Nanostructures, Thermoresponsiveness, and Assembly Mechanism of Hydrogel Microspheres during Aqueous Free-Radical Precipitation Polymerization
Nanostructures, Thermoresponsiveness, and Assembly Mechanism of Hydrogel Microspheres during Aqueous Free-Radical Precipitation Polymerization
复制标题
水凝胶微球的纳米结构、热响应性和水自由基沉淀聚合过程中的组装机制
DOI：
10.1021/acs.langmuir.0c02654
复制
发表时间：
2020
期刊：
影响因子：
3.9
通讯作者：
Suzuki Daisuke
中科院分区：
文献类型：
--
作者：
Nishizawa Yuichiro;Minato Haruka;Inui Takumi;Uchihashi Takayuki;Suzuki Daisuke
虽然通过水自由基沉淀聚合生产均匀大小的水凝胶微球（微凝胶）的技术已经很好地建立起来，但聚合过程的细节仍然是神秘的。在本研究中，利用高速原子力显微镜对微凝胶在聚合过程中的结构演变和热响应性进行了研究。这一分析表明，由于交联剂的大量掺入，在聚合的早期阶段形成的前驱体微凝胶的膨胀性能很低，并且前驱体微凝胶中已经存在非热响应的十纳米球形结构域。此外，通过实时观测，我们成功地跟踪了水溶液中核的形成和生长过程，这是以前从未完全了解的。这些发现将有助于我们通过沉淀聚合设计具有所需纳米结构的功能微凝胶。
Although techniques to produce uniformly sized hydrogel microspheres (microgels) by aqueous free-radical precipitation polymerization are well established, the details of the polymerization process remain mysterious. In the present study, the structural evolution and thermoresponsiveness of the developing microgels during the polymerization were evaluated by temperature-controlled high-speed atomic force microscopy. This analysis clarified that the swelling properties of the precursor microgels formed in the early stages of the polymerization are quite low due to the high incorporation of cross-linkers and that non-thermoresponsive deca-nanosized spherical domains are already present in the precursor microgels. Furthermore, we succeeded in tracking the formation of nuclei and their growth process, which has never been fully understood, in aqueous solution by real-time observations. These findings will help us to design functional microgels with the desired nanostructures via precipitation polymerization.