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α,α-二甲基-β-丙内酯(即PVL)的嵌段共聚近年来受到人们的重视。1979年G.Broze等发现只有α,β或γ位带有极性基团或双键的羧端基才可以进行嵌段共聚,否则只能引发均聚。但他们的实验都是以四正丁铵做为反离子的。我们改用其它季铵反离子发现可以改变嵌段效率,同时发现未嵌段的双羧戊酰端基的聚1,2-丙二醇己二酸酯(PPA)上带有微量的酸酐键,因而提出引发PVL时同时存在烷氧与酰氧开环两种引发机制,前者导致嵌段共聚,后者则导致均聚。本文进一步研究了不同季铵与冠醚络合钾反离子对嵌段效率的影响。
In recent years, the block copolymerization of α, α-dimethyl-β-propiolactone (PVL) has drawn great attention. In 1979, G.Broze et al. Found that only carboxyl end groups with polar groups or double bonds in the α, β or γ position could undergo block copolymerization, otherwise they could only initiate homopolymerization. But their experiment is to tetra-n-butylammonium as a counterion. We switch to other quaternary ammonium counterions to change the block efficiency, and we found that the unblocked biscarboxypentanoyl end groups of poly-1,2-propanediol adipate (PPA) with trace amounts of anhydride linkages It is proposed that both the initiation mechanism of alkoxide and acyl ring opening occur when PVL is initiated, the former leads to block copolymerization and the latter leads to homopolymerization. This paper further studied the different quaternary ammonium and crown ether complex potassium counterions on the block efficiency.