SAXS investigation on aggregation phenomena in supercritical CO2
SAXS investigation on aggregation phenomena in supercritical CO2
复制标题
超临界 CO2 中聚集现象的 SAXS 研究
DOI：
10.1140/epje/i2002-10021-5
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
R. Triolo
中科院分区：
文献类型：
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作者：
F. Lo Celso;A. Triolo;F. Triolo;D. I. Donato;M. Steinhart;M. Kriechbaum;H. Amenitsch;R. Triolo
本文报道了超临界 CO2 中聚乙酸乙烯酯-b-全氟丙烯酸辛酯 (PVAc-b-PFOA) 嵌段共聚物聚集体形成的同步加速器小角 X 射线散射 (SAXS) 测量。在一系列不同的热力学条件下进行了实验，通过分析恒定温度下的压力和恒定压力下的温度来改变溶剂密度。这种嵌段共聚物和一般的碳氟化合物-碳氢化合物二嵌段根据二氧化碳密度值形成聚集体。当 CO2 密度达到临界值时，溶解为无规线圈的单体和以亲溶剂壳和疏溶剂核为特征的胶束之间会发生急剧转变。本文报道了从压力和温度斜坡实验得出的临界胶束化密度 (CMD) 的结果以及与之前的 SANS 结果的比较，为溶剂密度驱动的聚集过程提供了额外的实验支持。
Synchrotron Small-Angle X-Ray scattering (SAXS) measurements on aggregate formation of a Polyvinyl acetate-b-Perfluoro octyl acrylate (PVAc-b-PFOA) block copolymer in supercritical CO2 are here reported. Experiments were carried out for a series of different thermodynamic conditions, changing the solvent density by profiling both the pressure at constant temperature and the temperature at constant pressure. This block copolymer and in general fluorocarbon-hydrocarbon di-blocks form aggregates depending on the value of CO2 density. A sharp transition between monomers dissolved as random coils and micelles characterized by a solvophilic shell and a solvophobic core occurs when the CO2 density reaches a critical value. Results of critical micellization density (CMD) derived from pressure and temperature ramps experiment along with the comparison with previous SANS results are here reported to give additional experimental support to the solvent density-driven aggregation process.