Structure and Properties of Silicone Rubber/Styrene-Butadiene Rubber Blends with in Situ Interface Coupling by Thiol-ene Click Reaction

The low surface energy of silicone rubber (SiR) makes it difficult to blend SiR with conventional rubbers such as solution styrene-butadiene rubber (SSBR) and natural rubber. In this study, to enhance the interface interaction between SiR and SSBR, trimethylolpropane tris(3-mercaptopropionate) (TMPMP) was carefully chosen to couple SiR and SSBR by in situ thiol-ene click reactions between mercapto groups of TMPMP and vinyl groups of SiR and SSBR. The reaction of TMPMP with SiR and SSBR was characterized via torque-time curves, element analysis, and the dissolving-swelling test. Accordingly, a two-step strategy was proposed to prepare SiR/SSBR composites. Transmission electron microscopy indicated that the two-step strategy reduced the phase domain size of the blend. The composite exhibited higher mechanical properties and lower hysteresis. The results would extend SiR applications.