Effect of pharmacutically acceptable glycols on the formation and structure of poloxamer block copolymer micelles in water

摘要

The self-assembly, micelle structure, and phase behavior of surfactants in solvents less poalr than water or in mixtures of such solvents with water have fundamental and practical importance.~1 For example, non-aqueous cosolvents, such as glycerol and ethanol and simple salts are often present in the formualtions that employ micelles as drug delivery carries.~2 Our interest is on macromolecular amphiphiles, namely, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-PPO-PEO), commercially available as Poloxamers or Pluronics.~3 Poloxamer block copolymers find numerous applications~4 on the basis of their ability to self-assemble in aqueous solution (forming micelles and gels) and to modify interfacial properties. The solvent quality is a controlling factor in the self-assembly and microstructure of block copolymers.~5 The addition of cosolutes or cosolvents to water provides an extra degree of freedom in tailoring the Poloxamer solution properties for specified applications.~5 We address here the Poloxamer formation and structure in mixed solvents consisting of water and one of the followign cosolvents: ethanol, glycerol or formamide.~6 the principal means of characterization is small-angle neutron scattering (SANS).~7