Rational integration of molecular and surface interactions for low friction - high wear resistance of soft surfaces

开发高效且持久的机器和设备需要仔细控制表面特性，例如摩擦和磨损。软表面特别容易磨损，并且缺乏能够保护此类表面免受摩擦退化的技术，阻碍了人造软骨等众多技术的发展。该研究计划的主要目标是通过开发聚合物润滑剂和软水凝胶涂层平台来填补这一技术空白，这些平台可以协同作用以提供增强的润滑和磨损保护。我们的方法是利用最近在关节中发现的多种分子机制来设计这种协同相互作用。这些机制包括正常压缩下软骨孔中的滑液定向（各向异性）流向表面，压缩期间软骨表面内和软骨表面处的抗磨损大分子的局部捕获，以及最终高度分支的润滑蛋白（如润滑素（LUB）和糖胺聚糖（GAG））与软骨表面和透明质酸之间的强相互作用，透明质酸为软骨提供了低粘附力和高水合作用。表面。 为了实现我们的目标，我们提出了一个分为三个互补目标的研究计划。 目标1.开发仿生高效聚合物润滑剂 润滑剂开发的一个关键要素是分子结构，它定义了分子的构象、润滑效率和承载能力。我们将开发一个多嵌段聚合物库，展示广泛存在于天然润滑蛋白中的瓶刷结构。在增加水凝胶涂层系统的复杂性之前，将研究模拟润滑素和 GAG 的两个聚合物系列的承载能力、润滑性能和模型平坦表面的磨损保护能力。这些测量将使用表面力仪 (SFA) 进行，以便在分子水平上建立我们的聚合物的结构-性能关系，并确定负责良好润滑和抗磨损性能的关键结构参数。 目标 2. 将微米/纳米夹杂物设计到水凝胶涂层中，以提供卓越的耐磨性 水凝胶材料的耐磨性差阻碍了其生物技术应用。大自然使用大量柔软的多孔胶原材料来保护硬骨免受磨损。软骨的超微结构被认为是其良好抗磨损性能的原因。我们将通过制造已知耐磨性较差的软水凝胶涂层来探索这一假设，并将对其进行修改以纳入软骨结构的某些关键特征，例如孔结构、孔分布或表面粗糙度。不同系列涂层的耐磨性将通过 SFA 和成像进行评估，以阐明哪种结构能够显着改善摩擦学性能。 目标 3. 制定“瓶刷”润滑剂和结构化水凝胶涂层之间的协同相互作用，以增强其摩擦学性能 我们将确定仿生结构化水凝胶涂层和润滑聚合物的组合是否可以协同作用，以产生增强的耐磨性和润滑性。使用 SFA，我们将通过测量涂层结构如何控制润滑剂分子的吸附、构象、分布和润滑性能来阐明这种协同相互作用的起源。

The development of efficient and long lasting machines and devices requires a careful control of surface properties such as friction and wear. Soft surfaces are particularly vulnerable to wear and the lack of technology able to protect such surfaces from frictional degradation has hampered the development of numerous technologies such as artificial cartilage. The main goal of this research program is to fill this technological gap by developing a platform of polymeric lubricants and soft hydrogel coatings that can act synergistically to provide enhanced lubrication and wear protection. Our approach is to design such synergistic interactions using multiple molecular mechanisms recently discovered in articular joints. These mechanisms include the directional (anisotropic) flow of synovial fluid in the cartilage pores to the surfaces under normal compression, the local trapping of anti-wear macromolecules in and at the cartilage surface during compression and finally the strong interaction between highly ramified lubricating proteins such as lubricin (LUB) and glycoaminoglycans (GAGs) with the cartilage surface and hyaluronic acid which provides low adhesion and high hydration to the surfaces. To reach our goal, we propose a research program divided into three complementary aims. Aim 1. To develop bio-inspired and efficient polymeric lubricants A key element in the development of a lubricant is the molecular architecture which defines the conformation, lubricating efficiency and load bearing capacity of the molecule. We will develop a library of multiblock polymers exhibiting the bottle-brush architecture which is extensively found in natural lubricating proteins. Two families of polymers mimicking lubricin and GAGs will be studied for their load bearing capacity, lubricating properties and wear protection ability on model flat surfaces before increasing the complexity of the system to hydrogel coatings. These measurements will be performed using the Surface Forces Apparatus (SFA) in order to establish structure-properties relationships of our polymers at the molecular level and to identify key structural parameters responsible for good lubrication and anti-wear properties. Aim 2. To engineer micro/nano inclusions into hydrogel coatings to provide superior wear resistance The poor wear resistance of hydrogel materials has hampered their biotechnological use. Nature uses abundantly soft porous collagen materials to protect hard bones from abrasion and wear. The ultrastructure of cartilage is thought to be responsible for its good anti-wear properties. We will explore this hypothesis by fabricating soft hydrogel coatings known to exhibit poor wear resistance and will modify them to incorporate certain key features of cartilage structure such as the pore structure, the pore distribution or the surface roughness. Wear resistance of the different families of coatings will be assessed by SFA and imaging in order to elucidate which structure is able to provide a significant improvement in the tribological properties. Aim 3. To formulate synergistic interactions between "bottle-brush" lubricants and structured hydrogel coatings for the enhancement of their tribological properties We will determine if combinations of bio-inspired structured hydrogel coatings and lubricating polymers can act synergistically to generate enhanced wear resistance and lubrication. Using the SFA we will elucidate the origin of such synergistic interactions by measuring how lubricant molecules adsorption, conformation, distribution and lubricating properties are controlled by the coating structure.