is widely used to tune the properties of polyelectrolytes, while the reentrant behavior of polyelectrolytes in the presence of multivalent ions still remains poorly understood. The ionic hydrophilicity/hydrophobicity effects not only can be applied to make strong polyelectrolytes thermosensitive, but also can be used to prepare polymeric nano-objects and to control the wettability of polyelectrolyte brush-modified surfaces. The not well-studied ionic hydrogen bond effects are also discussed in the last section of this review.
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Affiliation(s)
- Haiyang Yuan
- Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Department of Chemical Physics, University of Science and Technology of China, No. 96, Jinzhai Road, Hefei 230026, P. R. China.
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21
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Ehtiati K, Moghaddam SZ, Daugaard AE, Thormann E. How Dissociation of Carboxylic Acid Groups in a Weak Polyelectrolyte Brush Depend on Their Distance from the Substrate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:2339-2348. [PMID: 32069409 DOI: 10.1021/acs.langmuir.9b03537] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A weak polyelectrolyte brush is composed of a layer of polyacids or polybases grafted by one end of their chains to a substrate surface. For such brush layers immersed in an aqueous solution, the dissociation behavior of the acidic or basic groups and the structural and physical properties of the brush layer will thus be strongly dependent on the environmental conditions. For a polyacid brush layer consisting of, e.g., poly(acrylic acid), this means that the chains in the brush layer will be charged at high pH and uncharged at low pH. However, theoretical scaling laws not only foresee the structural changes occurring in response to the pH-induced dissociation behavior but also how the dissociation behavior of the brush layer depends on the ionic strength of the aqueous solution and the density of acidic groups within the brush layer. We have herein employed spectroscopic ellipsometry and a quartz crystal microbalance with dissipation monitoring (QCM-D) to experimentally evaluate the theoretically predicted dissociation and structural behavior of PAA brushes. Spectroscopic ellipsometry allows us to study the brush thickness as a function of pH and ionic strength, while QCM-D gives us an opportunity to investigate the swelling behavior of PAA brushes at various penetration depths of propagating acoustic waves. Our studies show that the dissociation degree of the carboxylic acid groups in a PAA brush increases with increasing distance from the substrate. Moreover, the ionic strength enhances carboxylic acid dissociation, such that a higher ionic strength leads to a narrower distribution and higher average dissociation degree. In conclusion, our results provide an experimental verification of the theoretically predicted gradient in the degree of dissociation of the acid groups in weak polyacid brush layers and shows that at a pH value equal to approximately the average pKa value of the brush, the state of the acid groups varies from being almost uncharged to almost fully dissociated depending on the ionic strength and vertical position in the brush.
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Affiliation(s)
- Koosha Ehtiati
- Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Saeed Z Moghaddam
- Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Anders E Daugaard
- Danish Polymer Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Esben Thormann
- Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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Clegg JR, Wagner AM, Shin SR, Hassan S, Khademhosseini A, Peppas NA. Modular Fabrication of Intelligent Material-Tissue Interfaces for Bioinspired and Biomimetic Devices. PROGRESS IN MATERIALS SCIENCE 2019; 106:100589. [PMID: 32189815 PMCID: PMC7079701 DOI: 10.1016/j.pmatsci.2019.100589] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
One of the goals of biomaterials science is to reverse engineer aspects of human and nonhuman physiology. Similar to the body's regulatory mechanisms, such devices must transduce changes in the physiological environment or the presence of an external stimulus into a detectable or therapeutic response. This review is a comprehensive evaluation and critical analysis of the design and fabrication of environmentally responsive cell-material constructs for bioinspired machinery and biomimetic devices. In a bottom-up analysis, we begin by reviewing fundamental principles that explain materials' responses to chemical gradients, biomarkers, electromagnetic fields, light, and temperature. Strategies for fabricating highly ordered assemblies of material components at the nano to macro-scales via directed assembly, lithography, 3D printing and 4D printing are also presented. We conclude with an account of contemporary material-tissue interfaces within bioinspired and biomimetic devices for peptide delivery, cancer theranostics, biomonitoring, neuroprosthetics, soft robotics, and biological machines.
