Ring-Opening Copolymerization of Four-Dimensional Printable Polyesters Using Supramolecular Thiourea/Organocatalysis

Ring-opening copolymerization (ROCOP) of polyesters may be used to achieve a wide variety of functional polymers using commercial monomer libraries, but primarily make use of metallic catalysts such as tin, magnesium, or cobalt complexes. However, the limitations of such catalysts include toxicity risks and environmental concerns for both the desired application, such as biomaterials, and the end-of-life consideration. There is a need for cleaner, friendlier, and less expensive routes to polymeric materials and devices. Therefore, organobase-catalyzed ROCOP is an intriguing opportunity to improve both the safety and the structural control of the resultant polyesters. Here, organobases with and without supramolecular thiourea co-catalysts are demonstrated for ROCOP of functional polyesters made of cis-4-cyclohexene-1,2-dicarboxylic anhydride and allyl glycidol ether, with ROCOP performed in bulk, open-air conditions. The catalysts resulted in molecular weights of >25 kDa while maintaining controlled polymerization behaviors and a dispersity of <1.3. The role of the thiourea co-catalysts is further explored, with a proposed mechanism for initiation of the ROCOP system. The resultant polyesters are utilized in vat polymerization four-dimensional (4D) printing using thiol-ene cross-linking to manufacture complex prototypes that display shape memory. The role of molecular weight on physical properties, including mechanical and thermal behaviors, is explored along with hydrolytic degradation rates, shape memory responsiveness, and cytocompatibility. Ultimately, the use of organobase catalysis for ROCOP of polyester photopolymer is shown to be an efficient, tunable method of controlling resultant physical properties for improving the environmental friendliness, as well as biomaterial potential

Additional file 2: of Diabetes educator role boundaries in Australia: a documentary analysis

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Translating research into rural health practice: a qualitative study of perceived capability building needs

Translating research into rural health practice: a qualitative study of perceived capability building need