Synthesis And Characterization Of Pyridine/Pyrrole Fluoride Ionic Liquids And Polypyrrole

Ionic liquids(ILs)have the same advantages to high-temperature molten salt and water solution,such as low volatility,non-combustion,high-thermal stability,good conductivity,multiple species,wide electrochemical window and range of liquid.Therefore,ILs have been widely used in various fields.As we known,we can use ILs to produce polypyrrole(PPy),and the properties and morphology of PPy films which were prepared in ILs have many unique properties.In this paper,we mainly studied the preparation and characterization of pyridine fluoride,and we also explored the effect of different experimental conditions on the synthesis of PPy films.Pyridine(pyrrole)chloride and silver fluoride were used to react each other,to synthesize pyridine(pyrrole)fluoride in this thesis.It is observed that the higher temperature is,the lower water content of ionic liquid is.The structure of the synthesize fluorides was characterized by Raman spectroscopy,mass spectrometry and nuclear magnetic resonance spectroscopy.The results of characterization showed that the synthesized pyridine fluoride cantained only[Bpy]⁺cations,while the synthesized pyrrole fluoride was dissociated into both[Bmpy]⁺and [[Bmpy]₂F]⁺cations.Based on the princible of density functional(DFT)and ab initio(initio AB),the structure of the fluoride synthesized were calculated and simulated by using Gauss software with the B3LPY/6-31G+(d)or HF/6-31G+(d)level.The most stable structure,bond length,bond angle and dihedral angle of pyridine obtained from calculation showed that the bond of pyridine ring had the average trend of single bond and double bond.The atoms on the pyridine ring were in the plane structure of sp2 hybrid orbitals,while the rest of p orbital formed conjugated ? bonds.The hydrogen atom on the pyridine ring was positively charged.By determination and analysis of the physic-chemical properties of the fluorides synthesized,the experimental results showed that there was a linear functional relationship between the density of pyridine/pyrrole fluoride aqueous solution and temperature.The higher temperature was,the smaller density was.The fitting curve of the relationship between the density of pyridine/pyrrole fluoride aqueous solution and temperature were:?=1.15-3.82×10^-4T(K)(g/cm³)and p=1.23-6.07× 10^-4T,respectively.The viscosity of pyridine fluoride and pyrrole fluoride solution was decreased with the increase of temperature,and the fitting curve of relationship between the viscosity of pyridine/pyrrole fluoride solution and temperature were 1n?=-4.75+1883.51T-1(K)(mPa·s)and ln?=-8.15+2972.36T-1(K)(mPa·s),respectively.The electrical conductivity of the pyridine/pyrrole fluoride solution were increased with the increase of temperature.The fitting curve of relationship between the electrical conductivity of the pyridine/pyrrole fluoride solution and temperature were:?=-529.94+2.15T6.91 ×10^-4T2(K)(mS/cm)and ?=-529.94+2.15T-6.91×10^-4T2(K)(mS/cm).The electrochemical window of pyridine fluoride and pyrrole fluoring solution obtained from cyclic voltammetry were 2.11V and 2.09V,respectively.By mean of a differential thermal analysis,it is showed that the pyridine fluoride solution had no definite melting point,and its hydrolysis temperature was 106.6 degrees centigrade while the glass transition process began at-96.7 degrees centigrade and ended at-83.7 degrees centigrade.The pyridine fluoride solution had no glass transition process,and the evaporation temperature of water was 108.6 degrees centigrade and the decomposition temperature was 183.3 degrees centigrade.Using 0.25mol/L pyrrole fluoride-0.25mol/Lpyrrole-0.25mol/L-tartaric acid solution as electrolte,the effects of electrochemical polymerization conditions on the morphology and electrochemical properties were studied under different polymerization conditions(electrolyte composition,temperature,applied potential,time duration).It is observed that the polymerization potential was 0.2V,and the thicker polypyrrole deposited,the larger resistance was.When the electrochemical deposition temperature increased,the formation rate of polypyrrole film and the radius of polypyrrole molecular were increased,and the conductivity was also increased.The radius of polypyrrole molecular which was electrodeposited in electrolyte containing ionic liquids was larger and more symmetrical shape than that electrodeposited in free ionic liquids electrolyte.In this way,the electrochemical activity obtained from the former one was also better than the last one.The polypyrrole film contained F-ion.The lower electrochemical deposition potential was,the more tight film was.When the electrochemical deposition potential was-0.1 V,the pore structure of the film would be generated.If the electrochemical deposition potential was too high,the conductivity of the film would be decreased.When the deposition time was longer,the radius of polypyrrole molecular was greater and the surface smoothness was lower.If the deposition time was too long,the conductivity would be decreased.