Department of Civil and Environmental Engineering, Rice University, Houston, Texas 77005, USA.
Langmuir. 2013 Jun 25;29(25):8154-63. doi: 10.1021/la4014015. Epub 2013 Jun 11.
The geometry and material property mismatch across the interface of hybrid materials with dissimilar building blocks make it extremely difficult to fully understand the lateral chemical bonding processes and design nanocomposites with optimal performance. Here, we report a combined first-principles study, molecular dynamics modeling, and theoretical derivations to unravel the detailed mechanisms of H-bonding, deformation, load transfer, and failure at the interface of polyvinyl alcohol (PVA) and silicates, as an example of hybrid materials with geometry and property mismatch across the interface. We identify contributing H-bonds that are key to adhesion and demonstrate a specific periodic pattern of interfacial H-bond network dictated by the interface mismatch and intramolecular H-bonding. We find that the maximum toughness, incorporating both intra- and interlayer strain energy contributions, govern the existence of optimum overlap length and thus the rupture of interfacial (interlayer) H-bond assemblies in natural and synthetic hybrid materials. This universally valid result is in contrast to the previous reports that correlate shear strength with rupture of H-bonds assemblies at a finite overlap length. Overall, this work establishes a unified understanding to explain the interplay between geometric constraints, interfacial H-bonding, materials characteristics, and optimal mechanical properties in hybrid organic-inorganic materials.
混合材料的界面存在几何形状和材料特性不匹配，这使得人们极难完全理解横向化学键合过程，并设计出具有最佳性能的纳米复合材料。在这里，我们报告了一项结合第一性原理研究、分子动力学模拟和理论推导的研究，以揭示聚醋酸乙烯酯（PVA）和硅酸盐界面的氢键、变形、载荷传递和失效的详细机制，以此为例说明具有界面不匹配的混合材料。我们确定了有助于粘附的氢键，并证明了由界面不匹配和分子内氢键决定的界面氢键网络的特定周期性模式。我们发现，最大韧性，同时包含了内层和层间应变能的贡献，控制了最佳重叠长度的存在，从而控制了界面（层间）氢键组装的断裂，这在天然和合成混合材料中都是如此。这一普遍有效的结果与之前的报告形成了对比，后者将剪切强度与有限重叠长度处氢键组装的断裂联系起来。总的来说，这项工作建立了一个统一的理解，以解释几何约束、界面氢键、材料特性和混合有机-无机材料中最佳机械性能之间的相互作用。
