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

Abstract

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−1 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.

The Preparation of a novel moisture-curing silicone conformal coating

“…The peak observed at 1261 cm −1 is attributed to the bending vibration of C-H in the methyl group bonded to the silicone atom, whereas the peaks at 2962 cm −1 and 2906 cm −1 are associated with the stretching vibration of C-H [22]. The absorption peaks observed at 1020 cm -1 and 1095 cm -1 are indicative of the Si-O-Si bond [22], while the absorption peak at 1413 cm -1 corresponds to the Si-C bond [23].The absorption peak at 1413 cm -1 corresponds to the characteristic of Si-C [23], while the stretching vibration peak at 2837 cm -1 is indicative of O-CH3 [24]. The presence of a weak hydroxyl characteristic absorption peak at 3400-3600 cm -1 [24] is hypothesized to be a result of the hydrolysis of the methoxy group during testing.…”

Bioinspired High-Performance Silicone Elastomers by Catalyst-Free Dopamine Cross-Linking

“…For example, Kizilkan et al 9 treated the surface of silicone elastomer with air plasma, resulting in a 30% increase in adhesion. The second approach is to add adhesion promoters to the silicone elastomers precuring system, such as Wu et al 10 developed boron-modified polydimethylsiloxane (PDMS-B) and epoxy alkoxy bifunctionalized tetramethylcyclotetrasiloxane (D 4 HMSEP) as coadhesive promoters. The third approach is to modify polysiloxanes by introducing reactive functional groups.…”

Binary Promoter Improving the Moderate-Temperature Adhesion of Addition-Cured Liquid Silicone Rubber for Thermally Conductive Potting

“…The above-mentioned methods can effectively improve the adhesion of LSR to various substrates; however, both methods are time-consuming and complicated processes, and they are harmful to the environment. Therefore, the addition of adhesion promoters into LSR to provide a self-adhesive capacity has spurred intensive research interest due to the simple and scalable process and eco-friendly properties [ 29 , 30 , 31 , 32 , 33 ]. Pan et al reported a vinyl and epoxy groups-functionalized silane oligomer and used it as an adhesion promoter to prepare a self-adhesive addition-cure silicone encapsulant [ 32 ].…”

“…These reactive groups (i.e., epoxy, alkoxy and methacryloxy groups)-containing adhesion promoters generally demonstrated their great improvement in bonding performance at high working temperatures (>120 °C). However, most of the adhesion promoters are unable to offer an efficient adhesion ability for LSR at moderate curing temperatures (e.g., 80 °C) [ 31 , 32 , 33 ]. Therefore, it remains a challenge to achieve efficient encapsulation and provide long-term reliable protection for temperature-sensitive electronic devices.…”