Quell Aggeliki, Sottmann Thomas, Stubenrauch Cosima
Institute of Physical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany.
Langmuir. 2017 Jan 17;33(2):537-542. doi: 10.1021/acs.langmuir.6b03762. Epub 2017 Jan 6.
During our studies on emulsion-templated monodisperse polymer foams we found significant differences in the finestructure if the locus of initiation is changed. This motivated us to study the phase behavior of the liquid template. Our studies indicate that the template consists of droplets of three different length scales: The water droplets generated via microfluidics (∼70 μm) are surrounded by a continuous phase in which a w/o emulsion (≤100 nm) coexists with a w/o microemulsion (∼5 nm). We speculate that the w/o-emulsion droplets act as seeds for the porous finestructure observed in AIBN-initiated polymer foams. We have experimental evidence that the w/o emulsion inverts to an o/w emulsion with progressing polymerization. This explains the granular texture observed in KPS-initiated polymer foams. The control of the finestructure is important in the preparation of tailor-made polymer foams because it directly impacts the material's density and thus, in turn, its mechanical stability.
在我们对乳液模板法制备单分散聚合物泡沫的研究中，我们发现如果引发位点发生变化，其微观结构会有显著差异。这促使我们研究液体模板的相行为。我们的研究表明，模板由三种不同长度尺度的液滴组成：通过微流控技术产生的水滴（约70μm）被连续相包围，在该连续相中，油包水乳液（≤100nm）与油包水微乳液（约5nm）共存。我们推测，油包水乳液滴作为在AIBN引发的聚合物泡沫中观察到的多孔微观结构的晶核。我们有实验证据表明，随着聚合反应的进行，油包水乳液会转变为水包油乳液。这就解释了在KPS引发的聚合物泡沫中观察到的颗粒状纹理。微观结构的控制在定制聚合物泡沫的制备中很重要，因为它直接影响材料的密度，进而影响其机械稳定性。
