Effect of different chemical liquid deposition methods on the microstructure and properties of polyimide-polyvinylpolymethylsiloxane composite aerogels.

• Preparation of PPCAs via different CLD methods: SCLD and DCLD methods. • Endow PPCAs with both superior mechanical property and high thermal stability. • Introduction of PI chains into the PVPMS backbone by SCLD method. In this study, the polyimide-polyvinylpolymethylsiloxane composite aerogel (PPCA) was synthesized by two different methods, stepwise chemical liquid deposition (SCLD) and direct chemical liquid deposition (DCLD). It is found that polyimide (PI) chains can only be introduced into the backbone of amine-modified polyvinylpolymethylsiloxane (PVPMS) by SCLD method. The introduced PI can further crosslink with PVPMS to form a PI-PVPMS cross-linked network structure, which makes the skeleton dense and endows the sample with high mechanical strength. For DCLD method, PI chains can only be coated on the surface of the sample rather than the whole skeleton, which leads to a loose internal structure. Furthermore, samples prepared by SCLD method possess higher initial thermal decomposition temperature compared with that by DCLD method. [ABSTRACT FROM AUTHOR]