Evidence of Cooperativity among van der Waals Interactions in Segmented Polysiloxane

The cooperativity of van der Waals interactions in biomolecules and supramolecular assemblies has drawn significant scientific attention due to its offering of seamless opportunities to generate new materials. However, the potential of such cooperativity in synthetic polymers has not yet been explored. In this study, we demonstrate a strategy to achieve cooperativity via enhancement of weak interactions in a designed siloxane copolymer. Segmentation of siloxane copolymer with specific alkyl chain length (C18) induces cooperativity in van der Waals interaction among the alkyl chains, resulting in interdigitated as well as end-to-end packing. The cooperativity of van der Waals interactions is also evident by an excess melting enthalpy of ΔH = 1.86 kJ/mol in the designed block siloxane copolymer as compared to its control counterpart, i.e., a compositionally similar random siloxane copolymer. The dynamic relationship of cooperativity and physical properties is established by various analytical tools and further substantiated by disturbing the regularity of the block segments using a trace amount (1 per 99 octadecyl units) of a dissimilar alkyl chain as “dopant”.