新型极性多苯基聚硅氧烷的合成和气相色谱分离性能研究

This project aims at exploring strong polar stationary phases for capillary gas chromatography with high separation selectivity and excellent property. In a high boiling point solvent, all kinds of polar multiphenyl cyclopenta-2,4-dienone containing conjugated diene react with high molecular weight linear methyl- polysiloxane with dispersed vinyl side chain through Diels-Alder reaction. High molecular weight polymer elastomers with five conjugate rings of functional groups can be obtained. The functional groups directly connect with Si atom of main chain. We systematically investigate the influence of this new class of functional group on the physical and chemical properties, chromatographic separation performance of the polymers, as well as the interaction mechanism. This series of novel polymers can be used as stationary phases. Their side chain polarizability are five times more than a single phenyl, and their total polarity are above 900. They can be used at room temperature and high temperature (330℃～ 360℃). Their coating efficiency and cross-linking efficiency are greater than 80%. This class of polymer possesses unique properties such as low glass transition temperature, high viscosity, low viscosity-temperature coefficient and wide working range. Besides, their side chains contain lots of benzene rings, delocalized conjugated π bond with dozens of electron can be generated, making the polymers have large deformation of electron clouds, high polarizability and high polarity. The polymers have unique separation selectivity for unsaturated compounds containing double bonds, due to their strong induction and dispersion forces.

为探索新的具有高分离选择性和良好使用性能的极性更强的毛细管气相色谱固定相，本项目利用Diels―Alder反应，将含有共轭双烯的各种极性多苯基环戊二烯酮与含分散乙烯基侧链的高分子量线型甲基聚硅氧烷，在高沸点溶剂中进行加成反应，得到与主链Si原子直接相连的、共轭环数为5个的高分子量聚合物弹性体。通过这类新型功能基团对聚合物的理化性质、色谱分离和使用性能的影响规律及作用机理的系统研究，得到侧链极化率在单个苯基的5倍以上，总相常数在900以上，最低使用温度在室温附近，最高使用温度在330℃～360℃，涂渍效率和交联效率均大于80%的新型固定相系列产品。该类聚合物具有玻璃化温度低、粘度高、黏温系数小、使用温度范围宽等优点，且侧链苯环高度集中，可产生含几十个电子的离域共轭大π键，电子云变形性大，可极化率高，极性大。依靠其超强的诱导作用力和色散力，对含不饱和双键的化合物具有优异的分离选择性。

现有气相色谱固定相虽然很多，但这些固定相对于芳烃异构体的分析结果并不理想。为解决上述问题，本项目探索并合成了一系列具有高分离选择性和良好使用性能的毛细管气相色谱固定相。首先，我们利用Diels-Alder 反应，将含有共轭双烯的各种极性多苯基环戊二烯酮与含分散乙烯基侧链的聚甲基硅氧烷，在高沸点溶剂二苯醚中进行反应，得到高分子量的多环芳基接枝聚硅氧烷弹性体。将这些聚合物通过静态法涂渍到毛细管柱内壁，作为气相色谱固定相使用，并对其柱效、极性、工作温度范围、分离机理及选择性进行了研究。研究结果表明这类固定相具有柱效高（3800-4200 plates/m）、工作温度范围宽（30-360℃）、可重复性好（RSD≤0.10%）等优点。依靠溶质分子与固定相间较强的偶极-诱导偶极作用力、π-π作用力及色散力，该类固定相对苯的取代物异构体、多环芳烃等环境污染物具有优异的分离选择性。