Super-Resolution Imaging of Spatial Heterogeneities in Model Thermosensitive Hydrogels with Implications for Their Origins,Macromolecules

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Super-Resolution Imaging of Spatial Heterogeneities in Model Thermosensitive Hydrogels with Implications for Their Origins
Macromolecules ( IF 5.1 ) Pub Date : 2021-08-25 , DOI: 10.1021/acs.macromol.1c00754
Gopal S. Kenath ₁ , Apostolos A. Karanastasis ₁ , Chaitanya K. Ullal ₁

Affiliation

Three-dimensional nanoscale cross-link density variations are an important and incompletely understood morphological aspect of polymer gels. Here, within the context of establishing a deeper understanding of these so-called spatial heterogeneities, we study the spatial distribution of dye-tagged acrylamide monomers in bulk thermosensitive PNIPAM gels using a combination of 3D STED and multicolor confocal microscopy. We identify consistent microstructural trends for the various dye-tagged monomers, thereby expanding the prevailing picture of spatial heterogeneities in thermosensitive gels. Specifically, we provide new morphological insights into the distribution of cross-links, the nature of the interface that defines the polymer-rich regions, and the incidence and connectivity of higher cross-link density regions as a function of quench time and preparation temperature. While phase separation and reactivity rate constant differences have only been studied in isolation as the dominant cause of spatial heterogeneities in thermosensitive gels, our results show that both phenomena play an important role in determining cross-link density distributions.

中文翻译：

模型热敏水凝胶中空间异质性的超分辨率成像及其起源的意义

三维纳米级交联密度变化是聚合物凝胶的一个重要且尚未完全了解的形态方面。在这里，为了更深入地了解这些所谓的空间异质性，我们使用 3D STED 和多色共聚焦显微镜的组合研究了散装热敏 PNIPAM 凝胶中染料标记的丙烯酰胺单体的空间分布。我们确定了各种染料标记单体的一致微观结构趋势，从而扩展了热敏凝胶中空间异质性的普遍情况。具体来说，我们提供了对交联分布的新形态学见解，定义了富含聚合物区域的界面的性质，以及作为淬火时间和制备温度的函数的较高交联密度区域的发生率和连通性。虽然相分离和反应速率常数差异仅作为热敏凝胶中空间异质性的主要原因被单独研究，但我们的结果表明，这两种现象在确定交联密度分布方面都起着重要作用。

更新日期：2021-09-14

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