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Affiliation(s)
- John R Clegg
- Department of Biomedical Engineering, the University of Texas at Austin, Austin, Texas, USA
| | - Angela M Wagner
- McKetta Department of Chemical Engineering, the University of Texas at Austin, Austin, Texas, USA
| | - Su Ryon Shin
- Division of Engineering in Medicine, Department of Medicine, Brigham Women's Hospital, Harvard Medical School, Cambridge, Massachusetts, USA
| | - Shabir Hassan
- Division of Engineering in Medicine, Department of Medicine, Brigham Women's Hospital, Harvard Medical School, Cambridge, Massachusetts, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ali Khademhosseini
- Center for Minimally Invasive Therapeutics (C-MIT), University of California - Los Angeles, Los Angeles, California, USA
- California NanoSystems Institute (CNSI), University of California - Los Angeles, Los Angeles, California, USA
- Department of Bioengineering, University of California - Los Angeles, Los Angeles, California, USA
- Department of Bioindustrial Technologies, College of Animal Bioscience and Technology, Konkuk University, Seoul, Republic of Korea
| | - Nicholas A Peppas
- Department of Biomedical Engineering, the University of Texas at Austin, Austin, Texas, USA
- McKetta Department of Chemical Engineering, the University of Texas at Austin, Austin, Texas, USA
- Institute for Biomaterials, Drug Delivery, and Regenerative Medicine, the University of Texas at Austin, Austin, Texas, USA
- Department of Surgery and Perioperative Care, Dell Medical School, the University of Texas at Austin, Austin, Texas, USA
- Department of Pediatrics, Dell Medical School, the University of Texas at Austin, Austin, Texas, USA
- Division of Molecular Pharmaceutics and Drug Delivery, College of Pharmacy, the University of Texas at Austin, Austin, Texas, USA
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23
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Tanc B, Orakdogen N. A phenomenological approach for structure-property relationship of polybasic cryogels based on n-alkyl methacrylate esters: Anion-specific effect on swelling kinetics and elasticity. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.02.065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Liu G. Tuning the Properties of Charged Polymers at the Solid/Liquid Interface with Ions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:3232-3247. [PMID: 29806944 DOI: 10.1021/acs.langmuir.8b01158] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In conventional theories, where ions are treated as point charges, the properties of charged polymers can be tuned using ions via the ionic strength. However, this article will show that the properties of charged polymers at the solid/liquid interface, including charged polymer brushes and polyelectrolyte multilayers, can be tuned by ions beyond ionic strength effects. Ion specificity, multivalency, ionic hydrogen bonding, and ionic hydrophobicity/hydrophilicity are used to tune a range of properties of charged polymers at the solid/liquid interface such as hydration, conformation, stiffness, surface wettability, lubricity, adhesion, and protein adsorption. The ionic effects demonstrated here greatly broaden our understanding of the use of ions to tune the interfacial properties of charged polymers. It is anticipated that these ionic effects can be further expanded by incorporating new types of important ion-charged polymer interactions and can also be extended to neutral polymer systems.
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Affiliation(s)
- Guangming Liu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics , University of Science and Technology of China , Hefei , P. R. China 230026
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25
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Pomorska A, Wolski K, Wytrwal-Sarna M, Bernasik A, Zapotoczny S. Polymer brushes grafted from nanostructured zinc oxide layers – Spatially controlled decoration of nanorods. Eur Polym J 2019. [DOI: 10.1016/j.eurpolymj.2019.01.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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26
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Willott JD, Humphreys BA, Webber GB, Wanless EJ, de Vos WM. Combined Experimental and Theoretical Study of Weak Polyelectrolyte Brushes in Salt Mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2709-2718. [PMID: 30661354 PMCID: PMC6407915 DOI: 10.1021/acs.langmuir.8b03838] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/07/2019] [Indexed: 05/30/2023]
Abstract
The swelling behavior of a hydrophobic poly(2diisopropylamino)ethyl methacrylate (PDPA) brush immersed in aqueous solutions of single and mixed salts has been investigated using ellipsometry and numerical self-consistent field (nSCF) theory. As a function of solution ionic strength, the osmotic and salted brush regimes of weak polyelectrolyte brushes as well as substantial specific anion effects in the presence of K+ salts of Cl-, NO3-, and SCN- are found. For solutions containing mixtures of NO3- and Cl-, the brush swelling is the same as one would expect on the basis of the concentration-weighted average of the brush behavior in the single salt solutions. However, in mixtures of SCN- and Cl-, the swelling response is more complicated and substantial divergence from ideal behavior is observed. Mean-field theory shows excellent qualitative agreement with the ellipsometry findings. nSCF reveals that for the SCN-/Cl- cases the swelling behavior of the PDPA brush most likely arises from the predominant localization of the weakly hydrated SCN- within the brush compared to the more strongly hydrated Cl-.
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Affiliation(s)
- Joshua D. Willott
- Membrane
Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Ben A. Humphreys
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Grant B. Webber
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Erica J. Wanless
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Wiebe M. de Vos
- Membrane
Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
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27
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Sachar HS, Sivasankar VS, Das S. Revisiting the strong stretching theory for pH-responsive polyelectrolyte brushes: effects of consideration of excluded volume interactions and an expanded form of the mass action law. SOFT MATTER 2019; 15:559-574. [PMID: 30520929 DOI: 10.1039/c8sm02163e] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this paper, we develop a theory to account for the effect of excluded volume (EV) interactions in the strong stretching theory (SST) based description of pH-responsive polyelectrolyte (PE) brushes. The existing studies have considered the PE brushes to be present in a θ-solvent and hence have neglected the EV interactions; however, such a consideration cannot describe the situations where the pH-responsive brushes are in a "good" solvent. Secondly, we consider a more expanded form of the mass action law, governing the pH-dependent ionization of the PE molecules, in the SST description of the PE brushes. This expanded form of the mass action law considers different values of γa3 (γ is the density of chargeable sites on the PE molecule and a is the PE Kuhn length) and therefore is an improvement over the existing SST models of PE brushes as well as other theories involving pH-responsive PE molecules that always consider γa3 = 1. Our results demonstrate that the EV effects enhance the brush height by inducing additional PE inter-segmental repulsion. Similarly, the consideration of the expanded form of the mass action law would lead to a reduced (enhanced) brush height for γa3 < 1 (γa3 > 1). We also quantify variables such as the monomer density distribution, the distribution of the ends of the PE brush, and the EDL electrostatic potential and explain their differences with respect to those obtained with no EV interactions or γa3 = 1.
