Surface characterization and dissociation properties of carboxylic acid core-shell latex particle by potentiometric and conductometric titration
Surface characterization and dissociation properties of carboxylic acid core-shell latex particle by potentiometric and conductometric titration
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DOI：
10.1006/jcis.1995.9956
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发表时间：
1995-12-15
影响因子：
9.9
通讯作者：
Winnik, MA
中科院分区：
文献类型：
--
作者：
Kawaguchi, S;Yekta, A;Winnik, MA
用电位滴定法和电导滴定法研究了壳层富含羧酸基团的聚甲基丙烯酸正丁酯（PBMA）核壳乳胶粒的表面性质。采用连续三步乳液聚合法，在聚合的最后一步加入甲基丙烯酸（MA），制备了PBMA核壳乳胶粒。用电位滴定法测定了不同NaCl浓度下的胶乳水分散体。对无盐水分散体进行电导滴定。在1，4-二氧六环中用电导滴定法测定可电离基团的总含量。用电位滴定法和电导滴定法测得的贝壳中放射免疫测定量相当，但略小于返滴定法。我们的结论是，约27%的总电离基团埋在粒子内部。详细分析了乳胶表面MA基团的电位滴定行为，并与球对称的涂抹电荷模型的理论计算结果进行了比较。我们测定了RIA在表面的固有解离常数的负对数，pK（0）= 4.8 +/- 0.2，与低分子量异丁酸或聚（甲基丙烯酸）的一致。我们发现，所需的静电工作，以消除H+从乳胶粒子表面计算的涂抹电荷模型是在很好的协议与实验结果。(C)出版社：Academic Press
Surface characterization of poly(n-butyl methacrylate) (PBMA) core-shell latex particle with a shell rich in carboxylic acid groups has been investigated by means of potentiometric and conductometric titrations. PBMA core-shell latex particle was prepared by semicontinuous three-stage emulsion polymerization, Methacrylic acid (MA) was added at the final stage of the polymerization. Potentiometric titration was carried out on the latex aqueous dispersions containing various NaCl concentrations. Conductometric titration was carried out for the salt-free aqueous dispersion. The total content of ionizable groups was determined by conductometric titration in 1,4-dioxane. The RIA content in the shell, determined by potentiometric titration, is equal to that by conductometric titration, This quantity is, however, slightly smaller than that determined by back titration. We conclude that about 27% of total ionizable groups is buried in the particle interior. The potentiometric titration behavior of MA groups on the latex surface is analyzed in detail and compared to theoretical results calculated from a smeared-charge model with spherical symmetry. We determine the negative logarithm of intrinsic dissociation constant of RIA at the surface, pK(0) = 4.8 +/- 0.2, in agreement with that of low molecular weight isobutylic acid or poly(methacrylic acid). We find that the electrostatic work required to remove H+ from the latex particle surface calculated from the smeared-charge model is in good agreement with the experimental results. (C) 1995 Academic Press, Inc.