Chemical reaction in medium density fluid. Solvent density effects on the dimerization equilibrium of 2‐methyl‐2‐nitrosopropane in carbon dioxide

Polymeric Nanoparticles from Rapid Expansion of Supercritical Fluid Solution

In this concept paper we highlight applications of supercritical fluid technology in particle formation and production, especially some recent advances in the rapid expansion of supercritical solutions (RESS) processing technique. We also highlight the simple but significant modification to the traditional RESS by using a liquid solvent or solution at the receiving end of the supercritical solution expansion, or the rapid expansion of a supercritical solution into a liquid solvent (RESOLV), and applications of the technique to the preparation of nanoparticles. In particular, successes and challenges in the use of RESOLV for nanoscale (<100 nm) polymeric particles and the subsequent protection of the suspended nanoparticles from agglomeration are discussed.

Efficient Photodimerization Reaction of Anthracene in Supercritical Carbon Dioxide

The photodimerization reaction of anthracene in supercritical CO(2) was studied systematically at different CO(2) densities. Unlike in normal liquid solvents, the reaction in supercritical CO(2) is significant even at anthracene concentrations as low as a few micromolar. At comparable anthracene concentrations, the photodimerization reaction is 1 order of magnitude more efficient in CO(2) than in normal liquid solvents. The dramatic increases in the photodimerization reaction efficiency in supercritical CO(2) may be explained by a mechanism in which the reaction is diffusion-controlled even when the diffusion rate constants are on the order of 10(11) M(-1) s(-1). The results also show that the efficient photodimerization reaction of anthracene is hardly affected by the local density augmentation (or solute-solvent clustering) in supercritical CO(2).