Structural evolution of a colloidal crystal fiber during heating and annealing studied by in situ synchrotron small angle X-ray scattering.
Structural evolution of a colloidal crystal fiber during heating and annealing studied by in situ synchrotron small angle X-ray scattering.
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DOI：
10.1021/la102258b
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发表时间：
2010-08
期刊：
影响因子：
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通讯作者：
Shanshan Hu;J. Rieger;Zhiyong Yi;Jianqi Zhang;Xuelian Chen;S. Roth;R. Gehrke;Yongfeng Men
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文献类型：
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作者：
Shanshan Hu;J. Rieger;Zhiyong Yi;Jianqi Zhang;Xuelian Chen;S. Roth;R. Gehrke;Yongfeng Men
胶体晶体光纤在加热和退火过程中的结构演变采用原位同步加速器小角x射线散射。定向干燥制备纤维的聚合物分散体（粒径为118nm）中含有乳化剂和盐。干燥后形成的细胞结构，其中渗透相（“膜相”）由这些成分组成；这个膜相产生了散射对比，这是目前观测的基础。在加热和退火过程中，胶体晶晶格常数的变化以及晶体和非晶态相散射强度的变化表明了系统发生明显结构变化的特征温度。第一个特征温度被确定为125摄氏度，超过125摄氏度，膜材料中的残留水被蒸发，导致胶体晶格收缩。在大约140摄氏度以上的温度下，膜材料被逐出晶体域。这种效应伴随着相邻乳胶颗粒之间聚合物链的逐渐相互扩散，并导致胶体晶体进一步热收缩。第二个特征温度是由各向同性散射的快速增加来定义的。这种效应是由于形成越来越大的膜材料域和伴随的膜相从以前的晶体域消失。
The structural evolution of a colloidal crystal fiber during heating and annealing was followed by in situ synchrotron small-angle X-ray scattering. The polymer dispersion (with a particle size of 118 nm) from which the fibers were formed by directed drying contained emulsifier and salt. A cellular structure formed upon drying in which the percolating phase (the "membrane phase") is composed from these components; this membrane phase gives rise to the scattering contrast on which the present observations build. Changes of the lattice constant of the colloidal crystallites and the intensity evolution of the scattering from the crystalline and the amorphous phases during heating and annealing indicate characteristic temperatures where the system exhibits pronounced structural changes. The first characteristic temperature was identified as 125 degrees C above which residue water in the membrane material was evaporated leading to shrinkage of the colloidal crystalline lattice. At a temperature above about 140 degrees C the membrane material was expelled out of the crystalline domains. This effect is accompanied by the progressive interdiffusion of polymer chains between adjacent latex particles and leads to further thermal shrinkage of the colloidal crystals. The second characteristic temperature is defined by a rapid increase in isotropic scattering. This effect is attributed to the formation of increasingly large domains of the membrane material and the concomitant disappearance of the membrane phase from the former crystal domains.