Small-angle neutron scattering characterization of micelles formed by poly(dimethylsiloxane)-graft-polyether copolymers in mixed polar solvents

The self-assembled structure of an amphiphilic poly(dimethylsiloxane)-graft-polyether copolymer has been investigated in binary solvents consisting of water and one of the following polar organic solvents:  2-propanol, ethanol, formamide, or glycerol. Micelle structural parameters were obtained by fitting the core−corona form factor and hard-sphere interaction structure factor to small-angle neutron scattering (SANS) data obtained at contrast conditions where the solvents were fully deuterated and the copolymer was not. The siloxane copolymer forms in water at 20 °C micelles that consist of a “dry” core with a radius of about 6 nm and a solvated (about 40% polymer) corona with a thickness of 2 nm; the relatively thin corona may be due to the comb-type architecture of the siloxane copolymer. The micelle radii, micelle core radii, micelle association numbers, and polymer volume fractions in the micelle core and corona decreased with increasing cosolvent/water ratio in the mixed solvents containing 2-propano...