Fine-Tuning the Structure of Stimuli-Responsive Polymer Films by Hydrostatic Pressure and Temperature

Abstract

The response of stimuli-responsive polymer brushes to moderately elevated pressure is investigated by neutron reflectivity and a thermodynamically consistent density functional theory where pressure effects are included by a hydrophobic cavity model. Evidence is provided that temperature and pressure effects on the brush spatial structure are entirely antagonistic. A ∼100 bar/K cancellation effect is found, which we argue is a general feature for hydrophobically associating homopolymers and serves for experimental guidance and fine-control of polymer film structure. Our results also suggest that polymeric interfaces which do not show a marked temperature dependence are also rather insensitive to pressure effects for applied pressures below 1 kbar.

Thermal Compaction of Disordered and Elastin-like Polypeptides: A Temperature-Dependent, Sequence-Specific Coarse-Grained Simulation Model

“…Similar behavior has recently been evidenced from statistical mining of protein structures at different temperatures 80 . However, while the temperature-dependence of hydrophobic interactions is widely acknowledged to be of critical importance in the phase behavior of both folded and disordered polypeptide sequences, and generally for thermoresponsive hydrophobic polymers [94][95][96] , explicit temperature-dependence of pairwise hydrophobic interactions is not conventionally used in CG models [97][98][99][100][101][102] because of the challenges in the consistent thermodynamic mapping of the atomistic degrees of freedom to the CG representation [65][66][67] .…”

Stimulated Transitions of Directed Nonequilibrium Self‐Assemblies

“…[28] Theoretically, this effect can be explained by the pressure-induced decrease of the volume of the solventinaccessible cavities, which are formed by hydrophobic interactions. [29] This study also demonstrates that pressure and temperature act antagonistically. Beneficially, hydrostatic pressure can be applied and released more rapidly than temperature variations, pressure propagates uniformly and can be readily applied bidirectionally, i.e.…”

“…joints upon impact/jumping). [29] Herein, we demonstrate a directed formation of various diblock terpolymer nanostructures in A facile RAFT aqueous polymerization system ( Figure 1A) is utilized to synthesize equilibrium/non-equilibrium structures by simply changing the polymerization formulation.…”

Tuning the critical solution temperature of polymers by copolymerization

“…This behavior is found to be a universal feature of all polymers defined in Table I and Table II as we employ temperature-independent pair potentials. As discussed in literature, e.g., on thermosensitive polymer systems, 35 an explicitly temperature-dependent effective pair potential is needed (typically originating from hydrophobic interactions [32][33][34][35] ) to obtain a lower CST (LCST) behavior.…”