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Affiliation(s)
- Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, College Park, MD-20742, USA.
| | | | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, MD-20742, USA.
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Johnson EC, Murdoch TJ, Gresham IJ, Humphreys BA, Prescott SW, Nelson A, Webber GB, Wanless EJ. Temperature dependent specific ion effects in mixed salt environments on a thermoresponsive poly(oligoethylene glycol methacrylate) brush. Phys Chem Chem Phys 2019; 21:4650-4662. [DOI: 10.1039/c8cp06644b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The temperature induced swelling/collapse transition of poly(oligoethylene glycol methacrylate) (POEGMA) brushes has been investigated in electrolyte solutions comprised of multiple anions.
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Affiliation(s)
- Edwin C. Johnson
- Priority Research Centre for Advanced Particle Processing and Transport
- University of Newcastle
- Callaghan
- Australia
| | - Timothy J. Murdoch
- Priority Research Centre for Advanced Particle Processing and Transport
- University of Newcastle
- Callaghan
- Australia
| | | | - Ben A. Humphreys
- Priority Research Centre for Advanced Particle Processing and Transport
- University of Newcastle
- Callaghan
- Australia
| | | | | | - Grant B. Webber
- Priority Research Centre for Advanced Particle Processing and Transport
- University of Newcastle
- Callaghan
- Australia
| | - Erica J. Wanless
- Priority Research Centre for Advanced Particle Processing and Transport
- University of Newcastle
- Callaghan
- Australia
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29
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Zhang J, Cai H, Tang L, Liu G. Tuning the pH Response of Weak Polyelectrolyte Brushes with Specific Anion Effects. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:12419-12427. [PMID: 30220208 DOI: 10.1021/acs.langmuir.8b02776] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The positively charged poly( N, N'-dimethylaminoethyl methacrylate) (PDMAEMA) brushes have been employed as model weak polyelectrolyte brushes (WPBs) to demonstrate the tuning of the pH response of WPBs with specific anion effects. The charge density of PDMAEMA brushes can be modulated by specific ion-pairing interactions between counterions and the protonated dimethylamino group; as a result, the strength of the pH response of PDMAEMA brushes can be tuned by specific anion effects. A more chaotropic counterion can more strongly interact with the protonated dimethylamino group, thereby more effectively neutralizing the positively charged group associated with the grafted weak polyelectrolyte chains and more remarkably suppressing the pH response of PDMAEMA brushes. Although the pH response of PDMAEMA brushes is insensitive to the anion identity at a low salt concentration, it can be tuned by specific anion effects at relatively high salt concentrations. Our study demonstrates that the pH-responsive properties of PDMAEMA brushes including hydration, conformation, oil wettability, and adhesion can be tuned by specific anion effects. The work presented here provides a method to tune the pH response of WPBs by the anion identity.
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Affiliation(s)
- Jian Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics , University of Science and Technology of China , Hefei 230026 , P. R. China
| | - Hongtao Cai
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics , University of Science and Technology of China , Hefei 230026 , P. R. China
| | - Ling Tang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics , University of Science and Technology of China , Hefei 230026 , P. R. China
| | - Guangming Liu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics , University of Science and Technology of China , Hefei 230026 , P. R. China
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Murdoch TJ, Humphreys BA, Johnson EC, Webber GB, Wanless EJ. Specific ion effects on thermoresponsive polymer brushes: Comparison to other architectures. J Colloid Interface Sci 2018; 526:429-450. [DOI: 10.1016/j.jcis.2018.04.086] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/20/2018] [Accepted: 04/23/2018] [Indexed: 02/06/2023]
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31
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Zhu R, Baraniak MK, Jäkle F, Liu G. Anion Specificity in Dimethyl Sulfoxide-Water Mixtures Exemplified by a Thermosensitive Polymer. J Phys Chem B 2018; 122:8293-8300. [PMID: 30086631 DOI: 10.1021/acs.jpcb.8b06125] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In the present work, we have investigated the anion-specific upper critical solution temperature (UCST) behavior of polymer-supported borinic acid (PBA) in dimethyl sulfoxide-water (DMSO-H2O) mixtures. An inverted V-shaped series CH3COO- < Cl- < salt-free > NO3- > ClO4- > SCN- is observed in terms of the anion-specific UCST of PBA in the DMSO-H2O mixtures. Both direct anion-polymer interactions and indirect solvent-mediated anion-polymer interactions are involved in the specific anion effect on the UCST behavior of PBA. The direct binding of anions to the PBA surface generates a salting-in effect on PBA, causing the UCST for the different types of anions to increase from chaotropic to kosmotropic anions due to the stronger binding of the more chaotropic anions. On the other hand, the indirect anionic polarization of hydrogen bonding between PBA and DMSO molecules also produces a salting-in effect on PBA, leading the UCST for the different types of anions to increase from kosmotropic to chaotropic anions because of the stronger capability of the more kosmotropic anions to polarize the hydrogen bonding. Thus, the dominating anion-PBA interactions change from the direct anion binding to the indirect anionic polarization of hydrogen bonding as the anions change from chaotropes to kosmotropes. The observed inverted V-shaped series suggests that the specific anion effect on the UCST behavior of PBA in the DMSO-H2O mixtures is determined by the combined effects of the binding of anions to the PBA surface and the anionic polarization of hydrogen bonding between PBA and DMSO molecules.
