ABSTRACT
Abstract ..................................................................................................... 2 1.1 Introduction ...................................................................................... 2 1.2 Experimental Part ........................................................................... 10 1.3 Characterization ............................................................................. 19 1.4 Results and Discussion .................................................................. 23 1.5 Conclusion ..................................................................................... 40 Keywords ................................................................................................ 41 References ............................................................................................... 41
ABSTRACT
In this chapter, graphene oxide was prepared via modified Hummer’s method and then chemically reduced to graphene nanosheets. These graphene nanosheets were used to synthesize polyaniline/graphene nanocomposites with chemical oxidation of aniline monomer via in-situ emulsion polymerization in the presence of sodium dodecyl sulfate in acid media. Morphological studies confirmed that graphene nanosheets were prepared successfully with this chemical reduction method. Electrical conductivity of synthesized polymer and nanocomposites investigated using a standard four-point probe technique. Electrical conductivity, FTIR and UV-Vis investigation confirmed that conductive binary doped emeraldine salt polyaniline and its nanocomposites with graphene nanosheets should be synthesized via emulsion polymerization. Morphological studies illustrated that this conductive powder, which was designated as PAG, has almost spherical shape with size of about 10-20 nm. We used it to fabricate novel porous-conductive scaffolds composed of chitosan and gelatin via lyophilization method. Conductivity measurements of the scaffolds revealed that with low amount of PAG (~2.5 wt.%) the conductivity reached close to 10-3 S.cm-1, which was suitable for tissue engineering applications. Pore and swelling behavior studies showed porous scaffolds with porosity more than 50% and the pore size between 10-70 µ, with ability of absorbing more than 200% water, had successfully produced by freeze-drying process. The main mechanical properties, such as tensile strength, elongation at break point and tensile modulus of the scaffolds were examined in both dry and hydrated states. The results indicated that with increasing PAG content the scaffold showed relatively stiff behavior especially for the scaffolds with more than 5 wt.% PAG. However, many prepared scaffolds exhibited the desired mechanical strength for some kinds of tissue engineering applications.
