M. Azmi Bustam

Synthesis, characterization and the effect of temperature on different physicochemical properties of protic ionic liquids

In this work, eleven protic ionic liquids (PILs) containing different cations and anions were prepared and their physicochemical properties were measured. The structures of all the PILs were confirmed using NMR, and elemental analysis (CHNS) was carried out. The physicochemical properties such as density, surface tension, viscosity and thermal degradation behaviour were measured, and the effect of the cations/anions was investigated. The density and viscosity were measured within the temperature range of 293.15–373.15 K at atmospheric pressure. The thermal expansion coefficient values were calculated from the density data. Surface tension was measured in the temperature range of 293.15 to 353.15 K and the values were used to estimate the surface entropy and enthalpy of the ionic liquids at 303.15 K. The boiling and critical temperature are also estimated according to the Eotvos and Rebelo methods. The refractive indices were measured within the temperature range of 293.15 to 323.15 K. The thermal gravimetric analysis was performed in the temperature range of 373.15–773.15 K.

Thermal properties of different transition metal forms of montmorillonite intercalated with mono-, di-, and triethanolammonium compounds

In the present study, different transition metal forms of montmorillonite have been intercalated with mono-, di-, and triethanolammonium cations via d coordination mechanism to investigate their thermal behavior, structural characteristics, surface properties, and elemental composition using TG, XRD, BET, and CHNS techniques. Thermogravimetric analysis showed two thermal transition steps for transition metal-exchanged montmorillonites, which attributed to desorption of the physically adsorbed water and hydrated water, and dehydroxylation of the structural water; whereas for ammonium-montmorillonite complexes, the TG curves showed three thermal transition steps which attributed to desorption of the adsorbed water and dehydration, decomposition of the ammonium cations in the interlayer space of montmorillonite, and the dehydroxylation of the structural water. The thermal analysis of ammonium-montmorillonites affirmed that the molar mass of amine compounds used affects both desorption temperature (position) and the amount of the adsorbed water (intensity). XRD results revealed that the molar mass of amine used has linear relation with the basal spacings of the corresponding ammonium-montmorillonites, indicating structural changes. BET results showed that the molar mass of amines has an inverse effect on the surface area of the studied samples. CHNS analysis for the studied samples quantitatively confirmed the intercalation of ammonium cations into the interlayer space of montmorillonite.

Swelling mechanism of urea cross-linked starch–lignin films in water

ABSTRACT Coating fertilizer particles with thin films is a possibility to control fertilizer release rates. It is observed that novel urea cross-linked starch–lignin composite thin films, prepared by solution casting, swell on coming into contact with water due to the increase in volume by water uptake by diffusion. The effect of lignin content, varied from 0% to 20% in steps of 5% at three different temperatures (25°C, 35°C and 45°C), on swelling of the film was investigated. By gravimetric analysis, the equilibrium water uptake and diffusion coefficient decrease with lignin content, indicating that the addition of lignin increases the hydrophobicity of the films. When temperature increases, the diffusion coefficient and the amount of water absorbed tend to increase. Assuming that swelling of the thin film is by water uptake by diffusion, the diffusion coefficient is estimated. The estimated diffusion coefficient decreases from 4.3 to 2.1 × 10−7 cm2/s at 25°C, from 5.3 to 2.9 × 10−7 cm2/s at 35°C and from 6.2 to 3.8 × 10−7 cm2/s at 45°C depending on the lignin content. Activation energy for the increase in diffusion coefficient with temperature is observed to be 16.55 kJ/mol. An empirical model of water uptake as a function of percentage of lignin and temperature was also developed based on Fick’s law.

