NMR Study of Polyacrylamide Tacticity Synthesized by Precipitated Polymerization Method

作者：Ziaee Farshid^*; Bouhendi Hosein; Ziaie Farhood

来源：Iranian Polymer Journal, 2009, 18(12): 947-956.

• polyacrylamide
• precipitated polymerization
• tacticity
• NMR
• microstructure

In this study polyacrylamide was prepared in various molar ratio contents of ethyl acetate and ethanol at 60 degrees C by free-radical precipitated polymerization method. The assignment of all stereosequences at pentad level of methine, hexad level of methylene, and triad level of carbonyl carbons of the polyacrylamide were observed using (13)C nuclear magnetic resonance spectroscopy ((13)C NMR) in deuterium oxide at room temperature. Bernoullian and 1st-order Markov statistics were used for all carbons and the results were compared with experimental data by statistical method. It was shown that Bernoullian statistics model fit slightly better than 1st-order Markov statistics model for the assigned sequences. The results indicated that corresponding values of the probability (P(m)) and length average (N(m)) of meso addition were 0.443 and 1.698, respectively and no significant differences were observed by changing the molar ratios of the two solvents. By heteronuclear multiple quantum coherence (HMQC) as two-dimensional NMR spectroscopy, the methylene and methine groups were assigned by triad sequences in which isotactic contour was thoroughly isolated from syndiotactic and atactic contours. Therefore, isotactic triad sequence could only be calculated by (1)H NMR. In other words, isotactic placement value was calculated by using the integration of areas of methylene and methine protons (mm = 0.21) peaks.

• 出版日期2009-12