Study On Preparation And Properties Of Composite Solid Polymer Electrolytes Based On Modified Carboxylated Nitrile Rubber

Carboxylated nitrile rubber?XNBR?or its blends were used as polymer matrix,methoxypolyethylene glycols?mPEG?or its derivatives were used to modify the polymer matrix or filled system,several composite solid polymer electrolytes?CSPE?were preparad by introducing lithium perchlorate?LiClO₄?and fillers into the polymer matrix.The effect of polymer matrix and fillers on the properties of CSPE was studied.Organic–inorganic hybrid of epoxycyclohexyl polyhedral oligomeric silsesquioxanes?e-POSS?-grafted-carboxylic methoxypolyethylene glycols?mPEG-COOH?,i.e.,POSS-g-mPEG graftomer was synthesized.The grafting reaction of e-POSS and mPEG-COOH was characterized by Fourier transform infrared?FTIR?spectroscopy.Then the graftomer was used to develop XNBR-ENR/POSS-g-mPEG/LiClO₄ CSPE films with carboxylated nitrile rubber-epoxidized natural rubber?XNBR-ENR?self-crosslinked blend system as dual-phase polymer matrix.The self-crosslinked reaction of the XNBR-ENR matrix was investigated using ATR-FTIR.The morphology of the SPE films and the distribution of lithium salt were investigated using Field Emission Scanning Electron Microscope?FESEM?and X-ray diffraction?XRD?and the result illustrated that addition of POSS-g-mPEG could promote and accelerate the dissociation of LiClO₄ and the best effect within the range of this study was achieved when 25 phr POSS-g-mPEG was involved.The differential scanning calorimetry?DSC?analysis proved that the T_g of the composite SPE films reduced with the increase of POSS-g-mPEG.The highest ionic conductivity in this study of 2.57×10^-5 S/cm was obtained with 25 phr POSS-g-mPEG loading.Epoxy resin?ER?of different epoxide equivalent was used to react with mPEG-COOH to prepare ER-g-mPEG prepolymer.As cross-linking agent,ER-g-mPEG prepolymer reacted with XNBR through unreacted epoxy group,and XNBR-ER-g-mPEG blending system was synthesized.Introducing LiClO₄ to the XNBR-ER-g-mPEG,XNBR-ER-g-mPEG/LiClO₄ CSPE was obtained by thermal curing.FTIR was applied to analyze the crosslinking reaction between epoxy group of ER and carboxy group of mPEG-COOH and XNBR.The EIS results indicated that the ionic conductivity of the CSPE films increased with increasing epoxide equivalent of ER.The highest ionic conductivity of 2.78×10^-5 S/cm in this study was obtained using DER663U with epoxide equivalent of 740⁸00g/eq.DSC analysis proved that the T_g of the CSPE films reduced with the increase of the epoxide equivalent of ER.Thermogravimetric analysis?TGA?indicated the CSPE could be stable until over 200?.Improved mechanical property were observed of the CSPE.Comb-like copolymers XNBR-g-mPEG were obtained by using methoxypolyethylene glycols?mPEG?attached to XNBR as short side chains through esterification.Mesoporous silica?SiO₂?was chosen as inorganic fillers.After blending SiO₂ and LiClO₄ into XNBR-g-mPEG or XNBR,CSPE of XNBR-g-mPEG/LiClO₄ and XNBR-g-mPEG/SiO₂/LiClO₄ with different content of SiO₂ were prepared by thermal curing.Improved ionic conductivity was observed by using XNBR-g-mPEG polymer matrix and the ionic conductivity of CSPE samples increased first and then decreased with raising SiO₂ content.The highest ionic conductivity in this study of 7.38×10^-5 S/cm was obtained with 6 phr SiO₂loading.XRD results indicated that LiClO₄ crystals were reduced with increasing SiO₂ content within certain limits.Dynamic mechanical analysis?DMA?indicated that with increasing SiO₂ content within certain limits,the T_g of CSPE samples decreased while the storage modulus increased.TGA indicated the CSPE showed good thermal stability and could be stable until over 200?.