Oak Ridge Institute for Science and Education , Belcamp, Maryland 21017, United States.
U.S. Army Research Laboratory , Aberdeen Proving Ground, Maryland 21005, United States.
Langmuir. 2018 Jan 30;34(4):1274-1286. doi: 10.1021/acs.langmuir.7b03178. Epub 2018 Jan 18.
Numerous studies have focused on the remarkable adhesive properties of polydopamine, which can bind to substrates with a wide range of surface energies, even under aqueous conditions. This behavior suggests that polydopamine may be an attractive option as a surface treatment in structural bonding applications, where good bond durability is required. Here, we assessed polydopamine as a surface treatment for bonding aluminum plates with an epoxy resin. A model epoxy adhesive consisting of diglycidyl ether of bisphenol A (DGEBA) and Jeffamine D230 polyetheramine was employed, and lap shear measurements (ASTM D1002 10) were made (i) under dry conditions to examine initial bond strength and (ii) after exposure to hot/wet (63 °C in water for 14 days) conditions to assess bond durability. Surprisingly, our results showed that polydopamine alone as a surface treatment provided no benefit beyond that obtained by exposing the substrates to an alkaline solution of tris buffer used for the deposition of polydopamine. This implies that polydopamine has a potential Achilles' heel, namely, the formation of a weak boundary layer that was identified using X-ray photoelectron spectroscopy (XPS) of the fractured surfaces. In fact, for longer deposition times (2.5 and 18 h), the tris buffer-treated surface outperformed the polydopamine surface treatments, suggesting that tris buffer plays a unique role in improving adhesive performance even in the absence of polydopamine. We further showed that the use of polydopamine-3-aminopropyltriethoxysilane (APTES) hybrid surface treatments provided significant improvements in bond durability at extended deposition times relative to both polydopamine and an untreated control.
许多研究都集中在聚多巴胺令人瞩目的粘附特性上，它可以与具有广泛表面能的基底结合，即使在水相条件下也是如此。这种行为表明，聚多巴胺作为结构性粘合应用中的表面处理剂可能是一个有吸引力的选择，因为需要良好的粘合耐久性。在这里，我们评估了聚多巴胺作为粘合铝板与环氧树脂的表面处理剂。使用了一种由双酚 A 的二缩水甘油醚（DGEBA）和 Jeffamine D230 聚醚胺组成的模型环氧树脂胶，进行了搭接剪切测量（ASTM D1002 10）（i）在干燥条件下检查初始粘合强度，（ii）在暴露于热/湿（在水中 63°C 下 14 天）条件下评估粘合耐久性。令人惊讶的是，我们的结果表明，聚多巴胺单独作为表面处理剂，除了将基底暴露于用于沉积聚多巴胺的三缓冲液的碱性溶液中所获得的效果之外，没有任何益处。这意味着聚多巴胺有一个潜在的弱点，即形成了一个薄弱的边界层，这是通过对断裂表面的 X 射线光电子能谱（XPS）分析来确定的。事实上，对于更长的沉积时间（2.5 和 18 小时），三缓冲液处理的表面表现优于聚多巴胺表面处理剂，这表明三缓冲液即使在没有聚多巴胺的情况下，也能在改善粘合性能方面发挥独特的作用。我们进一步表明，与聚多巴胺和未处理对照相比，使用聚多巴胺-3-氨丙基三乙氧基硅烷（APTES）混合表面处理剂可以在延长的沉积时间内显著提高粘合耐久性。
