Thiol‐Ene versus Binary Thiol–Acrylate Chemistry: Material Properties and Network Characteristics of Photopolymers

The versatile nature of photo‐induced thiol‐ene chemistry has made it one of the most popular reactions in the design of polymer networks. In the present work, the structure of uniform thiol‐ene and complex binary thiol‐acrylate networks are studied in detail by photopolymerizing cycloaliphatic and linear alkyl thiols with an allyl monomer and its acrylic counterpart. Along with the crosslink kinetics, the balance between step growth and chain growth mechanism of the two different systems is investigated by FT‐IR spectroscopy. Low field NMR experiments are carried out to obtain an insight into the chain dynamics and structure of the photopolymer networks. In addition, tensile properties and glass transition temperature are determined to correlate network properties with mechanical performance. Detailed insight into the network evolution of thiol‐ene and binary thiol‐acrylate photopolymers is given in view of the homopolymerization rate of acrylate and allyl monomers. Low field double quantum NMR studies show that the yield of homopolymerization contributes to the heterogeneity of thiol‐ene networks, which also clearly influences the corresponding thermo‐mechanical properties, such as tensile properties and glass transition temperature.