Controllable Synthesis Of Metal Sulfide-Polymer Composite Microspheres With Patterned Surface Structures

In recent years, the template techniques for preparing compositemicrospheres with special structures and unique properties have received considerableinterest in materials science field. The feature of template method is that to effectivelycontrol the surface morphlogies and structures of produced composites by using theirspace confinement and controllable effects on as-prepared materials. Therefore, it iseasy to obtain the composites with unusual surface morphologies as well as the betterhybridization between produced nanoparticles and template materials. Comparing toother polymeric templates, polymeric microgels have particular advantages of simplesynthesis and adjustable chemical functionality, and their sizes varied from nano- tomicroscale by choosing the appropriate polymerization technique. More importantly, microgels have distinct stimulus-responsive volume changes, and the stimuli could betemperature, pH, ionic strength, electric and magnetic fields, etc.Based on the unique physical and chemical properties of polymer microgels, ourgroup proposed a novel route for preparing inorganic-polymer composite microsphereswith patterned surface structures by a polymer microgel template. By employing thistechnique, a variety of hybrid inorganic-polymer microspheres with patterned surfacestructures have been synthesized in our laboratory. In this study, we focus on researchinterest on the controllable synthesis of metal sulfide-polymer composite microsphereswith patterned surface structures. This thesis includes three parts as follws:(1) CuS-P(NIPAM-co-20%MAA) composite microspheres with controllablesurface morphologies were prepared by using the polymer microgels acting as thetemplate for inorganic deposition and slowly introducing H₂S gas into the inversesuspension system. In this paper, the effects of the deposition rate of metal sulfide andreaction tempreture on the surface morphologies of the composite microspheres weremainly studied. Compared with the microgel template, the surface morphologies of thecomposite microspheres are characterized by coarse but clear surface structures. It wasfound that the surface structures of the composite microspheres could be altered to acertain extent by simply varying the rate of deposition reaction. It had been confirmedthat the proposed method can also be used for the preparation of other meatal sulfide-polymer composite microspheres, such as ZnS(CdS)-P(NIPAM-co-20%MAA).(2) Acrylamide (AM) and methacrylic acid (MAA) copolymer microgels wereprepared by inverse suspension polymerization technique. The CuS-P(AM-co-MAA)composite microspheres with surface patterned structures were prepared successfully byusing the polymer microgels acting as the template in the self-made closed vessel, andH₂S introducing from the slowly decomposition of TAA in acidic solution. Themorphologies of composite microspheres, the crystalline and the content of inorganicwere characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD)and thermogravimetric analysis (TGA), respectively. Compared with the microgeltemplate, the surface morphologies of the composite microspheres are characterized bythe wrinkled structures are randomly oriented and arranged. XRD analysis confirmedthat CuS formed during the process is in a crystal state of a hexagonal structure. It hasdemonstrated that the quantity of sulfide and the rate of precipitation affect the surfacestructures of the composite microspheres significantly. This route might provide a betterfoundation for controlling synthesis metal sulfide-polymer composites with surfacepatterned structures.(3) The Ag₂S-P(AM-co-MAA) composite microspheres with surface specialstructure were successfully prepared by employing the polymer microgel template. Inthis paper, the effects of the composition of the template, the quantity of the depositedAg₂S and their crystal behaviors on the surface morphologies of the compositemicrospheres were mainly studied. It was found that the Ag₂S-polymer compositemicrosphere might have various surface structures by choosing appropriate template, modulating the quantity of sulfide and the rate of precipitation reaction. It has beendemonstrated that nano-Ag₂S formed is in a crystal state of a monoclinic structure.Furthermore, it is expected that the proposed method can be also created a novel routefor the preparation of semiconductor nanomaterials with rnore complicatedmorphologies.