1
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Wang F, Liu X, Yang W, Chen Y, Liu L. Responses of assembled structures of block polyelectrolytes to electrostatic interaction strength. J Chem Phys 2024; 160:144903. [PMID: 38591688 DOI: 10.1063/5.0194617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Accepted: 03/19/2024] [Indexed: 04/10/2024] Open
Abstract
In this paper, the responses of assembled behaviors of block polyelectrolytes (PEs) to the strength of electrostatic interactions are studied through molecular dynamic simulations. The results show that the assembled structures closely depend on the electrostatic strength. It should be noted that PE coacervation can outweigh the nucleation of hydrophobic blocks and invert the micelle structures at strong electrostatic strengths, leading to the formation of inverted micelles of PE cores and hydrophobic coronas. In the poor solvent condition for neutral block, diverse anisotropic micelles are presented; candy-like conventional micelles of hydrophobic cores and PE patches coexist with inverted candy-like micelles of PE cores and hydrophobic patches and with Janus micelles of semi-neutral aggregate and semi-PE cluster in the presence of divalent and trivalent counterions. The formation of conventional or inverted micelle is largely determined by the type of micellar fusion, which results from the nucleation competition between electrostatic correlation and hydrophobic interaction. The merge of micelles mediated by hydrophobic attraction leads to conventional hydrophobic cores, and the fusion induced by electrostatic correlations results in PE cores micelles. At strong electrostatic strengths, the PE chains exhibit rich conformations at trivalent counterions, ranging from a fully collapsed state to a rod-like state, and parallel alignment of PE chains is found.
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Affiliation(s)
- Fujia Wang
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Xinyi Liu
- School of Biomedical Engineering and Technology, Tianjin Medical University, Tianjin 300070, China
| | - Wei Yang
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Yao Chen
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Liyan Liu
- College of Science, Civil Aviation University of China, Tianjin 300300, China
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2
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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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3
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Smook LA, de Beer S. Electrostatic Fields Stimulate Absorption of Small Neutral Molecules in Gradient Polyelectrolyte Brushes. Chemphyschem 2023; 24:e202300003. [PMID: 36811215 DOI: 10.1002/cphc.202300003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 01/27/2023] [Indexed: 02/24/2023]
Abstract
Molecules can partition from a solution into a polymer coating, leading to a local enrichment. If one can control this enrichment via external stimuli, one can implement such coatings in novel separation technologies. Unfortunately, these coatings are often resource intensive as they require stimuli in the form changes of bulk solvent conditions such as acidity, temperature, or ionic strength. Electrically driven separation technology may provide an appealing alternative, as this will allow local, surface-bound stimuli instead of system-wide bulk stimuli to induce responsiveness. Therefore, we investigate via coarse grained molecular dynamics simulations the possibility of using coatings with charged moieties, specifically gradient polyelectrolyte brushes, to control the enrichment of the neutral target molecules near the surface with applied electric fields. We find that targets which interact more strongly with the brush show both more absorption and a larger modulation by electric fields. For the strongest interactions evaluated in this work, we obtained absorption changes of over 300 % between the collapsed and extended state of the coating.
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Affiliation(s)
- Leon A Smook
- Sustainable Polymer Chemistry, Department of Molecules and Materials, MESA+ Institute for Nanotechnology, University of Twente, The Netherlands
| | - Sissi de Beer
- Sustainable Polymer Chemistry, Department of Molecules and Materials, MESA+ Institute for Nanotechnology, University of Twente, The Netherlands
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4
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Carrillo JMY, Chen Z, Premadasa UI, Steinmetz C, Coughlin EB, Doughty B, Russell TP, Sumpter BG. Assembly of polyelectrolyte star block copolymers at the oil-water interface. NANOSCALE 2023; 15:1042-1052. [PMID: 36421060 DOI: 10.1039/d2nr05113c] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
To understand and resolve adsorption, reconfiguration, and equilibrium conformations of charged star copolymers, we carried out an integrated experimental and coarse-grained molecular dynamics simulation study of the assembly process at the oil-water interface. This is important to guide development of novel surfactants or amphiphiles for chemical transformations and separations. The star block copolymer consisted of arms that are comprised of hydrophilic-hydrophobic block copolymers that are covalently tethered via the hydrophobic blocks to one point. The hydrophobic core represents polystyrene (PS) chains, while the hydrophilic corona represents quaternized poly(2-vinylpyridine) (P2VP) chains. The P2VP is modeled to become protonated when in contact with an acidic aqueous phase, thereby massively increasing the hydrophilicity of this block, and changing the nature of the star at the oil-water interface. This results in a configurational change whereby the chains comprising the hydrophilic corona are significantly stretched into the aqueous phase, while the hydrophobic core remains solubilized in the oil phase. In the simulations, we followed the kinetics of the anchoring and assembly of the star block copolymer at the interface, monitoring the lateral assembly, and the subsequent reconfiguration of the star via changes in the interfacial tension that varies as the degree-of-protonation increases. At low fractions of protonation, the arm cannot fully partition into the aqueous side of the interface and instead interacts with other arms in the oil phase forming a network near the interface. These insights were used to interpret the non-monotonic dependence of pH with the asymptotic interfacial tension from pendant drop tensiometry experiments and spectral signatures of aromatic stretches seen in vibrational sum frequency generation (SFG) spectroscopy. We describe the relationship of interfacial tension to the star assembly via the Frumkin isotherm, which phenomenologically describes anti-cooperativity in adsorbing stars to the interface due to crowding. Although our model explicitly considers long-range electrostatics, the contribution of electrostatics to interfacial tension is small and brought about by strong counterion condensation at the interface. These results provide key insights into resolving the adsorption, reconfiguration, and equilibrium conformations of charged star block copolymers as surfactants.
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Affiliation(s)
- Jan-Michael Y Carrillo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | - Zhan Chen
- Polymer Science and Engineering Department, Conte Center for Polymer Research, University of Massachusetts, Amherst, MA 01003, USA.
| | - Uvinduni I Premadasa
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | - Christian Steinmetz
- Polymer Science and Engineering Department, Conte Center for Polymer Research, University of Massachusetts, Amherst, MA 01003, USA.
| | - E Bryan Coughlin
- Polymer Science and Engineering Department, Conte Center for Polymer Research, University of Massachusetts, Amherst, MA 01003, USA.
| | - Benjamin Doughty
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
| | - Thomas P Russell
- Polymer Science and Engineering Department, Conte Center for Polymer Research, University of Massachusetts, Amherst, MA 01003, USA.
