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Preparation and Characteration of Composite Microspheres with Dual-, Triple- Responsive Properties

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Tutor: LiZhanShuang
School: Harbin Engineering University
Course: Applied Chemistry
Keywords: environmental responsive polymer,microgel,composite materials,magnetic microsphe
CLC: O631.3
Type: Master's thesis
Year:  2011
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In recent years,environmental responsive materials were applied in drug delivery, biological sensors,chemical separation,cell cultivated,and enzyme immobilization,as well as the potential application fields of bio-electro-catalyst which gives rise to much attention of scholars.Among the many environmental responsive polymer,temperature responsive and the magnetic responsive polymer were especially favoured by scholars of all ages,this is due to changes in temperature are easy to achieve and be controlled manually,and materials with magnetic responsive are easy to be targeted by magnetic field orientation,which are also easily separated from the solution. All of this makes the magnetic responsive and temperature responsive polymer have good application prospects.Compared with the traditional single responsive material,double (multiple) responsive polymer microspheres have become an important research area of intelligence materials.This paper is based on a research background,iron oxide and temperature sensitive polymer N-isopropylacrylamide (NIPAM) were as the research center. Core/shell microspheres with multiple responsive have been prepared by soap-free emulsion polymerization,and its structure,morphology and response were characterized.The main work is listed as following:Fe3O4 nanoparticles were prepared by solvothermal,and the impact of different reaction time and reaction temperature were discussed.The best reaction time is 8h,and the best reaction temperature is 200¡æ.Then Fe3O4 nanoparticles surface were modified,Fe3O4 and NIP AM were combined together by hydrogen bonds to prepare Fe3O4@SiO2@PNIPAM microspheres.We discussed temperature sensitivity of composite microspheres with the different cross-linking and different PNIPAM shell thickness.Research showed that Fe3O4@SiO2@PNIPAM microspheres were the obvious core/shell structure,spherical,with a large saturation magnetization and temperature sensitivity.Besides,the volume phase transition of microspheres were obvious with the lower crosslinking density and the thicker PNIPAM shell.Fe3O4@SiO2@PNIPAM microspheres were used as the basis,Ag nanoparticles were formed on the network structure of PNIPAM microgel in situ to prepare Fe3O4@SiO2@PNIPAM-Ag core/shell microspheres with triple response of magnetic,temperature sensitivity and catalytic properties.The formation process was analyzed and discussed,catalytic effect and temperature sensitivity of microspheres with different Ag loading were also discussed. Research showed that within a certain range,the increase of Ag loading of the microspheres reduced the temperature sensitivity and swelling rate of the microspheres,oppositely the catalytic effect was increased.Besides,catalytic effect of Fe3O4@SiO2@PNIPAM-Ag microspheres at different catalytic temperature can be divided into three intervals.Fe3O4@SiO2@PNIPAM microspheres were used as template again,the TiO2 and Fe3O4@SiO2@PNIPAM were compounded together to synthesis triple responsive Fe3O4@SiO2@PNIPAM-TiO2 microspheres which possess magnetic,temperature sensitivity and photo catalytic properties. The analysis of TEM,DLS,VSM,and XRD showed that: Fe3O4@SiO2@PNIPAM-TiO2 microspheres which present spherical were obvious core/shell structure,and the type of TiO2 did not change in the synthetic process.Catalytic effect and temperature sensitivity of microspheres with different TiO2 loading were discussed,the optimal loading of TiO2 was 10%.The photo catalytic effect of Fe3O4@SiO2@PNIPAM-TiO2 microspheres under different temperature were also discussed,and the photo catalytic effect of Fe3O4@SiO2@PNIPAM-TiO2 microspheres were also divided into three intervals.
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