Abstract：
Hydrogels consist of three-dimensional (3D) and complicated polymer networks that determine their physical properties. Among the methods for structural analyses of hydrogels, the real-space imaging of a polymer network of hydrogels on a nanometer scale is one of the optimal methods; however, it is highly challenging. In this study, we propose a direct observation method for cationic polymer networks using transmission electron microscopy (TEM). By combining the double network strategy and the mineral staining technique, we overcame the challenges of polymer aggregation and the low electron density of the polymer. An objective cationic network was incorporated into a neutral skeleton network to suppress shrinkage during subsequent staining. Titania mineralization along the cationic polymer strands provided sufficient electron density for the objective polymer network for TEM observation. This observation method enables the visualization of local structures in real space and plays a complementary role to scattering methods for soft matter structure analysis.
摘要：
水凝胶由三维（3D）和复杂的聚合物网络组成，这些网络决定了它们的物理性质。在水凝胶的结构分析方法中，在纳米尺度上对水凝胶的聚合物网络进行真实空间成像是最佳方法之一；然而，这是非常具有挑战性的。在这项研究中,我们提出了一种使用透射电子显微镜（TEM）直接观察阳离子聚合物网络的方法。通过结合双网络策略和矿物染色技术，我们克服了聚合物聚集和聚合物电子密度低的挑战。将目标阳离子网络掺入中性骨架网络中以抑制随后染色期间的收缩。沿着阳离子聚合物链的二氧化钛矿化为用于TEM观察的目标聚合物网络提供了足够的电子密度。这种观察方法可以实现真实空间中局部结构的可视化，并与散射方法在软物质结构分析中起到补充作用。
