Hou Jiawen, Wang Xiaoliang, Sun Pingchuan, Wang Fenfen
Key Laboratory of Functional Polymer Materials of Ministry of Education and College of Chemistry, Nankai University, Tianjin 300071, China.
School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
Langmuir. 2025 Jan 14;41(1):986-998. doi: 10.1021/acs.langmuir.4c04263. Epub 2024 Dec 26.
Polyelectrolyte complex (PEC) hydrogels provide a promising strategy to develop a class of physically cross-linked networks characterized by exceptional toughness and self-healing properties. However, the precise control of the microstructure and the enhancement of mechanical properties still pose challenges in the field of PEC hydrogels. Herein, we propose a strategy to manipulate the structure of PEC with competitively charged surfactant micelles, leveraging the spatially confined surface charge and excluded volume effects to overcome coacervation issues associated with the PEC, thus achieving a simple one-step preparation of macroscopically uniform and tough PEC hydrogels. Specifically, polyelectrolyte complex/surfactant micelle (PEC-SM) hybrid hydrogels were prepared by one-step copolymerization of chitosan (CS)/acrylic acid/cetyltrimethylammonium bromide (CTAB) micelles. The content of CTAB micelles was found to continuously modulate both the structure and the mechanical properties of the resulting PEC-SM hydrogel network. On one hand, reversible deformation-recovery behavior exhibited by CTAB cavity micelles through hydrophobic interactions efficiently dissipates energy; on the other hand, competition between CS chains and CTAB micelles for electrostatic binding sites with poly(acrylic acid), along with excluded volume effects of CTAB micelles, imparts a hierarchical structure upon the PEC-SM hydrogel. Rheology provided detailed insights into the viscoelastic behaviors of PEC-SM hydrogels at varying CTAB concentrations. The intermolecular interaction and heterogeneous network structure of physically cross-linked PEC-SM hydrogels with CTAB micelles were elucidated by solid-state nuclear magnetic resonance (NMR) spectroscopy. On the basis of rheology and NMR results, complemented by other characterization analyses, the physical illustration of the PEC-SM hybrid hydrogel network structure regulated by competitive surfactant micelles is presented. This work offers valuable in-depth insight into polyelectrolyte complexation and provides a foundation for the development of robust PEC hydrogel materials.
聚电解质复合物（PEC）水凝胶为开发一类具有出色韧性和自愈性能的物理交联网络提供了一种很有前景的策略。然而，在PEC水凝胶领域，对微观结构的精确控制和机械性能的增强仍然面临挑战。在此，我们提出一种策略，利用带竞争性电荷的表面活性剂胶束来操控PEC的结构，借助空间受限的表面电荷和排除体积效应来克服与PEC相关的凝聚问题，从而实现宏观均匀且坚韧的PEC水凝胶的简单一步法制备。具体而言，通过壳聚糖（CS）/丙烯酸/十六烷基三甲基溴化铵（CTAB）胶束的一步共聚制备了聚电解质复合物/表面活性剂胶束（PEC-SM）杂化水凝胶。发现CTAB胶束的含量可连续调节所得PEC-SM水凝胶网络的结构和机械性能。一方面，CTAB空腔胶束通过疏水相互作用表现出的可逆变形-恢复行为有效地耗散了能量；另一方面，CS链与CTAB胶束在与聚丙烯酸的静电结合位点上的竞争，以及CTAB胶束的排除体积效应，赋予了PEC-SM水凝胶一种分级结构。流变学详细深入地研究了不同CTAB浓度下PEC-SM水凝胶的粘弹性行为。通过固态核磁共振（NMR）光谱阐明了具有CTAB胶束的物理交联PEC-SM水凝胶的分子间相互作用和异质网络结构。基于流变学和NMR结果，并辅以其他表征分析，展示了由竞争性表面活性剂胶束调节的PEC-SM杂化水凝胶网络结构的物理示意图。这项工作为聚电解质络合提供了有价值的深入见解，并为开发坚固的PEC水凝胶材料奠定了基础。
