In-situ observation of heterogeneous nucleation of organic crystals induced by templates with Synchrotron radiation X-ray techniques

同步辐射X射线技术原位观察模板诱导有机晶体异质成核

基本信息

批准号：
14540305
负责人：
SATO Kiyotaka
金额：
$ 1.92万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540305/
关键词：
template heterogeneous nucleation Synchrotron radiation X-ray analysis alkane crystals emulsion 添加物効果

项目摘要

The principal aim of this research project was to clarify the mechanisms of heterogeneous nucleation of organic crystals that were induced by the presence of templates. The growth systems examined were bulk solution in which thin films prepared by physical vapor deposition were put as the template, and oil-in-water (0/W) emulsion in which hydrophobic surfactants with high-melting points were added. The in-situ observation of the nucleation processes were done by using Synchrotron radiation X-ray beam couples with DSC, both were analyzed at the same time for the same sample. The organic substances employed in the present work were n-alkanes with different carbon numbers, triacylglycerols and vegetable fats. The following results were obtained1) In the O/W emulsion made of n-alkanes, triclinic crystals were nucleated without the template additives. However, pseudo-hexagonal-orthorhombic crystal was nucleated prior to triclinic polymorph. This is ascribed to the template films of the additives that were preferentially crystallized before the nucleation of n-alkanes2) In the O/W emulsion made of triacylglycerols, alpha crystals were nucleated without the additives. The addition of the additives, however, induced the nucleation of beta-prime crystals. This result was also interpreted with the help of the template films formed at the oil-in-water interface3) In the bulk solution, orientation, polymorphism and rate of nucleation were modified by the presence of the template thin filmsThe above results were discussed in a theory of heterogeneous nucleation Induced by the template films. The template effect in the emulsion was revealed by the freezing of the hydrophobic chains with high-melting points. The template effects in the bulk solution showed epitaxial relationships of the template and newly-formed crystals

该研究项目的主要目的是阐明由模板的存在引起的有机晶体异质成核的机制。所检查的生长系统是散装溶液，其中将通过物理蒸气沉积制备的薄膜作为模板，并在其中加油（0/W）乳液，其中添加了具有高熔点点的疏水表面活性剂。对成核过程的原位观察是通过使用DSC的同步辐射X射线束夫妇对同一样品进行分析的。本工作中使用的有机物质是具有不同碳数，三酰基甘油和蔬菜脂肪的N-烷烃。在N-烷烃制成的O/W乳液中获得了以下结果1），在没有模板添加剂的情况下将三斜晶体成核。然而，在三斜层多晶型物之前对伪远远甲状腺晶体晶体成核。这归因于在由三酰基甘油制成的O/W乳液中成核之前优先结晶的添加剂的模板膜，而α乳液中的α晶体在没有添加剂的情况下被核粉成核。但是，添加添加剂诱导了β-蛋白晶体的成核。还借助于散装溶液中的油中界面上形成的模板膜的帮助来解释该结果，通过模板薄膜的存在，在存在模板薄膜的存在理论中，通过模板薄膜理论讨论了上述结果，从而改变了方向，多态性和成核的速率。乳液中的模板效应通过具有高熔点的疏水链的冻结来揭示。散装溶液中的模板效应显示了模板和新形成的晶体的外延关系