Influence of Initiation Efficiency and Polydispersity of Primary Chains on Gelation during Atom Transfer Radical Copolymerization of Monomer and Cross-Linker
Influence of Initiation Efficiency and Polydispersity of Primary Chains on Gelation during Atom Transfer Radical Copolymerization of Monomer and Cross-Linker
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DOI：
10.1021/ma8025833
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发表时间：
2009-02-24
期刊：
影响因子：
5.5
通讯作者：
Matyjaszewski, Krzysztof
中科院分区：
文献类型：
--
作者：
Li, Wenwen;Gao, Haifeng;Matyjaszewski, Krzysztof
研究了单乙烯基单体和二乙烯基交联剂原子转移自由基共聚（ATRO）过程中引发效率和主链多分散性对实验凝胶点的影响。甲基丙烯酸甲酯(MMA)和二甲基丙烯酸乙二醇酯(EGDMA)的ATRcP使用三种引发效率逐渐提高的引发剂——2-溴丙酸乙酯(EBrP)<2-溴异丁酸乙酯(FBiB)<2-溴丙腈(BPN)。使用效率最低的EBrP引发剂，由于EBrP的引发效率低，当EGDMA交联剂与EBrP的摩尔比低至0.25时，发生实验凝胶化。相比之下，即使当交联剂与引发剂的摩尔比等于1时，使用最有效的BPN引发剂也没有观察到凝胶化。使用较差的溶剂作为铜催化剂也会降低引发效率并导致单体转化率较低的凝胶化。通过使用电子转移再生活化剂（ARGET）ATRP进行丙烯酸甲酯（MA）和乙二醇二丙烯酸酯（EGDA）的共聚，研究了实验凝胶点对主链多分散性的依赖性。将铜浓度从几十 ppm 降低到几 ppm 拓宽了主链的分子量分布，这导致 MA 和 EGDA 共聚过程中单体转化率较低而较早凝胶化。
The influence of initiation efficiency and polydispersity of primary chains on the experimental gel points was studied during atom transfer radical copolymerization (ATRO) of monovinyl monomer and divinyl cross-linker. Three initiators with progressively increased initiation efficiency-ethyl 2-bromopropionate (EBrP) < ethyl 2-bromoisobutyrate (FBiB) < 2-bromopropionitrile (BPN)-were used for the ATRcP of methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA). With the least efficient EBrP initiator, experimental gelation Occurred when the molar ratio of EGDMA cross-linker to EBrP was as low as 0.25 due to the low initiation efficiency of EBrP. In contrast, no gelation was observed by using the most efficient BPN initiator, even when the molar ratio of cross-linker to initiator was equal to unity. The use of a poorer solvent for copper catalyst also decreased the initiation efficiency and resulted in a gelation at lower monomer conversion. The dependence of experimental gel points on the polydispersity of primary chains was studied by using activators regenerated by electron transfer (ARGET) ATRP for copolymerization of methyl acrylate (MA) and ethylene glycol diacrylate (EGDA). Decreasing the copper concentration from tens of ppm to a few ppm broadened the molecular weight distribution of primary chains, which resulted in an earlier gelation at lower monomer conversion during the copolymerization of MA and EGDA.