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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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Lang M, Scholz R, Löser L, Bunk C, Fribiczer N, Seiffert S, Böhme F, Saalwächter K. Swelling and Residual Bond Orientations of Polymer Model Gels: The Entanglement-Free Limit. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael Lang
- Leibniz Institut für Polymerforschung, Hohe Straße 6, 01069 Dresden, Germany
| | - Reinhard Scholz
- Leibniz Institut für Polymerforschung, Hohe Straße 6, 01069 Dresden, Germany
| | - Lucas Löser
- Martin-Luther Universität Halle-Wittenberg, Institute of Physics − NMR Group, Betty-Heimann-Straße 7, D-06120 Halle/Saale, Germany
| | - Carolin Bunk
- Leibniz Institut für Polymerforschung, Hohe Straße 6, 01069 Dresden, Germany
- Organic Chemistry of Polymers, Technische Universität Dresden, 01062 Dresden, Germany
| | - Nora Fribiczer
- Johannes Gutenberg University Mainz, Department of Chemistry, Duesbergweg 10−14, D-55128 Mainz, Germany
| | - Sebastian Seiffert
- Johannes Gutenberg University Mainz, Department of Chemistry, Duesbergweg 10−14, D-55128 Mainz, Germany
| | - Frank Böhme
- Leibniz Institut für Polymerforschung, Hohe Straße 6, 01069 Dresden, Germany
| | - Kay Saalwächter
- Martin-Luther Universität Halle-Wittenberg, Institute of Physics − NMR Group, Betty-Heimann-Straße 7, D-06120 Halle/Saale, Germany
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3
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Müller T, Sommer JU, Lang M. Tendomers - force sensitive bis-rotaxanes with jump-like deformation behavior. SOFT MATTER 2019; 15:3671-3679. [PMID: 30950476 DOI: 10.1039/c9sm00292h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We consider tendomers, which are formed by pairs of rotaxane molecules where each one consists of a linear chain with N Kuhn segments that are threaded through m + 1 small rings. These rings can slide freely along the chains but cannot pass through each other or detach from the chain. By crosslinking the first slide rings of the two rotaxanes a slip-link between the two polymer backbones is formed. The remaining m slide rings form a one-dimensional real gas confined between the slip-link and the other chain end. When pulling the two ends of the chains which are next to the slip-link, an applied external force causes a compression of the slide rings. We consider the exact partition function of this model taking into account the repulsion between the slide rings and the finite extensibility of the polymer chains which is compared with Monte-Carlo simulation data for the tendomer under external force. To understand the underlying physics of the tendomer, we discuss also a simplified thermodynamic approach by taking into account the interplay between chain deformation and compression of the gas of slide rings. We show that tendomers exhibit a jump like mechanical response at a critical pulling force ∝ (m/N)1/2, where the compression of the gas of slide rings sets is. While the tendomer deforms at low forces similar to a short chain of about 2(N - m)/(m + 2) segments, it displays a jump-like decrease in elasticity beyond the critical force and deforms then like a chain of about 2(N - m) segments, before the finite extensibility of the chains sets in. This results in a strong peak of the mechanical susceptibility of the tendomer as a function of the applied force. Thus, tendomers are molecular-elastic elements with a jump-like strain-softening behavior. Our results are generalized to asymmetric tendomers that differ in the number of slide rings per rotaxane, which allows to design multi-step force extension curves with defined critical forces. Finally, we discuss some aspects of gels formed by tendomers, which are promising candidates for tailor-made stress sensitive elastomers.
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Affiliation(s)
- Toni Müller
- Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden, Hohe Straße 6, 01069 Dresden, Germany.
