Synthesis of polyamide microcapsules and effect of critical point drying on physical aspect

摘要

Polyamide microcapsules were synthesized at room temperature by an interfacial polymerization technique, by reaction of terephthaloyl dichloride with diethylenetriamine in an aqueous medium. Partially hydrolyzed polyvinyl alcohol was used as the emulsifier and toluene as the organic dispersed phase. For polyamide microcapsules, the drying technique has a strong influence on the physical aspect of the resulting microcapsules. In this paper the physical aspect of polyamide microcapsules was studied with various drying methods such as air, vacuum and CO2 critical point. It was observed that drying the microcapsules at room temperature under atmospheric conditions or vacuum resulted in an aggregated mass of broken microcapsules, whereas CO2 critical point drying (CPD) in a microfiltration teflon vessel preserved the spherical shape of polymer microcapsules with high collection efficiency. Similar results were observed on vertically aligned polypyrrole nanowires.