Polymerization of Styrene in Fluorinated Solvents

Micelle formation of our block copolymers in fluorinated solvents indicates that these polymers might act as stabilizers or surfactants in a number of stabilization problems with high technological impact, e.g., the surface between standard polymers and media with very low cohesion energy such as short-chain hydrocarbons (isopentane, butane, propane), fluorinated solvents (hexafluoroben-zene, perfluoro(methylcyclohexane), perfluorohexane) and supercritical C02. As 

Solvent Fluoro-PSB-II Fluoro-PSB-III Fluoro-PSB-IV Fluoro-PSB-VIII Fluoro-triblock 

Toluene 176.1 0.321 89.2 0.251 Soluble None Soluble None Insoluble Swelling 

Heterophase polymerization in general is a current trend in polymer science as it allows solvent-free polymer synthesis polymer powders are obtained when the dispersion agent is removed. DeSimone improved this procedure significantly by performing the heterophase polymerization in supercritical C02, which simplifies the synthesis of powders with excellent handling of the polymerization and evaporation process.7 9 

To keep the precipitating polymers in the dispersed state throughout the polymerization, requires steric stabilizers. This problem is classically tackled via copolymerization with fluoroalkylmethacrylates or the addition of fluorinated surfactants, both being only weak steric stabilizers. DeSimone el al. also applied a fluorinated block copolymer,9 proving the superb stabilization efficiency of such systems via a rather small particle size. One goal of the present chapter is therefore an investigation of our fluorinated block copolymers as steric stabilizers in low-cohesion-energy solvents. 

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