Hybridization of Poly(oxazoline) and Poly(ethylene oxide)-Based Amphiphilic Copolymers into Thermosensitive Mixed Micelles of Tunable Cloud Point

This paper reports the development in aqueous solution of mixed micelles of tunable cloud point temperature through blending in various proportions of two copolymers of different chemical natures. For that purpose, a lipid-b-poly(2-isopropyl-2-oxazoline) (lipid-b-P(iPrOx)) copolymer, self-assembling into thermosensitive micelles that phase-separate above a cloud point temperature of 38 degrees C, was blended in various proportions with commercial C-18-b-PEOx. The latter was constituted of a hydrophobic saturated C-18 chain and a hydrophilic poly(ethylene oxide) (PEO) block with varying polymerization degrees (x) and does not have any thermosensitive properties on the studied temperature range for any value of x. The different blends were thoroughly characterized by light scattering and UV-visible spectroscopy, revealing that hybridization between both copolymers always occurred, independent of the PEO block length. The resulting mixed micelles present TCP values progressively increasing with the C-18-b-PEOx proportion, from 38 to 61 degrees C. This study demonstrates the relevance of the blending approach to tune the phase separation of micellar systems by formulation rather than by more tedious synthetic efforts. Shifting TCP through this approach extends the range of temperature where lipid-b-P(iPrOx) can find an application.

Automated summary

This study reports the development of mixed micelles in aqueous solution with tunable cloud point temperature by blending two copolymers of different chemical natures. The blending approach demonstrated the relevance in tuning the phase separation of micellar systems, extending the range of application temperature for lipid-b-P(iPrOx).