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Xiang L, Zhang J, Gong L, Zeng H. Surface forces and interaction mechanisms of soft thin films under confinement: a short review. SOFT MATTER 2020; 16:6697-6719. [PMID: 32648881 DOI: 10.1039/d0sm00924e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Surface forces of soft thin films under confinement in fluids play an important role in diverse biological and technological applications, such as bio-adhesion, lubrication and micro- and nano-electromechanical systems. Understanding the involved interaction mechanisms underlying the adhesion behaviors and tribological performances (i.e., friction and lubrication) of various confined soft thin films is significant in the development of both fundamental science and practical technologies. In this review, the fundamentals of surface forces are briefly presented. The widely utilized force measurement techniques including surface forces apparatus (SFA), atomic force microscopy (AFM) and spacer layer interferometry tribometer techniques are introduced. The advances in the fundamental understanding of a wide range of adhesion and tribological phenomena have been reviewed, in terms of the intermolecular and surface interaction mechanisms involved. The influences of various factors such as confined film properties, experimental conditions (e.g., normal load, and sliding velocity) and environmental variables (e.g., salts, salinity, additives and pH) on the adhesion, friction or lubrication forces of confined soft thin films are presented. The correlation between adhesion hysteresis and friction/lubrication behaviors has been discussed. Some of the challenging issues remaining and future perspectives are also provided.
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Affiliation(s)
- Li Xiang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada.
| | - Jiawen Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada.
| | - Lu Gong
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada.
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada.
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52
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Liu LY, Yu ZX, Liu LX, Yang JQ, Hao QH, Wei T, Tan HG. Self-assembly of polyelectrolyte diblock copolymers within mixtures of monovalent and multivalent counterions. Phys Chem Chem Phys 2020; 22:16334-16344. [PMID: 32648562 DOI: 10.1039/d0cp01019g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, the self-assembly behavior of polyelectrolyte (PE) diblock copolymers in solutions containing mixtures of monovalent and multivalent counterions was investigated using molecular dynamics simulation. The properties of the assembled micelles and counterion condensations at different charge fractions of multivalent ions have been discussed. The bridging effect of multivalent ions induces the electrostatic correlations of the PE chains, leading to the fusion of large micelles and the formation of bulky aggregates. Notably, lamellar and well-organized face-centered cubic (FCC) arrangements of the assembled micelles were observed in the mixture of monovalent and trivalent ions. At large fractions of multivalent ions, cylindrical and lamellar precipitates composed of the assembled micelles were formed owing to the inter-connecting coronas. The mixtures of monovalent and multivalent counterions allow the regulation of the electrostatic interactions and tuning of the properties in assembled micelles.
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Affiliation(s)
- Li-Yan Liu
- College of Science, Civil Aviation University of China, China.
| | - Zhong-Xun Yu
- School of Materials Science and Engineering, Beijing University of Chemical Technology, China
| | - Li-Xiang Liu
- College of Science, Civil Aviation University of China, China.
| | - Jing-Qi Yang
- College of Flight Technology, Civil Aviation University of China, China
| | - Qing-Hai Hao
- College of Science, Civil Aviation University of China, China.
| | - Tong Wei
- College of Science, Civil Aviation University of China, China.
| | - Hong-Ge Tan
- College of Science, Civil Aviation University of China, China.
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53
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Tolmachev D, Lukasheva N, Mamistvalov G, Karttunen M. Influence of Calcium Binding on Conformations and Motions of Anionic Polyamino Acids. Effect of Side Chain Length. Polymers (Basel) 2020; 12:E1279. [PMID: 32503199 PMCID: PMC7362111 DOI: 10.3390/polym12061279] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 05/29/2020] [Accepted: 05/31/2020] [Indexed: 11/21/2022] Open
Abstract
Investigation of the effect of CaCl2 salt on conformations of two anionic poly(amino acids) with different side chain lengths, poly-(α-l glutamic acid) (PGA) and poly-(α-l aspartic acid) (PASA), was performed by atomistic molecular dynamics (MD) simulations. The simulations were performed using both unbiased MD and the Hamiltonian replica exchange (HRE) method. The results show that at low CaCl2 concentration adsorption of Ca2+ ions lead to a significant chain size reduction for both PGA and PASA. With the increase in concentration, the chains sizes partially recover due to electrostatic repulsion between the adsorbed Ca2+ ions. Here, the side chain length becomes important. Due to the longer side chain and its ability to distance the charged groups with adsorbed ions from both each other and the backbone, PGA remains longer in the collapsed state as the CaCl2 concentration is increased. The analysis of the distribution of the mineral ions suggests that both poly(amino acids) should induce the formation of mineral with the same structure of the crystal cell.
