Preparation And Photochromism Of Pullulan Grafting Copolymers With Substituded Azobenzene Side Groups

This thesis consists of the following four chapters:Chapterâ… :The optical activity of azobenzene compolymers and their optical applicationIn this chapter we reviewed recently progress in photochromism of azobenzene compolymers.The review concentrates compolymer's system,photoisomerization,and potential application as optical data storage.Investigations of photochromism,nonlinear optical properties and optical anisotropic are associated with probable applications for optical data storage,nonlinear optical materials,liquid crystal polymer,photoelectric devices, photoregulation of bioactivity of biomolecule and nanometer technology.However,the difficulties that stand in the way to practical applications are also listed.With the development research on azobenzene compolymers,these difficulties will be overcome.Chapterâ…¡:The synthesis and structural characterization of Pullulan-based Graft copolymerThe soluble pullulan was modified by means of graft copolymerization in experiment. Based on literatures,a study on graft emulsion copolymerzation of vinyl monomer onto pullulan was carried out by using ammonium persulfate as initiator and Sodium dodecyl benzene sulfonate as emulsifier.The inluence of initiator concentration,vinyl monomer concentration,reaction temperature,and reaction time on grafting parameters of pullulan copolumers was investigated.The evidence and characterization of graft copolymers has been researched by means of FTIR spectroscopy,X-ray,diffraction analysis,scanning electron microscopy(SEM),thermograrimetry analysis(TGA)and differential thermal analysis(DTA).chapterâ…¢:The photoisomerization behavior of copolymers soluble starch and vinyl monomer in solutionsThe photoisomerization of 20 copolymers of vinyl monomer and pullulan were investigated in solutions.The effects of spatial hindrance,solvent,free volume were investigated.The result showed that the structure of graft copolymers exhibit a marked influence on photoisomerization.The smaller of the spatial hindrance is,the easier the photoisomerization will be,and copolymers manifest better photoisomerization than their corresponding monomers,In addition,para-acrolyloxy substitution exhibits good photoisomerization,while ortho-acroloyloxy substitution appears to take place photochromic hindrance.Chapterâ…£:Thermochromic Properties Studied on Azobenzene compoundsIn this chapter we observed the thermochromic phenomena of some azobenzene compounds through heated them.We also performed DTA testing on the compounds which have reversible thermochromism.Base on the conclusions of experiment,we find out the relationship between thermochromic and compound's structure,From the point view of kinetics,thermo-isomerization was studied.The differentiation between thermochromism and thermo-isomerization has been contrasted.