Spine-Inspired Fabrication of Polynorbornene Copolymers with Multi-stimulus, Multiple Shape Memory, and Self-Healing Performances

Multiple shape memory polymers (MSMPs), capable of remembering multiple temporary shapes in response to distinct stimuli, hold broad prospects for application. The design of MSMPs generally extends from the concept of dual shape memory polymers, yet innovating methods for their design and preparation remain challenging. In this work, we drew inspiration from the spine and developed an approach for the design and preparation of MSMPs. This approach employs intramolecular hydrogen bonds and resistance among semirigid chains to stabilize all the transition states in situ. The formation of metastable states was used to shape the memory design. Through this strategy, we have synthesized a series of polynorbornene copolymers PNB-mSi-nAc-DCPD (m/n = 3/1, 1/1, or 1/3) with dual- and triple-shape memory effect when subjected to stimuli such as thermal, alcohol/water, and pH. Furthermore, these copolymers demonstrate superior self-healing, mechanical, and easy processing performance, markedly broadening their potential applications.