Facile Method for the Preparation of Cyclodextrin-Rotaxanated Silicone Elastomers with Excellent Stretchability

Polysiloxane is an industrially important polymer, as it serves as the platform for the preparation of silicone materials with excellent thermal stability. Even though the fact that introducing rotaxanes into a polymer network provides a novel way to build new materials with peculiar mechanical properties is well-known, this tactic has rarely been applied to silicones, perhaps due to the lack of efficient synthetic methods. Here, in this work, we report the preparation and characterization of novel rotaxanated silicone elastomers by a simple two-step synthetic method. Starting from commercially available γ-cyclodextrin (CD) and vinyl-terminated polydimethylsiloxane, poly[(dimethylsiloxane)-pseudorotaxa-(γ-cyclodextrin)]s were facilely prepared. These pseudopolyrotaxanes were then used to prepare silicone elastomers of different structures and compositions. Mechanical tests of these elastomers show that they have moderate tensile strength but an excellent extension ratio (∼800% for the sample with the highest extension ratio). γ-CD plays a unique and important role in shaping the network's topological structure and mechanical properties. This role was unveiled by applying various techniques such as solid-state NMR measurements and cyclic tensile tests to the elastomers obtained. Due to the simplicity of the current method, it may be used for large-scale preparation of stretchy silicone rubbers with optimum mechanical properties.