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Zhou T, Zhao J, He X, Shi L, Wen L. Effect of brush roughness on volume charge density. J Electroanal Chem (Lausanne) 2023. [DOI: 10.1016/j.jelechem.2023.117368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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Polymer brushes for friction control: Contributions of molecular simulations. Biointerphases 2023; 18:010801. [PMID: 36653299 DOI: 10.1116/6.0002310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
When polymer chains are grafted to solid surfaces at sufficiently high density, they form brushes that can modify the surface properties. In particular, polymer brushes are increasingly being used to reduce friction in water-lubricated systems close to the very low levels found in natural systems, such as synovial joints. New types of polymer brush are continually being developed to improve with lower friction and adhesion, as well as higher load-bearing capacities. To complement experimental studies, molecular simulations are increasingly being used to help to understand how polymer brushes reduce friction. In this paper, we review how molecular simulations of polymer brush friction have progressed from very simple coarse-grained models toward more detailed models that can capture the effects of brush topology and chemistry as well as electrostatic interactions for polyelectrolyte brushes. We pay particular attention to studies that have attempted to match experimental friction data of polymer brush bilayers to results obtained using molecular simulations. We also critically look at the remaining challenges and key limitations to overcome and propose future modifications that could potentially improve agreement with experimental studies, thus enabling molecular simulations to be used predictively to modify the brush structure for optimal friction reduction.
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Higaki Y, Furusawa R, Otsu T, Yamada NL. Zwitterionic Poly(carboxybetaine) Brush/Albumin Conjugate Films: Structure and Lubricity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9278-9284. [PMID: 35866870 DOI: 10.1021/acs.langmuir.2c01040] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Artificial cartilages build up a highly lubricious system with the harmony of biomacromolecules and water. Bioconjugate thin films composed of a zwitterionic poly(carboxybetaine methacrylate) (PCB) brush platform and bovine serum albumin (BSA) were designed. BSA conjugation to the PCB brush chains was achieved by carbodiimide chemistry to give PCB brush/BSA conjugate films. The PCB brush/BSA conjugate films exhibited adaptable interfacial properties due to the amphiphilic nature of BSA. Neutron reflectivity showed that BSAs were localized at the liquid side of the conjugate films in PBS and the BSA conjugation slightly reduced the water content of the top layer, while the swollen state of the carpet PCB brush layer remained unchanged. The PCB brush/BSA conjugate films showed improved lubricity in the boundary lubrication mode but slightly worse fluid lubrication induction properties. This conjugate film could be a model system for the investigation of zwitterion/protein composite interfaces and is worth developing biomaterials that require lubrication in vivo.
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Affiliation(s)
- Yuji Higaki
- Department of Integrated Science and Technology, Faculty of Science and Technology, Oita University, 700 Dannoharu, Oita 870-1192, Japan
| | - Riku Furusawa
- Graduate School of Engineering, Oita University, 700 Dannoharu, Oita 870-1192, Japan
| | - Takefumi Otsu
- Department of Innovative Engineering, Faculty of Science and Technology, Oita University, 700 Dannoharu, Oita 870-1192, Japan
| | - Norifumi L Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Ibaraki 305-0801, Japan
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Shi Y, Mudugamuwa CJ, Abeysinghe TN, Alotaibi YSM, Monteiro MJ, Chalker JM, Lutkenhaus JL, Jia Z. Ionic Effect on Electrochemical Behavior of Water-Soluble Radical Polyelectrolytes. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yanlin Shi
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane Queensland 4072, Australia
| | - Chanaka J. Mudugamuwa
- Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Thidas N. Abeysinghe
- Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Yasser S. M. Alotaibi
- Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Michael J. Monteiro
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane Queensland 4072, Australia
| | - Justin M. Chalker
- Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Jodie L. Lutkenhaus
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Zhongfan Jia
- Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Bedford Park, South Australia 5042, Australia
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Copp SM, Hamblin RL, Swingle K, Rai D, Urban VS, Ivanov SA, Montaño GA. Complex pH-Dependent Interactions between Weak Polyelectrolyte Block Copolymer Micelles and Molecular Fluorophores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2038-2045. [PMID: 35119286 DOI: 10.1021/acs.langmuir.1c02889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Amphiphilic block copolymers with weak polyelectrolyte blocks can assemble stimulus-responsive nanostructures and interfaces. Applications of these materials in drug delivery, biomimetics, and sensing largely rely on the well-understood swelling of polyelectrolyte chains upon deprotonation, often induced by changes in pH or ionic strength. This deprotonation can also tune interfacial interactions between the polyelectrolyte blocks and surrounding solution, an effect which is less studied than morphological swelling of polyelectrolytes but can be just as critical for intended function. Here, we investigate whether the pH-driven morphological response of polyelectrolyte-bearing nanostructures also affects the interactions of these nanostructures with molecules in solution, using micelles of a short-chain polybutadiene-block-poly(acrylic acid) (pBd-pAA) as a model system. We introduce a Förster resonance energy transfer (FRET) approach to probe interactions between micelles and fluorescent molecular solutes as a function of solution pH. As expected, the pAA corona of these pBd-pAA micelles increases in thickness monotonically as a function of pH. However, FRET efficiency, which provides a metric of the spatial proximity of fluorescently labeled micelles and freely diffusing fluorophores, exhibits complex nonmonotonic behavior as a function of pH, indicating that the average separation of micelles and acceptor fluorophores is not strictly correlated with micelle swelling. Dialysis experiments quantify the affinity of fluorophores for micelles as a function of pH, confirming that changes in FRET are driven almost entirely by the pH-dependent affinity of the pAA block for the investigated molecular fluorophores, not simply by a shape change of the pAA corona. This study provides key insights into the interfacial interactions between weak-polyelectrolyte-bearing nanostructures and molecular solutes, of importance for the development of their stimulus-responsive applications.
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Affiliation(s)
- Stacy M Copp
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697-2585, United States
- Department of Physics and Astronomy, University of California, Irvine, Irvine, California 92697-4575, United States
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697-2580, United States
| | - Ryan L Hamblin
- Center for Integrated Nanotechnologies, Los Alamos National Laboratories, Los Alamos, New Mexico 87545, United States
| | - Kirstie Swingle
- Center for Integrated Nanotechnologies, Los Alamos National Laboratories, Los Alamos, New Mexico 87545, United States
| | - Durgesh Rai
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Volker S Urban
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Sergei A Ivanov
- Center for Integrated Nanotechnologies, Los Alamos National Laboratories, Los Alamos, New Mexico 87545, United States
| | - Gabriel A Montaño
- Department of Applied Physics and Materials Science, Northern Arizona University, Flagstaff, Arizona 86011, United States
- Center for Materials Interfaces in Research and Applications, Northern Arizona University, Flagstaff, Arizona 86011, United States
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