乙烯系单体自由基聚合的阻聚效应——Ⅸ.受阻胺-醌类电荷转移络合物对甲基丙烯酸甲酯自由基聚合的阻聚及历程

IHIBITION EFFECTS OF RADICAL POLYMERIZATIONS OF VINYL MONOMERS IX. STUDIES ON THE MECHANISM OF INHIBITION OF THE RADICAL POLYMERIZATIONS OF METHYL METHACRYLATE USING THE CHARGE-TRANSFER COMPLEXES OF HINDERED AMINE-QUINONES

用膨胀计法研究了西氯苯醌(CA)、苯醌(BQ)与受阻胺二异丙胺(DIPA)、2,2,6,6-四甲基-4-羟基哌啶(TMP)形成的电荷转移络合物(CTC)对偶氮二异丁腈(AIBN)引发的甲基丙烯酸甲酯(MMA)自由基聚合阻聚效应。结果表明,CA-DIPA、CA-TMP、BQ-DIPA和BQ-TMP对MMA的自由基聚合均产生较单独的醌或胺更显著的阻聚能力。其中以CA-DIPA阻聚效果更佳。比较了MMA在苯或乙腈中的溶液聚合,得类似结果。初步讨论了受阻胺-醌电荷转移络合物对MMA自由基聚合的阻聚反应机理。

Inhibititing effects of charge-transfer complexes (CTC) of hindered amine, such as, di-isopropylamine (DIPA) and 2, 2, 6, 6-tetramelhyl-4-piperidinol (TMP) to react with ch-loranil (CA) or benzoquinone (BQ) on radical polymerization of methyl methacrylate (MMA), initiated by azobisisobutylonitrile (AIBN), has been investingated by dilatometric method. The results showed that these complexes demonstrated greater inhibiting efficiency than those of quinones and hindered amines to be used alone Especially CTC formation of DIPA with CA could inhibite more remarkable the polymerization of MMA in presence of AIBN. In addition, polymerization to be process in solvents such as benzene and acetonitrile were compared with those of bulk polymerization of MMA. Those tests all reveal that CTC are polymerization inhibitors so that the efficiency of inhibition will be determined through the feasibility of CTC formation in polymerizating system. In other words, the results proved preliminary inhibition by the mixture of quinones and hindered amine for MMA might be also to involes electron-transfer from the hindered amine into quinones forming CTC of hindered amine cation and semiquinones anion. The semiquinones anions are the actual inhibiting species.