水分散体系中丙烯酸四氟丙酯与苯乙烯的原子转移自由基共聚合

以2－溴代异丁酸乙酯（EBiB）为引发剂、CuBr/CuBr_2/1, 10-邻二氮菲（ phen）配合物为催化剂,在水分散体系中进行了丙烯酸四氟丙酯（TFPA）与苯乙烯 (St)的原子转移自由基共聚合,所得共聚物的分子量（M_n）随着单体总转化率的 增加而增大,分子量分布（M_w/M_n）较窄（1.26～1.65）,表现出“活性”聚合 的特征。用拓展的Kelen-Tudos法和Fineman-Ross法估算了共单体的表观竞聚率, 发现St的相对反应活性高于TFPA,因此当St和TFPA起始组成为1:1（摩尔比）时, 反应自发生成了含氟的准梯度或“渐变”共聚物。实验分别考察了三种乳化剂体系 ,即十二烷基磺酸钠（SLS）、全氟辛酸钠（SPFS）／SLS和全氟壬烯氧基苯磺酸钠 （OBS）／SLS对共聚合反应的影响,发现它们对共聚合的可控制性影响不大,且反 应过程中均无破乳现象发生;然而,以OBS/SLS复合乳化剂体系制备的共聚物乳液 的贮存稳定性明显优于以SLS或SPFS／SLS为乳化剂体系制备的共聚物乳液的稳定性 。

Atom Transfer Radical Copolymerization of 2,2,3,3-Tetrafluoropropyl Acrylate and Styrene in Water Dispersion System

Atom transfer radical copolymerization of 2,2,3,3-tetrafluoropropyl acrylate (TFPA) and styrene (St) was successfully conducted in the water dispersion system with ethyl 2-bromoisobutyrate as initiator and CuBr/CuB_2/ phenanthroline as catalyst, respectively. The increase of molar masses with the increase of the total monomer conversion and relatively narrow molar mass distributions of the copolymers exhibited that the good control over the copolymerization was achieved. The apparent monomer reactivity ratios were estimated with extended Kelen- TtidSs method (γ_(st) = 0.48, γ_( TFPA)=0.08) and Fineman-Ross method (γ_(st) = 0.50, γ_(TFPA) = 0.11). It was found that the spontaneous fluorinated "gradient copolymer" was produced in this water dispersion copolymerization system due to the difference of relative reactivity between St and TFPA. Three kinds of emulsifier systems, i.e., sodium laurylsulfonate (SLS), sodium perfluorononenyloxyl benzene sulfonate (OBS)/SLS and sodium perfluoronocaprylate (SPFS)/SLS, were used and examined in this work. The results showed that both good controllability and stable copolymer latex were achieved during the course of the copolymerization by using these emulsifier systems, of which the copolymer latex prepared with OBS/SLS as emulsifier was most stable.