Sol gel synthesis of hybrid chitosan/calcium aluminosilicate nanocomposite membranes and its application as support for CO2 sensor.

Modification of chitosan with cross-linkers, blends with various kinds of polymers, nanoparticles and new organic-inorganic hybrid composites in order to obtain some improved properties attached more attention nowadays due to their good sensitivity in changing electrical and optical properties. In the current work modified hybrid chitosan/calcium aluminosilicate (CH/CAS) nanocomposite membranes and doped with (3, 5 & 7 mol%) Al2O3 nanoparticles were synthesized via sol-gel process in acidic conditions, which can be efficiently employed to capture CO2 gas at lower and moderate temperatures. Furthermore, the fabricated CH/CAS nanocomposite membrane loading with (3, 5 & 7 mol%) Al2O3 were investigated using XRD, SEM, FTIR and dielectric measurements. The results indicated that the incorporation of Al2O3 in CH/CAS matrix significantly affected on the structural, dielectric and appeared good reliability for sensing CO2 at atmospheric pressure. The dielectric behaviour for the prepared CH/CAS indicates that the dielectric constant (ε') decreases. According to XRD the introducing of Al2O3 leads to increase the crystallinity of the system and thus the dipoles of the system orient hardly with the applied field and results in lesser dielectric constant (ε'). Correspondingly, the CH/CAS nanocomposite membranes were characterized and its performance as CO2 gas sensor was evaluated.

Conducting cellulose/TiO2 composites by in situ polymerization of pyrrole.

Cellulose/polypyrrole and cellulose/polypyrrole-TiO2 composites were prepared via in situ oxidative chemical polymerization of pyrrole using FeCl3 as oxidant. The concentration effect of pyrrole on the structure and properties of prepared matrix has been investigated. Furthermore, the structure of the prepared materials was characterized using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), X-ray Diffraction (XRD), and Thermal gravimetrical analysis (TGA). The results exhibited that the addition of cellulose and TiO2 increase the thermal stability of the polypyrrole system. Moreover, dielectric properties of the obtained composites were studied over frequency range from 42Hz to 5MHz. The electrical measurements including dielectric constant, ε'(ω), dielectric loss, ε''(ω), loss tangent, tan δ and ac conductivity, σac were carried.