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，其结构中含有水。这种水合作用有助于使它们光滑并具有生物相容性，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。每天都有新的水凝胶化学物质被开发出来，用于药物输送、假肢软性装置和合成软组织等目标应用。然而，在这些预期的应用中，当它们与其他材料滑动时，保持软滑材料的耐久性对它们的成功至关重要。目前尚不清楚水凝胶在滑动作用下降解的具体方式，因此该奖项支持了对水凝胶结构、滑动条件和表面耐久性之间联系的根本性发现。这些联系将产生新的水凝胶制造机械设计准则，影响卫生和工业部门。由于这项研究将材料特性与机械性能联系起来，因此它非常适合作为跨学科活动的基础，旨在为科学和工程领域未被充分代表的少数民族学生提供支持。软水合材料界面的摩擦和润滑特性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质润滑理论，以及水凝胶表面磨损的实验证据。本项目的研究目标是通过应用、原位测量和绘制滑动、低摩擦水凝胶界面机械退化的过程来发现由于表面剪切而导致的软界面表面退化的机制。仪器微摩擦测量，光学和力为基础的显微镜，微压痕将被用来测量退化的进展。这些知识将使水凝胶润滑的竞争理论背景化，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