The Synthesis Of Optical PA11DT/SiO₂ Core-Shell Particles And The Research On Application

Optically active polymers have structural or conformational specificities,which gives unique properties to such polymer materials,such as chiral recognition and chiral separation.Due to the polarity of the amide bond and the ability to form hydrogen bonds,polyamides provide new ideas for the preparation of optically active polymers.In this thesis,an optically active polyamide PA11DT was synthesized by interfacial polymerization using D-tartaric acid and eleven-carbon diamine.However,the PA11DT prepared had poor dispensability and lost its optical activity at 100°C.Therefore,in order to improve the structural regularity of PA11DT and improve its thermal stability,PA11DT/SiO₂ core-shell particles with different shell thicknesses were prepared using PA11DT as the core and SiO₂ as the shell.Further,PA11DT/SiO₂core-shell particles were used as the chiral inducer to induce the supersaturated racemic alanine.The specific research content and results are as follows:1.Polyamide PA11DT was prepared by interfacial polymerization using D-tartaric acid as the raw material and eleven-carbon diamine as the monomer.The relevant test results show that the synthesized PA11DT has a certain optical activity,exhibits negative Cotton effect,which is opposite to the monomer D-tartaric acid,and has a certain chiral amplification effect,but PA11DT loses its optical activity at100°C.The PA11DT has a hexagonal crystal structure and belongs to theγcrystal form.The morphology of the PA11DT powder is basically a sheet structure and shows obvious agglomeration.2.PA11DT/SiO₂ core-shell particles were prepared by the emulsion method using PA11DT as the core and SiO₂ as the shell.By adjusting the volume of TEOS added to the system,PA11DT/SiO₂ core-shell particles with different shell thicknesses were synthesized.The correlation test results show that the particle size distribution of PA11DT/SiO₂ core-shell particles is between 200 nm and 500 nm,and the particles are uniformly dispersed,which proves agglomeration phenomenon is significantly reduced after the SiO₂ shell is added.The PA11DT/SiO₂ core-shell particles with different ratios of PA11DT/TEOS have almost the same optical activity and still have certain optical activity at 100°C,which shows that the thermal stability of PA11DT/SiO₂ core-shell particles increases significantly with the addition of SiO₂.3.PA11DT/SiO₂ core-shell particles were used as chiral inducer to induce supersaturated racemic alanine enantiomers.The relevant test results show that the core-shell particles successfully induce the precipitation of D-alanine crystals.When0.125%of the inducer was added,of the total mass of racemic alanine,induced crystallized product is the most,and the e.e.%is also higher.Using different PA11DT/TEOS ratios of core-shell particles as inducers can induce the slender needle-like D-alanine crystals,and the crystals obtained have good regularity.Different PA11DT/TEOS ratio inducers have different SiO₂ shell thicknesses,and they have different inducing crystallization efficiencies and the crystals obtained have different optical purity.