Ni(Ⅳ)引发丙烯酸甲酯与三元尼龙接枝共聚反应的研究

以二过碘酸合镍(Ⅳ)钾〔Ni(Ⅳ)〕为氧化剂,共聚尼龙上的弱的还原基团(酰胺基)为还原剂,组成氧化还原引发体系,于碱性介质中直接在共聚尼龙分子骨架上产生接枝点,引发丙烯酸甲酯(MA)的接枝共聚合反应,获得了较高的接枝效率(可达90%以上)。探讨了引发剂浓度、单体浓度、反应温度对接枝参数的影响,结果表明:当c〔Ni(Ⅳ)〕=8×10-4mol/L,c(MA)=1 5mol/L,θ=35℃时,接枝效率和接枝百分比可达到最高值。用红外光谱、X射线衍射、扫描电镜对接枝共聚物进行了表征,提出了建立在镍(Ⅳ)还原为镍(Ⅱ)的过程为两步单电子转移的基础之上的引发机理。将所得接枝共聚物用作尼龙/聚甲基丙烯酸甲酯体系的增容剂,通过扫描电镜分析表明:该共混体系的相容性得到一定程度的改善。

Graft Copolymerization of Methyl Acrylate onto Terpolyamide of Nylon 6/Nylon 66/Nylon 1010 Initiated by Potassium Diperiodatonickelate(Ⅳ)

The graft copolymerization of methyl acrylate onto nylon 6/nylon 66/nylon 1010 (terpolyamide) was studied in aqueous alkaline medium,with potassium diperiodatonickelate(Ⅳ)〔Ni(Ⅳ)〕-terpolyamide redox system as initiator.Graft copolymers with high grafting efficiency (～ 90%) were obtained,which indicated that Ni (Ⅳ)-terpolyamide system is an efficient redox initiator for this graft copolymerization.The dependence of grafting parameters on the concentrations of initiator and monomer,as well as temperature was investigated.Maximum grafting efficiency and percent grafting were obtained at c〔Ni(Ⅳ)〕=8×10~(-4) mol/L,c(MA)=1.5 mol/L,θ=35 ℃.FTIR,X-ray diffraction and SEM were employed to study the structure of the graft copolymers.A mechanism based on the two separate single-electron-transfer process of Ni (Ⅳ) to Ni (Ⅱ) was proposed to explain the formation of radicals and the initiation.In addition,the graft copolymer was employed as compatibilizer in blends of terpolyamide and poly(methyl methacrylate).The SEM photographs illustrated that the graft copolymer efficiently improved the miscibility of the blends.