Investigating Photocurable Thiol‐Yne Resins for Biomedical Materials

Abstract

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.

Electrical Characterization of Thin PEDOT:PSS Films on Alumina and Thiol–Ene Substrates

“…However, above a relative humidity of 70%, the rate of the change in resistance increased significantly and reached up to 0.31%/%RH. The main reason for this can be explained by swelling of the thiol-ene substrate at higher relative humidity due to the polarity and affinity to water of the ester groups present in the thiol crosslinker (PETMP) [53]. The total increase in resistance in the range from 30 to 90% of the relative humidity did not exceed 2.66% and 8.10% for the samples on alumina and thiol-ene substrates, respectively.…”

Synthesis and Characterization of Alkyne-Functionalized Photo-Cross-Linkable Polyesters

“…Premature thiol–yne addition is caused by peroxide impurities in the thiol cross-linkers, as well as by radicals spontaneously generated by atmospheric oxygen. 9 Meanwhile, 10% PAPS ( M n = 4274 g/mol, PDI = 2.11) failed to cross-link into handleable samples in the same condition, potentially due to its lower molecular weight and lower percentage of alkyne groups.…”

“… 9 Small molecule stabilizers inhibit the side reactions to some degree, but they might reduce the cytocompatibility. 9 Compared to primary thiol cross-linkers, secondary thiol cross-linkers have a significantly improved shelf life due to the additional steric hindrance. 13 In our design, we lowered the concentration of thiols and alkynes by functionalizing the polymer with alkyne groups.…”

Fast Hydrolytically Degradable 3D Printed Object Based on Aliphatic Polycarbonate Thiol‐Yne Photoresins

“…Additionally, to avoid the rapid gelation of the resin during the printing process, pyrogallol was added into the formulation to stabilize the radical species involved in the resin. [ 48 ] Meanwhile, light absorber Sudan II, which has proper light absorption under 405 nm and has no catalytic reactivity for thiol‐yne photopolymerization was added for obtaining higher printing fidelity. The formulation has good printability, which can continuously perform 3D printing for around 10 h without gelation.…”