With a wide array of formulations, chemistries and mechanisms to choose from, the science of making a stimuli responsive material has been studied and documented extensively over the past decade. In particular, the benefits of forming smart polymers that respond to irradiation have been widely studied as the ability to trigger a response based on light exposure provides spatiotemporal control to the process. Herein, we focus on the reaction processes and secondary functionalities that are incorporated into networks to enable light initiated, tunable dynamic covalent chemistry within these polymer systems. Shape memory polymers (SMPs) with network properties such as high and tunable glass transition temperatures, multiple shape memory transitions, shape memory composites and two-way transition materials are recent examples of new directions that have been undertaken within the broad field of ‘smart’ materials. Among these new directions, the ability to reshape and resize materials repeatedly is particularly appealing. Such shape manipulations are desirable from the standpoint of SMP applications, especially those requiring the excellent mechanical properties of thermosets. The concept of photoinduced addition-fragmentation chain transfer (AFCT) enables Covalent Adaptable Networks (CANs) in which the presence of photochemically active moieties can be used to induce network rearrangement in a controlled manner. Adopting this concept, it is demonstrated that by incorporating the photochemically active monomers, crosslinked polymer networks can then be induced to repeatedly undergo covalent bond rearrangement, and hence bulk material rearrangement. The fundamental mechanisms, benefits and opportunities associated with these smart materials with photoinducable dynamic covalent chemistry will be highlighted.

Photoinducing dynamic covalent chemistry in covalent adaptable networks:  Addition fragmentation for material reconfiguration<i> </i>

256th National Meeting (2018)

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