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Affiliation(s)
- Renwei Zhu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics , University of Science and Technology of China , Hefei , P. R. China 230026
| | - Monika K Baraniak
- Department of Chemistry , Rutgers University-Newark , 73 Warren Street , Newark , New Jersey 07102 , United States
| | - Frieder Jäkle
- Department of Chemistry , Rutgers University-Newark , 73 Warren Street , Newark , New Jersey 07102 , United States
| | - Guangming Liu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics , University of Science and Technology of China , Hefei , P. R. China 230026
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32
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Ramirez R, Woodcock J, Kilbey SM. ARGET-ATRP synthesis and swelling response of compositionally varied poly(methacrylic acid-co-N,N-diethylaminoethyl methacrylate) polyampholyte brushes. SOFT MATTER 2018; 14:6290-6302. [PMID: 30014055 DOI: 10.1039/c8sm00882e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Modifying the composition of polyampholytes, which are comprised of charge-positive and charge-negative repeat units, directly contributes to trade-offs between charge and structure, which are externally regulated by solution pH and added salt. Here, the relative ratio of anionic and cationic comonomers is varied to tailor the stimuli-responsiveness of poly(methacrylic acid-co-N,N-diethylaminoethyl methacrylate) (P(MAA-co-DEAEMA)) brushes to changes in solution pH and an added zwitterion. These systems display a strong dependence on excess repeating units of either type and the random incorporation appears to facilitate self-neutralization of charges. Pseudo-living growth with smooth comonomer incorporation is achieved using activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP), creating well-defined brushes. In situ ellipsometry measurements of solvated brush thickness indicate that at low and high pH, the brushes display polyelectrolyte behavior with a strong compositional dependence, but at intermediate pH values, the brushes show the characteristic collapse attributed to self-neutralization of polyampholytes. The polyampholyte brushes maintain these patterns of behavior across all compositions and in the presence of an added zwitterion, which contributes additional hydrophobic character as evidenced by decreases in the swollen layer thicknesses. The response of the P(MAA-co-DEAEMA) brushes to the organic osmolyte betaine is consistent with its tendency to stabilize proteins and peptides in a kosmotropic fashion. These studies add perspective to efforts to manipulate sequence in polyampholytic polymers, support broader efforts to tailor interfacial soft films for applications in biotechnology and sensing, and understand aggregation and stability of biological polymers.
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Affiliation(s)
- Rachel Ramirez
- Department of Chemistry, University of Tennessee Knoxville, Tennessee 37996, USA.
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33
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Zhao B, Yuan G, Chu X, Yang J, Zhao J. Response of a Permanently Charged Polyelectrolyte Brush to External Ions: The Aspects of Structure and Dynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6757-6765. [PMID: 29781623 DOI: 10.1021/acs.langmuir.8b01195] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Structure and dynamics inside permanently charged polyelectrolyte brushes, sodium polystyrene sulfonate brushes, during their response to the introduction of external ions (NaCl) are investigated by neutron reflectivity and dielectric spectroscopy. Neutron reflectivity measurements show that the segmental density of the inner part of the brushes decreases and that of the outer part increases when the salt level is tuned from the salt-free condition to a moderate level (<10-2 M)-the brushes swell further compared with the salt-free condition. This is attributed to the breakup of the multiplets formed by dipole-dipole pairs, and by this process, the previously constrained chain segments by the multiplets are released. Dielectric spectroscopy discovers a giant dipole by the charge separation of the adsorbed counterions and the PSS- chains, induced by electric field. The dynamics of the induced giant dipole is accelerated with the increase of external salt, as a result of the charge regularization by elevated salt level. At high-enough salt level, the screening effect reduces the electrostatic repulsion between the neighboring chains and makes the brushes shrink.
