Synthesis of amphiphilic random copolymers and fluorescence study of theirassociation behavior in water

A series of different copolymers of 2-acryl-amido-2-methylpropanesulfonic a cid, AMPS, and butyl methacrylate, BuMA, were prepared by free radical poly merization at 70 degreesC in N,N ' -dimethylformamide under nitro-en atmosp here varying the composition feed. the polyamphiphiles isolation was carrie d out by passing the polymeric solutions through a sodium cation exchange, resin. The stabilities of the obtained homopolymers, and copolymers were ch aracterized by thermal analysis (TGA,, DSC). Fluorescent probes were used t o study the hydrophobic microdomain formation due to the association, pheno mena observed in water solution when the amphiphilic copolymer concentratio n was increased. The fluorescence: emission of amino derivatives of 7-nitro benz-2-oxa-1,3-diazole (NBD) showed sensitivity to detect polarity and micr oviscosity changes in the microenvironment of the copolymers. The minimum c oncentration for the hydrophobic microdomains formation, C-m, decreased by. increasing the molar fraction of BuMA in the AMPS(Co) copolymers. Hence, c opolymer composition and charge density allowed tuning the pseudo-micellar characteristics of these new polyamphiphilic copolymers.