Synthesis And Spatial Structure Characterization Of Novel Optically Active Poly(meth)acrylamides

In this thesis, novel monomers (S)-N-(1-hydroxy-3-phenylpropyl) methacrylamide((S)-NPMA) and (S)-N-(2-hydroxy-1-phenylethyl) acrylamide ((S)-HPEA) were designedand synthesized. Polymers with different stereoregularity were obtained under differentreaction conditions by stereospecific radical polymerization. The proton nuclear magneticresonance spectroscopy (1H NMR) and carbon nuclear magnetic resonance spectroscopy (13CNMR) were used to characterize the chemical structure of the monomers and polymers.Circular dichroism (CD) and polarimeter was applied to characterize optical activity of theobtained polymers. High performance liquid chromatography (HPLC) was used to evaluatethe chiral separation ability of the chiral column prepared with different polymer.When a proton acid, such as methanol and n-butanol, was used as polymerization solvent,the rare earth metal trifluoromethanesulfonate could increase the isotactic stereoregularity ofthe polymer. However, when DMSO was applied as the polymerization solvent, no effectswere observed for increasing isotactic stereoregularity of the polymer with the addition ofLewis acid. Among these rare earth metal trifluoromethanesulfonates, Nd(OTf)3showed thebest results for improving the isotactic stereoregularity of the poly-(S)-NPMA, whileYb(OTf)3showed the best results for improving the isotactic stereoregularity of thepoly-(S)-HPEA.The chiral recognition ability of the polymers with different chemical structure andtacticity were characterized by high performance liquid chromatography (HPLC), whichshowed both the chemical structure change of the polymers and the stereoregularity change ofthe polymers would change their chiral recognition ability.Verified by proton nuclear magnetic resonance spectra (1H NMR), the Lewis acid and(meth)acrylamide monomer can form a complex. Using Job’s Method, the coordination molarratio was measured out:[Monomer]:[Lewis acid]>1. On the basis of the experiments, themechanism of sterospecific radical polymerization in the presence of Lewis acid for(meth)acrylamide monomer was supposed. When forming a chelate between the Lewis acidand the monomer, the radical polymerization mainly improve the isotactic stereoregularity ofthe obtained polymers, while the Lewis acid and the monomer form monodentate complex,the syndiotactic polymers ware improved dominantly. The monomer structure, solvents and Lewis acid affected the tacticity of the polymer together.