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Bobby G Sumpter
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
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Yuan J, Wang Y. Conformation and Ionization Behavior of Charge-Regulating Polyelectrolyte Brushes in a Poor Solvent. J Phys Chem B 2021; 125:10589-10596. [PMID: 34494845 DOI: 10.1021/acs.jpcb.1c04451] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Understanding the structural response of weak polyelectrolyte brushes upon external stimuli is crucial for their applications ranging from modifying surface properties to the development of smart and intelligent materials. In this work, coarse-grained molecular dynamics simulations were carried out to investigate the conformation and ionization behavior of charge-regulating polyelectrolyte brushes under poor solvent conditions, using an implicit solvent model. The results show that, while the thickness of a sparse polyelectrolyte brush shows a similar behavior to that of a single chain, namely, a monotonic change as a function of solvent quality (modeled by an effective segment-segment attraction strength parameter) and solution pH, a dense polyelectrolyte brush exhibits more complex behavior. An unexpected reexpansion is observed when the effective segment-segment attraction strength is further increased, especially in the case of a high pH. In the latter case, strong attraction in polymer segments promotes the formation of large, interchain, cylindrical aggregates, leading to an increase in brush thickness.
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Affiliation(s)
- Jiaxing Yuan
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yanwei Wang
- Department of Chemical and Materials Engineering, School of Engineering and Digital Sciences, Nazarbayev University, 53 Kabanbay Batyr Avenue, Nur-Sultan 010000, Kazakhstan.,Laboratory of Computational Materials Science for Energy Applications, Center for Energy and Advanced Materials Science, National Laboratory Astana, 53 Kabanbay Batyr Avenue, Nur-Sultan 010000, Kazakhstan
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6
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Luo Y, Wang C, Pang AP, Zhang X, Wang D, Lu X. Low-Concentration Salt Solution Changes the Interfacial Molecular Behavior of Polyelectrolyte Brushes. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00119] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yongsheng Luo
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
| | - Chu Wang
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
| | - Ai-Ping Pang
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
| | - Xiang Zhang
- National Center for International Joint Research of Micro−Nano Molding Technology, School of Mechanics & Engineering Science, Zhengzhou University, Zhengzhou 450001, P. R. China
| | - Dayang Wang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, Jilin Province, P. R. China
| | - Xiaolin Lu
- State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu Province, P. R. China
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7
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Sachar HS, Chava BS, Pial TH, Das S. All-Atom Molecular Dynamics Simulations of the Temperature Response of Densely Grafted Polyelectrolyte Brushes. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Bhargav Sai Chava
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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8
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Wang L, Wang S, Tong C. The collapse of polyelectrolyte brushes made of 4-arm stars mediated by trivalent salt counterions. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.1932875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Lijuan Wang
- Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo, People’s Republic of China
| | - Shaoyun Wang
- Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo, People’s Republic of China
| | - Chaohui Tong
- Department of Physics, School of Physical Science and Technology, Ningbo University, Ningbo, People’s Republic of China
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9
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Pial TH, Sachar HS, Das S. Quantification of Mono- and Multivalent Counterion-Mediated Bridging in Polyelectrolyte Brushes. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00328] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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10
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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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11
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Li Y, Hao QH, Xia SY, Yan DX, Tan HG. Morphologies of spherical bidisperse polyelectrolyte brushes in the presence of trivalent counterions. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2020.110941] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Sachar HS, Pial TH, Chava BS, Das S. All-atom molecular dynamics simulations of weak polyionic brushes: influence of charge density on the properties of polyelectrolyte chains, brush-supported counterions, and water molecules. SOFT MATTER 2020; 16:7808-7822. [PMID: 32747883 DOI: 10.1039/d0sm01000f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
All atom molecular dynamics (MD) simulations of planar Na+-counterion-neutralized polyacrylic acid (PAA) brushes are performed for varying degrees of ionization (and thereby varying charge density) and varying grafting density. Variation in the PE charge density (or degree of ionization) and grafting density leads to massive changes of the properties of the PE molecules (quantified by the changes in the height and the mobility of the PE brushes) as well as the local arrangement and distribution of the brush-supported counterions and water molecules within the brushes. The effect on the counterions is manifested by the corresponding variation of the counterion mobility, counterion concentration, extent of counterion binding to the charged site of the PE brushes, water-in-salt-like structure formation, and counterion-water-oxygen radial distribution function within the PE brushes. On the other hand, the effect on water molecules is manifested by the corresponding variation of water-oxygen-water-oxygen RDF, local water density, water-water and water-PE functional group hydrogen bond networks, static dielectric constant of water molecules, orientational tetrahedral order parameter, and water mobility. Enforcing such varying degree of ionization of weak polyelectrolytes is possible by changing the pH of the surrounding medium. Thus, our results provide insights into the changes in microstructure (at the atomistic level) of weak polyionic brushes at varying pH. We anticipate that this knowledge will prove to be vital for the efficient design of several nano-scale systems employing PE brushes such as nanomechanical gates, current rectifiers, etc.
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Affiliation(s)
- Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, 4298 Campus Drive, College Park, MD 20742, USA.
| | - Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, 4298 Campus Drive, College Park, MD 20742, USA.
| | - Bhargav Sai Chava
- Department of Mechanical Engineering, University of Maryland, 4298 Campus Drive, College Park, MD 20742, USA.
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, 4298 Campus Drive, College Park, MD 20742, USA.
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13
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Senechal V, Saadaoui H, Vargas-Alfredo N, Rodriguez-Hernandez J, Drummond C. Weak polyelectrolyte brushes: re-entrant swelling and self-organization. SOFT MATTER 2020; 16:7727-7738. [PMID: 32735003 DOI: 10.1039/d0sm00810a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We have studied the combined influence of pH and ionic strength on the properties of brushes of a weak polyion, poly(acrylic acid), in conditions of grafting density close to the mushroom-brush crossover. By combining atomic force microscopy AFM and quartz crystal microbalance, we show that at low ionic strengths the conformational change of grafted polyions is non-monotonic with increasing pH due to the counterintuitive variation of the ionization degree. Thus, reentrant swelling of the polymer chains is observed with increasing pH. This effect is more important at low polymer grafting densities, when it is accompanied by in-plane heterogeneous distribution at intermediate pH values. In addition, we observed self-assembly on the polymer brush (formation of holes and islands) at pH values below pKa, due to the short-range attractive interaction between uncharged grafted chains. The sensitivity of the ionization of grafted chains to the physicochemical environment was also studied by measuring the interaction force between a silica tip and polymer brushes by atomic force microscopy. The dependence of the ionization of polyions on the presence of the tip points toward important charge regulation effects, in particular at pH values corresponding to partial ionization of the polyion.
