Stimuli responsive supramolecular materials for self healing compartmentalization and strain stiffening applications

Abstract

Nature has unprecedented handle over the conformation and dynamics of its macromolecular morphologies. One of the precise example is the finite arrangement of amino acids in living system into a spatial organization by means of chain folding which results in higher order structures that can carry out specific functions like enzymatic catalysis in extremely efficient way. This intricate structure activity relationships observed in biopolymers like proteins has been an inspiration for chemists and material scientists to understand the fundamentals of nature s design. This led us to design synthetic macromolecular architectures by bottom up approach biomimetic applications such as self-healing and compartmentalization. In the quest of designing such nanostructures with intelligent stimuli-response and adaptable nature, we developed single chain polymers utilizing controlled living polymerization and anchored with stimuli responsive moiety e. g. coumarin. We demonstrate intra-chain collapse of the extended coiled chain of the polymer to uniform sized nanoparticles in dilute condition mediated by photo-dimerization of coumarin under UV B light (and#61548; max = 320 nm). At the crowded macromolecular solution the polymer folds in higher order nanostructures with polydispersed topologies that are far from condensed globule or partially swollen globule conformation. The flexo- rigid chain crosslinks has structural analogy with thermoplastic elastomers and prompted us to investigate the thermal and self-healing behaviour of polymers. They show autonomous and intrinsic self-healing at ambient condition, that can be modulated by the photo-crosslinking. Next, thermo-responsive single chain polymers were developed that exhibited chain collapse via coumarin cycloaddition along with host guest interaction by cyclodextrin linker and act as nanocompartments in aqueous environment. The system was utilized for controlled loading of cargo molecules irrespective of their hydrophobicity and triggered their release over heating above lower crit