Metastable Polymer Adsorption Dictates the Dynamical Gradients at Interfaces

Polymer adsorption proceeds through a wide variety ofmetastablestates due to kinetic constraints originating from the pinning ofsegments on solid interfaces, creating an interfacial adsorption layercomposed of flattened trains, loosely adsorbed loops, and tails of chains. In this work,we show that the metastable structures of adsorption layers developedvia thermal annealing at a temperature above glass-transition temperature T (g) determine the length scale of interfacialmobility gradient dynamics (xi(dyn)). Specifically,we find that 1) the evolution of xi(dyn) mimics thetrend in the slow kinetics of polymer absorption and 2) xi(dyn) grows linearly with the thickness of the overall interfacialadsorption layer. The findings reinforce the idea that the interfacialdynamical gradients are relevant to polymer adsorption and also implythat extension of the loosely adsorbed chains into the film interiorcould facilitate the propagation of suppressed dynamics originatingat the interface.

Automated summary

Polymer adsorption involves various metastable states due to kinetic constraints from solid interfaces, resulting in an interfacial adsorption layer composed of flattened trains, loosely adsorbed loops, and tails of chains. This study demonstrates that the metastable structures of the adsorption layers developed via thermal annealing above the glass-transition temperature T(g) determine the length scale of interfacial mobility gradient dynamics (xi(dyn)). It is found that 1) the evolution of xi(dyn) follows the trend in the slow kinetics of polymer absorption, and 2) xi(dyn) increases linearly with the thickness of the overall interfacial adsorption layer. These findings highlight the relevance of interfacial dynamical gradients to polymer adsorption and suggest that extension of the loosely adsorbed chains into the film interior could enhance the propagation of suppressed dynamics originating at the interface.