In Situ Variation of Interpenetrating Polymer Network Topology using a Photolabile Connector.

A photo-controlled approach is developed to regulate the interpenetrating polymer network (IPN) topology by varying the connecting structure between the first and second networks. The approach is based on multifunctional inimer (Vinyl-oNB-Br) possessing three moieties, i.e., an acrylate-based double bond for incorporation within a polymer network, a Br group for grafting polymerization to get connect-IPN (c-IPN), and an o-nitrobenzyl spacer for photocleaving to convert the c-IPN to disconnected-IPN (d-IPN) with UV light irradiation. Such design allows for finely controlling the connection degree between two networks. A systematic study on the mechanical property of a series of samples with different connection degrees thus can be conducted. The results reveal that decreasing the connecting degree between two networks of IPN made a negligible contribution to materials' mechanical properties. [ABSTRACT FROM AUTHOR]