【摘要】 以钴Ⅱ肟氟化硼络合物(CoBF)为催化剂,2,2′-偶氮二异丁腈(AIBN)为引发剂,实现了甲基丙烯酸甲酯(MMA)与γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)在60℃甲苯体系中的催化链转移聚合(catalytic chaintransfer polymerization,CCTP),制备出末端含有双键的共聚物.利用核磁共振证明了其末端双键的存在,并通过热重分析证明CCTP产物与自由基聚合产物的结构区别.用凝胶渗透色谱(GPC)对7种单体组成下不同催化剂CoBF用量的聚合产物进行分子量表征,结果表明以催化链转移聚合合成的共聚物具有分子量低及分子量分布较窄,且聚合物的分子量随着催化剂CoBF的增加呈明显下降趋势.又分别采用了基于DPn(数均聚合度)、DPw(重均聚合度)的Mayo方程和基于ΛP、ΛH的链长分布方程计算出催化剂的表观链转移常数,发现基于DPw的Mayo方程和基于ΛP的链长分布方程的计算结果最为接近.并通过对共聚体系中不同单体组成的研究发现,催化剂表观链转移常数随着单体组成中MPS的增加而增加.更多还原

【Abstract】 Catalytic chain transfer polymerization(CCTP) of methyl methacrylate(MMA) and γ-methacryloxypropyltrimethoxysilane(MPS) was performed using toluene as the solvent at 60℃ in the present of bis(boron difluorodimethylglyoximate) cobaltate(Ⅱ)(CoBF) as catalytic chain transfer agent and AIBN as the initiator.Vinyl-terminated copolymers with low molecular weight were successfully prepared by CCTP in this case.()~1H-NMR was employed to prove the presence of vinyl unsaturated end groups of the as-prepared polymer.The effect of structure on thermal behavior was investigated by using thermogravimetry(TG) in nitrogen atmosphere.In contrast to PMMA-co-PMPS prepared in absence of CoBF,the differential thermogravimetry(DTG) curves of the copolymer synthesized by CCTP show that only one sharp peak appears at 283℃,which presents the degradation resulting from the random scission of the backbone and the terminal double bonds.GPC was carried out to analyze molecular weight information of copolymers synthesized in different conditions.Results illuminated that average molecular weight decreased with the increase of CoBF.Apparent chain transfer constants(C_t) were determined with the conventional Mayo procedure based on number(M_n) and weight(M_w) average molecular weights,and with chain length distribution procedure based on peak(Λ_P) and high(Λ_H) molecular weight slopes.It could be found that the apparent chain transfer constants determined from M_w and Λ_P were similar and much better than others.In addition,on the basis of different monomer feed compositions,we found that C_t values were increased with the concentration of MPS.更多还原