Modification of PAA

The strategy of PAA modification was to convert the primary amines of PAA to the secondary amines using acrylate or 6-bromoalkanoic acid derivatives. Based on the previous studies, the reaction can take place in water free solution without the use of conjunctive reagents.³ Modification was performed with hexyl acrylate in substitution percent of 10, 30 and 50; butyl acrylate in substitution percent of 50 and also with 6-bromohexanoic acid and 6-bromodecanoic acid in substitution percent of 30 and 50 of each. Chain length and substitution percent of each derivative was selected based on the results of our previous studies.^3,9 The modified polymers were labeled as HAX or BAX or BHX or BDX in which X is percentage of PAA primary amines substituted with acrylate or bromoalkane derivatives, HA is hexyl acrylate, BA is butyl acrylate, BH is 6-bromohexanoic acid and BD is 6-bromodecanoic acid.

Briefly, various amounts of acrylate or 6-bromoalkanoic acid derivatives were dissolved in dimethylformamide (DMF). This solution was added dropwise to the stirring solution of PAA 15 kDa (0.1 g in 5 ml DMF) and the reaction was stirred for 24 overnight at room temperature. After 24 hours, the reaction mixture was dialyzed once against 0.25 M NaCl and twice against water (10,000 Da cut-off dialysis tubes) in order to remove unreacted agents. The solution of final product was freeze dried.^3,9