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首页> 美国政府科技报告 >Preparation and Characterization of Polyelectrolyte Copolymers Containing MethylMethacrylate and 2-Hydroxyethyl Methacrylate. Part 1: Polymers Based on Methacrylic Acid
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Preparation and Characterization of Polyelectrolyte Copolymers Containing MethylMethacrylate and 2-Hydroxyethyl Methacrylate. Part 1: Polymers Based on Methacrylic Acid

机译：含甲基丙烯酸甲酯和甲基丙烯酸2-羟乙酯的聚电解质共聚物的制备与表征。第1部分：基于甲基丙烯酸的聚合物

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Acidic polyelectrolyte copolymers containing 2-hydroxyethyl methacrylate (HEMA),methyl methacrylate (MMA), and methacrylic acid (MAA) were prepared by free radical polymerization to high conversion in solution. Copolymer yields were obtained by gravimetry (all in the 30-50 percent range) relative molecular weights estimated by intrinsic viscosity measurements (all in the 50-70 cc/g range), tacticity by C-13 nuclear magnetic resonance (NMR) spectroscopy (all polymers were predominantly syndiotactic with some atactic content), and composition by acid/base titrations in conjunction with H-1 NMR spectroscopy (all close to the monomer charge ratios). Acid strength or apparent pKa's were examined as a function of extent of ionization. Measurements performed in water indicated that the compact/extended coil transformation in predominantly syndiotactic polymethacrylic acid occurres also in copolymers of similar tacticity containing moderate to high concentrations of MAA. The apparent pKa of such polymers containing only small amounts of MAA did not vary with extent of ionization, indicating a low degree of interaction between the acid groups. In copolymer pairs containing similar amounts of MAA but differing HEMA and MMA contents, the polymer containing more HEMA appeared the stronger acid, presumably due to a better solvation of that polymer which would increase the net spatial charge-charge separation, and decrease cooperative effects which lead to suppressed ionization.

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