Synthesis and Property of an Organosilicon Polyurethane Acrylate Prepolymer Containing Disulfide Bonds for Photopolymerization

Photocurable organosilicon polyurethane acrylate materials combine the merits of both polyurethane and organosilicon and have become the most widely used class of photocurable resins due to the advantages of easy preparation and performance tunability, but they suffer from serious volume shrinkage and difficult degradation. In this article, an organosilicon polyurethane acrylate prepolymer (SSiPUA) containing disulfide bonds is designed and synthesized. The prepolymer exhibits good ability to photopolymerize and reduce the volume shrinkage. The final double bond conversion (DBC) of the system with SSiPUA reaches 92%, and the volume shrinkage is decreased to 4.9% that is much less than that (13.9%) without SSiPUA. Besides, with the increase of SSiPUA content within a certain range, the hydrophobicity, heat resistance, the tensile strength, and the elongation at break of the photocured films gradually increase. The water contact angle, initial decomposition temperature, the tensile strength, and the elongation at break reach up to 93°, 282 °C, 1.8 MPa, and 576.2%, respectively. However, the glass transition temperature is reduced with the increase of SSiPUA content owing to the excellent flexibility of polysiloxane chain segments. More significantly, the SSiPUA containing disulfide bonds endows the photocured film with good degradation properties. An organosilicon polyurethane acrylate prepolymer containing disulfide bonds is designed and synthesized; through the dynamic exchange of disulfide bonds, the volume shrinkage can be reduced from 13.9% to 4.2%. Moreover, the material also can be completely degraded by the action of tributylphosphine.