Weak Intermolecular Interactions during the Melt Crystallization of Poly(l-lactide) Investigated by Two-Dimensional Infrared Correlation Spectroscopy
Weak Intermolecular Interactions during the Melt Crystallization of Poly(l-lactide) Investigated by Two-Dimensional Infrared Correlation Spectroscopy
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DOI：
10.1021/jp048308q
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发表时间：
2004-07
影响因子：
3.3
通讯作者：
Jianming Zhang;H. Tsuji;I. Noda;Y. Ozaki
中科院分区：
文献类型：
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作者：
Jianming Zhang;H. Tsuji;I. Noda;Y. Ozaki
采用红外光谱法研究了聚乳酸（PLLA）在150 °C下的等温结晶行为。在熔融结晶过程中收集的随时间变化的红外光谱的二维（2D）相关分析揭示了关于CH 3和CO基团的分子间相互作用以及C-O-C骨架中的构象变化的细节，这些细节不容易通过传统的一维光谱检测到。结果表明，在PLLA熔融结晶的诱导期和生长期均存在CH 3基团的分子间相互作用，而CO基团的分子间偶联作用仅在结晶期出现。在二维同步光谱中也可以清楚地观察到PLLA熔融结晶诱导期内C−O−C主链的有序形成。这些观察结果不仅为α晶体中PLLA链的103螺旋构象畸变是由于α晶体中PLLA链的内禀作用提供了直接的证据，而且也为α晶体中PLLA链的103螺旋构象畸变提供了理论依据。
The isothermal crystallization behavior of poly(l-lactide) (PLLA) at 150 °C from the melt was monitored by infrared (IR) spectroscopy. The two-dimensional (2D) correlation analysis of time-dependent IR spectra collected during the melt crystallization process revealed details about the intermolecular interaction of the CH3 and CO groups and the conformational changes in the C−O−C backbone that are not easily detected by conventional one-dimensional spectra. It was found that the intermolecular interaction of the CH3 group appears during both the induction period and the growth period of PLLA melt crystallization, while the intermolecular coupling of the CO group can only be observed during the crystallization period. The order formation of C−O−C backbone during the induction period of PLLA melt crystallization can also be clearly observed in the 2D synchronous spectra. These observations not only provide direct evidence that the distorted 103 helix conformation of PLLA chain in α crystals is due to the in...