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Affiliation(s)
- Dmitry Tolmachev
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, 199004 St. Petersburg, Russia;
| | - Natalia Lukasheva
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, 199004 St. Petersburg, Russia;
| | - George Mamistvalov
- Faculty of Physics, St. Petersburg State University, Petrodvorets, 198504 St. Petersburg, Russia;
| | - Mikko Karttunen
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, 199004 St. Petersburg, Russia;
- Department of Chemistry, the University of Western Ontario, 1151 Richmond Street, London, ON N6A 5B7, Canada
- Department of Applied Mathematics, the University of Western Ontario, 1151 Richmond Street, London, ON N6A 5B7, Canada
- The Centre of Advanced Materials and Biomaterials Research, the University of Western Ontario, 1151 Richmond Street, London, ON N6A 5B7, Canada
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54
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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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55
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Li C, Liu C, Li M, Xu X, Li S, Qi W, Su R, Yu J. Structures and Antifouling Properties of Self-Assembled Zwitterionic Peptide Monolayers: Effects of Peptide Charge Distributions and Divalent Cations. Biomacromolecules 2020; 21:2087-2095. [DOI: 10.1021/acs.biomac.0c00062] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chuanxi Li
- State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, PR China
| | - Chunjiang Liu
- State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China
| | - Minglun Li
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Xin Xu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Shuzhou Li
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Wei Qi
- State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, PR China
| | - Rongxin Su
- State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, PR China
| | - Jing Yu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
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56
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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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57
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Xu X, Mastropietro D, Ruths M, Tirrell M, Yu J. Ion-Specific Effects of Divalent Ions on the Structure of Polyelectrolyte Brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15564-15572. [PMID: 31414810 DOI: 10.1021/acs.langmuir.9b01984] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polyelectrolyte brushes consist of charged polymer chains attached on one end to a surface at high densities. They are relevant for many practical applications ranging from biosensors to drug delivery to colloidal stability. Their structure and functionality can be dramatically influenced by multivalent counterions in the solution environment. In this work, the surface forces apparatus (SFA) and atomic force microscopy (AFM) were used to investigate the effects of three alkaline earth divalent cations, Mg2+, Ca2+, and Ba2+, on the structures of polystyrenesulfonate (PSS) brushes tethered to mica and silicon oxide surfaces. While all these ions caused significant shrinkage of the height of the PSS brushes, strong ion-specific effects were observed. Mg2+ and Ca2+ caused homogeneous shrinkage; Ba2+ led to pinned-micelle like inhomogeneous structures. Isothermal titration calorimetry (ITC) demonstrated that this ion specificity was mainly caused by the difference in binding energy between sulfonate groups and the divalent cations. Considering the abundance of divalent cations in industrial processes, natural environments, and biological systems, the understanding of strong ion-specific effects of divalent counterions is of great importance for theoretical studies and various applications involving polyelectrolytes.
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Affiliation(s)
- Xin Xu
- School of Materials Science and Engineering , Nanyang Technological University , Singapore 639798
- Department of Chemistry , University of Massachusetts Lowell , Lowell , Massachusetts 01854 , United States
| | - Dean Mastropietro
- Pritzker School of Molecular Engineering , University of Chicago , Chicago , Illinois 60637 , United States
- Center for Molecular Engineering , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Marina Ruths
- Department of Chemistry , University of Massachusetts Lowell , Lowell , Massachusetts 01854 , United States
| | - Matthew Tirrell
- Pritzker School of Molecular Engineering , University of Chicago , Chicago , Illinois 60637 , United States
- Center for Molecular Engineering , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Jing Yu
- School of Materials Science and Engineering , Nanyang Technological University , Singapore 639798
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58
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Gong L, Xiang L, Zhang J, Chen J, Zeng H. Fundamentals and Advances in the Adhesion of Polymer Surfaces and Thin Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15914-15936. [PMID: 31436435 DOI: 10.1021/acs.langmuir.9b02123] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polymer materials have been widely used in industrial, agricultural, engineering, medical, electronic, and biological fields because of their excellent and diverse properties (e.g., mechanical, optical, electrical, and adhesive properties). The adhesion of polymer materials can affect the stability, alter the surface chemistry, change the surface structure, and influence the performance of the materials. It is of both fundamental and practical importance to understand the adhesion behaviors and interaction mechanisms of polymer surfaces and thin films for the development of new functional polymers and their applications. In this article, the fundamentals of surface energy, adhesion energy, and classical contact mechanics models are presented first, and the commonly used nanomechanical techniques for quantifying the intermolecular and surface interactions of polymers, including the surface forces apparatus (SFA) and atomic force microscope (AFM), are introduced. The advances in the adhesion of surfaces and thin films of various polymers (e.g., elastomers, glassy polymers) are reviewed. The effects of various factors, including the molecular weight, temperature, separation rate, and surface roughness, on the adhesion behaviors of these polymer surfaces and thin films are discussed. Their liquid- to solid-like behaviors during approach and detachment processes are shown. Several commonly applied methodologies used to modulate polymer adhesion are also introduced. Some recent applications based on polymer adhesion, remaining challenging issues, and future perspectives are also presented.
