Abstract:

The block copolymer of PSt-b-PBA with well-defined structure was synthesized via atom transfer radical polymerization(ATRP) by using 1-phenylethyl bromide(1-PEBr) as the initiator, cuprous bromide as the catalyst, 2,2′-bipyridine(bpy) as the ligand and xylene as the solvent. The block copolymer PSt-b-PBA was characterized and the living polymerization was validated by GPC, FTIR, and 1H NMR. Then the amphiphilic block copolymer of PSt-b-PAA was prepared by alkaline hydrolysis of PSt-b-PBA. The reversed micellization behavior of PSt-b-PAA in toluene was investigated by fluorescence probe technique with  polar fluorescence compound N-(1-naphthyl)ethylenediamine dihydrochloride(NEAH) as a polar fluorescence probe and by the observation of TEM. It was found that NEAH as a polar fluorescence compound can clearly reveal the reversed micellization behavior of PSt-b-PAA in toluene. The results show that the reversed micelles which have hydrophilic core and hydrophobic shell can formed spontaneously through self-aggregation of PSt-b-PAA macromolecules in toluene, the aggregates have the morphology of sphere, and the self-aggregation behavior of PSt-b-PAA depends apparently on the microstructure of the macromolecules and the temperature. The longer the PAA block is, the lower the critical micelle concentration is; the higher the temperature is, the lower the critical micelle concentration is.

Key words: Self-aggregation; Reversed micelle; Polar fluorescence probe; Amphiphilic block copolymer of styrene-acrylic acid, Self-aggregation, Reversed micelle, Polar fluorescence probe, Amphiphilic block copolymer of styrene-acrylic acid