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以可逆加成-断裂-链转移(RAFT)试剂顺序控制丙烯酸和不对称双烯化合物4-(3-丁烯氧基-甲基)苯乙烯(BEOMSt)的溶液聚合反应,得到了两亲结构的大分子RAFT试剂,同时将BEOMSt分子中的惰性烯双键定量地悬垂于试剂的亲水与亲油嵌段间.以该试剂分别调控苯乙烯(St)溶液和细乳液聚合,着重考察了聚合方法对惰性烯双键链增长反应特性的影响.溶液聚合中,惰性烯双键链增长反应速率极低,St转化率68.6%时,产物链中烯双键数目仍维持初值,产物分子量与理论值吻合,分子量分布较窄,聚合反应呈现典型“活性”聚合的特征.但细乳液聚合反应初期,烯双键已与St共聚合,并引起分子链间偶联和分子量与理论值的正偏差,产物分子量分布也很宽.初步推测,导致细乳液聚合时惰性烯双键链增长反应受到强化作用的原因是两亲结构RAFT试剂吸附于单体细液滴表面,引起液滴油水界面层内自由基浓度以及烯双键与St浓度比值增高.
The solution polymerisation of acrylic acid and the asymmetric dimeric compound 4- (3-butenyloxy-methyl) styrene (BEOMSt) was sequentially controlled by a reversible addition-fragmentation-chain transfer (RAFT) reagent to give amphiphilic structures Macromolecule RAFT reagent, and at the same time, the inert olefinic double bond in BEOMSt molecule is quantitatively suspended in the hydrophilic and oleophilic block of the reagent, the styrene (St) solution and miniemulsion polymerization are respectively regulated by the reagent, and the emphasis is put on Polymerization process on the growth of the inert double bond chain reaction characteristics.In solution polymerization, the growth rate of the inert double bond chain reaction rate is very low, St conversion of 68.6%, the product chain number of olefinic double bond remains the initial value, product molecular weight In agreement with the theoretical value, the molecular weight distribution is narrower, and the polymerization reaction is characterized by typical “living” polymerization. However, in the early stage of miniemulsion polymerization, the olefinic double bond has been copolymerized with St and caused the coupling and molecular weight between molecular chains and the theory Value of the positive deviation, the product molecular weight distribution is also wide.It is presumed that the reason that the growth of inert double bond chain of Inert olefins in miniemulsion polymerization is enhanced is that the amphiphilic RAFT reagent is adsorbed on the surface of monomer droplets, Oil-water interface within the free Concentration, and the concentration of olefinic double bonds and St ratio increased.