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Affiliation(s)
- Vincent Senechal
- CNRS, Centre de Recherche Paul Pascal (CRPP), UMR 5031, F-33600 Pessac, France. and Université de Bordeaux, Centre de Recherche Paul Pascal, F-33600 Pessac, France
| | - Hassan Saadaoui
- CNRS, Centre de Recherche Paul Pascal (CRPP), UMR 5031, F-33600 Pessac, France. and Université de Bordeaux, Centre de Recherche Paul Pascal, F-33600 Pessac, France
| | - Nelson Vargas-Alfredo
- Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva 3, 28006, Madrid, Spain
| | | | - Carlos Drummond
- CNRS, Centre de Recherche Paul Pascal (CRPP), UMR 5031, F-33600 Pessac, France. and Université de Bordeaux, Centre de Recherche Paul Pascal, F-33600 Pessac, France
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Mabuchi T, Huang SF, Tokumasu T. Dispersion of Nafion Ionomer Aggregates in 1-Propanol/Water Solutions: Effects of Ionomer Concentration, Alcohol Content, and Salt Addition. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b02725] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Takuya Mabuchi
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi 980-8577, Japan
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Sheng-Feng Huang
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Takashi Tokumasu
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi 980-8577, Japan
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15
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Yuan J, Antila HS, Luijten E. Structure of Polyelectrolyte Brushes on Polarizable Substrates. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b02749] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jiaxing Yuan
- School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hanne S. Antila
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - Erik Luijten
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208, United States
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16
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Mabuchi T, Huang S, Tokumasu T. Nafion Ionomer Dispersion in Mixtures of 1‐Propanol and Water Based on the Martini Coarse‐Grained Model. JOURNAL OF POLYMER SCIENCE 2020. [DOI: 10.1002/pol.20190101] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Takuya Mabuchi
- Frontier Research Institute for Interdisciplinary SciencesTohoku University 2‐1‐1 Katahira Aoba‐ku, Sendai Miyagi 980‐8577 Japan
- Institute of Fluid ScienceTohoku University 2‐1‐1 Katahira Aoba‐ku, Sendai Miyagi 980‐8577 Japan
| | - Sheng‐Feng Huang
- Institute of Fluid ScienceTohoku University 2‐1‐1 Katahira Aoba‐ku, Sendai Miyagi 980‐8577 Japan
| | - Takashi Tokumasu
- Institute of Fluid ScienceTohoku University 2‐1‐1 Katahira Aoba‐ku, Sendai Miyagi 980‐8577 Japan
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17
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Conformational Properties of Comb-shaped Polyelectrolytes with Negatively Charged Backbone and Neutral Side Chains Studied by a Generic Coarse-grained Bead-and-Spring Model. CHINESE JOURNAL OF POLYMER SCIENCE 2019. [DOI: 10.1007/s10118-020-2350-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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18
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Tan HG, Xia G, Liu LX, Miao B. Morphologies of a polyelectrolyte brush grafted onto a cubic colloid in the presence of trivalent ions. Phys Chem Chem Phys 2019; 21:20031-20044. [PMID: 31478539 DOI: 10.1039/c9cp03819a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the morphologies of a polyelectrolyte brush grafted onto a surface of cubic geometry under good solvent conditions in the presence of trivalent counterions, using molecular dynamics simulations. The electrostatic correlation effect and excluded volume effect on the morphologies are studied through varying the charge fraction and grafting density, respectively. Combining snapshots of surface morphologies, brush height, distribution profiles of polymer monomers, and monomer-monomer/counterion pair correlation functions, it is clearly shown that the electrostatic correlation effect, represented by the trivalent-counterion-mediated bridging effect, can induce lateral microphase separation of the cubic polyelectrolyte brush, resulting in the formation of pinned patches. These structures then lead to multi-scale ordering in the brush system and, thereby, a non-monotonic dependence of the brush height, corresponding to a collapse-to-swell transition, on the grafting density. Our simulation results demonstrate that, with the sequence of surface morphologies responsive to adjusting external parameters, the cubic polyelectrolyte brush can serve as a candidate system for the manufacturing of smart stimuli-responsive materials.
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Affiliation(s)
- Hong-Ge Tan
- College of Science, Civil Aviation University of China, Tianjin 300300, China.
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Fernandez-Alvarez R, Nová L, Uhlík F, Kereïche S, Uchman M, Košovan P, Matějíček P. Interactions of star-like polyelectrolyte micelles with hydrophobic counterions. J Colloid Interface Sci 2019; 546:371-380. [PMID: 30933716 DOI: 10.1016/j.jcis.2019.03.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 03/15/2019] [Accepted: 03/16/2019] [Indexed: 12/26/2022]
Abstract
Hydrophobicity of a counterion has a profound effect on the interaction with polyelectrolytes similar to that of multivalency. Specifically, understanding this interaction in weak polyelectrolyte micelles might assist in developing nanocarriers for pH-controlled encapsulation and release. We used star-like weak polyelectrolyte micelles of polystyrene-block-poly(2-vinyl pyridine) (PS-P2VP) with fixed aggregation number as a model polyelectrolyte, and cobalt bis(1,2-dicarbollide) (COSAN) as a model hydrophobic anion. We used NMR to assess the mobility of the polymer segments in the presence of varying amounts of COSAN, and at varying protonation degrees of the polyelectrolyte. Same experiments with indifferent electrolyte (NaCl) were used as a control. Furthermore, we used coarse-grained simulations to obtain a detailed picture of the effect of hydrophobic counterions on the conformation of the micelles. A small amount of hydrophobic counterions causes morphological changes within the micelles, whereas a bigger amount causes precipitation. This was confirmed both in simulations and in experiments. Furthermore, adsorption of the counterions induces ionization of the collapsed segments of the polyelectrolyte. Although the COSAN/P2VP system is rather specific, the generic model used in the coarse-grained simulations shows that the observed behavior is a consequence of synergy of hydrophobic and electrostatic attraction between polyelectrolytes and hydrophobic counterions. Our study provides general insights into the molecular mechanisms of these interactions.
