中文摘要：

采用聚乙烯醇（PVA）在室温下静置或UV光照射下活化改性马来酸酐共聚物。探讨了改性作用机理。结果表明：将PVA加入到醋酸乙烯酯／马来酸酐共聚物（P（MAn／VAc））的二甲基亚砜（DMSO）溶液中，溶液颜色立刻由浅紫红色变为深紫红色，紫外光谱分析在400～650nm处出现很强吸收峰，PVA羟基与酐基形成了四面体两性离子（tetrahedral zwitterion）结构；将PVA加入到苯乙烯／马来酸酐共聚物（P（MAn／St））的DMSO溶液中则观察不到溶液颜色变化及紫外吸收变化，四面体两性离子结构不稳定而使酐基直接开环得到块状交联凝胶。紫外辐照可促使四面体两性离子结构向其电中性同分异构体转化而使酐基开环，实现温和条件下马来酸酐共聚物的改性。

英文摘要：

Polyvinyl alcohol （PVA） has been used as a modifier to improve the properties of maleic anhydride copolymers under mild conditions, and the mechanism involved is discussed. When a solution of PVA in dimethyl sulfoxide （DMSO） was dropped into a solution of maleic anhydride/vinyl acetate copolymer （P（MAn/ VAc） ） in DMSO, the color of the P（MAn/VAc） solution turned immediately from light violet to purple. UV- visible spectroscopy show, ed a strong absorbance in the range 400 - 650 nm, indicating that a tetrahedral zwitterion structure is formed between hydroxyl groups of PVA and anhydride groups of P（MAn/VAc）. No such color change or UV-visible absorbance change was observed for a solution of a maleic anhydride/styrene copolymer （P （MAn/St）） when PVA was added, suggesting that in this case the tetrahedral zwitterion structure is unstable and the anhydride group opens directly to produce bulk hydrogel. UV irradiation promoted the transformation of the tetrahedral zwitterion structure to the electrically neutral isomer, and thus accelerated the ring opening of the anhydride group.