Surface topology and interior crystals of highly anisotropic Janus-faced spherulites from crystallization of semicrystalline poly(l-lactic acid) (PLLA) with amorphous poly(methyl methacrylate) (PMMA) have been characterized using polarized optical, atomic-force, and scanning electron microscopes. The morphologies in the two faces differ dramatically in optical birefringence, growth rates, as well as crystal dimensions and assembly. Dissection into the interior lamellar arrangement of the optically asymmetric spherulites is conducted via fracturing and selective etching with a proper solvent. Large α′-form platelet lamellae, along the direction of the sheaf-nuclei, grow faster, periodically bend or branch out, appearing as densely fan-like dendritic region(s) with strong birefringence. As opposed to this, the α-form nanosize rod-like lamellae grow more slowly in the perpendicular direction, with each rod slanting at an angle to the substrate, appearing as a bivalve-shaped region of weak birefringence. Both types of lamellae concomitantly grow into a half-and-half Janus-faced PLLA spherulite.

中文翻译：

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共结晶的纳米和微米级薄片在无定形聚（甲基丙烯酸甲酯）在聚（乳酸）中不对称生长为面向贾纳斯的球晶

半结晶聚（l）的结晶导致高度各向异性的Janus面球晶的表面拓扑结构和内部晶体使用偏光光学，原子力和扫描电子显微镜对带有非晶态聚（甲基丙烯酸甲酯）（PMMA）的β-乳酸）（PLLA）进行了表征。在光学双折射，生长速率以及晶体尺寸和组装方面，两个面的形貌差异很大。光学不对称球晶的内部层状结构的解剖是通过压裂和使用适当溶剂的选择性蚀刻进行的。沿束核方向的大α'型血小板薄片生长较快，周期性弯曲或分支，表现为密集的扇形树突区域，具有强双折射。与此相反，α型纳米棒状薄片在垂直方向上生长更慢，每个棒都相对于基板倾斜一个角度，表现为双折射弱的双瓣形区域。两种类型的薄片都随之长成半面的贾努斯面PLLA球晶。