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Affiliation(s)
- Roberto Fernandez-Alvarez
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic
| | - Lucie Nová
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic
| | - Filip Uhlík
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic
| | - Sami Kereïche
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic; Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Purkynie Ustav, Albertov 4, 12 801 Prague, Czech Republic
| | - Mariusz Uchman
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic
| | - Peter Košovan
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic.
| | - Pavel Matějíček
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague, Czech Republic.
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20
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Landsgesell J, Nová L, Rud O, Uhlík F, Sean D, Hebbeker P, Holm C, Košovan P. Simulations of ionization equilibria in weak polyelectrolyte solutions and gels. SOFT MATTER 2019; 15:1155-1185. [PMID: 30706070 DOI: 10.1039/c8sm02085j] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
This article recapitulates the state of the art regarding simulations of ionization equilibria of weak polyelectrolyte solutions and gels. We start out by reviewing the essential thermodynamics of ionization and show how the weak polyelectrolyte ionization differs from the ionization of simple weak acids and bases. Next, we describe simulation methods for ionization reactions, focusing on two methods: the constant-pH ensemble and the reaction ensemble. After discussing the advantages and limitations of both methods, we review the existing simulation literature. We discuss coarse-grained simulations of weak polyelectrolytes with respect to ionization equilibria, conformational properties, and the effects of salt, both in good and poor solvent conditions. This is followed by a discussion of branched star-like weak polyelectrolytes and weak polyelectrolyte gels. At the end we touch upon the interactions of weak polyelectrolytes with other polymers, surfaces, nanoparticles and proteins. Although proteins are an important class of weak polyelectrolytes, we explicitly exclude simulations of protein ionization equilibria, unless they involve protein-polyelectrolyte interactions. Finally, we try to identify gaps and open problems in the existing simulation literature, and propose challenges for future development.
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Affiliation(s)
- Jonas Landsgesell
- Institute for Computational Physics, University of Stuttgart, Allmandring 3, Stuttgart, Germany.
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21
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Hao QH, Xia G, Tan HG, Chen EQ, Yang S. Surface morphologies of spherical polyelectrolyte brushes induced by trivalent salt ions. Phys Chem Chem Phys 2018; 20:26542-26551. [PMID: 30306970 DOI: 10.1039/c8cp04235g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The surface morphologies of spherical polyelectrolyte brushes in salt solutions with opposite trivalent ions are studied using molecular dynamics (MD) simulations. The impact of salt concentration, grafting density, and charge fraction on brush morphologies is investigated systematically. A variety of surface patterns are predicted and the phase diagrams are presented. Both lateral and radial microphase separated structures in the brushes are observed upon varying the salt concentration. With low grafting density the spherical brush is separated into several patches, the number of which decreases with the addition of salt. At high grafting density, the polymer brush changes its morphology from an extended micelle to a 'carpet + brush' to the collapsed state upon increasing the salt concentration. Especially, the 'carpet + brush' structure consists of a core formed by partially collapsed brush chains and a corona formed by other stretched chains. The inter-chain 'bridging' interactions mediated by trivalent ions and the curvature effect play important roles in determining the chain conformations and brush structures.
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Affiliation(s)
- Qing-Hai Hao
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Gang Xia
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Hong-Ge Tan
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Er-Qiang Chen
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Shuang Yang
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
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22
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Liu L, Hyeon C. From octopus to dendrite—Semiflexible polyelectrolyte brush condensates in trivalent counterion solution. J Chem Phys 2018; 149:163302. [DOI: 10.1063/1.5027161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Lei Liu
- Korea Institute for Advanced Study, Seoul 02455, South Korea
| | - Changbong Hyeon
- Korea Institute for Advanced Study, Seoul 02455, South Korea
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23
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Hao QH, Xia G, Miao B, Tan HG, Niu XH, Liu LY. Morphological Response of a Spherical Polyelectrolyte Brush to Solvent Quality and Electrostatic Interaction Strength. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01466] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Qing-Hai Hao
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Gang Xia
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Bing Miao
- College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong-Ge Tan
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Xiao-Hui Niu
- College of Science, Civil Aviation University of China, Tianjin 300300, China
| | - Li-Yan Liu
- College of Science, Civil Aviation University of China, Tianjin 300300, China
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24
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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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25
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Sin JS, Kim UH. Ion size effect on electrostatic and electroosmotic properties in soft nanochannels with pH-dependent charge density. Phys Chem Chem Phys 2018; 20:22961-22971. [DOI: 10.1039/c8cp04185g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a theoretical study of the ion size effect on various properties in a soft nanochannel with pH-dependent charge density.
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Affiliation(s)
- Jun-Sik Sin
- Department of Physics, Kim Il Sung University
- Pyongyang
- Democratic People's Republic of Korea
- Natural Science Center, Kim Il Sung University
- Pyongyang
| | - Un-Hyok Kim
- Institute of Environmental Science and Water Technology, Academy of Sciences
- Pyongyang
- Democratic People's Republic of Korea
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26
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Yu J, Jackson NE, Xu X, Brettmann BK, Ruths M, de Pablo JJ, Tirrell M. Multivalent ions induce lateral structural inhomogeneities in polyelectrolyte brushes. SCIENCE ADVANCES 2017; 3:eaao1497. [PMID: 29226245 PMCID: PMC5722652 DOI: 10.1126/sciadv.aao1497] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/06/2017] [Indexed: 05/22/2023]
Abstract
Subtle details about a polyelectrolyte's surrounding environment can dictate its structural features and potential applications. Atomic force microscopy (AFM), surface forces apparatus (SFA) measurements, and coarse-grained molecular dynamics simulations are combined to study the structure of planar polyelectrolyte brushes [poly(styrenesulfonate), PSS] in a variety of solvent conditions. More specifically, AFM images provide a first direct visualization of lateral inhomogeneities on the surface of polyelectrolyte brushes collapsed in solutions containing trivalent counterions. These images are interpreted in the context of a coarse-grained molecular model and are corroborated by accompanying interaction force measurements with the SFA. Our findings indicate that lateral inhomogeneities are absent from PSS brush layers collapsed in a poor solvent without multivalent ions. Together, AFM, SFA, and our molecular model present a detailed picture in which solvophobic and multivalent ion-induced effects work in concert to drive strong phase separation, with electrostatic bridging of polyelectrolyte chains playing an essential role in the collapsed structure formation.
