Roman Maren, Gray Derek G
Department of Chemistry, Pulp and Paper Research Centre, McGill University, 3420 University Street, Montreal, Quebec, Canada H3A 2A7.
Langmuir. 2005 Jun 7;21(12):5555-61. doi: 10.1021/la046797f.
Suspensions of cellulose nanocrystals form colloidal chiral nematic phases. The liquid crystalline order in these suspensions can be captured in solid films by slow evaporation of the liquid. Studies of the microstructure of such chiral nematic solid films revealed parabolic focal conic (PFC) defects, a symmetric form of focal conic defects in which the line defects form a pair of perpendicular, antiparallel, and confocal parabolas. The cellulose films with PFC defects were characterized by polarized-light and atomic force microscopy. The film surface showed a regular array of large and small elevations resulting from the displacement of the structural layers. Film fracture lines showed a series of layered half-cones. The microstructure of the films was modeled by computer. The model revealed that many structural layers terminate at the film surface.
纤维素纳米晶体悬浮液形成胶体手性向列相。这些悬浮液中的液晶有序态可通过液体的缓慢蒸发而被捕获在固体薄膜中。对这种手性向列型固体薄膜微观结构的研究揭示了抛物线形焦锥（PFC）缺陷，这是一种焦锥缺陷的对称形式，其中线缺陷形成一对相互垂直、反平行且共焦的抛物线。具有PFC缺陷的纤维素薄膜通过偏光显微镜和原子力显微镜进行表征。薄膜表面呈现出由结构层位移导致的大小起伏的规则阵列。薄膜断裂线显示出一系列分层的半圆锥。通过计算机对薄膜的微观结构进行建模。该模型表明许多结构层在薄膜表面终止。
