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

Abstract

Silicone elastomers, as good sealants and adhesives, have been widely applied in protective coatings, architectural decoration, electronic packaging, and other fields. However, the traditional cross-linking of silicone elastomers is highly dependent on toxic catalysts or heavy metals, which may inevitably lead to severe environmental pollution. Moreover, most silicone elastomers suffer from a poor adhesive performance. In this study, inspired by the high adhesion properties of mussels, an eco-friendly and catalyst-free silicone elastomer with high adhesion properties was prepared by using dopamine as a cross-linker and amino-functionalized polysiloxane as a base. Under mild conditions (pH = 8.5), dopamine was self-polymerized and underwent Michael addition and Schiff base reactions with amino groups to form robust elastomers. It was found that the cross-linking degree gradually increases with the dopamine content increasing from 2 to 6%, and the solvent resistance and thermal stability exhibit significant improvement. Meanwhile, the tensile strength increased by 245% from 0.22 to 0.77 MPa. Especially, the as-obtained silicone elastomers have excellent adhesion to different materials. The lap shear strength with aluminum substrates (1.09 MPa) is 3.6 times higher than that of conventional silicone elastomers. The development of catalyst-free bioinspired silicone elastomers with high adhesion may shed light on the research of eco-friendly silicone materials and offer innovative insight for mussel-inspired adhesives.

Mussel-Inspired Green Cross-Linking of Silicone Elastomers and Its Tunable Adhesion Behavior and Underwater Curing Capability

“…The critical aspect of these strategies is the rational selection of green cross-linkers and the polysiloxanes with appropriate functional groups . Among them, amino-functionalized polysiloxanes, benefiting from their commercial availability and high reactivity, can be easily cross-linked by a variety of catalyst-free reactions, such as the aza-Michael reaction, , the urea reaction with isocyanates, , and the imine bond with aldehydes. , However, the elastomers of these cross-linking systems do not have adhesion properties and cannot meet their underwater curing and adhesion needs. Therefore, it is important to develop an eco-friendly silicone elastomer cross-linking system with underwater adhesion.…”