基于Pickering乳液聚合的木材防腐防水保护体系构建与作用机制研究

The integration of wood preservation and waterproof is significant for wood protection. It is a big challenge to increase the ability to decay resistance and hydrophobicity of wood simultaneously and effectively in the field of wood protection. Based on the mechanism for stabilizing Pickering emulsion and the theory of interfacial membrane, a compound system of polyacrylate emulsion is synergistically stabilized by didecyl dimethyl ammonium chloride (DDAC) and nano-silica, which is used for wood protection. In this system, DDACs are used as emulsion stabilizers and wood preservatives, nano-silicas are used as solid stabilizers and wood modifying agents, and polyacrylates are used for the formation of a complete hydrophobic barrier, increasing the hydrophobicity and leaching resistance. The compound system for wood protection based on Pickering emulsion polymerization with smaller droplet size and better stability is proposed by adjusting the surface wettability of silica by DDAC addition and optimizing the structure of the interfacial membrane via the sol-gel technology. The dimensional stability, decay resistance, and leaching resistance of wood are investigated to clarify the synergistic effect among emulsion ingredients (DDAC, nano-silica and polyacrylate). Also, the effect of compound emulsion on hydroxyl groups and pore structure in wood is studied by analyzing the behaviors of dynamic vapour sorption (DVS) and nitrogen adsorption. Thereafter, the mechanism for wood preservation and waterproof of the emulsion treated wood is clarified. The results from this project can provide a new idea for developing multi-functional systems for wood protection, which will provide scientific and theoretical supports for developing functional woods with high-performance.

防腐防水一体化对木材保护意义重大，如何同步有效赋予木材防腐和防水性能是木材保护领域的重要挑战。项目基于Pickering乳液稳定机理和界面膜理论，构建以二癸基二甲基氯化铵（DDAC）为乳液稳定剂与防腐剂、纳米SiO2为固体稳定剂与改性剂的协同稳定的聚丙烯酸酯木材保护复合乳液体系。经浸渍处理与干燥固化，在木材内形成连续完整疏水膜，发挥防水、防腐和抗流失作用。通过DDAC调控纳米SiO2表面亲/疏水性、采用溶胶-凝胶技术优化界面膜结构，实现低粒径、高稳定性Pickering乳液聚合型木材保护复合体系构建。研究处理材尺寸稳定性、耐腐性、抗流失性等，阐明乳液有效成分之间协同作用机制；考察处理材动态水分吸附特性和氮气吸附特性，解析乳液对木材中羟基和孔隙结构的影响规律，揭示乳液组分对木材防腐防水的作用机制。研究成果将为多功能木材保护体系构建提供新思路，为高性能功能性木材构筑提供科学依据与理论支持。

本项目借鉴种子乳液聚合技术，基于界面膜理论与Pickering乳液稳定机理，制备了核壳结构聚丙烯酸酯乳液，可同步赋予木材防水和防腐性能。通过调控核壳结构单体比例，结合固体稳定剂纳米二氧化硅等，实现了软核硬壳结构聚合物乳液体系构建，具有粒径小、稳定性高、分布均匀和成模性好等特点。聚合物核壳分层梯度结构，降低了不同组分之间内耗阻力，具备剪切变稀特性，赋予了聚合物胶粒良好的流动延展性，有利于木材浸渍改性处理。通过聚合物乳液改良石蜡乳液处理材，基于响应曲面法优化并预测了处理工艺条件。结果表明，聚合物乳液可通过细胞壁润胀作用和孔隙填充效应，减少木材吸湿位点，占据水分渗透空间，构建了木材内完整疏水屏障，显著改善了木材防水性和尺寸稳定性等。针对木材吸水率与增重率，模型预测误差可控制在约10%；针对木材吸湿率，模型预测误差可控制在1%，预测效果良好。进一步，为提升聚合物乳液木材内高效沉积与均匀分布，研究了热处理诱导细胞壁聚合物组分降解，延展了孔隙结构尺寸，促进了分散型改性剂木材内高效渗透。通过化学键合作用与物理填充效应，实现了环境友好型木材性能改良效果。本研究成果为多功能木材保护体系构建提供新思路，为高性能功能性木材构筑提供科学依据与理论支持。