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Affiliation(s)
- Jing Yu
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Nicholas E. Jackson
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Xin Xu
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Blair K. Brettmann
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Marina Ruths
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Juan J. de Pablo
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Matthew Tirrell
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
- Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
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27
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Larin DE, Govorun EN. Surfactant-Induced Patterns in Polymer Brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:8545-8552. [PMID: 28759241 DOI: 10.1021/acs.langmuir.7b01850] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The properties of surfaces with grafted macromolecules are determined by a fine structure of the macromolecular layer, whereas the mixtures of macromolecules with surfactants are very rich in structure types. Using the scaling mean-field theory, we consider the self-assembly in polymer brushes into various patterns induced by interactions with low-molecular surfactants. The interaction energies of the parts of a surfactant molecule with the polymer units are assumed to be greatly different. With increasing the grafting density, the formation of lamellae perpendicular to the grafting plane, a continuous layer with oblong or round pores, or a homogeneous brush is predicted. The driving force of the pattern formation is a gain in the interaction energy of surfactant molecules oriented at the lateral surfaces of lamellae or pores. The process of pore formation in a homogeneous brush caused by a temperature change at definite grafting densities is described as the first-order phase transition. It is accompanied by a stepwise extension of the brush and by orientational ordering of surfactant molecules. The transitions between the other patterns are of the second order. The thickness of lamellae and the distance between pores are approximately twice the surfactant molecule size except for the extremely high grafting densities. The diagrams of brush patterns are presented and discussed.
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Affiliation(s)
- Daniil E Larin
- Faculty of Physics, M. V. Lomonosov Moscow State University , Leninskie gory, Moscow, 119991 Russia
| | - Elena N Govorun
- Faculty of Physics, M. V. Lomonosov Moscow State University , Leninskie gory, Moscow, 119991 Russia
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28
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Gleria I, Mocskos E, Tagliazucchi M. Minimum free-energy paths for the self-organization of polymer brushes. SOFT MATTER 2017; 13:2362-2370. [PMID: 28275766 DOI: 10.1039/c6sm02725c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A methodology to calculate minimum free-energy paths based on the combination of a molecular theory and the improved string method is introduced and applied to study the self-organization of polymer brushes under poor solvent conditions. Polymer brushes in a poor solvent cannot undergo macroscopic phase separation due to the physical constraint imposed by the grafting points; therefore, they microphase separate forming aggregates. Under some conditions, the theory predicts that the homogeneous brush and the aggregates can exist as two different minima of the free energy. The theoretical methodology introduced in this work allows us to predict the minimum free-energy path connecting these two minima as well as the morphology of the system along the path. It is shown that the transition between the homogeneous brush and the aggregates may involve a free-energy barrier or be barrierless depending on the relative stability of the two morphologies and the chain length and grafting density of the polymer. In the case where a free-energy barrier exists, one of the morphologies is a metastable structure and, therefore, the properties of the brush as the quality of the solvent is cycled are expected to display hysteresis. The theory is also applied to study the adhesion/deadhesion transition between two opposing surfaces modified by identical polymer brushes and it is shown that this process may also require surpassing a free-energy barrier.
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Affiliation(s)
- Ignacio Gleria
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Computación, Buenos Aires, Argentina
| | - Esteban Mocskos
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Computación, Buenos Aires, Argentina and CONICET, Centro de Simulación Computacional para Aplicaciones Tecnológicas (CSC), Buenos Aires, Argentina
| | - Mario Tagliazucchi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química-Física, Buenos Aires, Argentina. and CONICET-Universidad de Buenos Aires, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Buenos Aires, Argentina
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29
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Jackson NE, Brettmann BK, Vishwanath V, Tirrell M, de Pablo JJ. Comparing Solvophobic and Multivalent Induced Collapse in Polyelectrolyte Brushes. ACS Macro Lett 2017; 6:155-160. [PMID: 35632885 DOI: 10.1021/acsmacrolett.6b00837] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Coarse-grained molecular dynamics enhanced by free-energy sampling methods is used to examine the roles of solvophobicity and multivalent salts on polyelectrolyte brush collapse. Specifically, we demonstrate that while ostensibly similar, solvophobic collapsed brushes and multivalent-ion collapsed brushes exhibit distinct mechanistic and structural features. Notably, multivalent-induced heterogeneous brush collapse is observed under good solvent polymer backbone conditions, demonstrating that the mechanism of multivalent collapse is not contingent upon a solvophobic backbone. Umbrella sampling of the potential of mean-force (PMF) between two individual brush strands confirms this analysis, revealing starkly different PMFs under solvophobic and multivalent conditions, suggesting the role of multivalent "bridging" as the discriminating feature in trivalent collapse. Structurally, multivalent ions show a propensity for nucleating order within collapsed brushes, whereas poor-solvent collapsed brushes are more disordered; this difference is traced to the existence of a metastable PMF minimum for poor solvent conditions, and a global PMF minimum for trivalent systems, under experimentally relevant conditions.
