高分子層晶的成長(lamellar growth)，普遍發展出周期扭曲(lamellar twisting)的形態。這個結晶形態的形成，推論是因為於層晶的結晶區與非結晶區界面，有著不平衡的表面應力(imbalanced surface stress)分佈所引起。而分子鏈的結構、排列方式及結晶成長環境，均和表面應力的形成息息相關。
這個研究是藉由聚乳酸分子(polylactic acid)於固定的磊晶成長(epitaxial growth)環境下，逐一探討溫度與分子量對單一層晶(individual lamella)成長習性的影響。並在同樣的溫度與環境下觀察，旋光性等分子結構因素，對層晶成長所扮演的角色。
經由電子顯微鏡可以觀察到，聚乳酸分子依據晶格對應關係所進行的有序結晶成長。由所獲得的電子繞射，可以進一步瞭解在層晶中規則排列的鏈段，斜傾(chain tilting )於層晶垂直方向(lamellar normal)的程度，與磊晶成長溫度及分子量成正比，並造成層晶厚度隨成長溫度增加而下降的異常現象。在維持成長環境及晶格對應關係的情形下，可以推論出彎摺鏈段(fold loop)於層晶界面的相互排擠，是造成鏈段斜傾現象的主要原因。
層晶彎曲的形態，和鏈段斜傾現象一樣，隨著溫度或分子量的增加，而有較明顯的發展。此外，層晶彎曲的方向亦與鏈段斜傾的方向一致。這些研究觀察明確的指出，層晶界面的應力分佈，會受到鏈段斜傾現象的影響，而決定層晶彎曲成長的方向。

Long chain molecules adopt a folded conformation during growth of ordered crystalline phases. This chain folding process leads to the formation of crystalline lamellae sandwiched by non-crystalline fold surface layers. Within this sandwiched structure, molecular packing stems can tilt to the lamellar normal, and consequently causes the orientation of unit cell to be changed. This chain tilting is an important factor for the morphology of single crystal grown in solution, and also for lamellar twisting in the crystallization from the bulk. Considering the applications of polymeric thin films, this crystal habit is closely related to materials density, interface stresses, and orientation of dipole moment, and thus capable of yielding significant effect on desired optic-electrical and mechanical properties.

However most of the carried studies regarding this subject are established on the growth of lamellar bundles within spherulite, which necessarily involves complicated interactions with neighboring lamellar growth. In this case, the mechanisms for the imbalanced surface stresses and dislocations to develop and influence the twisted habit, remain limitedly understood since being proposed twenty years ago. Therefore, it is needed to adopt an experimental strategy to crystallize polymers into arrays of individual lamellae with unperturbed twisting or bending tendency.

The success in growing oriented arrays of individual lamellae of polylactic acid on selected surface has been achieved in this research, which leads to the observation of unperturbed bending tendency of individual lamella. The involved lattice match results in a uniform nucleation and growth environments through universal contact plane of edge-on lamellae. Thus the exact effect of studied influential factor, for example, the transition from once-folded to twice-folded conformation of molecular chain, can be distinguished while keeping other growth factors unchanged.

Moreover, the diffraction patterns obtained from corresponding area of oriented edge-on lamellae unveiled the occurrence of chain tilt on the same plane of lamellar bending, which is named as coplanar chain tilt. This newly-discovered coplanar chain tilt exhibits a unique relationship with developed bending morphology of polylactide individual lamellae; as molecular stems tilt toward to the right, only clockwise lamellar bending is present.

The influential factors to be individually investigated are classified into two categories, which are of molecular features, like chirality and molecular weight, and of growth environments, like growth temperature. Through this study, it is found that the increases of temperature or molecular weight can both increase the bending tendency of individual edge-on lamellae, which help to significantly advance the understanding on the governing mechanism of twisted growth habit of synthetic polymers.

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