Study On Carbon Nanotube And Reduced Graphene Oxide Dispersion Systems Based On Liquid Crystalline Polymers

Carbon nanotube(CNT)and graphene have been widely used to fabricate advanced functional materials for their superior thermal,electric,optical,and mechanical properties.However,CNT and graphene easily form disordered aggregations due to strong π-πinteractions.In order to take full advantage of CNT and graphene,it is essential to effectively disperse them before fabricating composites.In this paper,a method of dispersing CNTs by using fluorinated liquid crystalline polymers(FLCPs)as liquid crystalline surfactants was firstly established.CNTs joined the nematic matrix of FLCPs in this dispersion system.The quantity of effectively loaded CNTs by FLCPs increased as the increase of mole fraction of nonmesogens on FLCPs.The concentrations of CNTs dispersed by FLCPs in chloroform,tetrahydrofuran and N,N-dimethylformamide reached 1.481 mg mL-1,1.468 mg mL-1 and 1.452 mg mL-1.Fourier transform infrared(FTIR)imaging system was firstly used to characterize the dispersion state of CNT dispersion system,higher mole fraction of nonmesogens induced better miscibility between CNTs and FLCPs.The homogeneously dispersed CNTs improved the thermal stability of FLCPs owing to the interaction between them.FLCPs possessed affinity for both CNTs and chiral liquid crystals(CLCs),therefore,CNTs possessed compatibility with CLCs.The dispersed CNTs strengthened the chiral stability and accelerated the electro-optical response of CLCs.Chiral liquid crystalline polymers(CLCPs)were designed and prepared as liquid crystalline surfactants to disperse CNTs.As for the binary system consisting of CNTs and CLCPs,the concentration of CNTs dispersed by CLCPs was firstly determined by FTIR spectrum combined with ultraviolet-visible-near infrared(UV-Vis-NIR)spectrum,the ability to disperse CNTs increased with the increase of mole fraction of polycyclic conjugated structure on chiral surfactants and the concentration reached 0.85 mg mL-1.FTIR images demonstrated that the dispersion state of CNTs in CLCPs was excellent.The evenly dispersed CNTs reduced the glass transition temperature and improved the thermal stability of CLCPs.As for the ternary system consisting of CNTs,CLCPs and low molecular weight CLC,the dispersion state of CNTs was characterized by polarized optical microscope.Result showed CNTs possessed excellent compatibility with low molecular weight CLC with the assist of CLCP.The dispersed CNTs increased the chiral stability of CLC.Chiral network liquid crystalline polymers(CNLCPs)were designed and prepared as liquid crystalline surfactants to disperse CNTs.UV-Vis-NIR absorption spectroscopy was used to quantitatively determine the CNT concentration in homogeneous CNT-CNLCP dispersions,results indicated that CNLCPs with more mole fraction of polycyclic conjugated structure had better ability to load and disperse CNTs and the maximal concentration reached 0.79 mg mL-1.FTIR imaging system was utilized to analyze the dispersibility of CNTs in CNT-CNLCP composites,and CNLCPs with higher mole fraction of polycyclic conjugated structure had better dispersibility.The CNT doped CNLCPs exhibited lower glass transition temperature and strengthened thermal stability.Furthermore,CNLCPs promoted the compatibility between CNTs and left-handed CLCs,and the dispersed CNTs accelerated the electro-optical response of CLCs.Carboxy chiral liquid crystalline polymers(CCLCPs)were designed and prepared as liquid crystalline surfactants to disperse reduced graphene oxide(RGO).The transmittances of CCLCPs with dispersed RGO exhibited S-shaped nonlinear increased with the increase of wavelength,but the total transmittances from 220 nm to 800 nm showed a linear decreasing trend with the increase of RGO content in the CCLCP-RGO composite.Due to the superior thermal properties of RGO and the interactions between RGO and CCLCP,the dispersed RGO improved the glass transition and increased the thermal stability and decomposition activation energy of CCLCPs.Furthermore,CCLCPs promoted the dispersion of RGO in CCLCP,and the dispersed RGO decreased the driving voltage and accelerated the electro-optical response of CLCs.The CCLCP modified RGO strengthened the photocatalytic degradation of nano zinc oxide.