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Affiliation(s)
- Bintao Zhao
- Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Guangcui Yuan
- Center for Neutron Research , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Xiao Chu
- Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China
| | - Jingfa Yang
- Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China
| | - Jiang Zhao
- Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China
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34
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Kou R, Zhang J, Chen Z, Liu G. Counterion Specificity of Polyelectrolyte Brushes: Role of Specific Ion-Pairing Interactions. Chemphyschem 2018; 19:1404-1413. [PMID: 29575481 DOI: 10.1002/cphc.201701256] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Indexed: 11/10/2022]
Abstract
We demonstrate here that the properties of poly (2-(methacryloyloxy) ethyl trimethylammonium chloride) brushes can be tuned by counterion species. When the brushes are exposed to external chloride (Cl- ) counterions, obvious dehydration and collapse are only observed at high salt concentrations. In the presence of very strongly chaotropic perchlorate (ClO4- ), the brushes strongly dehydrate and collapse at a very low salt concentration. For the strongly chaotropic thiocyanate ion (SCN- ), the changes in hydration and conformation of the brushes are similar to those observed for ClO4- but at a smaller extent at very low salt concentrations. With the addition of kosmotropic acetate (Ac- ), hydration of the brushes increases, accompanied by a swelling of the brushes in the low-salt-concentration regime. In contrast, the brushes dehydrate and collapse with increasing concentration of Ac- in the high-salt-concentration regime. The counterion specificity of the brushes demonstrated here is determined by specific ion-pairing interactions through modulating the osmotic pressure within the brushes and the hydrophobicity of the ion pairs.
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Affiliation(s)
- Ran Kou
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Jian Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Zhen Chen
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Guangming Liu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, 230026, P. R. China
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35
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Higaki Y, Inutsuka Y, Ono H, Yamada NL, Ikemoto Y, Takahara A. Counteranion-Specific Hydration States of Cationic Polyelectrolyte Brushes. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b00210] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Yuji Higaki
- Japan Science
and Technology Agency (JST), ERATO, Takahara Soft Interfaces Project, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | | | | | - Norifumi L. Yamada
- Neutron Science Laboratory, High Energy Accelerator Research Organization, Ibaraki 319-1106, Japan
| | - Yuka Ikemoto
- Japan Synchrotron Radiation
Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho,
Sayo-gun, Hyogo 679-5198, Japan
| | - Atsushi Takahara
- Japan Science
and Technology Agency (JST), ERATO, Takahara Soft Interfaces Project, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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36
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Effect of ionic strength and salt identity on poly(N-isopropylacrylamide) brush modified colloidal silica particles. J Colloid Interface Sci 2018; 516:153-161. [PMID: 29367066 DOI: 10.1016/j.jcis.2018.01.058] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/14/2018] [Accepted: 01/15/2018] [Indexed: 11/23/2022]
Abstract
HYPOTHESIS The thermoresponse of poly(N-isopropylacrylamide) stabilised particles is influenced by the presence of salt and is dependent on the concentration, and ions present. The conformation and electrophoretic mobility of core/shell PNIPAM brush modified silica particles is expected to vary as a function of these specific ion effects. EXPERIMENTS The thermoresponse of PNIPAM brush modified silica particles was investigated via dynamic light scattering and electrophoretic mobility measurements between 5 and 45 °C in the presence of 11 different salt solutions. FINDINGS Specific ion effects were observed in the presence of salt solutions for concentrations between 50 and 1000 mM. The temperature response could be mapped to a master curve unlike PNIPAM brush behaviour on planar substrates. The magnitude of brush layer lower critical solution temperature reduction was found to follow the order F- > CH3CO2- > Cl- > NO3- ∼ Br- > I- > SCN- for the potassium series and Na+ > K+ > Cs+ > Li+ ∼ NH4+ for the chloride salts. The electrophoretic mobility of the modified particles in the presence of 100 mM potassium salts increased in magnitude as the brush layer collapsed and also with the chaotropic nature of the anion.
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37
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Willott JD, Murdoch TJ, Leermakers FAM, de Vos WM. Behavior of Weak Polyelectrolyte Brushes in Mixed Salt Solutions. Macromolecules 2018; 51:1198-1206. [PMID: 29472729 PMCID: PMC5814957 DOI: 10.1021/acs.macromol.7b02244] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 12/22/2017] [Indexed: 12/25/2022]
Abstract
![]()
Hydrophilic
and hydrophobic weak polybasic brushes immersed in
aqueous solutions of mixed salt counterions are considered using a
mean-field numerical self-consistent field approach. On top of the
solvent quality of the polymer, the counterion–solvent interactions
are accounted for by implementing Flory–Huggins interaction
parameters. We show that ion specificity within the brush can bring
about large changes in conformation. It is found that the collapse
transition of hydrophobic, weak polyelectrolyte brushes features an
intermediate two-phase state wherein a subset of chains are collapsed
in a dense layer at the substrate, while the remainder of chains are
well-solvated and strongly stretched away from the it. Besides pH
and ionic strength, solvent quality of counterions and the composition
of ions in the solvent are important control parameters for the behavior
of polyelectrolyte brushes. Increasingly hydrophobic counterions penetrate
deeper within the brush and stabilize the collapsed region, while
hydrophilic counterions do the opposite.
