Investigating Photocurable Thiol-Yne Resins for Biomedical Materials

This study deals with the investigation of photocurable thiol-yne resins covering several important aspects for the production of medical devices by UV-based manufacturing processes. In this context, the performance of different low-toxic photoinitiators (PIs) and stabilizers are evaluated in thiol-yne formulations based on di(but-1-yn-4-yl) carbonate and various multifunctional thiol monomers. Photodifferential scanning calorimetry measurements reveal that the conversion of all resin formulations is mostly independent on the type and concentration of the applied photoinitiator; however, significant differences in their curing speed are observed. It turns out that the migration of an alkyne derivatized photoinitiator is significantly reduced while providing almost similar photoactivity as its nonfunctionalized reference. Moreover, it is found that lauryl gallate and butylated hydroxytoluene lead to significant stabilization without affecting the overall photoreactivity. Notably, the thermomechanical properties of the investigated photopolymers are only slightly affected by water absorption. Using ester free thiols, water absorption can be reduced and hydrolytically stable polymers are realized. These results highlight the versatility of the present thiol-yne system for the production of medical materials by photopolymerization.