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Affiliation(s)
- Nicholas E. Jackson
- The
Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Blair K. Brettmann
- The
Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | | | - Matthew Tirrell
- The
Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Juan J. de Pablo
- The
Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
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30
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Liu L, Pincus PA, Hyeon C. Heterogeneous Morphology and Dynamics of Polyelectrolyte Brush Condensates in Trivalent Counterion Solution. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b02685] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Lei Liu
- Korea Institute
for Advanced Study, Seoul 02455, Korea
| | - Philip A. Pincus
- Materials
and Physics Departments, University of California at Santa Barbara, Santa Barbara, California 93106, United States
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31
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Brettmann B, Pincus P, Tirrell M. Lateral Structure Formation in Polyelectrolyte Brushes Induced by Multivalent Ions. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b02563] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Blair Brettmann
- The
Institute for Molecular Engineering, The University of Chicago, 5640 S. Ellis Ave., Chicago, Illinois 60637, United States
| | - Philip Pincus
- Materials
Department, Room 3004 Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Matthew Tirrell
- The
Institute for Molecular Engineering, The University of Chicago, 5640 S. Ellis Ave., Chicago, Illinois 60637, United States
- The
Institute for Molecular Engineering, Argonne National Laboratory, 9700 Cass Avenue, Lemont, Illinois 60439, United States
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32
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Gao K, Kearney LT, Howarter JA. Planar Phase Separation of Weak Polyelectrolyte Brushes in Poor Solvent. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/polb.24281] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kai Gao
- School of Materials Engineering; Purdue University; 701 W Stadium Ave West Lafayette Indiana 47907
| | - Logan T. Kearney
- School of Materials Engineering; Purdue University; 701 W Stadium Ave West Lafayette Indiana 47907
| | - John A. Howarter
- School of Materials Engineering; Purdue University; 701 W Stadium Ave West Lafayette Indiana 47907
- Division of Environmental and Ecological Engineering; Purdue University; 500 Central Dr West Lafayette Indiana 47907
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33
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Cao Q, You H. Electroosmotic Flow in Mixed Polymer Brush-Grafted Nanochannels. Polymers (Basel) 2016; 8:polym8120438. [PMID: 30974715 PMCID: PMC6431973 DOI: 10.3390/polym8120438] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 12/10/2016] [Accepted: 12/12/2016] [Indexed: 01/21/2023] Open
Abstract
Mixed polymer brush-grafted nanochannels—where two distinct species of polymers are alternately grafted on the inner surface of nanochannels—are an interesting class of nanostructured hybrid materials. By using a coarse-grained molecular dynamics simulation method, we are able to simulate the electrokinetic transport dynamics of the fluid in such nanochannels as well as the conformational behaviors of the mixed polymer brush. We find that (1) the brush adopts vertically-layered and longitudinally-separated structures due to the coupling of electroosmotic flow (EOF) and applied electric field; (2) the solvent quality affects the brush conformations and the transport properties of the EOF; (3) the EOF flux non-monotonically depends on the grafting density, although the EOF velocity in the central region of the channel monotonically depends on the grafting density.
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Affiliation(s)
- Qianqian Cao
- College of Mechanical and Electrical Engineering, Jiaxing University, Jiaxing 314001, China.
| | - Hao You
- Center for Simulational Physics, Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA.
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34
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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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35
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Yu J, Mao J, Yuan G, Satija S, Jiang Z, Chen W, Tirrell M. Structure of Polyelectrolyte Brushes in the Presence of Multivalent Counterions. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01064] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Jing Yu
- Institute
for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Jun Mao
- Institute
for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Guangcui Yuan
- NIST
Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, United States
- Department
of Polymer Engineering, The University of Akron, Akron, Ohio 43250, United States
| | - Sushil Satija
- NIST
Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, United States
| | | | - Wei Chen
- Institute
for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Matthew Tirrell
- Institute
for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
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36
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Uhlík F, Košovan P, Zhulina EB, Borisov OV. Charge-controlled nano-structuring in partially collapsed star-shaped macromolecules. SOFT MATTER 2016; 12:4846-4852. [PMID: 27140226 DOI: 10.1039/c6sm00109b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Hydrophobic polyelectrolytes exhibit intra-molecular nano-scale self-organization instead of macroscopic phase separation because of the interplay between short-range hydrophobic attraction and long-range electrostatic repulsion. We aim to unravel how the morphology of the intra-molecular nanostructures can be controlled through the topology of the macromolecule on one hand and by adjustable ionization on the other hand. Specifically, we focus on hydrophobic star-branched polyelectrolytes, composed of either strong or weak acidic monomers. While both collapse in a globule when uncharged, and expand to full stretching of arms at high ionization, they exhibit quite different intermediate scenarios. For the strong ones, we observe the formation of bundles of arms as the main structural motif, and for the weak ones the intramolecular micelle-like structure is found at the same overall charge of the macromolecule. Here intramolecular disproportionation leaves some arms in a collapsed virtually neutral core, while others are substantially ionized and stretched in the corona.
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Affiliation(s)
- Filip Uhlík
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 00 Praha 2, Czech Republic
| | - Peter Košovan
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 00 Praha 2, Czech Republic
| | - Ekaterina B Zhulina
- Institute of Macromolecular Compounds of the Russian Academy of Sciences, 199004 St. Petersburg, Russia and St. Petersburg National Research University of Information Technologies, Mechanics and Optics, 197101, St. Petersburg, Russia
| | - Oleg V Borisov
- St. Petersburg National Research University of Information Technologies, Mechanics and Optics, 197101, St. Petersburg, Russia and CNRS, UMR 5254 - IPREM - Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Maériaux, 2 avenue du Président Angot, 64053 Pau, France.
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37
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Hao QH, Chen Q, Zheng Z, Liu LY, Liu TJ, Niu XH, Song QG, Tan HG. Molecular dynamics simulations of cylindrical polyelectrolyte brushes in monovalent and multivalent salt solutions. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2016. [DOI: 10.1142/s0219633616500267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Molecular dynamics simulations are applied to investigate the cylindrical polyelectrolyte brushes in monovalent and multivalent salt solutions. By varying the salt valence and concentration, the brush thickness, shape factor of grafted chains, and distributions of monomers and ions in the solutions are studied. The simulation results show that the single osmotic pressure effect in the brush leads to changes in conformation in the presence of monovalent salt, while the ion exchange effect induces the collapse of the brushes in the multivalent salt solutions. Furthermore, the snapshots combined with the distributions of the end-monomers and the mean bond angles demonstrate a nonuniform stretching picture of the grafted chains, which is different with the chains tethered on the planar surface. The charge ratios between the ions trapped in the brush and the monomers are also calculated to elucidate the details of ion exchange process.
