EFFECTS OF ORTHO-SUBSTITUENTS ON REACTIVITIES, TACTICITIES, AND CEILING TEMPERATURES OF RADICAL POLYMERIZATIONS OF PHENYL METHACRYLATES
EFFECTS OF ORTHO-SUBSTITUENTS ON REACTIVITIES, TACTICITIES, AND CEILING TEMPERATURES OF RADICAL POLYMERIZATIONS OF PHENYL METHACRYLATES
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DOI：
10.1002/pol.1980.170180715
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发表时间：
1980-01-01
影响因子：
--
通讯作者：
MORI, S
中科院分区：
文献类型：
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作者：
OTSU, T;YAMADA, B;MORI, S
研究了邻烷基苯基甲基丙烯酸酯的自由基聚合和共聚反应，研究了邻位取代基对单体均聚能力、单体反应活性和单体极限温度的影响。讨论了取代基对聚合物触感和热稳定性的影响。邻位取代基的引入显著降低了单体的反应活性和蜂蜜聚合能力。在60℃时，2，6-二叔丁基苯基甲基丙烯酸二叔丁基苯酯不形成不溶于甲醇的聚合物。根据测定的规整性，甲基丙烯酸二叔丁基苯酯在增殖反应中比甲基丙烯酸苯基苯酯或甲基丙烯酸甲酯更倾向于间规加成反应。由Theo-取代单体形成的聚合物的热稳定性不如聚甲基丙烯酸苯酯，与这一发现一致，Theo-取代甲基丙烯酸苯酯的上限温度似乎低于甲基丙烯酸苯酯。观察到的效应是取代基构象上接近单体的碳-碳双键或携带聚合物自由基未配对电子的碳。
Radical polymerization and copolymerization of someo‐alkylphenyl methacrylates were carried out and the effect of the ortho‐substituents on the ability to homopolymerize, on the monomer reactivities, and on the ceiling temperatures of the monomers was studied. The effect of the substituent on tacticities and thermal stabilities of the polymers formed was also discussed. The ability to honiopolymerize and the monomer reactivity were considerably decreased by the introduction of theo‐substituent. 2,6‐Di‐tert‐butylphenyl methacrylate formed no methanol‐insoluble polymer at 60°C. On the basis of the tacticity determined it was noted that theo‐substituted phenyl methacrylates preferred syndiotactic addition in the propagation reaction less than did phenyl methacrylate or methyl methacrylate. The polymers formed from theo‐substituted monomers were thermally less stable than poly(phenyl methacrylate), and, consistent with this finding, ceiling temperatures of theo‐substituted phenyl methacrylates seemed to be lower than that of phenyl methacrylate. The effects observed were characteristic of theo‐substituents conformationally close to the carbon‐carbon double bond of the monomer or the carbon carrying the unpaired electron of the polymer radical.