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Affiliation(s)
- Lu Gong
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Li Xiang
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Jiawen Zhang
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Jingsi Chen
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
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59
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Tan HG, Xia G, Liu LX, Niu XH, Hao QH. Surface Patterns of a Tetrahedral Polyelectrolyte Brush Induced by Grafting Density and Charge Fraction. CHINESE JOURNAL OF POLYMER SCIENCE 2019. [DOI: 10.1007/s10118-020-2351-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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60
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Li Y, Cao Y. The molecular mechanisms underlying mussel adhesion. NANOSCALE ADVANCES 2019; 1:4246-4257. [PMID: 36134404 PMCID: PMC9418609 DOI: 10.1039/c9na00582j] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 10/09/2019] [Indexed: 06/12/2023]
Abstract
Marine mussels are able to firmly affix on various wet surfaces by the overproduction of special mussel foot proteins (mfps). Abundant fundamental studies have been conducted to understand the molecular basis of mussel adhesion, where the catecholic amino acid, l-3,4-dihydroxyphenylalanine (DOPA) has been found to play the major role. These studies continue to inspire the engineering of novel adhesives and coatings with improved underwater performances. Despite the fact that the recent advances of adhesives and coatings inspired by mussel adhesive proteins have been intensively reviewed in literature, the fundamental biochemical and biophysical studies on the origin of the strong and versatile wet adhesion have not been fully covered. In this review, we show how the force measurements at the molecular level by surface force apparatus (SFA) and single molecule atomic force microscopy (AFM) can be used to reveal the direct link between DOPA and the wet adhesion strength of mussel proteins. We highlight a few important technical details that are critical to the successful experimental design. We also summarize many new insights going beyond DOPA adhesion, such as the surface environment and protein sequence dependent synergistic and cooperative binding. We also provide a perspective on a few uncharted but outstanding questions for future studies. A comprehensive understanding on mussel adhesion will be beneficial to the design of novel synthetic wet adhesives for various biomedical applications.
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Affiliation(s)
- Yiran Li
- Shenzhen Research Institute of Nanjing University Shenzhen 518057 China
- Department of Physics, Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Soli State Microstructure, Nanjing University Nanjing 210093 China
| | - Yi Cao
- Shenzhen Research Institute of Nanjing University Shenzhen 518057 China
- Department of Physics, Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Soli State Microstructure, Nanjing University Nanjing 210093 China
- Chemistry and Biomedicine Innovation Center, Nanjing University Nanjing 210093 China
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61
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Faubel JL, Patel RP, Wei W, Curtis JE, Brettmann BK. Giant Hyaluronan Polymer Brushes Display Polyelectrolyte Brush Polymer Physics Behavior. ACS Macro Lett 2019; 8:1323-1327. [PMID: 35651165 DOI: 10.1021/acsmacrolett.9b00530] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Polyelectrolyte brushes are important stimuli-responsive materials in a variety of technological applications as well as in biological systems. Their small size, however, introduces characterization challenges, particularly in studying 3D structure and time-dependent behavior. In this Letter, we report on the polyelectrolyte brush behavior of extra-large hyaluronan brushes (∼15 μm) recently developed using an enzyme-mediated growth process. In response to increasing ionic strength, the brush displays the osmotic brush regime and the salted brush regime. We also show a collapse of 96% when the brush is placed in a poor solvent. This collapse is rapid when changing from a good to poor solvent, but re-expansion is slow when changing back to a good solvent. The observed brush behavior described in this Letter is similar to that seen for smaller polyelectrolyte brushes, indicating that these larger brushes may serve as model systems to study more complex phenomena through confocal microscopy.
