The Preparation And Characterization Of Organic-Inorganic Hybrid Using Block Copolymer Micelles As Template

As we all know, amphiphilic block copolymer which has good patternability resulting from their ability to self-assemble into wide-range microdomains and the manipulation of these patterns by a variety of physical and chemical methods, even by weak force from external fields. So, amphiphilic block copolymer micelles can be used to control the nucleation, structure, morphology, crystal orientation during inorganic material’s growth. In the thesis, inorganic materials with special morphologies were prepared using crew-cut micelles as template in the guide of bionics.First, block copolymers of PS-b-PtBA with different molecular weight and low polydispersities were synthesized by atom transfer radical polymerization (ATRP) in closed solution polymerization system using benzyl bromide as initiator, cuprous bromide as catalyst,2, 2’-bipyridine (bpy) as ligand and xylene as solvent. The polymerization was conducted using an electromagnetism agitator under the protection of nitrogen atmosphere. Then amphiphilic block copolymers of polystyrene-b-poly(acrylic acid) (PS-b-PAA) were prepared by hydrolyzing of PS-b-PBtA. GPC, FTIR, and’H-NMR revealed that the block copolymers PS-b-PtBA and PS-b-PAA were synthesized successfully.Block copolymers PS-PAA were dissoluted in different common solvents (DMF, THF or dioxane) at room temperature, followed by the addition of water. Then common solvents were dialyzed by plenty of water. A wide range of aggregates, including spheres, rods, vesicles and large compound micelles (LCMs), were prepared from various PS-b-PAA block copolymers, and studied by transmission electron microscopy (TEM) and Malvern particle diameter instrument.Finally, Na2CO3 solution was added into PS-b-PAA micelles and stirred for an hour. CaCl2 solution then was added into the Na2CO3/PS-b-PAA mixture rapidly with strong stirring at room temperature. Next, the product was aged for 24 hours at 80℃. Finally, the precipitation was then filtered and dried in an oven at 100℃overnight to get the hybrid product. Spherical-like structure of 3-4μm in diameter and flower-like structure of 8-10μm in diameter CaCO3 hybrids were obtained using necklace-like and vesicle micelles as template, respectively. And then macroporous spherical calcium carbonate was obtained by removing the organisms. Furthermore, spherical-like SiO2 hybrid structure of 2-5μm in diameter and brick-like structure of>100μm in length and>50μm in width were assembled under specified condition and the effect of cooperative formation. After removing organism by calcination, many nanopores of 200nm-400nm were resulted in the brick-like with narrow distribution.