Tough Particle-Based Double Network Hydrogels for Functional Solid Surface Coatings

Tough Particle-Based Double Network Hydrogels for Functional Solid Surface Coatings
用于功能性固体表面涂层的坚韧颗粒双网络水凝胶

Coating solid surfaces with tough hydrogels is necessary for the practical application of hydrogels in various fields. Here a simple yet versatile method for coating tough double network (DN) hydrogels onto a wide range of solid surfaces, including various materials and geometries is reported. Particle based double network (P-DN) gels that combine ease-of-use and significantly strong mechanical properties are utilized. The P-DN gel coating process involves two steps. First, the solid surface (plastic, rubber, ceramic, and/ or metal) is treated to form a thin, physically bound primer layer containing radical initiators. The pre-gel solution is then applied to the treated surface, followed by photo-induced polymerization. The P-DN gel coatings show high toughness, with one notable formulation reaching over 1000 J m-2 in a 90º peeling test. The coatings also show high stability against long-term water-storage, elevated temperatures, and solvent exposure. Moreover, it is demonstrated that the P-DN gel-coated surfaces exhibit low friction properties with high wear resistance, by pin-on-flat tests. The simple coating process can be used even on surfaces with complex geometries, including 3D shapes. This work will enable the use of DN gels in applications such as biocompatible lubricants, scratch resistance coatings, and anti-fouling paints.
用坚韧的水凝胶涂覆固体表面对于水凝胶在各个领域的实际应用是必要的。这里报道了一种简单而通用的方法，用于将坚韧的双网络（DN）水凝胶涂覆到各种固体表面上，包括各种材料和几何形状。使用基于颗粒的双网络（P-DN）凝胶，其结合了易用性和显着强的机械性能。 P-DN凝胶涂覆工艺包括两个步骤。首先，处理固体表面（塑料，橡胶，陶瓷和/或金属）以形成含有自由基引发剂的薄的，物理结合的底漆层。然后将预凝胶溶液施加到处理过的表面上，然后进行光诱导聚合。 P-DN凝胶涂层具有高韧性，在90°剥离试验中，一种值得注意的配方达到1000 J m-2以上。该涂料还显示出对长期储水，高温和溶剂暴露的高稳定性。此外，通过平板销试验证明，P-DN凝胶涂覆的表面具有低摩擦性能和高耐磨性。简单的涂层工艺甚至可以用于具有复杂几何形状的表面，包括3D形状。这项工作将使DN凝胶在生物相容性润滑剂，抗划伤涂料和防污涂料等应用中得以应用。

Conclusions

In summary, tough P-DN hydrogel coatings for various solid substrates have been successfully developed. We systematically investigated the mechanical properties of P-DN gels and found the suitable conditions for making tough P-DN gels. By coating the substrates (plastic, ceramic, metal, and rubber) with a primer layer containing proper concentrations of initiator, we can synthesize tough P-DN gels on surfaces with robust bonding. The peeling strength of the hydrogel coating is strongly related to the competition between the strength to break the gel and the strength to peel at the interface. In the toughest peeling case, little debonding occurred at the interface, and the interfacial crack moved into the bulk of the P-DN gel, causing fracture of the bulk P-DN gel. Therefore, using tough P-DN gels as a coating is a novel method to fabricate robust hydrogel coatings. Another useful aspect of using tough hydrogels is that the coatings are sufficiently robust to exhibit wear resistance with low friction. Moreover, taking advantage of the free-formability of P-DN gels, we successfully attained tough P-DN gel coatings on complicated 3D shapes. These demonstrations suggest that hydrogels can be used for a variety of real-world applications where tough coatings are required.
总之，已成功开发出用于各种固体基质的坚韧P-DN水凝胶涂层。我们系统地研究了P-DN凝胶的机械性能，并找到了制备坚韧P-DN凝胶的合适条件。通过用含有适当浓度的引发剂的底漆层涂覆基材（塑料，陶瓷，金属和橡胶），我们可以在表面上合成坚韧的P-DN凝胶，并具有牢固的粘合性。水凝胶涂层的剥离强度与破坏凝胶的强度和界面剥离强度之间的竞争密切相关。在最坚韧的剥离情况下，在界面处发生很少的剥离，并且界面裂缝移动到大部分P-DN凝胶中，导致大块P-DN凝胶破裂。因此，使用坚韧的P-DN凝胶作为涂层是制造坚固的水凝胶涂层的新方法。使用坚韧水凝胶的另一个有用方面是涂层足够坚固以显示出低摩擦的耐磨性。此外，利用P-DN凝胶的自由成形性，我们成功地在复杂的3D形状上获得了坚韧的P-DN凝胶涂层。这些演示表明水凝胶可用于需要坚韧涂层的各种实际应用。