Synthesis And Mechanism Investigation Of Nanomaterials By Control Of Polyelectrolytes

In this dissertation, the polyelectrolytes with different functional groups have been used to control the morphology of nano structured materials. The polyelectrolyte has been introduced to synthesize organic microcrystals and 3D hierarchical superstructures can be fabricated by using simply functional organic molecules as starting materials. Therefore, a new approach has been developed to control the morphology of small molecular weight organic materials. The cooperative effect of polyelectrolyte and simple functional organic molecules has been discussed. Furthermore, vaterite hollow spheres of calcium carbonate were prepared. So it enriched the biomineralization method to synthesize inorganic biomaterials. In addition, polyelectrolyte was utilized in preparing zinc oxide hollow nanotubes by two-step method. The main results can be summarized as follows:1. Poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) have been used as crystal growth modifiers and directing reagents to prepare fluorescein crystals with novel coral-like hierarchical superstructures by adjusting reaction parameters including the concentrations of polymer and starting materials, shaking and ultrasonic treatments. The optical property can be adjusted by changing the size of fluorescein crystals and the adding of PAH. It should be mentioned that, the mechanism of controlled synthesis of organic materials under control of polyelectrolytes is similar to that works in inorganic system.2. By taking advantage of the cooperative effects of PAH and Rhodamine B, vaterite hollow spheres can be synthesized. Part of vaterite will transform into calcite tetrahedrons. Through several parallel experiments, it fully proves the cooperative effect between polyelectrolyte and organic dye. Therefore, it suggests that the performance of polyelectrolyte can be further improved by simple functional molecules. The novel biomimetic method by use of multi-modifiers brings a novel pathway to prepare well-defined functional biominerals.3. ZnO nanotubes (NTs) can be synthesized on glass substrate by two-step method using Poly(acrylic acid ) (PAA) as a structure direct reagent at low temperature (60℃). The interior of the ZnO tube is loose and porous, which demonstrates its potential applications in catalysis, sensor and energy. The influence of the concentration of PAA and the cooperation of PAA, Zn²⁺ and Hexamethylenetetramine (HMT) were discussed. The PL peaks of these tubular products show regular shift compared with ZnO NRs which act as the template in the first-step synthesis procedure. A possible growth mechanism of this unusual synthesis method to fabricate the ZnO NTs has been proposed.