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62
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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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63
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Zhu YL, Lu ZY, Li ZW, Sun ZY, Liu X. Effect of the Self-Assembled Structures of Hydrated Polyzwitterionic and Polyanionic Brushes on Their Self-Cleaning Capabilities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6669-6675. [PMID: 31034239 DOI: 10.1021/acs.langmuir.9b00714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The capability of polyelectrolyte brushes to spontaneously clean oil fouling via water is determined by factors including water wettability and the self-assembled structures of hydrated polyelectrolytes. Although the charged groups of polyelectrolytes provide the original source of water wettability, the self-assembled structures play a significant role in the self-cleaning performances. Here, we employ coarse-grained molecular dynamics simulations to study the general self-cleaning characteristics of two types of surface-grafted polyelectrolyte brushes (i.e., zwitterionic and anionic polyelectrolytes). It has been found that the high grafting density is favorable to fouling reduction for both polyzwitterions and polyanions. To be specific, the hydrated polyzwitterions form an intermolecular cross-linked network via zwitterionic complexes, resulting in better self-cleaning capabilities than the polyanions at lower grafting densities. However, polyanions form bundles with each consisting of several chains via hydrophobic interactions and electrostatic repulsions presenting better self-cleaning performances than the polyzwitterions at higher grafting densities.
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Affiliation(s)
- You-Liang Zhu
- State Key Laboratory of Polymer Physics and Chemistry , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022 , China
- University of Science and Technology of China , Hefei 230026 , China
| | | | - Zhan-Wei Li
- State Key Laboratory of Polymer Physics and Chemistry , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022 , China
- University of Science and Technology of China , Hefei 230026 , China
| | - Zhao-Yan Sun
- State Key Laboratory of Polymer Physics and Chemistry , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022 , China
- University of Science and Technology of China , Hefei 230026 , China
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64
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Liu LY, Xia G, Feng ZJ, Hao QH, Tan HG. Self-assembly of polyelectrolyte diblock copolymers at monovalent and multivalent counterions. SOFT MATTER 2019; 15:3689-3699. [PMID: 30888010 DOI: 10.1039/c9sm00028c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this work, the self-assembly behaviors of diblock copolymers consisting of one hydrophobic block and one ionizable polyelectrolyte (PE) block in the presence of monovalent and multivalent counterions are systematically discussed through molecular dynamics simulation. Copolymers are molded as bead-spring chains and the ions are explicitly considered. First, the self-assembled structures of symmetrical block copolymers at different charge fractions are analyzed in detail. Spherical hydrophobic cores are favored by all of the micelles. The effect of counterion valence is much more noticeable at high values of charge fraction. When the PE blocks are fully charged, the presence of multivalent counterions preferably provokes the formation of macroscopic structures. A precipitant spherical micelle is generated in the presence of divalent counterions. Special shapes of coronas are created in the presence of trivalent ions, and a remarkable one dimensional macroscopic cylindrical aggregation of micelles forms; the whole assembly is not typical core-shell micelles, but rather a cylinder with alternating spherical micelles arranged perpendicular to the cylinder axis. The self-assemblies with different lengths of fully charged PE blocks are also discussed. Surprisingly, in the presence of divalent counterions, two dimensional in-plane macroscopic aggregation of micelles is realized when the proportion of PE blocks is larger than 1/2; the self-assembled spherical micelles locate approximately in the same plane to form an inter-linked network. One dimensional aggregation of micelles in the presence of trivalent counterions is maintained with an increased proportion of the PE block. Owing to the dominant intra- and inter-condensation of divalent and trivalent counterions, respectively, two and one dimensional macroscopic aggregation of the micelles is achieved. Our findings indicate that varying the counterion valence is a powerful mechanism to tune the properties of self-assemblies, and the bridging effect introduced by multivalent counterions is the key parameter for the aggregation of the micelles.
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Affiliation(s)
- Li-Yan Liu
- College of Science, Civil Aviation University of China, Tianjin 300300, China.
