ASSOCIATION AND SURFACE-PROPERTIES OF DIBLOCK COPOLYMERS OF ETHYLENE-OXIDE AND DL-LACTIDE IN AQUEOUS-SOLUTION

Diblock copolymers of ethylene oxide and DL-lactide (EmLn copolymers) were prepared by sequential anionic polymerisation and characterised b y gel permeation chromatography (GPC) and C-13 NMR. Their association and surface properties in aqueous solution were studied by surface ten sion and dynamic and static light scattering. Comparison of the critic al micelle concentrations (cmc) and micelle association numbers (N-w) of the EmLn copolymers with published values for oxyethylene/oxybutyle ne (EmBn) copolymers indicated a slightly lower hydrophobicity for a l actide unit: i.e. L congruent to 0.75B. The tempera ture dependence of the cmc of copolymer E42L12 was analysed to obtain a standard enthalp y of micellisation Delta(mic)H(0) = 40 kJ . mol(-1).