Synthesis Star-Shaped Cationic Polyacrylamide- Dimethyl- Diallyl- Ammonium- Chloride by "Core-First" Method

A star-shaped cationic polyacrylamide(star-P(AM-DMDAAC)) was synthesized by free radical copolymerization of monomer of acrylamide(AM) and dimethyl diallyl ammonium chloride (DMDAAC) using the redox system of pentaerythritol(PETL) and (NH4)2S2O8 as initiator. And the factor influence the polymer molecular weight were detailed studied. The results indicate that the effects of polymerization temperature, the dosage of initiator, molar ratio of AM to DMDAAC have a greater influence on the viscosity-average molecular weight of the copolymer. and adding urea and ethylenediamine tetraacetic acid(EDTA) for additive and adding ammonia for adjustment the acidity of catalyst system can also increase the polymer molecular weight. The sludge dewatering performance of self-made star-P(AM-DMDAAC) is better than the commercial linear type cationic polyacrylamide flocculants in the market. The structures of the resulting products were characterized by nuclear magnetic resonance(1H-NMR), the PETL as "core" of the star polymer, the AM and DMDAAC as "arms" of the star polymer. And the synthesis mechanism was proposed in this paper.