Jr. Quintana et al., SIZE-EXCLUSION CHROMATOGRAPHY OF SOLUTIONS OF BLOCK-COPOLYMERS IN SELECTIVE SOLVENTS, Polymer international, 36(4), 1995, pp. 325-331
Solutions of polystyrene-block-poly(ethylene/propylene) and ne-block-p
oly(ethylene/butylene)-block-polystyrene copolymers in 5-methyl-2-hexa
none and 4-methyl-2-pentanone were studied by size exclusion chromatog
raphy. The association equilibrium was studied shifting from micelles
to free copolymer chains by increasing the temperature. A remarkable t
ailing was observed in diblock copolymer micelle peaks that may be exp
lained by the disturbance and reestablishment of the association equil
ibrium during separation in the chromatographic column. This phenomeno
n was very small for triblock copolymers. In this case, micelle hydrod
ynamic volumes obtained from SEC curves were compared to those calcula
ted from light scattering and viscosity measurements. The data agreeme
nt was very good. Comicellization was analysed by mixing two different
micelle solutions and injecting the solution mixture at different ela
psed times. The SEC curves showed an intermediate peak corresponding t
o mixed micelles. The results show that three micelle species coexist
in solution during the first period after mixing, which suggests that
comicellization proceeds via dissociation of pure micelles and associa
tion of both copolymer free chains to form uniform mixed micelles.