聚羟基丁酸酯环带球晶的形貌研究

聚羟基丁酸酯 ( PHB)是一种由细菌合成的手性高分子材料 ,其分子结构具有高度的规整性 1] ,球晶比较大 (直径可达几毫米 ) ,是研究高分子结晶行为和形态的理想材料 2 ] .在偏光显微镜下 ,Bauer3]和 Martinez- Salazar等 4 ] 曾在 PHB球晶上观察到消光带和同心的环线 .在聚环氧乙烷 5] 和小分子液晶4-氰基 - 4 -癸氧基联苯的球晶上 6 ] 也观察到了同心环线 .但这些工作都把同心环线归结为裂缝 ,并未提供证据 .事实上 ,偏光显微镜的低分辨率及其透视特点 7] ,使之无法真实反映材料的表面形貌 ,因而也无法区分裂缝和台阶 .我们对光…

Topography of Polyhydroxybutyrate Banded Spherulites

On polyhydroxybutyrate banded spherulites, concentric rings were observed between cross polarizers or without polarizers. The rings used to be considered as cracks. In this paper, we provide evidences to distinguish the concentric rings from cracks observed on PHB spherulites. Furthermore, atomic force microscopy confirmed that these concentric rings with varying spacing were growth terraces rather than cracks. The height of the terraces reached up to several hundred nanometers. It was observed that the external terraces were higher than the internal terraces, which was proposed to result from layer by layer growth. This is the first report on the new microscopic feature of polyhydroxybutyrate spherulites. Spherulites with birefringent bands, wavy fluctuation of height were also observed.