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

水凝胶是一种柔性塑料材料，它将水整合到结构中。这种水化作用有助于使它们变得光滑和生物相容，因此它们被用作薄型生物医学设备，如隐形眼镜和导管涂层，以及在石油工业中作为软颗粒。每天都有新的水凝胶化学成分被开发出来，用于靶向应用，如药物输送、假体软体装置和合成软组织。然而，在这些预期的应用中，当柔软、光滑的材料与其他材料滑动时，保持其耐用性对于它们的成功至关重要。水凝胶在滑动下降解的具体方式尚不清楚，因此该奖项支持水凝胶结构、滑动条件和表面耐久性之间的基本发现。这些连接将导致制造水凝胶的新的机械设计指南，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在一起，因此非常适合作为跨学科活动的基础，这些活动旨在增强科学和工程领域中未被充分代表的少数民族学生的能力。软质水化材料界面的摩擦和润滑性质决定了致密微凝胶体系的集体行为，但摩擦通常被视为滑移速度或剪切速率的简单函数。最近出现了基于材料的软水合物润滑理论，以及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、现场测量和绘制滑动、低摩擦水凝胶界面中的机械退化过程，来发现由于表面剪切而导致的软界面中的表面退化机理。将使用仪表式微摩擦计量术、光学显微镜和力显微镜以及微压痕来测量降解过程。这一知识将为水凝胶润滑的相互竞争的理论提供背景，并为新出现的科学、技术和工程设计问题催化关于水凝胶的化学和物理降解的假设。

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