Chen Wei, Wang Shijun, Zhang Wei, Ke Yutian, Hong You-Lee, Miyoshi Toshikazu
Department of Polymer Science, The University of Akron, Akron, Ohio 44325, United States.
ACS Macro Lett. 2015 Nov 17;4(11):1264-1267. doi: 10.1021/acsmacrolett.5b00685. Epub 2015 Oct 30.
Poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) alternatively pack with each other and form stereocomplex crystals (SCs). The crystal habits of SCs formed in the dilute solution highly depend on the molecular weight (⟨⟩). In this study, we investigated chain-folding (CF) structure for C labeled PLLA (-PLLA) chains in SCs with PDLAs that have either high or low ⟨⟩s by employing an advanced Double Quantum (DQ) NMR. It was found that the ensemble average of the successive adjacent re-entry number ⟨⟩ for the -PLLA chains drastically change depending on ⟨⟩s of the counter PDLA chains in the SCs. It was concluded that the CF structures of -PLLA depending on ⟨⟩s of PDLA determine the crystal habits of SCs.
聚左旋丙交酯（PLLA）和聚右旋丙交酯（PDLA）相互交替堆积并形成立体复合晶体（SCs）。在稀溶液中形成的SCs的晶体习性高度依赖于分子量（⟨⟩）。在本研究中，我们通过采用先进的双量子（DQ）核磁共振技术，研究了具有高或低⟨⟩值的PDLA与SCs中C标记的PLLA（-PLLA）链的链折叠（CF）结构。结果发现，-PLLA链的连续相邻再进入数⟨⟩的系综平均值会根据SCs中反式PDLA链的⟨⟩值而发生显著变化。得出的结论是，-PLLA的CF结构取决于PDLA的⟨⟩值，这决定了SCs的晶体习性。