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Affiliation(s)
- Qing-Hai Hao
- College of Science, Civil Aviation University of China, Tianjin 300300, P. R. China
| | - Qian Chen
- College of Science, Civil Aviation University of China, Tianjin 300300, P. R. China
| | - Zhen Zheng
- College of Science, Civil Aviation University of China, Tianjin 300300, P. R. China
| | - Li-Yan Liu
- College of Science, Civil Aviation University of China, Tianjin 300300, P. R. China
| | - Tie-Ju Liu
- College of Science, Civil Aviation University of China, Tianjin 300300, P. R. China
| | - Xiao-Hui Niu
- College of Science, Civil Aviation University of China, Tianjin 300300, P. R. China
| | - Qing-Gong Song
- College of Science, Civil Aviation University of China, Tianjin 300300, P. R. China
| | - Hong-Ge Tan
- College of Science, Civil Aviation University of China, Tianjin 300300, P. R. China
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38
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Mahalik JP, Yang Y, Deodhar C, Ankner JF, Lokitz BS, Kilbey SM, Sumpter BG, Kumar R. Monomer volume fraction profiles in pH responsive planar polyelectrolyte brushes. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/polb.24008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- J. P. Mahalik
- Computer Science and Mathematics Division; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
- Center for Nanophase Materials Sciences; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
| | - Yubo Yang
- Denison University; Granville Ohio 43023
| | - Chaitra Deodhar
- Department of Chemistry; University of Tennessee; Knoxville Tennessee 37996
| | - John F. Ankner
- Spallation Neutron Source; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
| | - Bradley S. Lokitz
- Center for Nanophase Materials Sciences; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
| | - S. Michael Kilbey
- Department of Chemistry; University of Tennessee; Knoxville Tennessee 37996
| | - Bobby G. Sumpter
- Computer Science and Mathematics Division; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
- Center for Nanophase Materials Sciences; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
| | - Rajeev Kumar
- Computer Science and Mathematics Division; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
- Center for Nanophase Materials Sciences; Oak Ridge National Laboratory; Oak Ridge Tennessee 37831
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39
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Ghelichi M, Malek K, Eikerling MH. Ionomer Self-Assembly in Dilute Solution Studied by Coarse-Grained Molecular Dynamics. Macromolecules 2016. [DOI: 10.1021/acs.macromol.5b02158] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Mahdi Ghelichi
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
| | - Kourosh Malek
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
- Energy,
Mining, and Environment, National Research Council of Canada, 4250
Wesbrook Mall, Vancouver, BC V6T 1W5, Canada
| | - Michael H. Eikerling
- Department
of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A
1S6, Canada
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40
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Cao Q, You H. Polyampholyte Brushes Grafted on the Surface of a Spherical Cavity: Effect of the Charged Monomer Sequence, Grafting Density, and Chain Stiffness. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:6375-6384. [PMID: 26011023 DOI: 10.1021/acs.langmuir.5b01190] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Molecular dynamics simulations are used to study the conformational behaviors of the flexible and semiflexible polyampholytes coated onto the internal surface of a spherical cavity. Dependences of the brush structure and the local conformation of grafted chains on the sequence of charged monomers, the grafting density, and the chain stiffness are addressed. In the range of parameters studied, it was found that a significant transition of the brush structure occurs due to the variation of the charged monomer sequence. As the number of repeat charged monomers increases, both the flexible and semiflexible polyampholyte brushes change to the collapsed conformation. The spherical concave geometry tends to exclude the conformation of chains perpendicular to the grafting surface for the semiflexible case. In addition, we find that most counterions are depleted in the polyampholyte brush due to the strong electrostatic correlation between the oppositely charged monomers.
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Affiliation(s)
- Qianqian Cao
- †College of Mechanical and Electrical Engineering, Jiaxing University, Jiaxing 314001, PR China
- ‡Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
- §College of Mechanical Science and Engineering, Jilin University, Changchun 130022, PR China
| | - Hao You
- ∥Department of Chemistry and Physics, Georgia Regents University, 1120 15th Street, Augusta, Georgia 30912, United States
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41
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Wang T, Long Y, Liu L, Wang X, Craig VSJ, Zhang G, Liu G. Cation-specific conformational behavior of polyelectrolyte brushes: from aqueous to nonaqueous solvent. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12850-12859. [PMID: 25300430 DOI: 10.1021/la5033493] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have investigated changes in the cation-specific conformational behavior of poly(sodium styrenesulfonate) (PSS) brushes as the solvent changes from water to methanol using a quartz crystal microbalance with dissipation (QCM-D). A solvation to desolvation transition of the grafted chains accompanied by swelling to the collapse transition of the brushes is observed for Na(+). In the case of Cs(+), the brushes undergo solvation to desolvation to resolvation accompanied by swelling to collapse to reswelling transitions. The resolvation and reswelling transitions for Cs(+) are induced by the charge inversion of the brushes via van der Waals interactions between Cs(+) and the brushes. All of the transitions for monovalent cations become less obvious as the methanol content increases. For divalent Ca(2+) and trivalent La(3+), a solvation to desolvation to resolvation transition of the grafted chains accompanied by a swelling to collapse to reswelling transition of the brushes can be observed. The resolvation and reswelling of the brushes for the multivalent cations are induced by the charge inversion of the brushes via charge-image charge interactions. The extent of the transitions for the PSS brushes in the presence of multivalent cations is only slightly influenced by the methanol content.
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Affiliation(s)
- Tao Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China , Hefei, PR China 230026
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42
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Cheng J, Vishnyakov A, Neimark AV. Morphological transformations in polymer brushes in binary mixtures: DPD study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12932-40. [PMID: 25295697 DOI: 10.1021/la503520e] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Morphological transformations in polymer brushes in a binary mixture of good and bad solvents are studied using dissipative particle dynamics simulations drawing on a characteristic example of polyisoprene natural rubber in an acetone-benzene mixture. A coarse-grained DPD model of this system is built based on the experimental data in the literature. We focus on the transformation of dense, collapsed brush in bad solvent (acetone) to expanded brush solvated in good solvent (benzene) as the concentration of benzene increases. Compared to a sharp globule-to-coil transition observed in individual tethered chains, the collapsed-to-expanded transformation in brushes is found to be gradual without a prominent transition point. The transformation becomes more leveled as the brush density increases. At low densities, the collapsed brush is highly inhomogeneous and patterned into bunches composed of neighboring chains due to favorable polymer-polymer interaction. At high densities, the brush is expanded even in bad solvent due to steric restrictions. In addition, we considered a model system similar to the PINR-acetone-benzene system, but with the interactions between the solvent components worsened to the limit of miscibility. Enhanced contrast between good and bad solvents facilitates absorption of the good solvent by the brush, shifting the collapsed-to-expanded transformation to lower concentrations of good solvent. This effect is especially pronounced for higher brush densities.
