Discovering the Mechanisms of Hydrogel Surface Weakening and Wear Under Applied Sliding Conditions

水凝胶是柔性塑料材料，其结构中整合有水。这种水合作用有助于使它们光滑和生物相容，因此它们被用作薄的生物医学设备，如隐形眼镜和导管涂层，以及在石油工业中作为软颗粒。每天都在开发新的水凝胶化学物质，用于靶向应用，如药物输送、假体软器械和合成软组织。然而，在这些预期应用中，当它们相对于其他材料滑动时，保持柔软、光滑材料的耐久性对于它们的成功是重要的。水凝胶在滑动下降解的具体方式尚不清楚，因此该奖项支持了水凝胶结构，滑动条件和表面耐久性之间联系的基本发现。这些连接将为制造水凝胶提供新的机械设计指南，影响健康和工业部门。由于这项研究将材料性能与机械性能联系起来，因此非常适合作为跨学科活动的基础，旨在增强科学和工程领域代表性不足的少数民族学生的能力。在软水合材料的界面处的摩擦和润滑性质决定了致密微凝胶系统的集体行为，但摩擦通常被视为滑移速度或剪切速率的简单函数。基于材料的润滑理论的软水合物质最近出现，沿着水凝胶表面磨损的实验证据。该项目的研究目标是通过应用、原位测量和绘制滑动、低摩擦水凝胶界面中机械降解的进展来发现由于表面剪切导致的软界面中的表面降解机制。将采用仪器化微摩擦测量法、基于光学和力的显微镜和微压痕来测量降解的进展。这些知识将使水凝胶润滑的相互竞争的理论背景化，并催化关于水凝胶的化学和物理降解的假设，以解决新兴的科学、技术和工程设计问题

Hydrogels are flexible plastic materials that have water integrated into the structure. This hydration helps make them slippery and biocompatible, so they are used as thin biomedical devices such as contact lenses and catheter coatings, as well as in the oil industry as soft particles. New chemistries of hydrogel are developed every day for targeted applications such as drug delivery, prosthetic soft devices, and synthetic soft tissues. However, retaining durability of soft, slippery materials in these intended applications when they are sliding against other materials is important for their success. The specific ways that hydrogels degrade under sliding is not yet known, so this award supports the fundamental discovery of connections between the hydrogel structure, sliding conditions, and surface durability. These connections will result in new mechanical design guidelines for manufacturing hydrogels, impacting health and industrial sectors. Because this research connects materials properties to mechanical performance, it is well-suited as the basis for interdisciplinary activities targeted to empower underrepresented minority students in science and engineering. The friction and lubrication properties at the interface of soft hydrated materials determine the collective behavior of dense microgel systems, but friction is often treated as a simple function of slip velocity or shear rate. Materials-based lubrication theories for soft hydrated matter have recently emerged, along with experimental evidence of hydrogel surface wear. The research goal of this project is to discover the mechanisms of surface degradation in soft interfaces due to surface shear by applying, measuring in situ, and mapping the progression of mechanical degradation in slipping, low-friction hydrogel interfaces. Instrumented micro-tribometry, optical- and force-based microscopy, and micro-indentation will be employed to measure the progression of degradation. This knowledge will contextualize competing theories of hydrogel lubrication and catalyze hypotheses regarding chemical and physical degradation of hydrogels for emerging scientific, technological, and engineering design problems