Tuning the Thermo-Sensitivity of Micellar Systems through a Blending Approach

This paper reports an original and easy route toward thermosensitive micelles based on a lipidic core and with adjustable cloud point temperatures ( T CP ) through a simple blending approach between two copolymers of different T CP . The cationic ring-opening polymerization (CROP) of various 2-alkyl-2-oxazoline monomers was first investigated from both mesylated and tosylated lipoinitiators and different lipid- b -poly(2-methyl-2-oxazoline), lipid- b -poly(2-ethyl-2-oxazoline), lipid- b -poly(2-isopropyl-2-oxazoline) and lipid- b -poly((2-ethyl-2-oxazoline)- co -(2-isopropyl-2-oxazoline)) copolymers were synthesized. Blending of lipid- b -p(EtOx) and lipid- b -p( i PrOx) copolymers in various proportions were then prepared and their T CP investigated through UV–visible spectroscopy. Very interesting results were obtained as the blends exhibit a single T CP ranging from 35 to 45 °C. Furthermore, the blends T CP correspond to those of the statistical lipid- b -p((EtOx)- co -( i PrOx)) for the same p(EtOx)/p( i PrOx) content up to 52 wt % of p(EtOx). The blending approach is then an attractive strategy to control the T CP of micellar systems through a simple and easy formulation approach rather than fastidious syntheses.