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稀土元素铈常呈正四价氧化态,它的盐是稳定的化合物。四价铈盐是一种强氧化剂,在氧化还原过程中,Ce~(4+)直接轉变为Ce~(3+),反应快速、直接、容易达到定量反应。用四价铈离子催化引发的氧化还原体系的聚合方法是G. Mino于1958年首先提出的。他指出四价铈盐在有机还原剂、醇、羧酸、硫醇、醛、胺的存在下,能形成非常有效的氧化还原体系,产生铈离子和能引发烯类单体聚合的瞬时自由基。铈离子氧化作用的重要特征是它进行单电子轉移,同时在还原剂上形成自由基。因此,如果还原剂是聚合物分子,自由基则产生于聚合物分子上,当該氧化还原体系中存在烯类单体时,则此聚合物自由基将引发单体聚合,产生接枝共聚物。用Ce~(4+)氧化还原体系引发的接枝聚合的研究已有不少。G. Mino等研究了丙烯酰胺、
The rare earth element cerium usually has a positive tetravalent oxidation state, and its salt is a stable compound. The tetravalent cerium salt is a strong oxidant. During the redox process, Ce ~ (4 +) is directly converted into Ce ~ (3 +), and the reaction is rapid, direct and easy to achieve quantitative reaction. The polymerization of a redox system catalyzed by tetravalent cerium ions was first proposed by G. Mino in 1958. He pointed out that tetravalent cerium salts can form very efficient redox systems in the presence of organic reducing agents, alcohols, carboxylic acids, mercaptans, aldehydes, and amines, producing cerium ions and transient free radicals that can initiate the polymerization of the vinyl monomer . An important feature of cerium ion oxidation is its single electron transfer while forming free radicals on the reducing agent. Therefore, if the reducing agent is a polymer molecule, the free radicals are generated on the polymer molecule. When an ethylenic monomer is present in the redox system, then the polymer radical will initiate the polymerization of the monomer to produce a graft copolymer. There are a lot of studies on graft polymerization initiated by Ce ~ (4+) redox system. G. Mino et al studied acrylamide,