الفهرس 
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Abstract
In
this thesis, different polymer/clay nanocomposites were prepared and characterized. The thesis is divided into three parts as follows:
Part I:
Four quaternary ammonium salt monomers (2a-d); benzyl-dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-ammonium chloride, dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-propyl-ammonium bromide, isobutyl-dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-ammonium bromide, dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-(3-methyl-butyl)-ammonium bromide, respectively, were synthesized from the reaction of N,N-dimethylaminoethyl methacrylate (DMAEMA) with benzyl chloride, propyl bromide, 2-methylpropyl bromide and 3-methylbutyl bromide, respectively. The synthesized ammonium salts were subsequently polymerized to afford cationic polymers (3a-d); poly(benzyl-dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-ammonium chloride), poly(dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-propyl-ammonium bromide), poly(isobutyl-dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-ammonium bromide), poly(dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-(3-methyl-butyl) ammonium bromide), respectively, as shown in Scheme (1).
The synthesized monomers and polymers were characterized by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. Molecular weights of the synthesized polymers were determined using gel permeation chromatography (GPC). The synthesized cationic polymers (3a-d) interacted with the clay through a cation exchange reaction to prepare polymer/clay nanocomposites (4a-d); poly(benzyl-dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-ammonium chloride)/clay nanocomposite, poly(dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-propyl-ammonium bromide)/clay nanocomposite, poly(isobutyl-dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-ammonium bromide)/clay nanocomposite, poly(dimethyl-[2-(2-methyl-acryloyloxy)-ethyl]-(3-methyl-butyl) ammonium bromide)/clay nanocomposite, respectively. Polymer/clay nanocomposites (4a-d) were prepared using solution-intercalation method and characterized by FTIR, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) and thermogravimetric analysis (TGA). The sodium bentonite showed a characteristic diffraction peak at 2θ =7.26° which is corresponding to the interlayer spacing (d-spacing) of 12.17Å. A displacement of this peak towards lower angles (2θ= 5.12°, 4.75°, 4.47°, and 4.84°) were observed for the polymer/clay nanocomposites (4a-d), which were corresponding to d-spacing of 17.24, 18.58, 19.75 and 18.26 Å, respectively. These results indicated the formation of intercalated structure for the polymer/clay nanocomposites. The results show that the d-spacing increases using polymers (3a-d). The increment in d- spacing may be attributed to the increase in the chain length of the alkyl group. The HRTEM results proved the nanostructure formation of the nanocomposites in which the particle size for clay is ranging from 15 to 25 nm, while the particle size for the corresponding polymer/clay nanocomposites (4a-d) is 14-21, 16-24, 12-25, and 22-24 nm, respectively. The elemental analysis performed by EDX showed the total exchange of Na ions in clay with the cationic polymers. The nanocomposite (4a) showed high thermal stability than the other nanocomposites and this may be attributed to the presence of aromatic ring in the polymer (3a). The real and imaginary parts of dielectric function for polymer/clay nanocomposites were found to be dependent on the molecular structure of polymers. They were found to increase with increasing temperature showing a peak before decreasing with further increase in temperature. The relaxation peak was found to depend on the molecular structure of polymer. The real (ε1) and imaginary (ε2) parts of dielectric function for polymer/clay nanocomposites decreased with increasing frequency.
Part II:
Poly(diallyldimethylammonium chloride), PDADMAC, with low (105-2×105) and high (4×105-5×105) molecular weight and with concentrations 0.5, 1 and 2 times the cation exchange capacity (CEC) of the clay was used to modify sodium bentonite clay to prepare hybrid PDADMAC/clay nanocomposites using solution-intercalation method. Data analysis showed that PDADMAC/clay nanocomposites have intercalated structure and the nanocomposite prepared using high molecular weight PDADMAC with concentration 1 times the CEC of the clay has the most intercalated structure and the highest thermal stability between the prepared