高碳含量新型亚微米无孔二氧化硅材料的修饰方法及其在反相加压毛细管电色谱平台上的应用
摘要
<p id=C2>Submicron nonporous silica (NPS) materials feature small particle sizes, smooth surfaces, and regular shapes. They also exhibit excellent performance as a stationary phase; however, their use is limited by their low specific surface area and low phase ratio. Therefore, a novel surface modification strategy tailored for NPS microspheres was designed, involving a multi-step reaction. 3-Glycidyloxypropyltrimethoxysilane (GPTS) was first grafted onto NPS particles as a silane coupling agent. Polyethyleneimine (PEI), a high-molecular-weight polymer, was then coated onto the particles, providing numerous amino reaction sites. In the final step, an acylation reaction was initiated between stearoyl chloride and the amino groups to obtain the final product, designated as C<sub>18</sub>-NH<sub>2</sub>-GPTS-SiO<sub>2</sub>. Elemental analysis, FT-IR spectroscopy, Zeta potential analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were employed to investigate the success of the chemical modifications at each step. The carbon content increased from 0.55% to higher than 8.29%. Thus, it solved the low carbon loading capacity problem when modifying NPS microspheres with traditional C<sub>18</sub> reversed phase (e. g., octadecyl chlorosilane modification). <p id=C200>Meanwhile, the reasons for the considerable differences between NPS and porous silica (PS) microspheres in terms of the reactivity to surface modification were investigated in detail. The BET method was employed to compare the pore structures. FT-IR and <sup>29</sup>Si solid-state NMR spectroscopy were employed to analyze the differences in the structure and quantity of silanol groups on the surfaces of the NPS and PS microspheres. Differences were observed not only in the pore size and surface area, but also in the types of silanol groups. FT-IR analysis indicated that the NPS and PS microspheres had different <italic>υ</italic><sub>Si-OH</sub> band positions, which shifted from