Covalently cross-linked polymer networks, once formed, cannot generally be reshaped, remolded, or deformed, which is attractive for creating robust materials but severely limits recyclability and repurposing, which is becoming evermore important with the advent of customized materials and devices as well as additive manufacturing. Recently, approaches incorporating dynamic covalent chemistries, particularly reversible exchange reactions, into the cross-links of these polymers challenged this paradigm. A thioester containing cross-link capable of dynamic exchange is reported here which is seamlessly incorporated into nearly any type of network forming polymerization. The thiol-thioester exchange gives rise to rapid bond rearrangement and plastic-like flow observable at ambient temperature in otherwise elastic networks. Based on this exchange reaction’s response to reagents released using photoinduced processes, light-induced switching of material plasticity from OFF to ON and vice versa was achieved. This system was utilized to spatially and temporally control network rearrangement, stress relaxation, and shape changes on scales ranging from 100’s of nm to 10 cm.

Photoinitiated thioester-containing polymer networks: Bistable, photoinduced (de)activation of dynamic covalent chemistry and fluid-solid transitions

256th National Meeting (2018)

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