End-Capping Strategies for Triggering End-to-End Depolymerization of Polyglyoxylates

Polymers that undergo end-to-end depolymerization in response to the cleavage of a stimuli-responsive end-cap are promising for diverse applications from drug delivery to responsive coatings and plastics. It is critical that the end-cap is designed to respond to an appropriate stimulus for the application. In the current work, end-caps for triggering the depolymerization of poly(ethyl glyoxylate) (PEtG) were explored. First, a phenylboronate, a disulfide, and an azobenzene were utilized to impart redox-responsive properties to PEtG. Then, methoxy-substituted trityl groups were used to provide sensitivity to mild acid. A multiresponsive platform was also introduced, allowing PEtG to respond to multiple stimuli, either simultaneously or independently. Incorporation of a cross-linkable trialkene end-cap enabled the preparation of networks that could subsequently be depolymerized. Finally, high molar mass PEtG could be depolymerized by mechanical stimulation independent of the end-cap. It is anticipated that ...