MICELLIZATION OF DIBLOCK AND TRIBLOCK COPOLYMERS IN AQUEOUS-SOLUTION - NEW RESULTS FOR OXYETHYLENE OXYBUTYLENE COPOLYMERS E(38)B(12) AND E(21)B(11)E(21) - COMPARISON OF OXYETHYLENE/OXYBUTYLENE, OXYETHYLENE/OXYPROPYLENE, AND OXYETHYLENE/ALLYL SYSTEMS/

Two oxyethylene/oxybutylene block copolymers of similar chain length a nd composition, E(38)B(12) and E(21)B(11)E(21), were prepared by seque ntial anionic polymerization and characterized by gel permeation chrom atography and NMR spectroscopy. Their association in dilute aqueous so lution was investigated by static and dynamic light scattering. Both c opolymers associated by closed processes to form micelles, those of th e diblock copolymer being the larger. The increment per B unit in the standard Gibbs energy of micellization of diblock E(m)B(n) copolymers was found to be 2.0 kJ mol(-1). The critical micelle concentrations of oxyethylene/oxybutylene (E(m)B(n) and E(m)B(n)E(m)), oxyethylene/alky l (E(m)C(n)), and oxyethylene/oxypropylene (E(m)P(n)E(m)) copolymers a re compared, and the effect of chain architecture (diblock and tribloc k) on the association of diblock and triblock copolymers is discussed.