Effect of Charge Density on Structural Characteristics of Cationic Polyacrylamide: Models Based on Reactivity Ratio and Characterization

By : Qingqing Guan, Huaili Zheng, Jin Xu, Fang Tian, Xiaoxu Sun

Page No: 365-377

Abstract
In this study, effect of charge density (CD) on structural characteristics especially the microstructure (i.e. unit sequence distribution) of cationic polyacrylamide (CPAM) poly(acrylamide(AM)-co-acryloxyethyltrimethyl ammonium chloride(DAC)) initiated by ultraviolet was extensively studied. The predicted models based on the determination of reactivity ratio were used to depict the microstructure. CPAM with different CD was further characterized by FT IR, TGA-DSC, 13C NMR and 1 H NMR. Results indicated that the reactivity ratios of AM and DAC monomer pair were determined as 2.27 and 0.38, respectively. The Igarashi and Pyun model based on reactivity ratio indicated that blockness percent and mean sequence length of AM unit decreased whereas those of DAC increased with the increasing of CD. The FT IR spectra confirmed the compositional component of the copolymers and TGA-DSC thermograms suggested their accepted thermo stability. However, these two characterization methods did not offer useful information of polymer microstructure. 13C NMR spectra further confirmed the rise tendency of AM unit blockness is proposed that 1 H NMR can be used to examine whether two monomers have been copolymerized. Furthermore, 1 H NMR, a valuable method in estimating cationic blockness percent of P(AM-co-DAC), was proposed for the first time.

Authors :
Qingqing Guan and Huaili Zheng : Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment, State Ministry of Education, Chongqing University, Chongqing 400045, China
Jin Xu, Fang Tian And Xiaoxu Sun : Department of the Environmental Engineering, Nanjing Institute of Technology, 1 Hongjing Avenue, Nanjing 211167, P. R. China.