Preparation And Properties Of Polyurethane Based Composite Functional Film

In recent years,with the rapid development of nanotechnology and photocatalytic technology,more and more nano-catalysts with high catalytic efficiency have been developed.However,nanocatalysts are easy to agglomerate and difficult to separate and recover from the reaction system in its practical applications.Nowadays,polymer nanocomposites as a supported catalyst have been studied.However,the research on polyurethane nanocomposites with both photocatalytic and antibacterial activities is not systematic and in-depth.Therefore,in this study,polyurethane was used as the research object,and the wet phase inversion and in-situ generation methods were used to prepare polyurethane nanocomposite films with catalytic and antibacterial functions.The photocatalytic and antibacterial properties of nanocomposite films were further studied,and the related degradation mechanisms of pollutants were also explored.The main obtained results are as follows:Ag@AgCl-polyurethane/silk fibroin（Ag@AgCl-PU/SF）composite porous films were prepared by wet phase inversion and impregnation-precipitation-photoreduction methods,and the effect of Ag⁺ions concentration on the performance of the composite films was investigated.The composition and structure of the composite films were analyzed by X-ray diffractometer（XRD）,field emission scanning electron microscopy（FESEM）,Fourier infrared spectroscopy（FTIR）and ultraviolet-visible spectrophotometer（UV-vis）.The results showed that the surface and cross-sectional structures of the composite films were porous.A large number of cubic Ag@AgCl NPs with a size of about 50-500 nm were distributed on the composite films,and their particle size gradually increased with the increase of Ag⁺ions concentration.Moreover,when Ag⁺ions concentration increased to 0.075 M,the agglomeration of Ag@AgCl NPs appeared.The composite films exhibited enhanced absorption in the ultraviolet（UV）and visible regions,and the absorption edge of films was found to be red-shifted.Rhodamine B（Rh B）was used as a model pollutant to investigate the photocatalytic activity and stability of the composite films.The results showed that0.050Ag@AgCl-PU/SF composite film had the highest photocatalytic activity,and about 88%and 97%of Rh B were degraded after 120 min of UV and visible light irradiation,respectively.After four cycles of photodegradation of Rh B,the photocatalytic activity of the composite film decreased slightly,but remained at a relatively high level overall.Taking S.aureus and E.coli as typical model bacteria,the antibacterial performance of the composite films was evaluated by the disk diffusion method.The experimental results showed that the composite films had good antibacterial activity.Ag₃PO₄@Ag Br-polyurethane/negative oxygen ion powder（Ag₃PO₄@Ag Br-PU/NI）composite porous film was prepared by wet phase inversion and impregnation-precipitation-ion exchange methods.The composition and structure of the composite films were analyzed by XRD,FESEM,X-ray spectrometer（EDX）,FTIR,UV-vis and electrochemical workstation.The results displayed that the surface and cross-sectional structures of the composite films were porous,and Ag₃PO₄@Ag Br particles with the size of 0.1-2μm were distributed on the composite film.After the ion exchange between Ag₃PO₄and Br^-ions,the edges and corners of Ag₃PO₄were passivated and changed from polygon to irregular shape,indicating that part of Ag₃PO₄was successfully transformed into Ag Br by the ion exchange method.Then,a heterostructure was formed between Ag₃PO₄and Ag Br.The composite film has a strong response in the UV and visible light regions,and the absorption edge is about 610 nm.Moreover,the photogenerated electron-hole pairs on the composite film can be separated and transported faster.Methyl orange（MO）was used as a model pollutant to evaluate the photocatalytic activity and stability of the composite film under visible irradiation.The results showed that approximately 92.07%of the MO solution was degraded under visible light irradiation for 75 min by Ag₃PO₄@Ag Br-PU/NI composite film.Furthermore,the degradation process was consistent with the pseudo-first-order kinetic model,and the apparent reaction rate constant(k_app)was 0.03331 min^-1.After three successive recycling runs for the photodegradation of MO,the degradation rate of the composite film was only reduced by7.3%.The active species trapping experiments found that h⁺and·O^2-radicals were the main oxidative species during the photocatalytic degradation reaction of MO over the Ag₃PO₄@Ag Br-PU/NI composite film,and a possible degradation mechanism was proposed.Taking S.aureus and E.coli as typical model bacteria,the antibacterial performance of the composite films was evaluated by the disk diffusion method.The experimental results showed that the composite films had good antibacterial activity.A series of Ag@Ag X-cerium oxide/polyurethane（X=Cl,Br and I）composite films（Ag@Ag X-Ce O₂/PU）were fabricated via a combination of facile one-step in situ coprecipitation and photoreduction method.The composition and structure of the composite films were analyzed by XRD,FESEM,EDX,FTIR and UV-vis.The results indicated that the surface and cross-sectional structures of the composite films were porous,and Ce O₂particles were uniformly embedded in the polyurethane matrix.At the same time,cubic Ag@AgCl,spherical Ag@Ag Br and Ag@Ag I NPs were observed on the Ag@Ag X-Ce O₂/PU（X=Cl,Br,and I）composite films,respectively.The size of Ag@Ag X（X=Cl,Br,and I）was rage from100 to 500 nm.Besides,the Ag@Ag Br and Ag@Ag I particles on the surface of Ag@Ag Br-Ce O₂/PU and Ag@Ag I-Ce O₂/PU films were found to be agglomerate to some extent,whereas Ag@AgCl particles were found to be uniform distribution on the surface of Ag@AgCl-Ce O₂/PU film.The composite films exhibited enhanced absorption in the UV and visible regions,and the absorption edge of composite films was found to be red-shifted.The band-gap values of the Ce O₂/PU,Ag@Ag X-Ce O₂/PU（X=Cl,Br,and I）composite films were proximately 3.01,2.65,2.88 and 2.81 e V.respectively.The photocatalytic degradation of tetracycline hydrochloride（TC）and MO under visible light irradiation were chosen as model pollutants to explore the photocatalytic activity and stability of composite films.The results implied that Ag@AgCl-Ce O₂/PU composite film had the highest photocatalytic activity,and about 72.30%of TC and 89.95%of MO were degraded after 150 and 100 min of visible light irradiation,respectively.Moreover,the MO and TC degradation processes were in accordance with the pseudo-first-order kinetic model,and the apparent reaction rate constant(k_app)was0.00847 and 0.02215 min^-1,respectively,which were 11.00 and 20.51 times of Ce O₂/PU composite film.After three cycles of TC and MO degradation,the photocatalytic efficiency of the composite film is still at a high level.The active species trapping experiments found that·OH,h⁺and·O^2-radicals were the main oxidative species during the photocatalytic degradation reaction of TC and MO over the Ag@AgCl-Ce O₂/PU composite film,and a possible degradation mechanism was proposed.Taking S.aureus and E.coli as typical model bacteria,the antibacterial performance of the composite films was evaluated by the disk diffusion method.The experimental results showed that the Ag@Ag X-Ce O2/PU（X=Cl,Br）composite films had good antibacterial activity.In summary,a series of polyurethane nanocomposites with low cost,good stability,high efficiency and easy separation and recovery were successfully prepared.This work may provide a new idea for the design of a new and efficient porous polyurethane film reactor,which has potential applications in the organic pollutant degradation and bacterial inactivation fields.