地聚物涂层研究进展：从制备工艺、疏水改性到分子动力学模拟

Research Progress in Geopolymer Coatings: From Preparation Processes, Hydrophobic Modification to Molecular Dynamics Simulations

摘要: 地聚物作为一种以工业固废为原料的新型无机胶凝材料，在混凝土结构防护涂层领域展现出广阔的应用前景。然而，传统地聚物涂层固有的亲水性和脆性严重制约了其长期耐久性。本文系统综述了地聚物涂层的制备工艺、性能调控、微观机理及分子动力学模拟研究进展。首先，阐述了地聚物的化学结构特征与地质聚合反应机理，分析了原材料体系(前驱体、碱激发剂、功能性添加剂)和制备工艺参数(养护制度、凝结时间调控)对涂层性能的影响规律。其次，重点讨论了地聚物涂层的粘结强度、耐久性(耐酸、耐氯离子、耐高温)及疏水改性性能，并分析了工作性能的影响因素。结果表明，PVA纤维增强可使界面黏聚力提高68%~84%，45℃热养护可有效抑制早期开裂；PDMS和MTOS等疏水改性剂可使涂层接触角从40˚增至130˚以上，但会导致粘结强度下降约59%。再次，从微观形貌、化学结构、孔隙特征和界面结合机制等方面揭示了涂层性能的微观机理，结合分子动力学模拟从原子尺度阐释了疏水改性剂降低表面能的机制、纳米SiO₂增强地聚物的界面反应机理以及钙含量对聚合度与力学性能的双重影响。最后，总结了地聚物涂层在混凝土修复、海洋工程防护和建筑防火等领域的应用现状，并针对疏水–力学性能平衡、长期耐久性数据匮乏、标准化测试方法缺失等问题提出了展望。

Abstract: Geopolymers, as a novel type of inorganic cementitious material derived from industrial solid wastes, have demonstrated promising application prospects in the field of protective coatings for concrete structures. However, the inherent hydrophilicity and brittleness of conventional geopolymer coatings significantly limit their long-term durability. This paper systematically reviews the recent advances in the preparation processes, performance regulation, microstructural mechanisms, and molecular dynamics simulations of geopolymer coatings. First, the chemical structural characteristics and geopolymerization reaction mechanisms of geopolymers are elucidated, and the effects of raw material systems (precursors, alkali activators, functional additives) and preparation parameters (curing regimes, setting time control) on coating performance are analyzed. Second, the bond strength, durability (acid resistance, chloride resistance, high-temperature resistance), hydrophobic modification performance, and workability of geopolymer coatings are critically discussed. Results indicate that PVA fiber reinforcement can increase interfacial cohesion by 68%~84%, and heat curing at 45˚C effectively inhibits early-age cracking. Hydrophobic modifiers such as PDMS and MTOS can increase the water contact angle from approximately 40˚ to over 130˚, but simultaneously reduce bond strength by about 59%. Third, the microscopic mechanisms underlying coating performance are revealed from the perspectives of microstructure, chemical structure, pore characteristics, and interfacial bonding mechanisms. Combined with molecular dynamics simulations, the mechanisms of surface energy reduction by hydrophobic modifiers, the interfacial reaction of nano-silica reinforcement, and the dual effects of calcium content on polymerization degree and mechanical properties are elucidated at the atomic scale. Finally, the application status of geopolymer coatings in concrete repair, marine engineering protection, and fire protection for buildings is summarized. Challenges such as the hydrophobicity-mechanical property trade-off, the lack of long-term durability data, and the absence of standardized testing methods are discussed, along with future research directions.