Macrocycles 2 -: Living macrocyclic polymerization of ε-caprolactone with 2,2-dibutyl-2-stanna-1,3-dioxepane as initiator
Macrocycles 2 -: Living macrocyclic polymerization of ε-caprolactone with 2,2-dibutyl-2-stanna-1,3-dioxepane as initiator
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DOI：
10.1002/(sici)1521-3935(19980201)199:2
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发表时间：
1998-02-01
影响因子：
2.5
通讯作者：
Eggerstedt, S
中科院分区：
文献类型：
--
作者：
Kricheldorf, HR;Eggerstedt, S
ε-己内酯在80 ℃下以2，2-双-2-锡-1，3-二氧杂环庚烷（DSDOP）作为引发剂进行本体聚合。反应时间随单体/引发剂摩尔比为20、100和500而变化。在较长的反应时间后，发现单体的快速和完全转化和仅轻微的酯交换或回咬降解。然而，在180 ℃下观察到这些副反应的显著加速。无论M/I比和反应时间的多分散性几乎是恒定的。从GPC测量获得的数均分子量（（M）/巴（n））比从端基分析获得的值大15-25%，并且随着摩尔比M/I的增加而增加（在100%转化率下）。Sn-O“端基”的活性特征通过与4-硝基苯甲酰氯的酰化和通过含有β-D，L-丁内酯的大环嵌段化合物的合成来证明。
epsilon-Caprolactone was polymerized in bulk at 80 degrees C with 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP) as initiator. The reaction time was varied for monomer/initiator molar ratios of 20, 100 and 500. A rapid and complete conversion of the monomer and only slight transesterification or back-biting degradation were found after longer reaction times. However, significant acceleration of these side reactions was observed at 180 degrees C. Regardless of the M/I ratios and of the reaction time the polydispersities were nearly constant. Number average molecular weights ((M) over bar(n)'s) as obtained from GPC measurements are larger than the values obtained from end-group analyses by 15-25% and increase with increasing molar ratio M/I (at 100% conversion). The living character of the Sn-O "end-groups" was demonstrated by acylation with 4-nitrobenzoyl chloride and by the synthesis of a macrocyclic block copolyester containing beta-D,L-butyrolactone.