Relaxation dynamics of polymers under soft confinement

Abstract

Soft materials under nanoscopic confinement exhibit a range of fascinating properties owing to the reduced degrees of freedom and modified molecular interactions. Here, we report the temperature dependent structural relaxation dynamics of the bio-polymer gelatin in solid as well as in hydrated form and also under soft-spatial confinement, probed using dielectric relaxation spectroscopy. The soft confinement of hydrated gelatin is achieved by enclosing the polymer inside the droplet core of water-AOT-n-decane reverse microemulsions, where the fluctuating surfactant shell constitutes the soft confining boundary. The stability of the droplet phase of microemulsion loaded with gelatin polymer is confirmed from the small-angle neutron scattering experiments. Notably, the hydrated gelatin exhibits faster relaxation dynamics in comparison to the bulk gelatin in solid form and the dynamics further get accelerated under soft-spatial confinement provided by the microemulsions. The enhancement in the relaxation dynamics of gelatin polymer in soft confinement is presumably originating from the proximity induced co-operativity with the enclosing surfactant shell which undergoes thermal fluctuations. Our observations demonstrate that the properties of the confining boundary strongly influence the dynamics of the enclosed material.