Details

Autor(en) / Beteiligte

• Jacquin, M.
• Muller, P.
• Talingting-Pabalan, R.
• Cottet, H.
• Berret, J.F.
• Futterer, T.
• Théodoly, O.

Titel

Chemical analysis and aqueous solution properties of charged amphiphilic block copolymers PBA- b-PAA synthesized by MADIX

Ist Teil von

• Journal of colloid and interface science, 2007-12, Vol.316 (2), p.897-911

Ort / Verlag

San Diego, CA: Elsevier Inc

Erscheinungsjahr

2007

Quelle

MEDLINE

Beschreibungen/Notizen

• We have linked the structural and dynamic properties in aqueous solution of amphiphilic charged diblock copolymers poly(butyl acrylate)- b-poly(acrylic acid), PBA- b-PAA, synthesized by controlled radical polymerization, with the physico-chemical characteristics of the samples. Despite product imperfections, the samples self-assemble in melt and aqueous solutions as predicted by monodisperse microphase separation theory. However, the PBA core are abnormally large; the swelling of PBA cores is not due to AA (the Flory parameter χ PBA / PAA , determined at 0.25, means strong segregation), but to h-PBA homopolymers (content determined by liquid chromatography at the point of exclusion and adsorption transition, LC-PEAT). Beside the dominant population of micelles detected by scattering experiments, capillary electrophoresis CE analysis permitted detection of two other populations, one of h-PAA, and the other of free PBA- b-PAA chains, that have very short PBA blocks and never self-assemble. Despite the presence of these free unimers, the self-assembly in solution was found out of equilibrium: the aggregation state is history dependant and no unimer exchange between micelles occurs over months (time-evolution SANS). The high PBA/water interfacial tension, measured at 20 mN/m, prohibits unimer exchange between micelles. PBA- b-PAA solution systems are neither at thermal equilibrium nor completely frozen systems: internal fractionation of individual aggregates can occur. The self-assembly of amphiphilic diblocks in water (large core size of micelles, low CMC but presence of free unimers, hysteretic fractionation) are explained via a precise physico/chemical analysis of samples.