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Affiliation(s)
- Joshua D Willott
- Membrane Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Timothy J Murdoch
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Frans A M Leermakers
- Physical Chemistry and Soft Matter, Wageningen University and Research, Wageningen 6708 WE, The Netherlands
| | - Wiebe M de Vos
- Membrane Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, The Netherlands
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38
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Raftari M, Zhang ZJ, Carter SR, Leggett GJ, Geoghegan M. Salt Dependence of the Tribological Properties of a Surface-Grafted Weak Polycation in Aqueous Solution. TRIBOLOGY LETTERS 2017; 66:11. [PMID: 31983863 PMCID: PMC6951817 DOI: 10.1007/s11249-017-0963-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 11/23/2017] [Indexed: 06/10/2023]
Abstract
The nanoscopic adhesive and frictional behaviour of end-grafted poly[2-(dimethyl amino)ethyl methacrylate] (PDMAEMA) films (brushes) in contact with gold- or PDMAEMA-coated atomic force microscope tips in potassium halide solutions with different concentrations up to 300 mM is a strong function of salt concentration. The conformation of the polymers in the brush layer is sensitive to salt concentration, which leads to large changes in adhesive forces and the contact mechanics at the tip-sample contact, with swollen brushes (which occur at low salt concentrations) yielding large areas of contact and friction-load plots that fit JKR behaviour, while collapsed brushes (which occur at high salt concentrations) yield sliding dominated by ploughing, with conformations in between fitting DMT mechanics. The relative effect of the different anions follows the Hofmeister series, with I- collapsing the brushes more than Br- and Cl- for the same salt concentration.
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Affiliation(s)
- Maryam Raftari
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH UK
| | - Zhenyu J. Zhang
- Department of Chemistry, University of Sheffield, Sheffield, S3 7HF UK
- Present Address: School of Chemical Engineering, University of Birmingham, Birmingham, B15 2TT UK
| | - Steven R. Carter
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH UK
| | - Graham J. Leggett
- Department of Chemistry, University of Sheffield, Sheffield, S3 7HF UK
| | - Mark Geoghegan
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH UK
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39
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Sekido T, Kappl M, Butt HJ, Yusa S, Nakamura Y, Fujii S. Effects of pH on the structure and mechanical properties of dried pH-responsive latex particles. SOFT MATTER 2017; 13:7562-7570. [PMID: 28972614 DOI: 10.1039/c7sm01625e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Micrometer-sized monodisperse polystyrene (PS) particles carrying a pH-responsive poly[2-(diethylamino)ethyl methacrylate] (PDEA) colloidal stabilizer were synthesized via free radical dispersion polymerization. X-ray photoelectron spectroscopy and electrophoretic measurements verified that PDEA covered the PS particle surface. At pH 3.0 and 6.3, where the PDEA is protonated and cationically charged, the PDEA-PS particles were well dispersed in aqueous media thanks to the water soluble PDEA stabilizer and slowly sedimented due to gravity and enriched at the bottom of the glass vials. At pH 10.0, where the PDEA is non-protonated and neutral, the PDEA-PS particles weakly aggregated due to non-hydrated and collapsed PDEA. These PDEA-PS particles and aggregates sedimented to the bottom. The sediment height observed at pH 10.0 was higher than those observed at pH 3.0 and 6.3 in both wet and dry systems, which indicated that a larger porosity was formed at pH 10.0. Mechanical testing experiments confirmed that the fracture toughness of the dried materials decreased with an increase of pH. The fracture toughness was found to be correlated with the degree of particle ordering in the dried particulate materials: more ordered, dense packings lead to a higher fracture toughness compared to amorphous, less dense packings. Thus, we could tune fracture toughness and degree of particle ordering by controlling the pH.
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Affiliation(s)
- T Sekido
- Division of Applied Chemistry, Graduate School of Engineering, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka, 535-8585, Japan
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40
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Lee J, Moesari E, Dandamudi CB, Beniah G, Chang B, Iqbal M, Fei Y, Zhou N, Ellison CJ, Johnston KP. Behavior of Spherical Poly(2-acrylamido-2-methylpropanesulfonate) Polyelectrolyte Brushes on Silica Nanoparticles up to Extreme Salinity with Weak Divalent Cation Binding at Ambient and High Temperature. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b01243] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Joohyung Lee
- The
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Ehsan Moesari
- The
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Chola Bhargava Dandamudi
- The
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Goliath Beniah
- The
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Behzad Chang
- The
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Muhammad Iqbal
- Michelman Inc., 9080 Shell Rd, Cincinnati, Ohio 45040, United States
| | - Yunping Fei
- Intel Corporation, 9750
Goethe Rd, Sacramento, California 95827, United States
| | - Nijia Zhou
- The
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Christopher J. Ellison
- Department
of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Keith P. Johnston
- The
McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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41
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Murdoch TJ, Humphreys BA, Willott JD, Prescott SW, Nelson A, Webber GB, Wanless EJ. Enhanced specific ion effects in ethylene glycol-based thermoresponsive polymer brushes. J Colloid Interface Sci 2017; 490:869-878. [DOI: 10.1016/j.jcis.2016.11.044] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 11/14/2016] [Accepted: 11/14/2016] [Indexed: 12/26/2022]
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42
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Zoppe JO, Ataman NC, Mocny P, Wang J, Moraes J, Klok HA. Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes. Chem Rev 2017; 117:1105-1318. [PMID: 28135076 DOI: 10.1021/acs.chemrev.6b00314] [Citation(s) in RCA: 587] [Impact Index Per Article: 83.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.
