苯乙烯和马来酸酐共聚物的^(13)C NMR谱解析和分子链结构表征

MICROSTRUCTURE OF STYRENE-MALEIC ANHYDRIDE COPOLYMERS STUDIED BY ^(13)C NMR

通过比较高温 1 1 0℃下特定苯乙烯 马来酸酐共聚物H1 0和常温紫外辐照特定共聚合的苯乙烯 马来酸酐共聚物UV4的1 3C质子去偶谱和DEPT1 35谱 ,总结给出共聚物链中马来酸酐环中酸酐基的取代效应参数 (α =1 3.5、β =2 .5、γ =- 2 )及引用苯基取代参数 :α =1 6、β =6、γ =- 2 ,对共聚物主链碳的化学位移进行了经验计算 ,对所有碳 ,尤其是主链碳在三单元组或四单元组水平上进行了链序列结构归属 .在进行峰面积积分的基础上 ,对共聚物分子链两种组份摩尔比或摩尔含量、交替度、链嵌段长度、马来酸酐环残基中顺反异构体比和共聚物数均分子量等进行了表征 .共聚物UV4比H1 0的交替度高许多 。

Two styrene/maleic anhydride copolymers (St/MAh), H10 and UV4, were prepared by controlled polymerization at 110 ℃, using 1 (ethoxycarbonyl) prop 1 yl dithiobenzoate (EPDTB) as a chain transfer agent and AIBN as an initiator, and by copolymerization in THF with EPDTB as an initiator under UV irradiation at room temperature respectively. Normal 13 C NMR spectra and DEPT135 spectra were measured for both copolymers. All carbon chemical shifts in St/MAh copolymers were assigned. As a comparison, chemical shifts of the main chain carbons were calculated based on the substitution constants for phenyl group of St unit: α=16, β=6, γ=-2 , and for anhydride group of MAh: α=13.5, β=2.5, γ=-2 . The molar ratio of St to MAh, (F S/F M) , alternation degree, number average sequence length of St block, molar ratio of cis to trans configuration of MAh ring and number average molecular weight for the samples H10 and UV4 were calculated using integral values of the corresponding peaks. The copolymer UV4 had much higher alternating degree than that of H10, indicating a big influence of polymerization temperature on the formation of alternating structure in the copolymerization of St and MAh.