Photo-Induced Thiol-ene Polysulfide-Crosslinked Materials with Tunable Thermal and Mechanical Properties

Photo-induced thiol-ene crosslinked polymeric networks have been extensively explored in constructing a variety of new materials with enhanced mechanical properties for optical, biomedical, and sensing applications. Toward the broad applications, however, tunable mechanical properties are greatly desired. Here, an effective approach utilizing high-molecular-weight methacrylate copolymers having pendant thiol and vinyl groups (MCPsh and MCPenes) to modulate thermal and mechanical properties of photo-induced thiol-ene crosslinked materials is reported. The MCP copolymers are synthesized by an industrially friendly polymerization method, followed by post-modification including either a facile coupling reaction or reductive cleavage. Upon UV irradiation, thiol-ene reactive blends of MCPsh and MCPenes yield highly cross-linked materials through the formation of flexible sulfide linkages. These polysulfide-crosslinked materials based on rigid MCP backbones exhibit enhanced mechanical properties. Further, their thermal and mechanical properties are tuned by modulating monomer compositions of MCPs as well as varying numbers of pendant SH or vinyl groups (i.e., extent of crosslinking densities). This approach is versatile and effective for development of high performance polymeric materials. (c) 2014 Wiley Periodicals, Inc.