Graft copolymerization of 2-(dimethylamino)ethyl methacrylate onto carboxymethylated cellulose

Amphoteric graft copolymers of carboxymethylated cellulose (CMC) with 2-(dimethylamino)ethyl methacrylate (DMAEM) were prepared in aqueous solutions using ammonium persulfate (APS) and N,N,N ′,N ′-tetramethylethylenediamine (TMEDA) as the initiation system. They were characterized by the grafting parameters, IR and solubility measurements. The effects of the reaction variables on the grafting percentage of the graft copolymer (%GP), grafting efficiency of the reaction (%GE) and grafting conversion of the monomer (%GC) were studied. It is observed that the %GP, %GE and %GC increase and then decrease with increasing concentrations of TMEDA and APS, pH of reaction medium and polymerization temperature. Increasing DMAEM amount is accompanied by an increase in the %GP but the opposite holds true for CMC. Under similar conditions, %GP, %GE and %GC increase upon increasing degree of substitution of carboxymethyl groups of CMC up to a value of 0.22, beyond which %GP and %GC did not cause a significant change while %GE decreases. Addition of an appropriate amount of salt to the synthesis system is favorable for the grafting. The overall activation energy for the grafting is calculated to be 10.3 kJ/mol.