Ionica Ionita

Quartz Crystal Microbalance (QCM): An Alternative Analytical Method for Investigation in Real‐Time of Liquid Properties

In this paper we study the possibility to develop an alternative Analytical Method for Investigation in Real‐Time of Liquid Properties, the layout and the operation with Quartz Crystal Microbalance (QCM) Systems. The quartz crystal microbalance (QCM) can be accepted as a powerful technique to monitor adsorption and desorption processes at interfaces in different chemical and biological areas. In our paper, Quartz Crystal Microbalance is used to monitor in real‐time the polymer adsorption followed by azoic dye adsorption and then copolymer adsorption as well as optimization of interaction processes and determination of solution effects on the analytical signal. The solutions of azoic dye (5⋅10−4 g/L, 5⋅10−5 g/L and 5⋅10−6 g/L in DMF) are adsorbed at gold electrodes of QCM and the sensor responses are estimated through decrease and increase of QCM frequency. Also, the response of the sensor at maleic anhydride (MA) copolymer with styrene St (MA‐St copolymer concentration of solution: 5⋅10−4 g/L; 5⋅10−5 g/L ...

Investigations of the Correlation between the Preparation Method and the Properties of Anilinic Derivative Functionalised Polymer Thin Films for Non-Linear Optical Applications

This paper presents a study of two copolymers, maleic anhydride and methylmethacrilate/maleic anhydride and vinyl benzyl chloride, functionalised with polar chromophoric groups such as 2,4 dinitroaniline. Thin films have been prepared by vacuum evaporation and spin coating methods on silicon and glass substrates. UV-VIS, FTIR, XRD and Photoluminescence Spectroscopy have been used to comparatively investigate the effect of the preparation method on the properties of the thin films obtained with functionalized copolymer. SEM has evidenced differences in the morphologies of the layers suggesting a degradation of the polymeric chain during the evaporation process to fragments that conserve unchanged the chromophoric group. This explains the presence of two types of non-linear phenomena, the second harmonic emission and two-photon luminescence emissions for both vacuum evaporated and spin coated films.

The effects of UV irradiation in azo-derivatives

From all type of external stimuli the light rays are most commonly used because it involves only photochemical processes easily to control. One of the most studied of photochemical processes is photoisomerization groups, in particular the azobenzene groups. The azobenzene and his derivatives, known for Z(sin)-E(anti) reversible photoisomerization properties, have been extensively used as functional groups to synthesize various photosensitive compounds. The UV irradiation at different time of modified maleic anhydride - styrene copolymers with azo dye solutions were with UV light to increase the rate of Z(sin)-E(anti) isomerisation. The changes in the spectral absorption domain for azo compounds, a decrease in optic absorbance after irradiation, with a predisposition to come back at primary value was made with SECOMAMS750 UV–Vis spectrophotometer.

The azobenzene derivatives

Azobenzene derivatives constitute a group of dyes which have photochromic properties and have been investigated as promising systems for diverse applications in the unconventional optic area, their properties can be moulded with help of light.

Quartz crystal microbalance used for determination of dyes from wastewaters

The dyes resulted from textile industry are pollutants from POPs category which are responsible for wastewaters color and other environmental problems. Quartz crystal microbalance (QCM) allows the determination of dyes concentration values due to the high sensitivity of resonant crystal frequency. The obtained experimental results lead to the conclusion that the QCM method can be successfully used to obtain an accurate quantitative and qualitative analysis of dyes in wastewaters in real time.