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Affiliation(s)
- Justin O Zoppe
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères Bâtiment MXD, Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12 CH-1015 Lausanne, Switzerland
| | - Nariye Cavusoglu Ataman
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères Bâtiment MXD, Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12 CH-1015 Lausanne, Switzerland
| | - Piotr Mocny
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères Bâtiment MXD, Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12 CH-1015 Lausanne, Switzerland
| | - Jian Wang
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères Bâtiment MXD, Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12 CH-1015 Lausanne, Switzerland
| | - John Moraes
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères Bâtiment MXD, Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12 CH-1015 Lausanne, Switzerland
| | - Harm-Anton Klok
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères Bâtiment MXD, Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12 CH-1015 Lausanne, Switzerland
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43
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Willott JD, Murdoch TJ, Webber GB, Wanless EJ. Physicochemical behaviour of cationic polyelectrolyte brushes. Prog Polym Sci 2017. [DOI: 10.1016/j.progpolymsci.2016.09.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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44
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Murdoch TJ, Willott JD, de Vos WM, Nelson A, Prescott SW, Wanless EJ, Webber GB. Influence of Anion Hydrophilicity on the Conformation of a Hydrophobic Weak Polyelectrolyte Brush. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01897] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Timothy J. Murdoch
- Priority Research
Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Joshua D. Willott
- Priority Research
Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Wiebe M. de Vos
- Membrane Science
and Technology, Mesa+ Institute for Nanotechnology, University of Twente, Enschede 7500 AE, Netherlands
| | - Andrew Nelson
- Australian
Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Stuart W. Prescott
- School of Chemical Engineering, UNSW Australia, UNSW Sydney, NSW 2052, Australia
| | - Erica J. Wanless
- Priority Research
Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Grant B. Webber
- Priority Research
Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
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45
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Murdoch TJ, Humphreys BA, Willott JD, Gregory KP, Prescott SW, Nelson A, Wanless EJ, Webber GB. Specific Anion Effects on the Internal Structure of a Poly(N-isopropylacrylamide) Brush. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Timothy J. Murdoch
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Ben A. Humphreys
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Joshua D. Willott
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Kasimir P. Gregory
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Stuart W. Prescott
- School
of Chemical Engineering, UNSW Australia, UNSW Sydney, NSW 2052, Australia
| | - Andrew Nelson
- Australian Nuclear
Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Erica J. Wanless
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Grant B. Webber
- Priority
Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
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46
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Humphreys BA, Willott JD, Murdoch TJ, Webber GB, Wanless EJ. Specific ion modulated thermoresponse of poly(N-isopropylacrylamide) brushes. Phys Chem Chem Phys 2016; 18:6037-46. [PMID: 26840183 DOI: 10.1039/c5cp07468a] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The influence of specific anions on the equilibrium thermoresponse of poly(N-isopropylacrylamide) (pNIPAM) brushes has been studied using in situ ellipsometry, quartz crystal microbalance with dissipation (QCM-D) and static contact angle measurements between 20 and 45 °C in the presence of up to 250 mM acetate and thiocyanate anions in water. The thickness and changes in dissipation exhibited a broad swelling transition spanning approximately 15 °C from collapsed (high temperatures) to swollen conformation (low temperatures) while the brush surface wettability changed over approximately 2 °C. In the presence of the kosmotropic acetate anions, the measured lower critical solution temperature (LCST) by the three techniques was very similar and decreased linearly as a function of ionic strength. Conversely, increasing the concentration of the chaotropic thiocyanate anions raised the LCST of the pNIPAM brushes with variation in the measured LCST between the three techniques increasing with ionic strength. The thickness of the pNIPAM brush was seen to progressively increase with increasing thiocyanate concentration at all temperatures. It is proposed that specific ion binding of the chaotropic thiocyanate anion with pNIPAM amide moieties increases the electrostatic intra- and intermolecular repulsion within and between pNIPAM chains. This allows the brush to begin to swell at higher temperatures and to an overall greater extent.
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Affiliation(s)
- Ben A Humphreys
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia.
| | - Joshua D Willott
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia.
| | - Timothy J Murdoch
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia.
| | - Grant B Webber
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia.
| | - Erica J Wanless
- Priority Research Centre for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia.
