Metastable patterning of plasma nanocomposite films by incorporating cellulose nanowhiskers.

A new method is presented for developing patterned, thin nanocomposite films by introducing cellulose nanowhiskers during the pulsed plasma polymerization of maleic anhydride. Metastable film structures develop as a combination of dewetting and buckling phenomena. By controlling the maleic anhydride monomer to cellulose nanowhisker weight ratio, the whiskers can be incorporated into a homogeneously covering patterned polymer film. Excess nanowhiskers are required to prevent complete dewetting and deposit dimensionally stable films. The formation of anchoring points is assumed to stabilize the film through a "pinning" effect to the substrate. The latter control the in-plane film stresses, similar to the effects of surface inhomogeneities such as artificial scratches. The different morphologies are evaluated by optical microscopy, AFM, contact angle measurements, and ellipsometry. Further analysis by infrared spectroscopy and XPS suggests esterification between the maleic anhydride and cellulose moieties.

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.

New sensitive layer based on pulsed plasma-polymerized aniline for integrated optical ammonia sensor.

A new integrated optical sensor based on plasma-polyaniline sensitive layer for ammonia detection is designed and developed. The sensor is based on polyaniline elaborated by the plasma technique (Plasma Enhanced Chemical Vapor Deposition, PECVD) and deposited on a small section of a single-mode planar SU-8 waveguide. The sensing properties of the integrated optical sensor to ammonia at room temperature are presented. A significant change in the guided light output power of the sensor is observed after exposition to ammonia gas. This new ammonia sensor exhibits 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), the type of dopant and the light polarization. The sensor has a logarithmic linear optical response within the ammonia concentration range between 92 and 4618ppm.

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.