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Study Of The Influence Of Amphiphilic Copolymer Templates And Binary Solvents On The Morphology Of Inorganic Materials

Posted on:2006-02-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:D L JinFull Text:PDF
GTID:1101360155470242Subject:Physical chemistry
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Amphiphilic copolymers, which have many ordered configurations existed in solution, can act as a good template in liquid reaction to induce the growth of multi-morphological inorganic composites. Differed from most previous work, this work creatively made use of binary solvents instead of aqueous solution to prepare calcite composite and systematically investigated the solvation effect on the product morphology. By using the copolymer template together with special solvents, calcite composites with novel shapes were synthesized. This method was further extended to the preparation of other new multi-morphological inorganic materials. Research results showed that both the template and the solvent would greatly influence the product shape and an appropriate combination of the two effects might open a way to realize molecular design and morphology control for inorganic materials.A typical amphiphilic copolymer of polystyrene(PS) and poly(acrylic acid)(PAA) was used as template to synthesize calcium carbonate in both aqueous solution and binary solvents. SEM, XRD, TG-DTA, IR, Raman spectra and particle-size analyser were used to investigate the morphology, size, texture and structure of the products. The relationship of the above characteristics with the preparation conditions was studied to explore the feasibility for the material design meanwhile a possible formation mechanism was suggested. In addition, some potential application study was carried on for the spherical CaCO3 composite.The experiment results showed that the synthesized composites in aqueous solution were micron-sized aggregations composed of nano-scaled crystallite sub-units. It was also proved that the shape, size, texture, structure and other properties of the CaCO3 aggregation were greatly effected by the copolymer's molecular weight and concentration, reaction temperature, stirring rate, and the mass ratio of PS-PAA to CaCO3. It revealed a possible way to realize molecular design for CaCO3 composites through proper adjustments of these critical preparationconditions.The obtained spherical CaCO3 composite was analyzed by XRD, IR and Raman analysis. It was showed that the composite consisted of PS-b-PAA calcium salt and nano-scaled calcite crystallites. IR-TG combined analysis method further proved this standpoint.Based on the analysis of the composition, shape and crystal structure of the composites, combining with their thermal behavior as well as the critical micelle concentration (cmc) value of PS-PAA in the solution, it was found that the morphology and property of the composites were closely related to the copolymer configuration and motion mode in the solution. It strongly hinted there existed some geometrically matching configurations of PS-PA-Ca to calcite lattices. Besides, the water solvation effect around the reaction ions also played an important role during the formation of the composites.Porous calcite sphere was prepared by calcining the copolymer-containing spherical CaCC>3 composites at a very slow heating rate. A primary application study of this new material was carried on. It was found that this porous spherical CaCO3 composite acting as a lubricant additive could obviously decrease the frictional wear degree between the grater pairs.Instead of the aqueous solution, binary solvents, namely water mixed with another organic solvent such as acetone, isopropanol, glycol, THF or ether respectively, were used for further investigation. It was shown that the CaCOs composites prepared in binary solvents were mainly tropisic fringy-shaped. However, the competition of PS-PAA inducement effect with the solvation process led to a product shape change. With increasing the concentration of PS-PAA, the shape of CaCC>3 composites decreased in length and gradually changed from tropisic fringy to podgy double-pyramidal then to multi-armed flowery shape, finally to a spherical appearance with no more anisotropic. In addition, some unusual shapes such as mushroom liked or laminary shape could be obtained during the study. It seemed that the PS-PAA acted as a diversiform template in different mixed solvent systems.As to the case of MnCC>3, BaSO/t, BaC03 respectively, it was found that the inducement effect of PS-PAA no longer existed while the solvation effect could still realize morphology adjustment. For example, cubic MnCC>3 was obtained in alcohol/water mixed solution. Rod shaped BaSC>4 was synthesized in both alcohol/water and THF/water systems but the rod length was much longer in later case. Prismy BaCC>3 was prepared in ether/water system while it had isotropic particle shape if prepared in alcohol/water system.
Keywords/Search Tags:multi-shaped inorganic materials, CaCO3 composite, amphiphilic copolymer, mixed-solvent, XRD, TG-DTA, IR, Raman, morphology, size, crystalloid
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