Preparation and characterization of silicone rubber through the reaction between -chloropropyl and amino groups with siloxane polyamidoamine dendrimers as cross-linkers

摘要

A novel heat-curable silicone rubber (MCSR/Si-PAMAM) was prepared by using siloxane polyamidoamine (Si-PAMAM) dendrimers as cross-linkers and polysiloxane containing -chloropropyl groups as gums. The chemical cross-linking occurs through the reaction between Si-PAMAM dendrimers and polysiloxane containing -chloropropyl groups. The effect of various amounts of cross-linkers on mechanical properties of MCSR/Si-PAMAM was discussed in this paper. MCSR/Si-PAMAM exhibits favorable mechanical properties with a tensile strength of 10.06MPa and a tear strength of 47.9kN/m when the molar ratio r of [N-H]/[CH2CH2CH2Cl] is 1:1. These excellent mechanical properties can be attributed to the formation of concentrative cross-linking from Si-PAMAM dendrimers in the cross-linking networks, along with the introduction of Si-O-Si units in the internal structure of dendrimers. The introduction of Si-O-Si units reduces the steric hindrance of molecular structure, which facilitates the N-H bonds in the interior layers of dendrimers to react with -chloropropyl groups. In addition, thermogravimetric analysis results indicate that MCSR/Si-PAMAM is thermally stable even at high temperatures in a nitrogen atmosphere. Differential scanning calorimetry analysis reveals that the glass transition peak of MCSR/Si-PAMAM is not identified in the temperature range -150 to -30 degrees C, only a melting endothermic peak at -40 degrees C.