Multicompartment Polymeric Micelles Based on Hydrocarbon and Fluorocarbon Polymerizable Surfactants

The synthesis of multicompartment polymeric micelles (MCPMs) has been achieved by aqueous radical terpolymerization of a water-soluble monomer (acrylamide) with both hydrocarbon (H) and fluorocarbon (F) surfactants (surfmers) in the micellar state. The selected H- and F-surfmers are CH2CHCON(C2H5)CH2CH2N(CH3)2CH2COOC16H33/Br/Cl (HS6) and CH2CHCONHCH2CH2N(CH3)2CH2COOCH2CH2C8F17/Br (FS3), respectively. Their mutual incompatibility in aqueous solution has been checked by conductivity and surface tension experiments. Two cmc values are found, in favor of the coexistence of two distinct types of micelles at surfactant concentrations above 1 mmol/L (second cmc) over a broad composition range. The solubilization properties of the pure and mixed surfactant systems have been studied for different hydrophobic probes. Significant differences in the solubilization capacity occur due to the nature of the dye, of the surfactant, and of the micelle shape and composition. A kinetic study on the incorporation behavior of the H- and F-surfmers in the polyacrylamide backbone during a batch polymerization shows a compositional drift as a function of conversion which is attributed to micellar effects. A semicontinuous process has been designed which allows the correction for this compositional drift. The presence of well-segregated H- and F-microdomains in terpolymers could be inferred from viscosity and fluorescence experiments. Furthermore, the solubilization of decalin is enhanced in terpolymer solutions with respect to that of copolymer solutions. This was attributed to the formation of larger hydrocarbon cores in the former case due to repulsive H/F interactions in the polymeric chains.