Design of well-defined shape memory networks with high homogeneity: towards advanced shape memory polymeric materials

Designing precisely defined network architecture that could integrate desired material properties into a single network is a great challenge for the development of advanced polymeric materials. For thermally induced shape memory polymers, rapid response, controllable recovery in a narrow temperature window and a large achievable number of cycles are critical for their applications. Here, we report the synthesis of a well-defined shape memory network with high homogeneity via efficient step-growth thiol-norbornene photopolymerization. Because of the uniform distribution of the switch segments and netpoints, the single polymer network exhibits a combination of perfect shape fixity and recovery, rapid response, outstanding cycle life at the high strain and unusual tunable multiple shape memory effects in a narrow temperature range, which may lead to an even more diverse range of applications.