Preparation Of Dopamine Modified Conjugated Polymer And Research On Selective Dispersion Of Semiconducting Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes(SWCNTs)have attracted wide attention of many scientists because of the unique one-dimensional structure,excellent optoelectronic properties and chemical stability,and show great applications in many fields such as electronics,optical devices and biochemical sensors.At present,the commercial SWCNTs on the market is a mixture of metallic single-walled carbon nanotubes(m-SWCNTs)and semiconductor single-walled carbon nanotubes(s-SWCNTs).However,for electronic devices,pure semiconducting SWCNTs(s-SWCNTs)is highly desirable for realizing their higher performance.Effectively separating s-SWCNTs from m-SWCNTs at large scale is the primary task of the wide application of SWCNTs.Conjugated polymer extraction(CPE)is considered to be the most feasible method for the purification of s-SWCNTs because of its simplicity,high efficiency and advantages in large area deposition to fabricate film.In addition,compared with small-diameter SWCNTs,large-diameter SWCNTs are more suitable for printed thin film transistors and biochemical sensors because of their high carrier mobility,small resistance and Schottky barrier.Based on these factors,the main objective of this paper is to select semiconducting single-walled carbon nanotubes(SWCNTs)with different diameter by using dopamine modified conjugated polymers.Moreover,it is convenient to immobilize obtained conjugated polymer wrapped s-SWCNTs on universal substrates,such as films and particles,based on the feature of dopamine structure,which would facilitate the further development of their multifarious applications.The detail research contents are as follows:(1)Based on the literatures of sorting s-SWCNTs by conjugated polymers,a tailored 3-dopamine-substituted thiophene and fluorene conjugated polymer PDTF was prepared,and compared with the PFO and PHTF(3-alkyl-substituted thiophene and fluorene conjugated polymer)to selectively disperse s-SWCNTs in solution.These polymers were characterized by gel permeation chromatography(GPC),nuclear magnetic resonance spectroscopy(1H NMR),ultraviolet visible spectroscopy(UV-vis)and fluorescence spectroscopy(PL).Three polar solvents(ethanol,acetone and tetrahydrofuran)with good solubility of PDTF were used to selectively disperse s-SWCNTs.The characterization of UV-vis-NIR and Raman spectra showed that none of the three polymers had the ability to selectively disperse s-SWCNTs in the strong polar solvents both ethanol and acetone.In the less polar solvent tetrahydrofuran(THF),PHTF and PFO did not show the ability to select s-SWCNTs.Meanwhile,PDTF can separate semiconducting single-walled carbon nanotubes with high-purity in THF not only for the small diameter HiPco SWCNTs,but also for large-diameter Arc-Discharges SWCNTs.(2)The immobilization of conjugated polymer/s-SWCNT composite on the surface of film and nanoparticles was studied by two strategies,and characterized by Raman spectroscopy,scanning electron microscopy(SEM).Firstly,PDTF/s-SWCNT composites selectively dispersed in THF are conveniently and effectively immobilized on the surface of glass,silicon and magnetic nanoparticles Fe3O4.Secondly,the conjugated polymer PDTF is first immobilized on the surface of film and nanoparticles,and then the materials are used to study the selection of s-SWCNTs to develop new methods of separating s-SWCNTs in large scale.By these two strategies,we conveniently realized the immobilization of conjugated polymer/SWCNT composites on various surface of substrate,such as film and nanoparticles.