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4
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Wengenmayr M, Dockhorn R, Sommer JU. Multicore Unimolecular Structure Formation in Single Dendritic–Linear Copolymers under Selective Solvent Conditions. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01712] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Martin Wengenmayr
- Leibniz Institute
of Polymer Research Dresden, Hohe Strasse
6, 01069 Dresden, Germany
- Institute
for Theoretical Physics, Technische Universität Dresden, 01069 Dresden, Germany
| | - Ron Dockhorn
- Leibniz Institute
of Polymer Research Dresden, Hohe Strasse
6, 01069 Dresden, Germany
- Institute
for Theoretical Physics, Technische Universität Dresden, 01069 Dresden, Germany
| | - Jens-Uwe Sommer
- Leibniz Institute
of Polymer Research Dresden, Hohe Strasse
6, 01069 Dresden, Germany
- Institute
for Theoretical Physics, Technische Universität Dresden, 01069 Dresden, Germany
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Affiliation(s)
- M. Lang
- Leibniz-Institut für Polymerforschung
Dresden e.V., Hohe Str. 6, D-01069 Dresden, Germany
| | - M. Werner
- Leibniz-Institut für Polymerforschung
Dresden e.V., Hohe Str. 6, D-01069 Dresden, Germany
| | - R. Dockhorn
- Leibniz-Institut für Polymerforschung
Dresden e.V., Hohe Str. 6, D-01069 Dresden, Germany
| | - T. Kreer
- Leibniz-Institut für Polymerforschung
Dresden e.V., Hohe Str. 6, D-01069 Dresden, Germany
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7
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Kreer T. Polymer-brush lubrication: a review of recent theoretical advances. SOFT MATTER 2016; 12:3479-3501. [PMID: 27029521 DOI: 10.1039/c5sm02919h] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This review compiles recent theoretical advances to describe compressive and shear forces of polymer-brush bilayers, which consist of two opposing brushes in contact. Such model systems for polymer-brush lubrication are frequently used as a benchmark to gain insight into biological problems, e.g., synovial joint lubrication. Based on scaling theory, I derive conformational and collective properties of polymer-brush bilayers in equilibrium and out-of-equilibrium situations, such as shear forces in the linear and nonlinear response regimes of stationary shear and under non-stationary shear. Furthermore, I discuss the influence of macromolecular inclusions and electrostatic interactions on polymer-brush lubrication. Comparisons to alternative analytical approaches, experiments and numerical results are performed. Special emphasis is given to methods for simulating polymer-brush bilayers using molecular dynamics simulations.
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Affiliation(s)
- T Kreer
- Leibniz-Institut für Polymerforschung Dresden, Hohe Straße 6, 01069 Dresden, Germany.
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Zhulina EB, Leermakers FAM, Borisov OV. Ideal Mixing in Multicomponent Brushes of Branched Polymers. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b01722] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Ekaterina B. Zhulina
- Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg 199004, Russia
- St. Petersburg National University of Informational Technologies, Mechanics and Optics, St. Petersburg 197101, Russia
| | - Frans A. M. Leermakers
- Laboratory of Physical Chemistry and Colloid Science, Dreijenplein 6, 6703 HB Wageningen, The Netherlands
| | - Oleg V. Borisov
- Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg 199004, Russia
- St. Petersburg National University of Informational Technologies, Mechanics and Optics, St. Petersburg 197101, Russia
- Institut des Sciences Analytiques et de Physico-Chimie pour l’Environnement
et les Matériaux, CNRS, Université de Pau et des Pays de l’Adour UMR 5254, 64053 Pau, France
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Romeis D, Sommer JU. Binary and Bidisperse Polymer Brushes: Coexisting Surface States. ACS APPLIED MATERIALS & INTERFACES 2015; 7:12496-12504. [PMID: 25723841 DOI: 10.1021/am507959k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In the present work, we consider polydispersity effects on a mixed polymer brush. Two types of polymer chains with different solvent selectivity being densely grafted together onto an impenetrable surface are forming a binary mixed polymer brush. Using a numerical quasi off-lattice self-consistent field method for heterogeneous chains we study the brush profile upon varying the strength of solvent selectivity (e.g., temperature) and the degree of polymerization of the two chain types (N1 and N2, respectively). For a monodisperse brush (N1 = N2) it is well-known, that the two types of polymers segregate into a two-layer structure, if the difference in solvent selectivity is increased. The state where the chains exposed to their good solvent forming the top layer of the brush can be frustrated for shorter chains and an inversion of the layering takes place. In the inverted state, the top layer is formed by long chains exposed to poor solvent covering the layer of shorter chains. By varying the solvent selectivity of the long chains we show that coexistence of the two states occurs,which indicates a discontinuous phase transition scenario for the switching process. We consider further the case of a very low fraction of short chains and find these chains to undergo a conformational transition of first order from a "coil" state, found deep inside the compact brush layer, to a "flower" state, stretching to the top of the brush upon varying the strength of the solvent selectivity. At the transition both states are found to be quasi-stable with an energy barrier of the order of the chain length in units of kBT. The discontinuous nature of the switching process by combining solvent selectivity and bidispersity can be of high interest for the creation of stimuli-responsive surfaces.
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Affiliation(s)
- Dirk Romeis
- †Leibniz-Institut fuer Polymerforschung Dresden e.V., Hohe Strasse 6, 01069 Dresden, Germany
| | - Jens-Uwe Sommer
- †Leibniz-Institut fuer Polymerforschung Dresden e.V., Hohe Strasse 6, 01069 Dresden, Germany
- ‡Institut fuer Theoretische Physik, Technische Universitaet Dresden, 01069 Dresden, Germany
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Chen C, Tang P, Qiu F, Shi AC. Excluded volume effects in compressed polymer brushes: A density functional theory. J Chem Phys 2015; 142:124904. [PMID: 25833606 DOI: 10.1063/1.4916133] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Affiliation(s)
- Cangyi Chen
- The State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
| | - Ping Tang
- The State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
| | - Feng Qiu
- The State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University, Shanghai 200433, China
| | - An-Chang Shi
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
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