The Synthesis Of Hydroxyapatite And Zinc Oxide With PS-b-PAA As Crystal Groeth Modifiers

In nature, the outstanding mechanical properties of animals, like shells, bones and teeth, canbe attributed to their unique morphology and special structure. Usually, the shape and structure ofmineral phrase can get well controlled through the nucleation and growth of crystals, which wereunder the direction of biological macromolecules (proteins and polysaccharides). So inspired bybiomineralization, scientists have made great efforts to modulate the morphologies of inorganicmaterials with various organic templates (surfactants and copolymers). Among these, theamphiphilic block copolymers can be assembled into different morphologies, which plays animportant role in mediating the morphology of crystals. So in this thesis, the self-assembled “crew-cut” micelles of amphiphilic block copolymer polystyrene-b-polyacrylic acid (PS-b-PAA) was usedto mediate the crystal growth of hydroxyapatite (HA) and zinc oxide.In this thesis, the amphiphilic block copolymer PS-b-PAA was successfully synthesized byatom transfer radical polymerization (ATRP). The chemical structure, the ratio of block length,molecular weight and molecular weight distribution index of PS-b-PAAwere characterized by FTIR,1H-NMR and GPC, respectively.Then the hydroxyapatite crystals were synthesized by a homogenous precipitation methodwith PS112-b-PAA38“crew-cut” micelles as a crystals growth modifier. The rod-like HA wasprepared with ammonium hydroxide as a pH agent, while the ribbon-flower-shaped HA wassynthesized with urea as a pH agent. Due to the application of flower-like HA microspheres in thedrug release field, urea was chosen to be the pH agent in this thesis. With theincreaseof “crew-cut”micelles, different morphologies of HA particles with complex morphologies and hierarchicalstructures were obtained, such as needle-shaped and flower-shaped. The nucleation and growth ofHA crystals were further studied with the combination of SEM and XRD characterization. Inaddition, the analysis of FTIR, TG and EDS showed the prepared HA crystals were covered with organic matrix, which confirmed the roles of PS112-b-PAA38“crew-cut” micelles.Furthermore, the ZnO crystals were prepared in the presence of PS112-b-PAA38crew-cutmicelles as a crystals growth modifier. Rod-shaped ZnO crystals were prepared with zinc acetate asprecursor, while sphere-like superstructures were synthesized with zinc chloride as precursor. Theresults of XRD indicated that the mixtures of Zn(OH)2and Zn(OH)42-were the precursor of ZnOcrystals. In addition, the nucleation and growth of ZnO crystals were further studied by changingthe concentration of Zn2+, the solvent conditions and hydrothermal time. Finally, the photocatalyticdegradation activity of ZnO crystals was studied with methylene blue as probe. The results showedthat the uniform ZnO crystals which controlled by PS112-b-PAA38crew-cut micelles couldperformed better in photocatalysis area.