| As an organic conducting polymer,polythiophene could be used in many fields,such as supercapacitor,solar cell,due to its excellent stability and flexibility.The synthesis condition could affect the structure of polythiophene significantly,and thus affect its conductivity.However,the thermal stability of polythiophene remains to be improved due to its organic properties.Compared with polythiophene,graphene and carbon nanotube have excellent thermal stability and electrical conductivity,but they are all expensive.Here,we prepared polythiophene/carbon material composites,and its conductivity will reach the level of carbon material with a low cost.The composites have an important economic value and practical value.In this thesis,the influence of synthesis conditions on the structure and conductivity of polythiophene was investigated.Based on above,the optimized polythiophene with good electric conductivity was obtained and then composited with carbon nanotubes(MWCNTs)and graphene(rGO),respectively.The conductivity and thermal stability were measured by high resistance meter,electrochemical workstation,and thermogravimetric analysis.The structure of composites was determined by Fourier infrared spectrometer,ultra-visible diffuse reflectance spectromerter and scanning electron microscopy.The main results obtained are shown as follows:(1)Preparation conditions could greatly affect the structure and conductivity of polythiophenes.The conductivity of polythiophene increasedfrom 10-13 S/m to 10-8S/m with the increase of thiophene concentration from 0.05 mol/L to 0.20 mol/L.The highest conductivity of polythiophene at different reaction time is 10-10 S/m when the reaction time is 3 h.The conductivity of the polythiophenes prepared at different temperatures are all at the 10-13 S/m level.When the n(FeCl3)/n(Th)increased from 2 to 5,the conductivity of samples increased from 10-10 S/m to 10-13 S/m.The conductivity of the sample prepared by the treatment of direct filtration and washing increased 5 orders than that prepared by the treatment of solvent volatilization at room temperature followed by filtration and washing.From the aspect of the balance of conductivity and cost,the reaction conditions optimized is:cTh=0.1 mol/L,t=3 h,T=0 0C,n(FeCl3)/n(Th)=2,and using the direct filtration treatment on the products.Moreover,the conductivity of thepolythiophene optimized is 2.49×10-8 S/m.The increased conductivity of polythiophene is related with the higher amount of α-α connection and the lower degree of polymerization.And the order of the conductivity of different shapes of composites is:flower-like>sheets>globular>irregular stack.(2)In PTh/MWCNTs composites,when the mass ratio of MWCNTs to thiophene was lower than 7.5%,MWCNTs could directly inserte into PTh matrix and form a cross structure.Whereas,when this ratio is in the range of 7.5%-50%,PTh could grow in the outer wall of MWCNTs,and form a core-shell structure.The π-π interaction between PTh and MWCNTs could rise the conjugation degree,and thus improved the conductivity and thermostability of polythiophene.(3)During the preparation of PTh/rGO,when the feeding ratio of rGO to thiophene was lower than 5%,the conductivity and thermalstability of the prepared composite would be improved,and it increase with the increase of the feeding ratio,which revealed that rGO could enhance the thermalstability of PTh.Compared with PTh/MWCNTs,PTh/rGO exhibited higher thermalstability,and its conductivity was found to be 10-3 S/m when the feeding ratio was 4%.This could be attributed to the stronger interaction between rGO and polythiophene,which probably due to the larger specific surface area of rGO than that of MWCNTs. |
