Studies On The Preparation Of Polymeric-Inorganic Composites Microspheres Of Core-Shell Structures By Microgel Template Method

Recently, template approaches on the preparation of composite materials with special structure and properties have increased interest in materials science. The main advantage is that employing the effect of space confinement of template for guest can easily control the hybridization between template materials and guest with large difference in size as well as the surface morphology of composite microspheres. The composite materials made by this method can be used in special fields. Furthermore, the diversity for composition of template and guest provides an ample selection for obtaining expected composite materials. This dissertation mainly studies on the preparation of polymeric-inorganic composite microspheres of core-shell structure based on template method of polymeric hydrogel microspheres.Polymeric hydrogel is typical soft-solid materials with 3D network structures. The particularity of polymeric hydrogel in structure and property is advantageous for preparation of composite materials. Polymeric hydrogel microspheres with different size can be easily made by reverse suspension polymerization method. The 3D network structure and spherical morphology confine and orient the precipitation of inorganic compounds on the template, which thereby control the final size and morphology of the composite microspheres with unusual structures. Additionally, the template has excellent plasticity. So, these effects make polymeric-inorganic composite microsphers have peculiar surface morphology. Based on the idea mentioned above, the research in this thesis includes the following parts.(1) N-isopropylacrylamide (NIPAM) and acrylic acid (AA) copolymer micro-spheres with various compositions were prepared by reverse suspension polymerization technique. The microspheres thus prepared were employed as template for the deposition of CuS. In this way, several P(NIPAM-co-AA)/CuS composite microspheres with different surface morphologies were obtained. The composition and morphology of the composite microspheres materials have been characterized by SEM, XRD, IR and TG, respectively. It was demonstrated that the composite materials in shape are generally microspheres with the different surface morphology. The surface structures ofthe composite microspheres could be tailored to some certain extent by varying the ratio of the two-monomer units expected to copolymerization in the template (microgels) and/or the amount of CuS deposited. It is predicted that the inherent advantages of microgel templates (the size, swelling degree, composition, charge nature and density, and crosslinking density could be easily controlled) would make the microgel template method extremely useful in the preparation of composite microspheres with different patterned surface structures.(2) The poly(N-isopropylacrylamide-co-acrylic acid)(P(NIPAM-co-AA)) microgel were prepared by reverse suspension polymerization method. P(NIPAM-co-AA)/SiO2 complex microspheres with micrometer were prepared by following way. The polymeric microgels firstly were swelled by ammonium hydroxide, then the swelled microgels were put in organic phase, and TEOS was dropwised in the organic phase. The morphology, composition and crystalline of P(NIPAM-co-AA)/SiO2 were characterized by SEM, TEM, XRD, FT-IR and TG methods. It was shown that the shell of these complex microspheres consists of S1O2 with 200-300 nanometers. The hollow complex microspheres were obtained after calcinations of P(NIPAM-co-AA)/SiC>2 complex microspheres at 550 °C for 4h. The microspheres with special structure and composition may find some novel uses.(3) Taking preparation of P(NIPAM-co-AA)/CuS as an example, the formation mechanism for patterned surface morphology of the composite microspheres has been preliminarily proposed through observing a series of microphseres prepared in different conditions by SEM. After freeze-drying, the polymeric microspheres in swelled state by water or Cu(Ac)2 solution were characterized by SEM. It has been demonstrated that polymeric microgel is clearly shown 3D network structure. So, we believe that there are polymeric framework networks and rich-water domains in swelled template of polymeric hydrogels. Moreover, there is the relevance between polymeric framework networks and surface morphology of composite microspheres. Based on the experimental results, we have proposed the mechanism of "template confining deposition and deposition inducing deformation".The key of the mechanism is that nature of the complex surface structures of the composite materials is related to multifactors. The framework of template with softness is the immanent factor for the changeability of surface structure, and the surrounding factors for the patterned structure are the framework of template to confine inorganic...