Catalytic Synthesis And Controllable Polymerization Of Polyphosphazene

Polyphosphazene material is a new type of multifunctional polymer material that combines the advantages of organic materials and inorganic materials.Polydichlorophosphazene(PDCP)is an important intermediate for the synthesis of polyphosphazene materials.The synthesis mechanism and stability of PDCP,as well as the molecular design of functionalized polyphosphazene,are very important for the application of polyphosphazene and phosphorus.Based on the above research content,the main work of this paper is as follows:1.Established a new catalytic system for the ring-opening polymerization of HCCP solutions,namely oleum-water system.The yield of PDCP synthesized by the catalytic system can reach 60%,Mn can reach 50,000,and the polydispersity coefficient is 1.08 to 1.20.This method has high catalytic efficiency,high product quality and high yield.Based on the theoretical analysis of molecular structure and ring opening polymerization of the reactant molecular structure and ring-opening polymerization,experimental analysis of eight different catalytic systems,and the phenomenon of no gelation of PDCP,the mechanism of this polymerization was demonstrated in many aspects,providing powerful experimental and theoretical support for the mechanism of ring-opening cationic polymerization of HCCP solutions.The effects of the amount of oleum,the amount of trace water,the polymerization temperature and initial monomer concentration on PDCP yield,Mn,and polymerization time were explored,that maximizes the catalytic effect of oleum-water systems and broadens the application platform of the system.2.The stability of THF solutions with different concentrations of PDCP was studied.At low concentrations,gels are not produced,and this gel-free concentration is related to the molecular weight of PDCP.Further,a microscopic explanation of this discovery is given.A new preservation method for PDCP was proposed:the mixed solution after polymerization was cooled and stored,and then separated and purified when used.The storage time of PDCP can be increased to more than 60 days,which simplifies the process while maintaining the reactivity of PDCP,providing great convenience for the laboratory and industrial production of polyphosphazene.3.Three kinds of nucleophilic reagents of phenol,alcohol,and amine were nucleophilicly substituted for PDCP at different substitution times in the form of sodium salt(excluding amines)or triethylamine catalysis.The reaction characteristics of these three nucleophilic reagents with PDCP were explored,and their substitutions and substitution times were optimized.Through TG and DSC tests,the functional properties of substituted phosphazene of phenol,alcohol and amine were compared.The Glass transition temperature:PTFEP<PPOP<PPAP,The thermal decomposition temperature:PPOP>PTFEP>PPAP.The above studies provide scientific basis for the molecular design and application of functionalized polyphosphazene.