Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia.
Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
J Colloid Interface Sci. 2021 Sep;597:297-305. doi: 10.1016/j.jcis.2021.03.178. Epub 2021 Apr 5.
Polymer stimuli-responsive microgels find their use in various applications. The knowledge of its internal structure is of importance for further improvement and expanding the scope. Interpenetrating network (IPN) microgels may possess a remarkable feature of strongly non-uniform inner architecture, even microphase separation, in conditions of a selective solvent. In this research, we, for the first time, use a combination of static light scattering (SLS) and small-angle X-ray scattering (SAXS) techniques to collect the structure factors of aqueous dispersions of poly(N-isopropylacrylamide)-polyacrylic acid IPN microgels on the broad scale ofqvalues. We study the influence of solvent quality on microgel conformations and show that in a selective solvent, such a system undergoes microphase separation: the sub-network in a poor solvent conditions forms dense small aggregates inside the large swollen sub-network in a good solvent. We propose the microstructured sphere model for the IPN microgel structure factor interpretation and perform additional analysis and verification through coarse-grained molecular dynamics computer simulations.
聚合物刺激响应微凝胶在各种应用中得到了广泛应用。了解其内部结构对于进一步改进和扩大应用范围非常重要。互穿网络（IPN）微凝胶在选择性溶剂的条件下可能具有显著的强非均匀内部结构特征，甚至微相分离。在这项研究中，我们首次使用静态光散射（SLS）和小角 X 射线散射（SAXS）技术在广泛的 q 值范围内收集聚（N-异丙基丙烯酰胺）-聚丙烯酸 IPN 微凝胶水基分散体的结构因子。我们研究了溶剂质量对微凝胶构象的影响，并表明在选择性溶剂中，这样的体系会发生微相分离：在不良溶剂条件下的子网络在良溶剂中的大溶胀子网络内形成密集的小聚集体。我们提出了 IPN 微凝胶结构因子解释的微结构球模型，并通过粗粒化分子动力学计算机模拟进行了额外的分析和验证。
