Gas Sensitivity And Construction And Characterization Of Hollow Mesoporous Silica-based Nanofunctional Materials

There are several important factors including toxic and harmful gases in the environment and cancer that can endanger human health.Therefore,it is essential to design a responsive sensing element to construct the functional materials that can respond to environmental stimuli such as solvent vapors,pH,redox and temperature etc.for detection or monitoring of environmental pollutants and cancers,thus early preventing,protecting and treating diseases,and ensuring human health and life security.For this purpose,conductive polymer composites with unique responses to volatile organic compounds VOCs and hollow mesoporous silica nanocarriers were designed and prepared.The specific contents are as follows:(1)Polyaniline-coated multi-walled carbon nanotubes(MWCNTs)conductive polymer precursors(MWCNTs@PANI)were prepared by an in situ microemulsion oxidation polymerization of aniline in the case of MWCNTs,and then hydroxylterminated polybutadiene polyurethane conductive polymer nanocomposites based on MWCNTs@PANI(MWCNTs@PANI/HTPB PUs)were prepared through an in situ stepwise polymerization of HTPB and diisocyanates.The chemical structure was characterized by Fourier transform infrared spectroscopy(FTIR),Raman,X-ray diffraction,X-ray photoelectron spectroscopy and thermogravimetric analysis(TGA).The morphologies and dispersion behavior were examined by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and UV-vis transmittance.The MWCNTs@PANI/HTPB PUs nanocomposites were fabricated into film sensors for detection of volatile organic compound vapors,and displayed an evident response to trichloromethane vapor(CHCl3).The effect of MWCNTs on the conductivity and the responsivity to trichloromethane of conductive polymer nanocomposite films were studied,finding that the conductive composite films have fast and strong response,good repeatability and recoverability,and long-term stability.Consequently,they can be potentially applied for supervision and detection of interior and outdoor environmental gases or vapors.(2)A new type of hollow mesoporous silica nanocarriers(HMSNs-SS-Py@?-CDSeSe-mPEG)based on host-guest interaction was designed and prepared.HMSNs were prepared by using a hard-template method,and pyridine was grafted onto the surface of HMSNs using a redox cleavable disulfide bond as an intermediate linker.Subsequently,the functional molecule,polyethylene glycols grafted ?-cyclodextrin(?CD-SeSe-mPEG),that was synthesized by esterification reaction was immobilized on the surface of HMSNs through the host-guest interaction between ?-cyclodextrin and pyridine.The structural identification of different samples were characterized by the 1H nuclear magnetic resonance(1H NMR),FTIR,UV-vis,TGA,and nitrogen adsorptiondesorption isothermal test.The morphologies of different nanoparticles were observed by TEM.The self-assembly between ?-cyclodextrin and pyridine were studied by 2D 1H NOESY NMR and the results showed that HMSNs-SS-Py and ?-CD-SeSe-mPEG were successfully assembled.The novel supramolecular polymer nanocarriers are anticipated to have the potential for controlled drug release.