Photoactivated Healable Vitrimeric Copolymers

A composite polymer based on vinylogous urethane vitrimer bonding with both photodimerizable and thermally exchangeable functionalities is described. Polymers containing various ratios of photodimerizable diaminoanthracene monomers and thermally exchangeable diaminoalkyl monomers linked by a common bisacetoacetate group are studied. It is demonstrated that alkyl amines undergo the necessary thermal exchange reactions for vinylogous urethane vitrimers, while aromatic amines do not. UV-induced dimerization of the anthracene units results in changes to the rheological properties and the glass transition temperature due to polymer cross-linking. Rapid and near-complete scratch healing upon heating is demonstrated, with a tunable onset temperature for healing controlled by UV irradiation. The viability of a composite vitrimeric system, wherein vitrimeric monomers are combined with non-vitrimeric, stimuli-responsive monomers to generate random copolymers with new properties, is demonstrated.