Transparent liquid silica gel can be used for coating, impregnation and perfusion. For example, hydroxyl-terminated polydimethylsiloxane with viscosity of 0.07-50 Pa.s/25 C, methyl vinyl bispyrrolidone silane as chain growth agent and organic peroxides such as dibenzoyl peroxide and 25-dimethyl 5-di-tert-butyl peroxyhexane as vulcanizing agent have good fluidity and low viscosity and have been vulcanized. The chain growth reaction occurs at the same time in the process, so high molecular weight elastomer can be obtained, which has good physical and mechanical properties.
The chain growth agent, methyl vinyl bispyrrolidone silane, can be obtained by the reaction of pyrrolidone with methyl vinyl dichlorosilane in the presence of triethylamine. The product is easy to hydrolyze, so it needs to be stored in a dry and airtight container. The pyrrolidone group of this compound can react slowly with hydroxyl end group in polydimethylsiloxane at room temperature. The reaction rate increases with the increase of temperature.