Preparation of semi-conducting polymeric nanoparticles by supercritical carbon dioxide RESOLV process.

The rapid expansion of supercritical carbon dioxide solutions into a liquid solvent (RESOLV) technique with environmentally benign supercritical carbon dioxide was used to produce semi-conducting polymeric nanoparticles of fluoroalkyl ester substituted thiophenes. When the supercritical solutions of the conjugated polymer, poly[2-(3-thienyl) acetyl-3,3,4,4,5,5,6,6,7,7,8,8,8,tridecafluoro-1-octanate] (PSFTE) were expanded into aqueous solutions through a small capillary nozzle (150 microm), spherical nanoparticles in the range of 50-100 nm were obtained. However, after 15 min of expansion, the particles tended to aggregate to form larger objects due to the high surface energy of the polymeric nanoparticles. In order to prevent the agglomeration of particles, a relatively low concentration of sodium dodecyl sulphate (SDS) or NaCI was used as a stabilizing agent in aqueous solution. While NaCI did not give enough stabilization to the system, uniform spherical nanoparticles of PSFTE having an average size of 45 nm were successfully obtained by SDS stabilization.