Self-assembly System Of Air-water Interfacial Metallic Oxide Nanofilms

Under mild conditions, a soft chemistry preparation method, self-assembly technology can effectively produce various functional inorganic-organic complex nanomaterials. In this dissertation, we focus on the synthesis of air-water interfacial metallic oxide nanofilms by electrostatic self-assembly mechanism, utilizing anionic surfactants as template, proteins and polymers as modifier and metallic alkoxides and salts as precursor. The morphologies, structures, compositions and self-assembly mechanisms of the as-synthesized films have been carefully investigated and discussed, as well as their applications in photocatalysis and gas sensors. The main content is as follows:By using naphthalene sulfonate acid (NSA) and sodium naphthalene sulfonate (SNS) as template, polyethylene glycol (PEG) and bovine serum albumin (BSA) as modifier and Ti(OC4H9)4 as precursor, a number of air-water interfacial amorphous TiO2 nanofilms have been self-assembled. Partial TiO2 nanofilms are converted to TiO2 nanoparticles by heat-treatment. Both TiO2 films and nanoparticles are applied to the photodegradation of methylene blue (MB) in solution. Results show that well-ordered mesoporous piece-like TiO2 films and lamellar TiO2 precipitates derived from the same self-assembly system are attributed to electrostatic interactions between NSA (or SNS) micelles formed by?-?stacking and precursor. PEG has an effect on increasing the dispersion of TiO2 films, whereas BSA can cause serious aggregations.In addition, the assembled amorphous TiO2 nanofilms have a good photocatalytic performance.By dodecylbenzenesulfonic acid (DBSA), sodium dodecyl sulfonate (SDS), NSA and SNS as template, glucose (Glu), PEG and BSA as modifier and Zr(OC4H9)4 as precursor, a series of air-water interfacial ZrO2 films have been self-assembled. The effect of counterions (Cl-, NO3- and SO42-), temperature and organic solvents (e.g. C2H5OH, C6H5CH2OH and C12H25OH) on the assembled nanostructures of ZrO2 films have been discussed. Results show that the as-prepared (ZrO2+DBSA) films are composed of nanodisk clusters and the influence of counterions follows the order of SO42->NO3->Cl-, corresponding to the structural order of ambiguously mesoporous structures>worm-like mesoporous structures>multiring structures. The increased temperature can obviously change the microstructures of ZrO2 films and the employed organic solvents hinder the self-assembly process and result in irregular nanostructures. Glu molecules interact with SDS micelles and H2O by hydrogen-bonding, which can effectively increase the dispersion and modify the microstructures of (ZrO2+SDS) nanofilms. The "necklace and bead model" interaction between BSA and SDS facilitates the formation of stable multiring ZrO2 nanodisks.By SDS and DBSA as template, gelatin (G) as modifier and Sn(OC4H9)4 as precursor, air-water interfacial SnO2 films have been self-assembled. By heat-treatment, the as-synthesized SnO2 products are converted to SnO2 nanoparticles, which are applied in gas sensors for detecting several gases, e.g. C2H5OH, liquid petrol gas and H2. Results show that (SnO2+SDS) film comprises of mesoporous piece-like structures and (SnO2+SDS+G) film is composed by disk-like clusters. The as-fabricated gas sensors have good responses to the target gases. For the assembled (SnO2+DBSA) film system, there exist lamellar and mesoporous nanostructures. Remarkably, it is found that the byproduct C4H9OH came from the hydrolysis of Sn(OC4H9)4 in HC1 condition plays an important role on the well-ordered mesoporous structures due to the hydrogen-bonding interaction with DBSA micelles and H2O molecules.By 2-SNS, SDS and DBSA as template and Ti(OC4H9)4, Zr(OC4H9)4, Sn(OC4H9)4, MCl2·xH2O (M=Mg, Co, Ni, Cu or Zn) as precursor, a great many air-water interfacial metallic oxide composite nanofilms (e.g. TiO2-MO, ZrO2-SnO2 and ZrO2-MO) and ZnO-SnO2 colloidal particles have been prepared through the similar self-assembly process. (TiO2-ZnO+2-SNS) film composed by numerous cubic-like particles has a high efficiency on MB photodegradation. (ZrO2-SnO2+SDS) film has a superlattice ribbon-like structure. (ZnO-SnO2+DBSA) colloidal nanoparticles display a disk-like nanostructure and have a high gas sensing performance to many gases, such as CH3COCH3, C2H5OH, CH3COOH and HCHO.