Alladi Ramakrishnan Hall

Nonequilibrium Properties of Polymer Films

Sivasurender Chandran

IIT Kanpur

Rapid processing often freeze polymers in nonequilibrium conformations, which, in turn, manifest into material properties that differ significantly from the predictions of equilibrium theories. This suggest that controlling processing pathways may provide a lever to control properties of polymers. However, our understanding of the correlations between processing pathways and emerging macroscopic properties, and microscopic reasons underlying the observed deviations in properties are still elusive. Thus, we often rely on empirical relations, imposing a trial-and-error approach, to achieve desired material properties. Considering these aspects, I will discuss our recent efforts, based on spin-coated polymer films, revealing the existence of scaling relations between chain conformations inherited during preparation and their macroscopic mechanical properties like residual stresses, their relaxation times, and the probability of film rupture. Such quantitative correlations allowed us to propose that the rapid processing stages induce long-living molecular correlations, which might be the microscopic origin underlying the long lifetime of nonequilibrium phenomena observed in polymer films. Such detailed understanding allowed us to control the crystallization kinetics and viscoelastic properties of polymer films in a predictable way.