物理化学学报 >> 1993, Vol. 9 >> Issue (05): 604-609.doi: 10.3866/PKU.WHXB19930507

研究论文 上一篇    下一篇

分子活动性对iso-PMMA辐射裂解和消旋的影响

罗云霞; 杨弘; 虞斌; 丁孟贤; 姜炳政   

  1. 中国科学院长春应用化学研究所，长春 130022
  • 收稿日期:1992-03-24 修回日期:1992-07-16 发布日期:1993-10-15
  • 通讯作者: 罗云霞

The Effect of Mobility of Molecules on Radiation-induced Chain Scission and Racemization of iso-Poly(Methyl Methacrylate)

Luo Yun-Xia; Yang Hong; Yu Bin; Ding Meng-Xian; Jiang Bing-Zheng   

  1. Changchun Institute of Applied Chemistry, Academia Sinica, Changchun 130022
  • Received:1992-03-24 Revised:1992-07-16 Published:1993-10-15
  • Contact: Luo Yun-Xia

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摘要： 以全同立构聚甲基丙烯酸甲酯(iso-PMMA)为对象, 用核磁共振谱和分子量测定等手段, 研究了不同物理状态, 即无定型固态, 结晶态和稀溶液状态下的辐射裂解和辐射消旋反应. 结果表明, 在稀溶液状态下辐照, 其裂解反应最强, 而消旋反应最弱; 结晶状态下辐照, 则裂解反应最弱而消旋反应最强. 这充分说明了分子的活动性对反应的影响, 进一步验证了前已提出的高分子链断裂-重合-消旋的平衡反应机理.

关键词: 消旋, 裂解, 辐射效应, 聚甲基丙烯酸甲酯, 分子活动性

Abstract: The radiation-induced chain-scission and racemization of isotactic poly(methylmethacrylate)(iso-PMMA) in amorphous and semi-crystalline state as well as in solution have been studied with nuclear magnetic resonance and molar mass deter-mination. It is shown that the chain-scission is dominant for iso-PMMA in dilute solution while the racemization reaction is not favorable in this case. On the contrary, the racemization is favorable when iso-PMMA was irradiated in its crystalline state while chain-scission is not. Such experimental results could be well explained by the mobility of molecules and "cage effect". The hypothesis, we proposed previously that the chain-scission, racemization and recombination are in competition and the final result depends on the state of molecular motion at which iso-PMMA was irradiated, has been verified verified once again.

Key words: Racemization, Chain-scission, Radiation effect, Poly(methyl methscrylate), Molecular mobility