CO2 adsorption equilibria on calcium exchanged bentonite modified by mono-, di- and triethanolamines

M solvothermal process was used to synthesize anatase TiO2 nanocrystallines for the application of dyesensitized solar cells (DSSCs). The morphologies and sizes of TiO2 could be simply controlled by using different kinds of alcohols where no additives were needed. By using isopropanol (IPA) as solvent, TiO2 in size of 20-30 nm with dominant {001}/{010} facets was obtained; whereas ultrafine anatase TiO2 of about 5 nm with dominant {101}-facet was obtained using octanol (OCT). To investigate the influences of TiO2 on the photovoltaic performances of DSSCs, three different pastes were fabricated using IPA, OCT and mixed IPA/OCT as photoanodes. The results revealed that the requirements of TiO2 photoanodes used at one sun and room light conditions were quite different. OCT showed the highest power conversion efficiency (PCE) up to 9.58% under one sun irradiation because of its high specific surface area that provided high dye-loading capacity. However, the great amount of grain boundaries appeared in OCT became disadvantageous at room light condition. On the other hand, IPA/OCT combined the features of IPA and OCT that was optimal for room light harvesting and its PCE reached 12.46% under 200 lux T5 lamp irradiation. The photovoltaic properties of three different photoanodes in correlation with their band structures, electronic transport behaviors and light harvesting efficiency in different lighting conditions will be carefully discussed in this presentation.G the increasing interest for the biomaterials in medical and engineering field, the objective of this talk is the theoretical and experimental analysis of the biomaterials in order to define experimental procedures and mathematical models suitable for their mechanical characterization. The biomaterials exhibit a rheological behavior intermediate between that of purely elastic materials and that of the purely viscous materials and therefore are called viscoelastic ones. In the past the “classical” models as Maxwell and Kelvin-Voigt have been used to capture viscoelastic phenomena. However, these models are not consistent to model the viscoelastic behavior of real materials, since the Maxwell type can capture the relaxation tests only and the Kelvin-Voigt the creep tests. A more realistic description of creep and/or relaxation is given by a power law function with real order exponent. As soon as we assume a power law function for creep, the constitutive law relating deformation and stress is ruled by a Riemann-Liouville fractional integral with order equal to that of the power law. In this regard, recent studies have been stressed that the most suitable model for capturing the viscoelastic behavior is the spring-pot, characterized by a fractional constitutive law. Based on the aforementioned considerations, it is apparent that the need of theoretical as well as experimental development and exploration of materials with novel physical characteristics. For instance, if the giant grass Arundo donax (AD) has to be characterized; then, attention is devoted on searching a proper model for characterizing the behavior of giant reeds. To aim at this, firstly, meticulous experimental tests have been performed in the Laboratory of structural materials of University of Palermo. Further a novel aspect of using an advanced Euler-Bernoulli model to fit experimental data of bending tests will be introduced.M devices represent an emerging technology with a great potential in analytical life sciences. In particular lab-on-a-chip concerning genomic applications has attracted great interest; in such systems there is often the need to provide an efficient DNA amplification by PCR (polymerase chain reaction). Nowadays, polymers are the materials of choice for the fabrication of micro devices for genomic applications. For prototyping and small-scale production, soft lithographyA family of multiple-step techniques based on molding the thermally curable elastomer polydimethylsiloxane (PDMS) is the current gold standard. However, the commercial and common thermally curable PDMS shows some drawbacks that limit its applicability in biotechnology, such as the difficulty in controlling and modifying the surface chemistry and in tuning the physical and mechanical properties of the material. An appealing alternative to thermally curable PDMS prototyping is the use of specially designed UV curable polymers, as photopolymerization is a very fast reaction that leads to the synthesis of highly cross-linked networks in few seconds at room temperature. Moreover, this technique can be applied to a wide variety of photocurable polymers, allowing to select and tune the desired physico-chemical properties of the final device. In the present work, we introduce the use of a class of photocurable siloxane polymers for the fabrication of microfluidic devices for biomedical applications (i.e., PCR). New multifunctional acrylic oligomers are synthesized (Figure 1a) and then photo cross linked. Moreover, copolymerization is used as strategy to optimize the photopolymer properties. The polymers and copolymers synthesized are suitable for bio microfluidics: they are PCR compatible (Figure 1b), highly resistant to temperature and various solvents, transparent, dimensionally stable and essentially non-permeable to water vapor. Therefore, these materials are used to fabricate microfluidic devices (Figure 1c), in which PCR is successfully conducted as proof of principle.