RAFT与点击化学结合制备UV固化丙烯酸树脂

Synthesis of UV-Curing Acrylic Resin by the Combination of RAFT and Click Chemistry

以3-(苄硫基硫代羰基硫基)丙酸(BCTPA)为链转移剂,过硫酸铵(APS)/NaHSO3为氧化还原引发剂,用可逆加成-断裂链转移(RAFT)活性自由基乳液聚合制备了窄分布(PDI=1.21)的聚甲基丙烯酸烯丙酯(PAMA),并用核磁共振(1H-NMR)和凝胶渗透色谱(GPC)对其进行了表征,GPC测得PAMA数均分子量为7463,与通过单体转化率计算的理论分子量7483及氢谱计算分子量9358结果基本一致。采用巯基-烯烃点击反应对PAMA进行UV固化交联,固化后涂膜硬度由1H变为2H;耐水性测试表明,固化前40 min即发白,固化后24 h内仍未发白。PAMA固化前后的IR对照结果表明,固化后乙烯基信号3088 cm-1峰消失,表明烯丙基参与了固化交联反应。

Poly（allyl methacrylate）（PAMA） with narrow molecular weight distribution（PDI=1.21） was synthesized by radical addition-fragmen-tation chain transfer（RAFT） emulsion polymerization,using 3-（benzylthiocarbonothioylthio）propanoic acid（BCTPA） as chain transfer agent and ammonium persulfate（APS）/NaHSO3 as redox initiator.The PAMA was characterized by 1H-NMR and gel permeation chromatograph（GPC）.The number-average molecular weight of PAMA from GPC is 7463,which is consistent with that from 1H-NMR spectrum（9358） and monomer conversion（7483）.Then the PAMA was UV-cured with 1,2-ethanedithiol by thiol-ene click reaction.After that,the hardness of the film is increases from 1H to 2H,and the film doesn＇t turn white within 24 h in water.Compared with the IR spectra of pre-UV cured PAMA,disappearance of the peak at 3088 cm-1 of postUV cured PAMA indicates that the allylic groups undergo crosslinking reaction.