二步水解法制备凝胶渗透色谱用聚甲基丙烯酸标样

Preparation of Monodispersed PMAA for GPC Calibration Standards by Two-Step Hydrolysis

采用二步水解法水解单分散GPC用聚甲基丙烯酸甲酯标样,核磁共振测得其水解率达99%,制得的聚甲基丙烯酸钠经酸化析出后得到聚甲基丙烯酸标样。该聚甲基丙烯酸标样以磷酸盐缓冲水溶液为流动相,采用PLaquagel-OH mixed-H柱串联测得的GPC色谱峰峰形对称,半峰宽窄,分散系数均小于1.3,具有很好的单分散性。粘度法测得其Mη与通过聚甲基丙烯酸甲酯标样参数计算得到的Mη'平均相对误差小于10%,表明水解对聚甲基丙烯酸甲酯主链的聚合度无明显影响。因此,可以用聚甲基丙烯酸甲酯标样的分子量计算得到相应聚甲基丙烯酸标样的分子量。

Hydrolyzed monodisperse polymethyl methacrylate for GPC calibration standards by two-step hydrolysis, the degree of hydrolysis reached 99% measured by nuclear magnetic resonance analysis (NMR).The obtained monodisperse polymethylacrylic acid-Na transformed to polymethylacrylic acid by acidification. The polymethylacrylic acid with phosphate buffer solution as mobile phase, used PL aquagel-OH mixed-H columns in series, GPC figures had symmetrical peak shape, narrow half-peak, dispersity were all less than 1.3. Viscosity average molecular weight (Mη') of polymethylacrylic acid calculated by hydrolysis formula compared to the actual results measured by viscosity meas-uring method (Mη), the average relative error were less than 10%, which indicated the hydrolysis did not effect on the degree of polymerization of the main chain. Therefore, we can calculate molecular weight of polymethylacrylic acid from the corresponding molecular weight of polymethyl methacrylate.