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47
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Abbott SB, de Vos WM, Mears LLE, Skoda M, Dalgliesh R, Edmondson S, Richardson RM, Prescott SW. Switching the Interpenetration of Confined Asymmetric Polymer Brushes. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00310] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Stephen B. Abbott
- School
of Physics, University of Bristol, Bristol BS8 1TL, U.K
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | - Wiebe M. de Vos
- Membrane
Science and Technology, Mesa+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands
| | | | - Maximilian Skoda
- ISIS Facility, Rutherford-Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, U.K
| | - Robert Dalgliesh
- ISIS Facility, Rutherford-Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, U.K
| | - Steve Edmondson
- School
of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
| | | | - Stuart W. Prescott
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
- School
of Chemical Engineering, UNSW Australia, Sydney NSW 2052, Australia
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48
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van der Vegt NFA, Haldrup K, Roke S, Zheng J, Lund M, Bakker HJ. Water-Mediated Ion Pairing: Occurrence and Relevance. Chem Rev 2016; 116:7626-41. [DOI: 10.1021/acs.chemrev.5b00742] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nico F. A. van der Vegt
- Eduard-Zintl-Institut
für Anorganische und Physikalische Chemie and Center of Smart
Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Strasse
10, 64287 Darmstadt, Germany
| | - Kristoffer Haldrup
- Physics
Department, NEXMAP Section, Technical University of Denmark, Fysikvej
307, 2800 Kongens
Lyngby, Denmark
| | - Sylvie Roke
- Laboratory
for Fundamental BioPhotonics, Institute of Bioengineering, and Institute
of Materials Science, School of Engineering, and Lausanne Centre for
Ultrafast Science, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Junrong Zheng
- College
of Chemistry and Molecular Engineering, Beijing National Laboratory
for Molecular Sciences, Peking University, Beijing 100871, China
- Department
of Chemistry, Rice University, 6100 Main Street, Houston, Texas 77005-1892, United States
| | - Mikael Lund
- Division
of Theoretical Chemistry, Department of Chemistry, Lund University, SE-22100 Lund, Sweden
| | - Huib J. Bakker
- FOM Institute AMOLF, Science
Park 104, 1098 XG Amsterdam, The Netherlands
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49
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Willott JD, Murdoch TJ, Webber GB, Wanless EJ. Nature of the Specific Anion Response of a Hydrophobic Weak Polyelectrolyte Brush Revealed by AFM Force Measurements. Macromolecules 2016. [DOI: 10.1021/acs.macromol.5b02656] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Joshua D. Willott
- Priority
Research Centre
for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Timothy J. Murdoch
- Priority
Research Centre
for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Grant B. Webber
- Priority
Research Centre
for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Erica J. Wanless
- Priority
Research Centre
for Advanced Particle Processing and Transport, University of Newcastle, Callaghan, NSW 2308, Australia
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50
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Thomas M, Gajda M, Amiri Naini C, Franzka S, Ulbricht M, Hartmann N. Poly(N,N-dimethylaminoethyl methacrylate) Brushes: pH-Dependent Switching Kinetics of a Surface-Grafted Thermoresponsive Polyelectrolyte. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:13426-13432. [PMID: 26569145 DOI: 10.1021/acs.langmuir.5b03448] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The temperature-dependent switching behavior of poly(N,N-dimethylaminoethyl methacrylate) brushes in alkaline, neutral, and acidic solutions is examined. A novel microscopic laser temperature-jump technique is employed in order to study characteristic thermodynamic and kinetic parameters. Static laser micromanipulation experiments allow one to determine the temperature-dependent variation of the swelling ratio. The data reveal a strong shift of the volume phase transition of the polymer brushes to higher temperatures when going from pH = 10 to pH = 4. Dynamic laser micromanipulation experiments offer a temporal resolution on a submillisecond time scale and provide a means to determine the intrinsic rate constants. Both the swelling and the deswelling rates strongly decrease in acidic solutions. Complementary experiments using in situ atomic force microscopy show an increased polymer layer thickness at these conditions. The data are discussed on the basis of pH-dependent structural changes of the polymer brushes including protonation of the amine groups and conformational rearrangements. Generally, repulsive electrostatic interactions and steric effects are assumed to hamper and slow down temperature-induced switching in acidic solutions. This imposes significant restrictions for smart polymer surfaces, sensors, and devices requiring fast response times.
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Affiliation(s)
- Marc Thomas
- Physical Chemistry, Department of Chemistry, and ‡Technical Chemistry II, Department of Chemistry, University of Duisburg-Essen , 45117, Essen, Germany
- Center for Nanointegration Duisburg-Essen (CENIDE) and ∥Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen , 47057 Duisburg, Germany
| | - Martyna Gajda
- Physical Chemistry, Department of Chemistry, and ‡Technical Chemistry II, Department of Chemistry, University of Duisburg-Essen , 45117, Essen, Germany
- Center for Nanointegration Duisburg-Essen (CENIDE) and ∥Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen , 47057 Duisburg, Germany
| | - Crispin Amiri Naini
- Physical Chemistry, Department of Chemistry, and ‡Technical Chemistry II, Department of Chemistry, University of Duisburg-Essen , 45117, Essen, Germany
- Center for Nanointegration Duisburg-Essen (CENIDE) and ∥Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen , 47057 Duisburg, Germany
| | - Steffen Franzka
- Physical Chemistry, Department of Chemistry, and ‡Technical Chemistry II, Department of Chemistry, University of Duisburg-Essen , 45117, Essen, Germany
- Center for Nanointegration Duisburg-Essen (CENIDE) and ∥Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen , 47057 Duisburg, Germany
| | - Mathias Ulbricht
- Physical Chemistry, Department of Chemistry, and ‡Technical Chemistry II, Department of Chemistry, University of Duisburg-Essen , 45117, Essen, Germany
- Center for Nanointegration Duisburg-Essen (CENIDE) and ∥Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen , 47057 Duisburg, Germany
| | - Nils Hartmann
- Physical Chemistry, Department of Chemistry, and ‡Technical Chemistry II, Department of Chemistry, University of Duisburg-Essen , 45117, Essen, Germany
- Center for Nanointegration Duisburg-Essen (CENIDE) and ∥Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen , 47057 Duisburg, Germany
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