Controlled Phase Separation of Supercritically Dried Polymer-Based and Polymer Nanocomposite-Based Aerogels

The research and industrial interests on aerogels are growing rapidly due to the increasing demand for high-performance thermal insulation materials. More recently, polymer-based aerogels have drawn much attention, but to date have primarily focused on those from the phenolic-group. While the candidates for polymer aerogels are very limited, the primary method for processing has been freeze drying. Challenges associated with freeze dried aerogels arise in the resultant morphology and properties which are inferior to those processed using super critical drying (SCD). This work presents SCD process optimization and process-structure-property studies on polymer nano-composite based aerogels. This work investigates the formation of gels via non-solvent induced phase separation and polymer crystallization approach, which aims to control solvent/non-solvent ratios as well as undercooling temperatures. The subsequent precursor gels are optimized to retain a semi-crystalline three-dimensional network during the SCD process. The mechanisms of solvent exchange and diffusion during initial gelation and aerogel processing have been investigated and will be presented. In addition, this unique processing approach is also used to enhance blending for polymer-nanofillers based aerogels. Current work has shown that the composite precursor gels and aerogels exhibit enhanced mechanical and thermal performance. A fundamental study regarding these materials will be presented here.