聚合物接枝纳米 $ SiO_{2} $ 的制备及其对水泥基材料性能的影响

文章采用偶联剂 KH550 改性后的纳米 $ SiO_{2} $ 与丙烯酸甲酯（MA）、乙二胺（EDA）进行反应，再将甲氧基聚乙二醇-丙烯酸酯（MPEG-DA）接枝在经过 MA 和 EDA 扩链处理后的纳米 $ SiO_{2} $ 表面。采用傅里叶变换红外光谱仪（Fourier transform infrared spectrometer，FTIR）和热失重分析仪（thermogravimetric analyzer，TGA）对 MPEG-DA 改性的纳米 $ SiO_{2} $ 的结构进行表征，并分析掺杂纳米 $ SiO_{2} $ 和 MPEG-DA 改性纳米 $ SiO_{2} $ 水泥浆体的水化过程、微观结构以及孔径分布。结果表明：MPEG-DA 改性纳米 $ SiO_{2} $ 可以调控水泥浆体水化过程、精炼水泥试件的微观结构，抑制水泥试件的孔隙率的增加；MPEG-DA 改性纳米 $ SiO_{2} $ 不仅能优化水泥基材料的施工性能，还可以显著强化水泥基材料的力学强度；在 MPEG-DA 改性纳米 $ SiO_{2} $ 的掺量为胶凝材料质量的 0.5% 时，砂浆和混凝土 28 d 的抗压强度较空白样增长了 43.1% 和 27.8%。

On the base of nano- $ SiO_{2} $ modified by KH550, the surface of nano- $ SiO_{2} $ was treated with methyl acrylate(MA) and ethylenediamine(EDA) for chain extension, and then methoxy polyethylene glycol diacrylate(MPEG-DA) was anchored onto the nano- $ SiO_{2} $ surface. The specific structure of MPEG-DA modified nano- $ SiO_{2} $ was characterized by Fourier transform infrared spectrometer (FTIR) and thermogravimetric analyzer (TGA). The hydration process, electron microscopic patterns and pore size distribution of cement pastes doped with nano- $ SiO_{2} $ and MPEG-DA modified nano- $ SiO_{2} $ were analyzed. The results show that MPEG-DA modified nano- $ SiO_{2} $ can control cement paste hydration process, refine the microstructure and decrease the porosity of cementitious material. Besides, the nano- $ SiO_{2} $ modified by MPEG-DA not only can optimize the workability of cement-based materials, but also can enhance their mechanical strength. When the content of MPEG-DA modified nano- $ SiO_{2} $ was 0.5% of cementitious material, the compressive strength of fabricated cement mortar and concrete increased by 43.1% and 27.8%, respectively, compared to the reference sample after curing for 28 days.