Synthesis And Gas Chrorrnatographic Performance Of Polysiloxane Stationary Phases Containing Polyaryl And Fluorine Atoms

Gas chromatographic stationary phase,as the core part of the gas chromatography system,plays a decisive role in the separation and analysis of mixtures.With the increasing demands for analysis in the field of analysis,traditional polysiloxane-based stationary phases are no longer sufficient.Therefore,it is an urgent problem to develop gas chromatographic stationary phases with high stability,strong separation selectivity and long life.Because polysiloxane has excellent stability,good film-forming ability,better solubility,small viscosity temperature coefficient and mass transfer resistance,higher column efficiency,it is an ideal material as gas chromatographic stationary phase after modification.The work of this paper is introducing a rigid conjugated and planar polyphenyl group and polar fluorine atoms on the polysiloxane side chain.While increasing the stationary phase's polarizability,the interaction between the stationary phase and the analyte is enhanced,thereby improving separation selectivity of the stationary phases.The main work studied in this thesis includes(1)Systematic dissertation and comprehensive analysis of gas chromatography from three aspects:research progress of gas chromatographic stationary phases,development of gas chromatography technology and application of gas chromatography technology.(2)Synthesis of methyl vinyl polysiloxane polymer.At a certain temperature,octamethylcyclotetrasiloxane(D4)and tetramethyltetravinylcyclotetrasiloxane(D4Vi)are catalyzed by tetramethylammonium hydroxide silicon alkoxide to undergo ring-opening polymerization to form long-chain polymer.The molecular weight of the polymer is controlled by adding hexamethyldisiloxane(MM)(3)Synthesis of 1,4-diphenyltriphenylene-grafted polysiloxane(DPTP).9,10-phenanthrenequinone and dibenzyl ketone undergo aldol condensation reaction under strong base conditions to form 1,3-bis(phenyl)cyclopenta[1]-phenanthrene-2-one.Then,at high temperature,a rigid coplanar polyphenyl group was grafted to the methyl vinyl polysiloxane side chain by the Diels-Alder reaction to obtain a DPTP stationary phase with a side chain branching rate of 14.2%(4)Synthesis of 2,5-bis(4-fluorophenyl)-3,4-bis(3,4,5-trifluorophenyl)graft polysiloxane(FTFP).The intermediate substance of 2,5-bis(4-fluorophenyl)-3,4-bis(3,4,5-trifluorophenyl)cyclopentadienone was synthesized by the reactions of condensation and oxidation with 3,4,5-trifluorobenzaldehyde and p-fluorophenylacetic acid as raw materials.Then,2,5-bis(4-fluorophenyl)-3,4-bis(3,4,5-trifluorophenyl)group was successfully grafted to the methyl vinyl polysiloxane side chain by Diels-Alder reaction under high temperature condition to obtain FTFP stationary phase with high polarity and thermal stability.The preferred 2,5-bis(4-fluorophenyl)-3,4-bis(3,4,5-trifluorophenyl)-grafted polysiloxane stationary phase has a side chain graft ratio of 11.48%(5)DPTP and FTFP capillary gas chromatographic columns were prepared by the static coating method.Then the two columns were used to evaluate the chromatographic performance,including column efficiency,McReynolds constants,Abraham system constants,column inertness and temperature resistance.For 30 m and 10 m DPTP columns,the optimal linear velocity are 8?15 cm·s-1,and the column efficiency are 3646 plates·m-1 for 30 m and 3125 plates·m-1 for 10 m.For FTFP columns,the optimal linear velocity are 7-15 cm·s-1 for 30 m and 9?17 cm·s-1 for 10 m,and the column efficiency are 3796 plates·m-1 for 30 m and 3335 plates·m-1 for 10 m.Both the DPTP and FTFP belong to the medium-polarity column based on the measurement of McReynolds constants.(6)Evaluation of separation selectivity of DPTP and FTFP columns.Mixture samples made in our laboratory were separated by these two kinds of columns include:isomers,fatty acid esters,ethers,polycyclic aromatic hydrocarbons and their derivatives,nitrogen-containing heterocyclic mixtures,diesel,organic amines and aromatic aldehydes.Due to the special side chain groups,strong dipole-induced dipole,?-?stacking and dispersion interactions between stationary phases and the analytes are generated,which lead to strong separation selectivity.The separation of diesel on the DPTP column and the separation of environment contaminations,such as organic amines,on the FTFP column indicate that the two gas chromatographic columns prepared have potential application value in actual production and life.