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Affiliation(s)
- Jianli Cheng
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey , 98 Brett Road, Piscataway New Jersey 08854, United States
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43
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Tagliazucchi M, Li X, Olvera de la Cruz M, Szleifer I. Self-organized polyelectrolyte end-grafted layers under nanoconfinement. ACS NANO 2014; 8:9998-10008. [PMID: 25222704 DOI: 10.1021/nn502008x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Layers of end-grafted weak polyelectrolytes in poor solvent self-organize into a rich variety of structures (such as micelles, micelles coexisting with nonaggregated chains, stripes and layers with solvent-filled holes) due to the subtle competition among hydrophobic, electrostatic and steric interactions and the chemical acid-based equilibria of the weak polyelectrolyte. In this work, a molecular theory has been used to systematically study how nanoconfinement modulates the competition among these interactions and, therefore, dictates the morphology of the self-assembled layer. Two different types of confinement were considered and compared: (i) soft lateral confinement due to increasing surface coverage in a planar polyelectrolyte brush and (ii) hard vertical confinement due to the interaction of a planar polyelectrolyte brush with an opposing surface, as typically found in AFM-colloidal-tip and surface-force-apparatus experiments. It is shown that increasing the surface coverage (soft lateral confinement) or compressing the layer with an opposing wall (hard vertical confinement) have a similar qualitative effect on the morphology of the system: both types of nanoconfinement increase the stability of morphologies that extend in one or two dimensions (such as the homogeneous brush, holes and stripes) over nonextended aggregates (such as hemispherical micelles). However, vertical confinement can also lead to pillar-like structures that are not observed in the absence of the opposing wall. Interestingly, the pillar structures, which bridge the grafting and opposing surfaces, may coexist with metastable structures collapsed to the grafting surface only. This coexistence may help to understand the hysteresis commonly observed in surface-force experiments.
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Affiliation(s)
- Mario Tagliazucchi
- Department of Biomedical Engineering, Northwestern University , Evanston, Illinois 60208, United States
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44
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Guskova OA, Varanasi SR, Sommer JU. C60-dyad aggregates: Self-organized structures in aqueous solutions. J Chem Phys 2014; 141:144303. [DOI: 10.1063/1.4896559] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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45
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Borges J, Mano JF. Molecular Interactions Driving the Layer-by-Layer Assembly of Multilayers. Chem Rev 2014; 114:8883-942. [DOI: 10.1021/cr400531v] [Citation(s) in RCA: 609] [Impact Index Per Article: 60.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- João Borges
- 3B’s
Research Group—Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Zona Industrial da Gandra,
S. Cláudio do Barco 4806-909 Caldas das Taipas, Guimarães, Portugal
- ICVS/3B’s
− PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - João F. Mano
- 3B’s
Research Group—Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark, Zona Industrial da Gandra,
S. Cláudio do Barco 4806-909 Caldas das Taipas, Guimarães, Portugal
- ICVS/3B’s
− PT Government Associate Laboratory, Braga/Guimarães, Portugal
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46
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47
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He GL, Merlitz H, Sommer JU. Molecular dynamics simulations of polyelectrolyte brushes under poor solvent conditions: Origins of bundle formation. J Chem Phys 2014; 140:104911. [DOI: 10.1063/1.4867466] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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48
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Barr SA, Panagiotopoulos AZ. Conformational transitions of weak polyacids grafted to nanoparticles. J Chem Phys 2012; 137:144704. [PMID: 23061858 DOI: 10.1063/1.4757284] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The charge distribution on polyelectrolytes is a key factor, which controls their conformation and interactions. In weak polyelectrolytes, this distribution is determined by a number of factors, including the solvent conditions and local environment. In this work, we investigate charge distributions of chains end-grafted on a spherical nanoparticle in a salt solution, using grand canonical titration Monte Carlo simulations of a coarse-grained polymer model. In this approach, the ionization state of each polymer bead fluctuates based on the dissociation constant, pH of the solution, and interactions with other particles in the system. We determine charge and polymer conformations as functions of the pH and solvent quality. We compare the results to a fixed charge model and also investigate the role of grafting density and the effect of curvature on the film morphologies.
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Affiliation(s)
- S A Barr
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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49
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Angelova LV, Terech P, Natali I, Dei L, Carretti E, Weiss RG. Cosolvent gel-like materials from partially hydrolyzed poly(vinyl acetate)s and borax. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:11671-11682. [PMID: 21848256 DOI: 10.1021/la202179e] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A gel-like, high-viscosity polymeric dispersion (HVPD) based on cross-linked borate, partially hydrolyzed poly(vinyl acetate) (xPVAc, where x is the percent hydrolysis) is described. Unlike hydro-HVPDs prepared from poly(vinyl alcohol) (PVA) and borate, the liquid portion of these materials can be composed of up to 75% of an organic cosolvent because of the influence of residual acetate groups on the polymer backbone. The effects of the degree of hydrolysis, molecular weight, polymer and cross-linker concentrations, and type and amount of organic cosolvent on the rheological and structural properties of the materials are investigated. The stability of the systems is explored through rheological and melting-range studies. (11)B NMR and small-angle neutron scattering (SANS) are used to probe the structure of the dispersions. The addition of an organic liquid to the xPVAc-borate HVPDs results in a drastic increase in the number of cross-linked borate species as well as the agglomeration of the polymer into bundles. These effects result in an increase in the relaxation time and thermal stability of the networks. The ability to make xPVAc-borate HVPDs with very large amounts of and rather different organic liquids, with very different rheological properties that can be controlled easily, opens new possibilities for applications of PVAc-based dispersions.
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Affiliation(s)
- Lora V Angelova
- Department of Chemistry, Georgetown University, Washington, DC 20057-1227, USA
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50
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Russano D, Carrillo JMY, Dobrynin AV. Interaction between brush layers of bottle-brush polyelectrolytes: molecular dynamics simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:11044-11051. [PMID: 21809810 DOI: 10.1021/la2018067] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Interactions between tethered layers composed of aggrecan (charged bottle-brush) macromolecules are responsible for the molecular origin of cartilage biomechanical behavior. To elucidate the role of the electrostatic forces in interaction between bottle-brush layers, we have performed molecular dynamics simulations of charged and neutral bottle-brush macromolecules tethered to substrates. In the case of charged bottle-brush layers, the disjoining pressure P between two brush layers in salt-free solutions increases with decreasing distance D between substrates as P ∝ D(-1.8). A stronger dependence of the disjoining pressure P on the surface separation D was observed for neutral bottle-brushes, P ∝ D(-4.6), in the same interval of disjoining pressures. These scaling laws for dependence of disjoining pressure P on distance D are due to bending energy of the bottle-brush macromolecules within compressed brush layers. The weaker distance dependence observed in polyelectrolyte bottle-brushes is due to interaction between counterion clouds surrounding the bottle-brush macromolecules preventing strong brush overlap.
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Affiliation(s)
- Daniel Russano
- Polymer Program, Institute of Materials Science and Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
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