Preparation And Charactization Of Gradient Copolymers And Their Application In The Synthesis Of Nanomaterials

In this paper,γ-AlOOH and ZnO with special morphology were prepared in the presence of home-made gradient copolymers.Firstly, several gradient copolymers (such as P(St)-grad-P(HEMA) with different St/HEMA ratio, P(MMA)-grad-P(HEMA), P(St)-grad-P(AA) and P(St)-grad-P(t-BA)) were synthesized in two ways via atom transfer radical polymerization (ATRP) by using ethyl 2-bromoisobutyrate (EbiB) as initiator, CuBr as catalyst and bpy as ligand. The as-prepared products were characterized by GPC, DSC and FT-IR and their micellization in the different solvents were also observed simply by TEM analysis.Secondly,γ-AlOOH with coral-shape structure were prepared in the presence of P(St)-grad-P(HEMA) in the mixed solvent of DMF and H₂O via solvothermal method from the reaction of Al₂(SO₄)₃ and CO(NH₂)₂, thenα-Al₂O₃ was obtained after calcination ofγ-AlOOH at 1200℃for 2 h. Several products with different morphology were succesfully synthesized by changing of the concentrations of the gradient copolymer and CO(NH₂)₂. The obtainedγ-AlOOH andα-Al₂O₃ products were characterized by XRD, SEM, and TEM, respectively. It was considered that the morphology ofγ-AlOOH was greatly affected by the the concentration of CO(NH₂)₂ and the morphology ofα-Al₂O₃ was changed little after calcination at 1200℃for 2 h ofγ-AlOOH.Thirdly,γ-AlOOH microsphere and nanorods were prepared with the help of the above gradient copolymer (P(St)-grad-P(HEMA)) under the condition of the CH₃COOH-CH₃COONa buffer solution system via solvothermal method after different reaction time, respectively. The obtained products were characterized by XRD, SEM, TEM, IR and EDS, respectively, while the formation mechanism of γ-AlOOH were proposed to explain the evolution of the microsphere and nanorods morphology. The influences of reaction time and the concentration of gradient copolymer on the morphology ofγ-AlOOH was studied briefly. The results indicated that the morphology ofγ-AlOOH was changed obviously because of the strong corrosion effect of the acetic acid in this systemIn addition, ZnO nanomaterials with rod and sheet-like were achieved in the mixed solvent of DMF and H₂O using gradient copolymers P(MMA)-grad-P(HEMA) as surfactants by the methods of solvothermal, microwave and chemical precipitation method, respectively. The obtained ZnO nanomaterials products were characterized by XRD, SEM, TEM and EDS, respectively and the formation mechnasim was proposed. The results indicated that the ZnO microcrystals with different morphology were obtained by varying the conditions of the precursors and the concentration of gradient copolymers.