d,l-聚丙交脂、l-聚丙交酯与ε-聚已内酯之间的酯交换

The Transesterification Between Poly(ε-Caprolactone) And Poly(d,1-Lactide), Poly(1-Lactide)

本文采用的两种共混方式即熔融辗压共混与去溶剂共混,在添加与不添加催化剂Ti(OBu)_4·BF_3·OEt_2两种情况下于150℃都观察到两种均聚物的明显降解。共混d,l-聚丙交酯(d,l-PLA)/ε-聚已内酯(ε-PCL)时,d,l-PLA降解速率大于ε-PCL^(13)C-NMRDSC谱图证明它们间无明显的酯交换发生;在与上述相同条件下,共混l-PLA/ε-PCL时,^(13)C-NMR及DSC谱图都证实了发生明显酯交接,生成了共聚物。共聚物的摩尔组成由~1H-NMR加以测定,由精细^(13)C-NMR谱图计算出共聚物中l-LA与ε-CL平均链段长度。DSC表征了该共聚物的结晶情况。其结果与上述二者的分析完全一致。

This study is concerned with two different blend methods: the melt-milling blend and solvent-free blend. The degradation of two polymers was apparently observed in blending with or without catalyst titanium tetrabutoxide Ti(OBu)_4 or boron trifluoride etheate BF_3OEt_2 at 150℃. The absence of significant transesterification was proved by means of ^(13)C-NMR and DSC in blend of d,l-PLA/PCL. In contrast, the considerable transesterification occured in solvent-free blend/-PLA/PCL under above same condition and was detected by means of ^(13)C-NMR and DSC. The molar composition of the copolymer was determined from ~1H-NMR spectroscopy. The average block lengths of ε-hydroxycaprol and lactidyl unit in the copolyester were calculated from the fine ^(13)C-NMR Spectra. The crystallinity of the copolymer was characterized by means of DSC. A good agreement with the expectations from both molar composition and sequence distribution was found.