The Nucleation,Growth Control And The Study Of Related Mechanism Of Nanostructured Polyaniline In Micelle-like System

Compared with the conventional micelles composed of the surfactants,the micelle-like ones are compacted together through weak,short-ranged,and reversible interactions such as ionic and hydrogen bonds,?-? stacking interactions etc.The micelle-like,sensitive to the external stimuli,are easily rearranged and formed the transition state with various morphologies when they can not bear the external stimuli,which is helpful to prepare the products with abundant patterns and provide a broad space for controlling the morphology of nanoparticles.On the other hand,the nucleation plays an impotant role in the synthesis of the nanomaterials,but owing to the short timing of the nucleation process,the approach to determine the process is quite absent,which results in the lack of the corresponding mechanism research.In this dissertation,in situ Nuclear Magnetic Resonance(NMR)has been applied into the study of the nucleation formation of nanostructured polyaniline(PANI),owing to the timely and efficient response to the kinetics and thermodynamics of the main species,which is helpful for interpreting the driving forces of the phenomena in the process of polymerization.Therefore,the micelle systems composed of organic acids and aniline are adopted,and the formation mechanism of the micelle-like system and nanostructured PANI are studies through a series of differdnt NMR techniques.In addition,the different morphologies of nanostructured PANI,such as nanorods,nanowiers and helixes,are prepared by adjusting and controlling the experimental parameters,including inorganic salts,stirring and the electric field,and their influences on the morphology and the property of PANI in micelle-like system,are investigated in detail.Firstly,the formation mechanism of the micelle-like composed of aniline and salicylic acids(SA)through the weak molecular interactions are interpreted by NMR such as 1H,J-resolved,the spin-lattice relaxation time(T1)and diffusion ordered spectroscopy(DOSY)experiments.The formation mechanism of the micelle-like at the different concentration of SA is different.The one-to-many style in the loosely packed form of the micelle-like is put forward at the low concentration of SA,while the many cores in the tightly packed form of the micelle-like are illustrated at high concentration of SA.It is the structural difference from the micelle-like that leads to the different pathways of nucleation in micelle-like system.Later,the whole process of aniline polymerization are investigated through in situ 1H NMR spectra,in combination with the evolution information on the T1,Full Width at Half Maximum(FWHM),Nuclear Overhauser Effect(NOE)and integrated areas of each species,the nucleation mechanism of PANI nanotubes and hollow microspheres are explained in detail.It's obtained that the increasing amount of released protons in the polymerization makes the micelle-like unstable.The spherical micelles are changed to the rod-like ones through their rearrangements when the threshold of the micelle-like reaches in the loosely packed micelle,while the morphology of the micelle-like are retained in the tightly packed micelle,owing to the strong ability of the anti-disturbances from the polymerization.The micellar morphologies are copied into final products,so PANI nano tubes and microsphere are synthesized respectively.Later on,PANI nanofibers are fabricated through the addition of inorganic salt such as NaCl,MgSO4and AlCl3,into the micelle-like composed of aniline and camphor sulfonic acid(CSA).The influence of salts,doped acids and temperature on PANI is characterized by TEM and Uv-vis spectroscopy.In addition,in situ Uv-vis and 1H NMR are applied to observe the process of polymerization,which indicates the reaction rate of aniline changes after the addition of inorganic salt NaCl into the initial solution.Finally,PANI nanowires and nanorods are synthesized under the application of the external electric field throu gh adjusting and controlling the amount of NaF and CSA.The influences of the factors which contain the strength of electric filed,NaF and CSA,on the aggregated states of aniline in initial micelle-like,the morphologies and the electric property and PANI are investigated.It's found that the electrochemical performance of PANI is improved in the presence of external electric field.In addition,the helical PANI is prepared in the liquid crystal through adjusting and controlling the amount of CSA,and the the role of the factors including stiring and the electric field on helical PANI is investigated.