Fabrication Of Functional Multilayer Films Based On Urushiol And Tyrosine Through Layer-by-layer Assembly

On the basis of molecular design, urushiol(U) and tyrosine(Tyr), with unique chemical structure, were selected as units to fabricate five kinds of stable and functional multilayer films via layer-by-layer(LbL) self-assembly method. The results obtained mainly in this dissertation are listed as follows:Partâ… , three kinds of multilayer films based on U with different structures, morphologies and performances were designed and fabricated by means of the activity of phenolic hydroxyl groups in U.Firstly, using phenolic hydroxyl group as hydrogen-bonding donation, a sandwich polymerizable multilayer film was constructed via the hydrogen-bonding between U and poly(vinylpyrrolidone)(PVPON) by LbL technique. In the film, parts of U monomers were penetrated into the PVPON layer. Then, by means of the rapid photopolymerization of U under UV-exposed, with the transformation of sandwich PVPON/U multilayer film into the semi-interpenetrating networks PVPON/PU multilayer film, the hardness of the multilayer film was greatly improved and the thickness of the film was decreased. Experiment revealed that the PVPON/PU multilayer film preserved a well-defined layered structure, exhibited smooth and defect-free surface owing to the special backbone of PVPON.Secondly, as a kind of chelating ligand, the phenolic hydroxyl group in U coordinated with Ti⁴⁺ to construct a stable and fluorescent (PU/Ti) multilayer ultrathin film through LbL technique. The results show that the (PU/Ti) multilayer ultrathin film has good thermal stability and anti-corrosion performance because of the coordination between Ti⁴⁺ and phenolic hydroxyl group.Thirdly, by means of the chelation between the phenolic hydroxyl group in U and Cu²⁺, U-Cu nanoparticles (U-Cu) were obtained at pH=3.2. Then, by the method of stepwise self-assembly, a hydrophobic PVPON/U-Cu multilayer film with microstructure was prepared through LbL technique via hydrogen-bonding and coordination between U-Cu and PVPON. Introducing S^2- into the PVPON/PU-Cu multilayer film, a novel micro- and nanoscale hierachical surface with a water contact angle of 152°was finally obtained which indicated a superhydrophobic surface was achieved. Partâ…¡, two kinds of multilayer films were designed and fabricated through electrostatic self-assembly between TiO₂, Poly(ethyleneimine) (PEI) and Tyr-Fal respectively. Hereinto, Tyr-Fal was prepared from L-tyrosine and formaldehyde under alkaline conditions.Firstly, a new multi-functional film with well-defined layered structure was fabricated from Tyr-Fal and PEI via LbL method. Experiment revealed that this Tyr-Fal/PEI multilayer film emit yellow fluorescence under UV radiation. The ability of the Tyr-Fal/PEI multilayer film for adsorbing rosaniline (RL) improved after UV-exposed, which can be used in preparing micropattern. Using the adsorbed RL as probes, the Tyr-Fal/PEI multilayer film can distinguish the chirality of arginine, indicating that the film possesses the chiral recognition ability.Secondly, anatase TiO₂ colloidal particles were synthesized by hydrolyzation of tetra-n-butyl titanate. Then, a stable Tyr-Fal/TiO₂ composite multilayer film with well-defined layered structure was constructed by LbL technique. The results showed that this (Tyr-Fal)/TiO₂ multilayer film exhibited smooth and defect-free surface, and possessed fluorescence and photoinduced superhydrophilic properties.