Stimulus-responsive polymer brushes on surfaces: Transduction mechanisms and applications

Chen, Tao; Ferris, Robert L.; Zhang, Jianming; Ducker, Robert E.; Zauscher, Stefan

doi:10.1016/j.progpolymsci.2009.11.004

Cited by 355 publications

(310 citation statements)

References 134 publications

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“…Since the thickness of brush layers is typically in the nanometer range, they are interesting for the design of functional surfaces [3][4][5] with applications in a wide variety of areas ranging from colloidal stabilization [6], lubrication [7], controlled friction and adhesion [8], anti-fouling [9], biocompatibility [10], drug delivery [11], and smart stimuli-responsive materials [4]. In this respect, multicomponent polymer brushes are particularly promising [4,5]. If the brush chains are covalently bound to the substrate, they cannot phase separate on a global scale, but they can still develop structure on the Stimuli-induced phase separation provides the basic mechanism for the change in the brush surface properties depending on which of the two microphases forms the outer part of the brush.…”

Section: Introductionmentioning

confidence: 99%

Stimuli-Responsive Brushes with Active Minority Components: Monte Carlo Study and Analytical Theory

Klushin

Skvortsov

et al. 2015

Macromolecules

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Using a combination of analytical theory, Monte Carlo simulations, and three dimensional selfconsistent field calculations, we study the equilibrium properties and the switching behavior of adsorption-active polymer chains included in a homopolymer brush. The switching transition is driven by a conformational change of a small fraction of minority chains, which are attracted by the substrate. Depending on the strength of the attractive interaction, the minority chains assume one of two states: An exposed state characterized by a stem-crown-like conformation, and an adsorbed state characterized by a flat two-dimensional structure. Comparing the Monte Carlo simulations, which use an Edwards-type Hamiltonian with density dependent interactions, with the predictions from self-consistent-field theory based on the same Hamiltonian, we find that thermal density fluctuations affect the system in two different ways. First, they renormalize the excluded volume interaction parameter v bare inside the brush. The properties of the brushes can be reproduced by self-consistent field theory if one replaces v bare by an effective parameter veff, where the ratio of second virial coefficients Beff/B bare depends on the range of monomer interactions, but not on the grafting density, the chain length, and v bare . Second, density fluctuations affect the conformations of chains at the brush surface and have a favorable effect on the characteristics of the switching transition: In the interesting regime where the transition is sharp, they reduce the free energy barrier between the two states significantly. The scaling behavior of various quantities is also analyzed and compared with analytical predictions.

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Section: Introductionmentioning

confidence: 99%

Stimuli-Responsive Brushes with Active Minority Components: Monte Carlo Study and Analytical Theory

Klushin

Skvortsov

et al. 2015

Macromolecules

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“…They find important applications in colloid stabilization, lubrication, and developments where friction [4], adhesion and wetting properties are important [1]. They are also used as coatings in "smart surfaces" to fine tune reversibly some property of an interface upon changes in external stimuli, for example, PH [5], temperature, solvent quality [6,7]. Brushes are at the forefront of recent developments, ranging from responsive bio-interphases, controlled drug-delivery and release systems, thin films and particles, which act as sensors of minute amounts of analytes [3,6].…”

Section: Introductionmentioning

confidence: 99%

Brushes of semiflexible polymers in equilibrium and under flow in a super-hydrophobic regime

Speyer

Pastorino

2015

Soft Matter

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We performed molecular dynamics simulations to study equilibrium and flow properties of a liquid in a nano-channel with confining surfaces coated with a layer of grafted semiflexible polymers. The coverage spans a wide range of grafting densities from essentially isolated chains to dense brushes. The end-grafted polymers were described by a bead spring model with an harmonic potential to include the bond stiffness of the chains. We varied the rigidity of the chains, from fully flexible polymers to rigid rods, in which the configurational entropy of the chains is negligible. The brushliquid interaction was tuned to obtain a super-hydrophobic channel, in which the liquid did not penetrate the polymer brush, giving rise to a Cassie-Baxter state. Equilibrium properties such us brush height and bending energy were measured, varying the grafting density and the stiffness of the polymers. We studied also the characteristics of the brush-liquid interface and the morphology of the polymers chains supporting the liquid for different bending rigidities. Non-equilibrium simulations were performed, moving the walls of the channel in opposite directions at constant speed, obtaining a Couette velocity profile in the bulk liquid. The molecular degrees of freedom of the polymers were studied as a function of the Weissenberg number. Also, the violation of the no-slip boundary condition and the slip properties were analyzed as a function of the shear rate, grafting density and bending stiffness. At high grafting densities, a finite slip length independent of the shear rate or bending constant was found, while at low grafting densities a very interesting non-monotonic behaviour on the bending constant is observed.

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“…Some polymer brushes are environment-sensitive, with specific changes in solvent conditions triggering their expansion or collapse. These materials can be used to exert dynamic control over the spatial presentation of regulatory peptides and are under investigation for many applications 4,5 , including sensors 6 , flow valves 7 and controlled drug release systems 8 . However, because these brushes are almost universally constructed from synthetic polymers, they are frequently somewhat heterogeneous and are challenging to modify at specific monomeric positions along the chain.…”

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confidence: 99%

Stimuli-sensitive intrinsically disordered protein brushes

et al. 2014

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Grafting polymers onto surfaces at high density to yield polymer brush coatings is a widely employed strategy to reduce biofouling and interfacial friction. These brushes almost universally feature synthetic polymers, which are often heterogeneous and do not readily allow incorporation of chemical functionalities at precise sites along the constituent chains. To complement these synthetic systems, we introduce a biomimetic, recombinant intrinsically disordered protein that can assemble into an environment-sensitive brush. This macromolecule adopts an extended conformation and can be grafted to solid supports to form oriented protein brushes that swell and collapse dramatically with changes in solution pH and ionic strength. We illustrate the value of sequence specificity by using proteases with mutually orthogonal recognition sites to modulate brush height in situ to predictable values. This study demonstrates that stimuli-responsive brushes can be fabricated from proteins and introduces them as a new class of smart biomaterial building blocks.

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Stimulus-responsive polymer brushes on surfaces: Transduction mechanisms and applications

Cited by 355 publications

References 134 publications

Stimuli-Responsive Brushes with Active Minority Components: Monte Carlo Study and Analytical Theory

Stimuli-Responsive Brushes with Active Minority Components: Monte Carlo Study and Analytical Theory

Brushes of semiflexible polymers in equilibrium and under flow in a super-hydrophobic regime

Stimuli-sensitive intrinsically disordered protein brushes

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