Preparation And Properties Of Near-infrared Absorption Composites Based On Polyaniline

Near-infrared（NIR）absorbing materials have great application prospects in photothermal therapy and tumor elimination due to its excellent optical,electrical and magnetic properties.Polyaniline（PANI）has different states,such as oxidation state,reduced state,and intermediate state.The intermediate state of polyaniline,as also called emerald imide salt,can be obtained by doped,which demonstrated an excellent near-infrared absorption performance.In addition,copper sulfide（CuS）has strong absorption in the NIR area due to its own band transition.In this work,acid-doped PANI and flower-like CuS were prepared,respectively,and then PANI/CuS composite was synthesized and its NIR absorption properties were investigated carefully.The results are as follows:Firstly,acid-doped PANI was prepared by chemical oxidation method,and the effects of the amount of oxidant and the concentration of hydrochloric acid（HCl）on the NIR absorption performance of hydrochloric-doped polyaniline（PANI-HCl）were studied.The results showed that NIR absorption intensity of PANI-HCl was determined by the amount of oxidant and the concentration of HCl.The absorbance value of PANI-HCl was 35.0 a.u.at the wavelength of 631 nm when the concentration of HCl is 1.0 mol/L and the molar ratio of ammonium persulfate/aniline（APS/An）is 3:2.Formic acid（FA）,p-toluene sulfonic acid（TSA）,methyl sulfonic acid（CSA）,naphthalene sulfonic acid（NSA）and dodecylbenzene sulfonic acid（DBSA）–doped PANI were prepared using the same method and HCl was replaced by above organic acid.The NIR absorption performance of organic acid was much better than PANI-HCl.The results indicated that the NIR absorption value of CSA and DBSA can highly achieve 65.0 a.u and 54.0 a.u at 665 nm and 657 nm,respectively.Furthermore,the NIR absorption value of NSA is 22.0 a.u at the wavelength of 811 nm.The NIR absorption performance of organic acid doped-PANI was compared with PANI-HCl under the same conditions.Furthermore,CuS was prepared from copper pentahydrate sulfate（CuSO₄ 5H₂O）and sulfur powder（S）by the solvent-thermal method with n-methylpyrrolidone（NMP）was as solvent.The parameters were carefully investigated by orthogonal experiment method and univariate method.The optimal preparation conditions were obtained,which is 1.0 mL CuSO₄ 5H₂O（1.0 mol/L）and 0.064 g（2.0 mmol）S（Cu:S（molar ratio）=1:2）,the reaction temperature of 200 ^oC,the reaction time of 6 h,and the polyvinylpyrrolidone（PVP）of 0.25g.Finally,the composites were obtained via CuS nanomaterials,which were synthesized at the optimal conditions,compounding with PANI via in-situ polymerization.The results showed that NIR absorption intensity was highest（2.12 a.u.）at 30 wt%of CuS.