| Inorganic ceramic phase change materials have many disadvantages,such as high cost,difficult degradation and potential biological toxicity,which limit their application in the field of flexible wearable.Organic inorganic hybrid materials have always been one of the hot spots in the field of materials research due to their advantages such as large space for property design,low cost and easy to make films.In this paper,a series of new compounds were synthesized by organic-inorganic hybrid reaction between cyclic amine cation and inorganic tetrahedral acid,and the phase transition and dielectric properties of these compounds were discussed.1,1-Methyl-1,4,7,10-tetraazacyclododecane(1-Me-cyclen)was synthesized by introducing a methyl group on the nitrogen atom.A series of compounds[1-Me-cyclen(Cl O4)2](1),[1-Me-cyclen(Cl O4)3](2),[1-Me-cyclen(Re O4)2](3),[1-Me-cyclen(BF4)2](4),[1-Me-cyclen(BF4)3](5)were obtained by intermolecular hydrogen bonding of 1-Me-cyclen with different proportions of inorganic tetrahedral acids:perchloric acid,perchloric acid and tetrafluoroboric acid.Through the differential scanning calorimeter characterization test of the above substances,it is found that the phase transition temperature of compound 1 is 392.41 K;the phase transition temperature of compound 2 is 415.41 K;the phase transition temperature of compound 3 is 383.86 K;compound 4 showed no phase transition;the phase transition temperature of compound 5 is 389.6 K.2,1,7-Dimethyl-1,4,7,10-tetraazacyclododecane(1,7-dimethyl-cyclen)cyclic amine was synthesized by introducing two methyl groups into 1 and 7 nitrogen atoms of cyclen.A series of compounds[1,7-dimethyl-cyclen(Cl O4)](6),[1,7-dimethyl-cyclen(Cl O4)2](7),[1,7-dimethyl-cyclen(Re O4)](8),[1,7-dimethyl-cyclen(Re O4)2](9),[1,7-dimethyl-cyclen(BF4)2](10)were obtained by intermolecular hydrogen bonding of 1,7-dimethyl-cyclen with different proportions of inorganic tetrahedral acids:perchloric acid,perchloric acid and tetrafluoroboric acid.After performing differential scanning calorimeter characterization tests on the above substances,it is found that although compound 6 has an abnormality at 348.8 K,this is most likely a water peak;the phase transition temperature of compound 7 is around 431.86 K;During the heating and cooling process of the dielectric meter and DSC characterization,the peaks in compound 8 appeared at around 441.66 K,but because it appeared around the melting point,it was impossible to determine whether compound 8 had a phase change;compound 9 showed no phase transition.The DSC phase transition temperature of compound 10 is 415.58 K.3,1,3-Dibromopropane,hydrazine hydrate and formaldehyde were used as raw materials to design and synthesize the cyclic amine 1,5-diazabicyclo[3.3.1]nonane.A series of compounds[C7N2H14(Cl O4)](11),[C7N2H14(Re O4)](12),[C7N2H14(BF4)](13)were obtained by intermolecular hydrogen bonding 1,5-diazabicyclo[3.3.1]nonane with inorganic tetrahedral acids such as perchloric acid,perchloric acid and tetrafluoroboric acid.After performing differential scanning calorimeter characterization tests on the above substances,it is found that compound 11 has no phase transition;the two phase transition temperatures of compound 12 are 334.7 K and 319.6 K,respectively;the phase transition temperature of compound 13 is 360.2K.From the comparison of the phase transition temperatures of compounds 1?13,the following conclusions can be drawn:when 1-me-cyclen crystals are formed,the phase transition increases with the increase of the proportion of perchloric acid;the more methyl groups are introduced into the nitrogen atoms of cyclic amines,the higher the phase transition point of the crystal.Under the same ratio,the phase transition temperature of the crystal formed by perchloric acid and cyclic amine is about 16 K higher than the phase transition temperature of crystal formed by tetrafluoroboric acid.This shows that perchloric acid has a greater influence on the phase transition temperature of cyclic amines than tetrafluoroboric acid. |
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