二乙基二烯丙基氯化铵与丙烯酰胺、丙烯酸共聚竞聚率

Copolymerization Reactivity Ratios of Diethyldiallylammonium Chloride with Acrylamide or Acrylic Acid

以过硫酸铵为引发剂,在水溶液体系中二乙基二烯丙基氯化铵(DEDAAC)分别与丙烯酰胺(AM)、丙烯酸(AA)和丙烯酸钠(AANa)进行自由基共聚合。采用元素分析法分别测定了在低转化率时,不同单体摩尔比条件下共聚物的组成,得到了相应的共聚物组成曲线;通过Kelen-Tudos方法求得相应共聚体系的单体竞聚率。结果表明,DEDAAC与AM共聚竞聚率r_(DE)=0．31、r_(AW)=5．27,与AA的竞聚率r_(DE)=0．28、r_(AA)=5．15,与AANa的竞聚率r_(DE)=0．40、r_(AANa)=3．97;DEDAAC结构单元在共聚物中的摩尔分数均比在单体混合物中低, DEDAAC的活性远低于AM、AA和AANa。其主要原因是DEDAAC具有较强的自阻聚和链转移作用、较大的空间位阻以及DEDAAC与增长链间较大的末端与前末端效应。以上每个体系中2个单体的竞聚率的积均大于1,因此,DEDAAC与AM、AA和AANa等共聚为非理想共聚,得到的产物均为近似无规共聚物。

The radical copolymerizations of diethyldiallylammonium chloride （DEDAAC） with acrylamide （AM）, acrylic acid（AA） or sodium acrylic acid（AANa） were carried out in aqueous solutions using persulfate ammonium （APS） as initiator. The compositions of these copolymers at various monomer molar ratios and with low conversion were determined by elemental analysis and the corresponding composition curves were plotted. The reactivity ratios of monomers in copolymerization were also obtained by Kelen-Tudos method. The results show that the values of reactivity ratios r and r are 0. 31 and 5.27 for DEDAAC with AM, 0. 28 and 5.15 for DEDAAC with AA, and 0. 40 and 3.97 for DEDAAC with AANa. The molar fractions of the unit of DEDAAC in copolymers are lower than those in monomer mixtures and the reactivity of DEDAAC is far lower than those of AM, AA and AANa, and this is ly due to the strong chain transfer, self inhibition, and the large steric hindrance of DEDAAC, as well as the large end effect and penultimate effect between the growing chains and DEDAAC. For each system above, the product of the reactivity ratios of the two monomers is above 1, therefore, the copolymerization for DEDAAC with AM, AA or AANa is non-ideal copolymerization and the products are approximately random copolymers.