Fibers have traditionally been made through melt or solution processes from macromolecules. Most of these fibers have crystalline domains where the segregation of different crystalline features is extremely difficult due to the statistical nature of the formation and growth of these domains. A fibrous nano-crystalline sandwich is reported where distinctly different crystalline regions are formed in layers along the continuous fiber direction during the spinning process and locked in place. This approach employs side-by-side bicomponent nanofiber electrospinning where the components are the enantiomeric pair of poly(l-lactic acid) and poly(d-lactic acid). The formation of the poly(lactic acid) (PLA) stereo-complexes at the junction interphase of the two components is demonstrated through diffusion, which subsequently crystallize into continuous sandwich domains. The stereo-complex crystalline core in the fiber possesses a melting point 50 °C higher than, and properties substantially different from, the regular PLAs at the fringe areas of the fiber. This nano-crystalline sandwich fiber structure can be scaled to the micrometers in a commercial bicomponent process.

中文翻译：

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在聚乳酸纤维中形成的纳米晶三明治。

传统上，纤维是通过大分子的熔融或固溶过程制得的。这些纤维中的大多数具有晶域，由于这些晶域的形成和生长的统计性质，不同晶体特征的分离非常困难。报道了一种纤维纳米晶体三明治，其中在纺丝过程中沿着连续纤维方向在层中形成了明显不同的晶体区域，并将其锁定在适当的位置。该方法采用并列双组分纳米纤维静电纺丝，其中组分为聚（1-乳酸）和聚（d-乳酸）的对映异构体对。通过扩散证明了在两个组件的连接界面处聚乳酸（PLA）立体复合物的形成，随后结晶为连续的三明治结构域。纤维中的立体复杂晶体核的熔点比纤维边缘区域的常规PLA高50°C，并且性质与常规PLA实质上不同。可以在商业双组分工艺中将该纳米晶体夹心纤维结构定标为微米。