Crown Ether Functionalized Polymer/Glass Fiber Composite Material:Preparation And Study On The Separation Performance Of Lithium Isotopes

Lithium isotopes play an important role in the nuclear energy industry.The effective separation of lithium isotopes is of far-reaching significance for the development of clean energy in the future and for enhancing the military power to consolidate national defense.In this paper,based on the combination of polydopamine(PDA)chemistry and surfaceinitiated atom transfer radical polymerization(ATRP),crown ether functionalized polymer/glass fiber composites were prepared using glass fibers as substrate materials,and the performance for adsorptive separation of lithium isotopes was systematically studied.The main research results are as follows:(1)Based on the study of dopamine polymerization behavior,uniform deposition and secondary functionalization of PDA on glass fiber surfaces were achieved.A dense PDA coating consisting of 20-nm aggregates could be obtained after a coating time of 2 h in 2 g/L dopamine solution in the presence of NaIO4 oxidant.Taking advantage of the large number of active groups in the PDA structure,the immobilization of initiators on the surfaces was achieved without impairing the properties of the glass fibers.(2)Controllable growth of functional polymers on the surfaces of glass fibers was achieved by surface-initiated ATRP.The effect of initiator/catalyst ratio,solvent/monomer ratio(dilution multiple),polymerization time and monomer concentration on the surface growth behavior of the polymers were evaluated.Polymers with controlled molecular weight(Mn=6000 ~ 20000 Da),narrow molecular weight distribution(Mw/Mn=1.19 ~ 1.41)and structural regularity were prepared on the surfaces of the glass fibers through the regulation of polymerization conditions.(3)Crown ether functionalized polymer/glass fiber composites were prepared based on the optimized reaction conditions.The functionalization degree of the crown ether ligands was increased(grafting ratio 0.2 mmol/g),and the micro-morphology,composition and structure of the composite materials at various synthesis stages were comprehensively characterized.(4)The performance of crown ether functionalized polymer/glass fiber composites for adsorption and separation of lithium isotopes was systematically studied.The effects of various factors such as cation selectivity,solvent effect,and lithium salt anion species on the performance of the materials were investigated.The kinetic model and thermodynamic model fitting revealed the control factors and adsorption mechanism of the adsorption process.In this thesis,a new method by integrating the PDA chemistry with surface-initiated ATRP for preparing crown ether functionalized polymer/glass fiber composites was established,enabling the high-content grafting of crown ether ligands on the surfaces of glass fibers.enabling the high-content The adsorptive separation behaviors of the composite materials toward lithium isotopes in the solutions were studied.The findings in this research provides theoretical and experimental support for further improving the adsorptive separation efficiency of lithium isotopes in solid-liquid systems.