标题： 通过一步沉淀聚合反应合成的热响应共聚物微凝胶：随机结构还是嵌段结构？ 显示英文标题

标题： Thermoresponsive copolymer microgels synthesized via single-step precipitation polymerization: random or block structure?

摘要： 聚合物颗粒的内部结构对其相行为和功能起着关键作用，决定了其机械性能以及物理和化学相互作用。对于热响应微凝胶，即由交联聚合物网络构成的胶体颗粒，在温度变化时会发生体积转变，结构控制是调节材料响应性和扩展应用范围的关键。在本工作中，我们结合小角中子散射（SANS）、动态光散射（DLS）和核磁共振（NMR）测量与多尺度模拟，对聚（N-异丙基丙烯酰胺-共-N-异丙基甲基丙烯酰胺），P（NIPAM-co-NIPMAM），共聚物微凝胶的内部结构进行了全面研究。通过合成不同的样品，我们探测了微凝胶的溶胀行为，揭示了不同单体的独特特征。为了阐明其内部分布，我们在不同的共聚物模型上进行了单体解析的微凝胶模拟。在不同中子选择性条件下，实验与数值形式因子的直接比较提供了证据，表明微凝胶更倾向于形成块状结构而非随机排列。这些结果通过13C-NMR得到证实，该结果显示在剩余单体的更随机排列中存在明显的NIPAM块，并通过共聚物链的原子分子动力学模拟进一步揭示了氢键能力依赖于局部环境的可能原因。这些发现提供了P（NIPAM-co-NIPMAM）微凝胶内部结构的详细微观图像，揭示了一种意想不到的结构组织，这可能适用于其他共聚物系统，并有望用于定制微凝胶设计并增强材料响应性的控制。 显示英文摘要

摘要： The inner structure of polymeric particles critically influences their phase behavior and functionality, governing their mechanical properties and their physical and chemical interactions. For thermoresponsive microgels, i.e. colloidal particles comprising a crosslinked polymer network that undergo a volume transition upon temperature changes, structural control is key to tailor the material responsivity and broaden the range of applications. In this work, we present a comprehensive investigation of the internal structure of poly(N-isopropylacrylamide-co-N-isopropylmethacrylamide), P(NIPAM-co-NIPMAM), copolymer microgels, combining small-angle neutron scattering (SANS), dynamic light scattering (DLS), and nuclear magnetic resonance (NMR) measurements with multi-scale simulations. By synthesizing different samples, we probe the microgels swelling behavior, revealing distinct signatures of the individual polymers. To elucidate their internal distribution, we perform monomer-resolved microgel simulations across different copolymer models. A direct comparison between experimental and numerical form factors under different, neutron-selective conditions provides evidence of a preferential organization into block structures rather than a random arrangement. These results are confirmed by 13C-NMR which reveals the clear presence of NIPAM blocks within a more random arrangement of the remaining monomers and by atomistic molecular dynamics simulations on copolymer chains, which also shed light on a possible origin in the dependence of the hydrogen bonding capability on the local environment. These findings provide a detailed microscopic picture of the inner architecture of P(NIPAM-co-NIPMAM) microgels, revealing an unexpected structural organization that may be generalized to other copolymer systems and could be promising to tailor microgel design and enhance control of material responsivity.