Entropy-enthalpy compensation (EEC) effect signifies a linear correlation between the activation parameters of a relaxation process and is routinely observed in the dynamics of many condensed materials such as molecular additives and glass-forming materials. Herein we present relaxation behaviour of nanoparticle-brush filled imprinted polymer films showing similar compensation effect leading to slower decay kinetics above the compensation temperature (Tcomp) compared to the neat polymer film. The compensation of the activation enthalpy with the entropy of activation led to the observed increase in the relaxation time constant with concentration above Tcomp. Kinetics of structural decay in imprinted thin films of polymethyl methacrylate (PMMA) matrix with different nanoparticle-brush systems (PMMA-grafted TiO2 and PMMA-grafted SiO2) were investigated and EEC was robustly observed for both the systems. This is the first experimental study of structural decay (“slumping”) of a patterned nanocomposite film and the relaxation behaviour witnessed here is similar to relaxation dynamics of ultrathin wrinkled polymer films. Our results suggest a common origin of EEC behaviour in patterned thin films and provides a simple nanoparticle additive strategy to tune the structural stability.

Underlying entropy-enthalpy compensation effect in relaxation dynamics of imprinted polymer surfaces

2019 Fall National Meeting

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