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65
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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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66
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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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67
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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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68
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Nap RJ, Szleifer I. Effect of calcium ions on the interactions between surfaces end-grafted with weak polyelectrolytes. J Chem Phys 2018; 149:163309. [DOI: 10.1063/1.5029377] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Rikkert J. Nap
- Department of Biomedical Engineering, Department of Chemistry, and Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208-0001, USA
| | - Igal Szleifer
- Department of Biomedical Engineering, Department of Chemistry, and Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208-0001, USA
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69
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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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70
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Xu X, Billing M, Ruths M, Klok HA, Yu J. Structure and Functionality of Polyelectrolyte Brushes: A Surface Force Perspective. Chem Asian J 2018; 13:3411-3436. [PMID: 30080310 DOI: 10.1002/asia.201800920] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Indexed: 11/11/2022]
Abstract
The unique functionality of polyelectrolyte brushes depends on several types of specific interactions, including solvent structure effects, hydrophobic forces, electrostatic interactions, and specific ion interactions. Subtle variations in the solution environment can lead to conformational and surface structural changes of the polyelectrolyte brushes, which are mainly discussed from a surface-interaction perspective in this Focus Review. A brief overview is given of recent theoretical and experimental progress in the structure of polyelectrolyte brushes in various environments. Two important techniques for surface-force measurements are described, the surface forces apparatus (SFA) and atomic force microscopy (AFM), and some recent results on polyelectrolyte brushes are shown. Lastly, this Focus Review highlights the use of these surface-grafted polyelectrolyte brushes in the creation of functional surfaces for various applications, including nonfouling surfaces, boundary lubricants, and stimuli-responsive surfaces.
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Affiliation(s)
- Xin Xu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.,Department of Chemistry, University of Massachusetts Lowell, Lowell, MA, 01854, USA
| | - Mark Billing
- Institut des Matériaux et Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, École Polytechnique Fédérale de Lausanne (EPFL), Bâtiment MXD, Station 12, CH-1015, Lausanne, Switzerland
| | - Marina Ruths
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA, 01854, USA
| | - Harm-Anton Klok
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.,Institut des Matériaux et Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, École Polytechnique Fédérale de Lausanne (EPFL), Bâtiment MXD, Station 12, CH-1015, Lausanne, Switzerland
| | - Jing Yu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore
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71
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Yu J, Jackson NE, Xu X, Morgenstern Y, Kaufman Y, Ruths M, de Pablo JJ, Tirrell M. Multivalent counterions diminish the lubricity of polyelectrolyte brushes. Science 2018; 360:1434-1438. [PMID: 29954973 DOI: 10.1126/science.aar5877] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 05/08/2018] [Indexed: 01/06/2023]
Abstract
Polyelectrolyte brushes provide wear protection and lubrication in many technical, medical, physiological, and biological applications. Wear resistance and low friction are attributed to counterion osmotic pressure and the hydration layer surrounding the charged polymer segments. However, the presence of multivalent counterions in solution can strongly affect the interchain interactions and structural properties of brush layers. We evaluated the lubrication properties of polystyrene sulfonate brush layers sliding against each other in aqueous solutions containing increasing concentrations of counterions. The presence of multivalent ions (Y3+, Ca2+, Ba2+), even at minute concentrations, markedly increases the friction forces between brush layers owing to electrostatic bridging and brush collapse. Our results suggest that the lubricating properties of polyelectrolyte brushes in multivalent solution are hindered relative to those in monovalent solution.
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Affiliation(s)
- J 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
| | - N E Jackson
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.,Institute for Molecular Engineering, Argonne National Laboratory, Lemont, IL 60439, USA
| | - X Xu
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Y Morgenstern
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Y Kaufman
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - M Ruths
- Department of Chemistry, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - J 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
| | - M 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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72
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Affiliation(s)
- Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin and Institute of Physics, Humboldt-Universität zu Berlin, Germany
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73
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Qian C, Asoh TA, Uyama H. Sea cucumber mimicking bacterial cellulose composite hydrogel with ionic strength-sensitive mechanical adaptivity. Chem Commun (Camb) 2018; 54:11320-11323. [DOI: 10.1039/c8cc05779f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A novel sea cucumber-mimicking bacterial cellulose composite hydrogel shows stiffness changes in response to ionic strength without significant volume changes.
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Affiliation(s)
- Chen Qian
- Department of Applied Chemistry
- Graduate School of Engineering
- Osaka University
- Suita
- Japan
| | - Taka-Aki Asoh
- Department of Applied Chemistry
- Graduate School of Engineering
- Osaka University
- Suita
- Japan
| | - Hiroshi Uyama
- Department of Applied Chemistry
- Graduate School of Engineering
- Osaka University
- Suita
- Japan
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