Polylactones, 39 -: Zn lactate-catalyzed copolymerization of L-lactide with glycolide or ε-caprolactone
Polylactones, 39 -: Zn lactate-catalyzed copolymerization of L-lactide with glycolide or ε-caprolactone
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DOI：
10.1002/macp.1998.021990623
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发表时间：
1998-06-01
影响因子：
2.5
通讯作者：
Kricheldorf, HR
中科院分区：
文献类型：
--
作者：
Kreiser-Saunders, I;Kricheldorf, HR
以乙交酯(Glyc)和L-丙交酯(L-Lac)为原料，在150℃下进行本体共聚，制备无规共聚酯。比较了四种可吸收催化剂：氯化锌、碘酸锌、硬脂酸锌(2)和乳酸锌(2)。用H-1NH红外光谱分别记录了乙交酯和丙交酯的时间-转换曲线。在所有条件下，乙交酯的聚合速度均快于L-丙交酯，但以乳酸锌？被用作催化剂。用C-13核磁共振波谱进行序列分析。从来没有得到过完全随机的序列，但用ZnLac(2)催化得到的序列最接近所需的随机性。以ZnSte(2)和ZnLac(2)为原料进行1：1(摩尔比)制备聚合反应。两种催化剂的产率都很高，但ZnLac(2)的相对分子质量要高得多。此外，还研究了乳酸锌(2)催化的共聚反应，考察了糖胶比的变化。研究发现，小规模和大规模共聚反应产生的共聚酯具有不同的性质，这是因为聚合早期的过热(由乙交酯引起)有利于酯交换反应。最后，在150℃下进行了己内酯-己内酯和L-丙交酯的1：1共聚反应，得到了高产率、高相对分子质量和几乎无规的聚合产物。
Copolymerizations of glycolide (Glyc) and L-lactide (L-Lac) were conducted at 150 degrees C in bulk to prepare random copolyesters. Four resorbable catalysts were used and compared: ZnCl2, ZnI2, Zn stearate (ZnSte(2)) and Zn lactate (ZnLac(2)). Separate time-conversion curves were recorded for glycolide and lactide by means of H-1 Nh IR spectroscopy. Glycolide polymerized faster than L-lactide under all circumstances, but the difference was smallest when ZnLac? was used as catalyst. Sequence analyses were performed using C-13 NMR spectroscopy. Completely random sequences were never obtained, but the sequences resulting from a catalysis with ZnLac(2) came closest to the desired randomness. Preparative 1:1 (mole ratio) polymerizations were conducted with ZnSte(2) and ZnLac(2). High yields were obtained with both catalysts, but ZnLac(2) yielded far higher molecular weights. Furthermore, ZnLac(2)-catalyzed copolymerizations were conducted with variation of the Glyc/Lac ratio. It was found that small scale and large scale copolymerizations yield copolyesters having different properties, because the superheating in the early stage of the polymerizations (resulting from glycolide) favors the transesterification. Finally, 1:1 copolymerization of epsilon-caprolactone and L-lactide were studied in bulk at 150 degrees C. Again high yields, high molecular weights and nearly random sequences were obtained.