Topological alternation from structurally adaptable to mechanically stable crosslinked polymer

Stimuli-responsive polymers with complicated but controllable shape-morphing behaviors are
critically desirable in several engineering fields. Among the various shape-morphing materials,
cross-linked polymers with exchangeable bonds in dynamic network topology can undergo
on-demand geometric change via solid-state plasticity while maintaining the advantageous
properties of cross-linked polymers. However, these dynamic polymers are susceptible to creep
deformation that results in their dimensional instability, a highly undesirable drawback that
limits their service longevity and applications. Inspired by the natural ice strategy, which
realizes creep reduction using crystal structure transformation, we evaluate a dynamic crosslinked polymer with tunable creep behavior through topological alternation. This alternation
mechanism uses the thermally triggered disulfide–ene reaction to convert the network topology – from dynamic to static – in a polymerized bulk material. Thus, such a dynamic polymer
can exhibit topological rearrangement for thermal plasticity at 130°C to resemble typical
dynamic cross-linked polymers. Following the topological alternation at 180°C, the formation
of a static topology reduces creep deformation by more than 85% in the same polymer. Owing
to temperature-dependent selectivity, our cross-linked polymer exhibits a shape-morphing
ability while enhancing its creep resistance for dimensional stability and service longevity after
sequentially topological alternation. Our design enriches the design of dynamic covalent
polymers, which potentially expands their utility in fabricating geometrically sophisticated
multifunctional devices.