聚乙烯醇-b-聚苯乙烯嵌段星形聚合物的制备

通过CCl₄调聚反应制备出了末端带有氯原子的聚醋酸乙烯酯(PVAc)，进一步引发苯乙烯原子转移自由基聚合得到聚醋酸乙烯酯-b-聚苯乙烯嵌段共聚物(PVAc-b-PSt)，此嵌段共聚物与偶联剂二乙烯基苯反应后醇解，得到了聚乙烯醇-b-聚苯乙烯星形嵌段共聚物(PVA-b-PSt)_n。分别以GPC，¹H-NMR及FT-IR对各步反应产物进行了表征，聚醋酸乙烯酯比较完全地引发苯乙烯进行原子转移自由基聚合(ATRP)，聚合物相对分子质量与单体转化率呈线性关系，证明聚合过程为活性聚合；以二乙烯基苯偶联PVAc-b-PSt，得到了星形共聚物，并出现了星形共聚物之间的偶合；醇解过程进行比较完全，¹H-NMR及FT-IR谱图表明酯基团已较完全地转变成羟基。

Synthesis of poly (vinyl alcohol)-block-polystyrene star-shaped polymers

A star block copolymer was prepared by four steps: 1.Through telomerization of vinyl acetate by tetrachloride carbon,poly(vinyl acetate) with chlorine atom in the end of macromolecules(PVAc-CCl_3) was synthesized;2.The PVAc-CCl_3 was used to initiate the polymerization of styrene to proceed atom transfer radical polymerization;3.The poly(vinyl acetate)-b-polystyrene was coupled with divinyl benzene to form the poly(vinyl acetate)-b-polystyrene star polymer(PVAc-b-PSt)_n;4.Alcoholysis of(PVAc-b-PSt)_n formed the poly(vinyl alcohol)-b-polystyrene star polymer(PVA-b-PSt)_n.The macromolecule products in all steps were analyzed by GPC,1H NMR or FT-IR,and the results show that: almost all of poly(vinyl acetate) macromolecules have initiated the polymerization of styrene,the living polymerization is proved by the linear relationship between monomer conversion and polymer molecular weight;in preparation of star polymer,the coupling of stars are observed;the complete alcoholysis of(PVAc-b-PSt)_n is proved by()~1H NMR and FT-IR.