Amine-functionalized POSS as cross-linkers of polysiloxane containing γ-chloropropyl groups for preparing heat-curable silicone rubber

A series of heat-curable silicone rubber is designed and prepared through cross-linking reaction of two structurally similar amine-functionalized polyhedral oligosilsesquioxane (POSS), octa(aminophenyl)silsesquioxane, and N-phenylaminomethylsilsesquioxane, with polysiloxane containing γ-chloropropyl groups (CPPS). Curing characteristics measured with a rheometer show that the amine-functionalized POSS can participate in chemical cross-linking during curing. Scanning electron micrographs illustrate that silicone rubber prepared by solution mixing exhibits a homogeneous morphology. Mechanical and thermal properties of silicone rubber are evaluated through mechanical testing, thermogravimetric analysis, and differential scanning calorimetry. The effect of POSS distribution in the polymer matrix on vulcanizate properties is discussed. Compared with that prepared through melt mixing, the methyl chloropropyl silicone rubber prepared through solution mixing exhibits excellent mechanical properties. Concentrative cross-linking occurs in this network, and the mechanical properties are improved. The sample exhibits a tensile strength of 9.9 MPa and tear strength of 48.1 kN/m. Thermogravimetric analytical results show that introducing POSS can enhance the thermal stability of silicone rubber. [Display omitted] •Silicone rubber was prepared through a reaction of amine-functionalized POSS with PDMS containing γ-chloropropyl groups.•The sample exhibits excellent mechanical and thermal properties.•The concentrative cross-linking improves the mechanical properties, especially the tear strength.