Poly(N,N-diallylaspartic acid-alt-sulfur dioxide): its synthesis and application

Abstract

Monomer pairs, dimethyl N,N-diallylaspartate hydrochloride [(CH2=CH–CH2)2NH+CH(CO2Me)CH2CO2Me Cl−] (I)/SO2 and N,N-diallylaspartic acid hydrochloride [(CH2=CH-CH2)2NH+CH(CO2H)CH2CO2H Cl−] (II)/SO2, underwent alternate cyclocopolymerization to give cationic polyelecyrolytes (CPEs), poly(I-alt-SO2) (III) and poly(II-alt-SO2) (IV), respectively, in very good yields. (+) III upon acid hydrolysis was converted to cationic (+) IV, bearing in each repeating unit the triprotic acid residues [(NH+…(CO2H)2] of aspartic acid hydrochloride. Under the influence of pH, (+) IV has been equilibrated to water-insoluble diprotic polyzwitterionic acid (±) V, water-soluble monoprotic poly(zwitterion-anion) (± −) VI and finally its conjugate base polydianion (=) VII. Basicity constants of CO2− and amine group have were determined. The pH-responsive polymer was demonstrated to be an efficient antiscalant against CaSO4 scaling. For potential separation and purification of biomolecules, a recyclable aqueous two-phase system (ATPS) was constructed using water-soluble (=) VII and urethanized polyvinyl alcohol; the ionic polymer can be recycled by precipitating it as (±) V at a lower pH.