Promoters for Improved Adhesion Strength between Addition-Cured Liquid Silicone Rubber and Low-Melting-Point Thermoplastic Polyurethanes.

A polydimethylsiloxane armed with epoxy, alkoxy and acrylate groups was synthesized from silanol terminated-PDMS and epoxy and acrylate groups functionalized silane coupling agents, and utilized as the adhesion promoter (AP) to prepare addition-cured liquid silicone rubber that exhibited self-adhesion ability (SA-LSR) with biocompatible thermoplastic polyurethanes (TPU) sheets. The structural characteristics of AP were characterized by Fourier transform infrared (FTIR) spectroscopy, which demonstrated the strong adhesion to polyester-based TPU sheets due to a sufficient amount of acrylate groups, epoxy groups and silanol groups obtained by the hydrolysis of alkoxy groups. In detail, the peel-off strength of SA-LSR and TPU joints reached up to 7.63 N mm after the optimization of adhesion promoter including type and content, and curing condition including time and temperature. The cohesive failure was achieved during the sample breakage process. Moreover, the SA-LSR showed a good storage stability under proper storage conditions. This design strategy provided the feasibility to combine the advantages of addition-cured liquid silicone rubber and plastics with low melting points, promoting the potential application range of those silicone-based materials.