Application of small-angle X-ray scattering as a tool for the structural analysis of industrial polymer dispersions
Application of small-angle X-ray scattering as a tool for the structural analysis of industrial polymer dispersions
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DOI：
10.1002/mame.200390046
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发表时间：
2003-06-30
影响因子：
3.9
通讯作者：
Rudhardt, D
中科院分区：
文献类型：
--
作者：
Bolze, J;Ballauff, M;Rudhardt, D
小角X射线散射（SAXS）被应用于工业聚合物在水中的分散体（合成胶乳）的结构分析。为了制备所研究的球形胶乳颗粒，丁二烯、苯乙烯和丙烯酸被用作种子乳液聚合过程中的单体。该产品被广泛用作造纸工业涂料的成膜剂。它表明，通过测量SAXS曲线在不同的对比度的整体粒度，质量密度多分散性和程度的异质性可以估计具有良好的准确性，即使没有必要的详细的拟合程序。特别地，获得关于颗粒内的各种单体单元的空间分布的信息。在对比度变化测量中可以观察到五个等散射点，并且可以用完全一致的拟合参数集对所有对比度下的散射曲线进行建模。因此，可以安全地得出结论，造影剂蔗糖不会影响颗粒结构。实验数据集的定量拟合显示，大量的聚（丙烯酸）优先位于薄壳的ca。2 nm厚度的颗粒的核心周围，这主要是由聚（苯乙烯-共-丁二烯）形成。所获得的结果是完全一致的附加测量的流体动力学颗粒半径的颗粒质量密度，通过动态光散射，和通过电位滴定的颗粒表面电荷。它的结论是SAXS是一个非常有用的工具，用于表征工业胶乳的结构。
Small-angle X-ray scattering (SAXS) was applied for the structural analysis of an industrial polymer dispersion in water (synthetic latex). For the preparation of the spherical latex particles under investigation, butadiene, styrene, and acrylic acid were used as monomers in a seeded emulsion polymerization process. The product is widely being used as a film-forming agent for coatings in the paper making industry. It is demonstrated that by measuring the SAXS curves at different contrasts the overall particle size, mass density polydispersity and degree of heterogeneity can be estimated with a good accuracy, even without the necessity of a detailed fitting procedure. In particular, one obtains information about the spatial distribution of the various monomer units within the particles. Five isoscattering points could be observed in the contrast variation measurements and the scattering curves at all contrasts could be modeled with a fully consistent set of fit parameters. It is thus safe to conclude that the contrast agent sucrose does not affect the particle structure. A quantitative fitting of the experimental data set revealed that a significant amount of the poly(acrylic acid) is preferentially located in a thin shell of ca. 2 nm thickness around the core of the particles, that is mainly formed by poly(styrene-co-butadiene). The obtained results are fully consistent with additional measurements of the particle mass density of the hydrodynamic particle radius by dynamic light scattering, and of the particle surface charge by potentiometric titration. It is concluded that SAXS is a highly useful tool for characterizing the structure of industrial latexes.