Aissam Airoudj

Development of an optical ammonia sensor based on polyaniline/epoxy resin (SU-8) composite

Polyaniline (PANI)/glycidyl ether of bisphenol A (SU-8) composite film is elaborated in order to detect ammonia gas. These composite films are characterized by ultraviolet-visible (UV-vis) spectroscopy, Fourier transformed infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The sensitivity to ammonia is measured by optical absorption changes. The ammonia sensing properties of PANI/SU-8 composite films are studied, and then are compared to pure PANI films elaborated by chemical way. Experimental results show that the PANI/SU-8 optical sensor has simultaneously a rapid response to ammonia gas and regenerates easily, that is advantageous compared to pure PANI films.

Design and sensing properties of an integrated optical gas sensor based on a multilayer structure.

In this paper, a new multilayer integrated optical sensor (MIOS) for ammonia detection at room temperature is proposed and characterized. The sensor is integrated on a single-mode TE0-TM0 planar polymer waveguide and based on polyaniline (PANI) sensitive material. A polymethyl methacrylate (PMMA) passive layer is deposited between the waveguide core and PANI sensitive layer in order to decrease optical losses induced by evanescent wave/sensitive material coupling. The design of this new sensor is discussed. Moreover, in order to investigate the feasibility of this sensor, the sensing properties to ammonia at room temperature are studied. A significant change is observed in the guided light output power after the sensor is exposed to ammonia gas, due to PANI absorption coefficient variation. This new ammonia sensor shows fast response and recovery times, good reversibility and repeatability. The metrological parameters (sensitivity, response time and recovery time) of the sensor are strongly influenced by the interaction length (length of sensing region) and the PANI forms (doped and dedoped). The sensor has a logarithmic linear optical response within the ammonia concentration range between 92 to 4618 ppm. These experimental results demonstrate that the MIOS structure presents a potential innovation to elaborate integrated optical sensor based on non transparent (opaque) sensitive material.

A new evanescent wave ammonia sensor based on polyaniline composite

A single-mode TE(0)-TM(0) optical planar waveguide ammonia sensor based on polyaniline/polymethyl methacrylate (PANI/PMMA) composite is designed and developed. The sensing properties of the photonic sensor to ammonia at room temperature are studied. A significant change is observed in the guided light output power of the sensor after it is exposed to ammonia gas. The metrological parameters (sensitivity, response time and recovery time) of the sensor are strongly influenced by the interaction length (length of sensing region). Compared with the conventional optical ammonia sensor based on absorption spectroscopy, the integrated optical sensor is more sensitive to ammonia.

Influence of Covalent Bonds on the Adhesion Energy at Elastomer-Glass Interfaces

The aim of this study was to analyze the effect of interfacial covalent bonds on the adhesive behavior of an elastomer, a crosslinked polydimethylsiloxane, and a glass substrate. These covalent bonds were created by applying to both materials an appropriate surface treatment by means of plasma polymerization. Adhesion measurements were carried out by analyzing the contact area between a rubber hemisphere and a flat rigid glass plate. The contact was forced under a given compressive loading for different times tc, then the load was removed and the fracture propagation at the interface was recorded as a function of relaxation time tr. Finally, adhesion energies were also determined by means of a probe test using a tensile testing machine.

Synthesis by ATRP of Polystyrene-b-Poly(4-vinylpyridine) and Characterization by Inverse Gas Chromatography

A linear diblock copolymer [Polystyrene-b-Poly(4-vinyl-pyridine)] (PS-b-P4VP) was successfully prepared through Atom Transfer Radical Polymerization (ATRP). This synthesis is performed in two successive steps: using the (1-bromoethyl) benzene as initiatorand and Hexamethyl tris [2(dimethylamino)ethyl] amine as ligands in a protic solvent. The first step of the synthesis allows the realization of block polystyrene having a terminal function; however, Bromine (Br) permits the grafting of the second successive block P4VP. RMN -1H demonstrates that the P4VP block has been grafted onto the PS block. The molecular weight of PS-b-P4VP is determined by size exclusion chromatography, and its thermal stability is examined by TGA. The surface and the thermodynamic properties of this copolymer are studied by inverse gas chromatography (IGC). The new Hamieh Model shows that the synthesized copolymer PS-P4VP has an amphoteric behavior with rather very basic character that is six times stronger than acidic character (in Lewis terms), reflected the presence of acidic and basic groups in the structure of the PS-P4VP copolymer, more particularly the presence of benzenic, methyl and vinylpyridine groups.