Control of Surface Morphology, Adhesion and Friction of Colloidal Gels with Lamellar Surface Interactions
Control of Surface Morphology, Adhesion and Friction of Colloidal Gels with Lamellar Surface Interactions
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DOI：
10.1002/adfm.202300896
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发表时间：
2023-04-06
影响因子：
19
通讯作者：
Espinosa-Marzal, Rosa. M. M.
中科院分区：
文献类型：
--
作者：
Deptula, Alexander;Rangel-Galera, Jessica;Espinosa-Marzal, Rosa. M. M.
尽管聚电解质系统最近取得了进展，但设计响应性水凝胶界面以满足应用要求仍然是具有挑战性的。本文研究了由聚(甲基丙烯酰胺-甲基丙烯酸)组成的半晶胶体凝胶在水中的储存模数在Mpa范围内的变化。结合扫描电子显微镜、X射线散射仪和核磁共振谱揭示了胶体微结构、结晶度和氢键随单体比例的变化。具有最精细胶体微结构的凝胶表现出最耗散的流变性，并被选择用于研究它们的界面特征和潜在的相互作用。微观结构的稳定性和动力学来自短程(吸引人的)氢键和疏水力，以及长程(排斥)静电相互作用--“SALR”对势能。此外，由于胶体网络的粘弹性变形，凝胶表面呈现出亚微米胶体形貌，这在很大程度上决定了(胶体状)摩擦，而静电近表面相互作用在片层粘合中传播。所涉及的相互作用的动态和可逆性引入了刺激响应行为，从而实现了粘附力和摩擦力的电可调性。这项研究提高了设计复杂水凝胶界面所需的知识，使其能够实现表面性质的空间和动态控制，这对生物医学设备、软组织设计、软机器人和其他工程摩擦系统的应用具有重要意义。
Despite recent advances in polyelectrolyte systems, designing responsive hydrogel interfaces to meet application requirements still proves challenging. Here, semicrystalline colloidal gels composed of poly(methacrylamide-co-methacrylic acid) are investigated in water with storage moduli in the MPa range. A combination of SEM, X-ray scattering, and NMR reveals the evolution of the colloidal microstructure, crystallinity, and hydrogen bonding with varying monomer ratio. The gels with the finest colloidal microstructure exhibit the most dissipative rheological behavior and are selected for the study of their interfacial characteristics and underlying interactions. Microstructure stabilization and dynamics results from short-range (attractive) hydrogen bonding and hydrophobic forces, and long-range (repulsive) electrostatic interactions-the "SALR" pair potential. Further, the gel's surface exhibits a submicron colloidal topography that greatly determines (colloidal-like) friction as a result of the viscoelastic deformation of the colloidal network, while electrostatic near-surface interactions propagate in lamellar adhesion. The dynamic and reversible nature of the involved interactions introduces a stimulus responsive behavior that enables the electrotunability of adhesion and friction. This study advances the knowledge necessary to design complex hydrogel interfaces that enable spatial and dynamic control of surface properties, which is of relevance for applications in biomedical devices, soft tissue design, soft robotics, and other engineered tribosystems.