| As a"green"medium,ionic liquids have been widely studied and applied in many fields for more than 20 years.The influence of the molecular structures of ionic liquids on its thermodynamic properties is investigated.It is meaningful to establish correlation models between the structural parameters of ionic liquids and thermodynamic properties,which provide the research basis and theoretical basis for the design,synthesis,and application of new functional phase change energy storage ionic liquids.In the past decade,the application of ionic liquids in the field of polymer flame retardant has been gradually developed.Compared with traditional flame retardants,ionic liquids have the advantages of strong designability,environmental friendliness,high efficiency,and high thermal stability.Phosphorus-nitrogen flame retardants are non-polluting,low-smoke and high-efficiency.It is of very important social significance and application value using ILs together with phosphorus-nitrogen flame retardants to improve the flame retardance of polymer materials.The main research results of this dissertation are as follows:(1)C4(mim)2(Br)2?C4(eim)2(Br)2?C4(n-pim)2(Br)2?C4(n-bim)2(Br)2?C4(mim)2(BF4)2?C4(mim)2(PF6)2?C4(mim)2(NTf2)2?C4(2-mim)2(Br)2?C4(1,2-mmim)2(Br)2?C4(2,5-mmim)2(Br)2 were synthesized.The yields are all higher than 90%,water content are less than450 ppm.The structure of the compounds were characterized by EA,1H NMR and 13C NMR,and the results showed that the structure of the product was consistent with the design.(2)The imidazole-based geminal dicationic ionic liquids(GDILs)has good thermal stability at high temperature.The molecular structure of ionic liquids has a huge impact on its thermal properties.The molecular structures of the imidazole-based GDILs were optimized by the quantum chemical density functional theory(DFT)method using Gaussian 09 software.Structural factors such as the interaction between anion and cation,the size of the imidazole ring substituent,the substituent at the 2 position of the imidazole ring,the anion type and molecular size are analyzed,and a structure-property relationship model of the structural parameters and the thermodynamic properties was established.The results showed:the decomposition temperature(Td)of 1,4-bis(N-alkylimidazolium)butane bromide has a linear relationship with its molecular volume,as the volume of the cation increases,Td decreases.Td has a polynomial relationship with the anion volume.When the cation or anion is the same one,the melting point(Tm)of the ionic liquids has a polynomial relationship with the density or molecular volume.The melting enthalpy of the ionic liquid has a polynomial relationship with the interaction energy of anion and cation.The anion volume of the imidazole-based GDILs with the same cation has the same effect on its melting heat and melting temperature in the same order:Br->[PF6]->[NTf2]-?[BF4]-.,The melting point and heat of fusion of the ionic liquid decrease sharply,when the C2-H on the imidazole ring is replaced by a methyl group.(3)Using trichlorooxy,ethylenediamine and phenol as raw materials,the phosphorus-nitrogen flame retardant ethylenediamine diphenyl bisphosphate(TDBDP)was successfully synthesized by the"one-pot method",with a yield of 89.3%.Its structure was characterized by EA,MR,1H NMR and 13C NMR,the results showed that its structure was consistent with the design.The thermal performance of TDBDP was tested by TG and DSC.The initial decomposition temperature of TDBDP was 562.5K,and the thermal decomposition was completed at 772K.The residual carbon content was 27.9%,and the thermal stability was high.The melting point of TDBDP is 412.41K,and the melting enthalpy value is 84.38k J·kg-1.(4)C4(mim)2(Br)2/TDBDP/EP and C4(mim)2(BF4)2/TDBDP/EP flame retardant composites were prepared,and the thermal properties,flame retardant properties and mechanical properties of flame retardant composites were analyzed.The results were showed as follows:the decomposition temperature of both composite flame retardant composites were decrease,so the thermal stability was slightly reduced.C4(mim)2(Br)2/TDBDP and C4(mim)2(BF4)2/TDBDP had good synergistic flame retardant effect on EP.When TDBDP and ionic liquid was added at12wt%and 3wt%,respectively,the two flame retardant EP had the best flame retardant effect,and both could reach UL-94 V-0,at the same time,the LOI values of EP/TDBDP/C4(mim)2(BF4)2 and EP/TDBDP/C4(mim)2(Br)2 flame retardant composites wer32.5%and 31.4%,respectively.The results of CONE test and residual carbon analysis showed that both of them worked in condensed phase and gas phase,and TDBDP/C4(mim)2(BF4)2 has better flame retardant effect.The mechanical performance results showed that the two composite flame-retardant EP materials still had good mechanical properties when they reached the UL-94 V-0.(5)C4(mim)2(Br)2/TDBDP/PLA and C4(mim)2(BF4)2/TDBDP/PLA flame retardant composites were prepared,and the thermal properties,flame retardant properties and mechanical properties of flame retardant composites were analyzed.The results were showed as follows:Td of C4(mim)2(BF4)2/TDBDP/PLA were increase,their thermal stability was slightly improved,and Td of C4(mim)2(Br)2/TDBDP/PLA were decrease,their thermal stability was slightly reduced.C4(mim)2(Br)2/TDBDP and C4(mim)2(BF4)2/TDBDP had good synergistic flame retardant effect on PLA.When TDBDP and ionic liquid was added at 21wt%and 4wt%,respectively,the two flame retardant PLA had the best flame retardant effect,and both could reach UL-94 V-0,at the same time,the LOI values of PLA/TDBDP/C4(mim)2(BF4)2and PLA/TDBDP/C4(mim)2(Br)2 flame retardant composites were 30.9%and 29.7%,respectively.The results of CONE test and residual carbon analysis showed that both of them worked in condensed phase and gas phase,and TDBDP/C4(mim)2(BF4)2 has better flame retardant effect.The mechanical performance results showed that the two composite flame-retardant PLA materials still had good mechanical properties when they reached UL-94 V-0. |
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