Investigation of the effect of SSP in stabilizing the structure of condensation polymer blends via rheological measurements

We investigated the influence of solid-state polymerization (SSP) process on the reactions that could be taken place at the interphase of polycondensation polymer blends to stabilize the structure obtained after melt mixing. Polyethylene terephthalate (PET) and polyamide 66 (PA66) were melt blended in a mixer, and subsequent SSP process was performed for each sample. FTIR spectra indicated reactions between two polymers. Viscosity behavior and interfacial slip were investigated by measuring shear viscosity of components and blends before and after SSP and then compared with the viscosity calculated from the log-additivity model. The results showed that after SSP, there was no sign of interfacial slip, the slope of viscosity reduction with increasing shear rate became smaller, and the viscosity of blends showed positive deviation at all examined shear rate from the log-additivity model while this deviation was negative at higher shear rate before SSP. SEM micrographs, which were taken after shear stress was imposed on the samples, also indicated the morphological stability after SSP. Furthermore, we studied the effect of functional groups concentration on the reactions at the interphase by using hydrolyzed PET as a precursor for blends. The results showed that slip at the interface would decrease with increasing functional groups of the precursors. These results are particularly valuable for using recycled polymers.     

Flow-injection potentiometric determination of clobutinol hydrochloride in pure state and pharmaceutical preparations

Clobutinol (Cb) ion-selective plastic-membrane electrodes based on ion associates of clobutinolium phosphotungstate (Cb-PTA), clobutinolium phosphomolybdate (Cb-PMA), or a mixture of both Cb-PTA and PMA were prepared. The electrodes were fully characterized in terms of membrane composition, life span, pH, and temperature. The electrodes were applied to the potentiometric determination of clobutinol in pure form and pharmaceutical preparations under batch and flow-injection conditions. Also, conductimetric titrations were applied to the assay of clobutinol in its pure form and pharmaceutical preparations. The selectivity of the electrodes towards a large number of inorganic cations, amino acids, and sugars was tested. The solubility product of ion-associates and the formation constant of the precipitation reactions leading to the ion-associate formation were determined conductimetrically. The text was submitted by the authors in English.     

Synthesis of Ag nanoparticles for the electrochemical detection of anticancer drug flutamide

Ag nanoparticles were synthesized on the surface of a glassy carbon electrode modified with p‐tert‐butylcalix[4]arene and p‐tert‐butylcalix[6]arene by the deposition of Ag+at an open circuit potential ...     

Facile and direct synthesis of symmetrical acid anhydrides using a newly prepared powerful and efficient mixed reagent

An efficient mixed reagent for direct synthesis of symmetrical carboxylic anhydrides from carboxylic acids has been prepared. Carboxylic acids are converted to anhydrides using triphenylphosphine/trichloroisocyanuric acid under mild reaction conditions at room temperature. Short reaction time, excellent yields of products, low cost, availability of reagents, simple experimental procedure, and easy work-up of the products are the main advantages of the presented method.     

Cellulose@Fe2O3 nanoparticle composites: magnetically recyclable nanocatalyst for the synthesis of 3-aminoimidazo[1,2-a]pyridines

Research on Chemical Intermediates - 3-Aminoimidazo[1,2-a]pyridines have been synthesized through a condensation reaction of 2-aminopyridine, an aldehyde and an alkyl or aryl isocyanide in high...     

Sulfur multilayer formation on Au(111): new insights from the study of hexamethyldisilathiane

Hexamethyldisilathiane was successfully used as a new precursor for the formation of S layers on Au and to study their interaction. Characterization of the S modified gold surface was done by X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and scanning tunneling microscopy (STM). Key findings include the direct observation by STM of (i) coexistence of different phases, (ii) multiple sulfur layers formation, (ii) formation of rectangular structures not only on the adlayer but also on the top layer, and (iv) rectangular structure mobility on different layers. These results provide clear evidence regarding the adsorbate nature of the rectangular structures, solving a highly debated question.     

An unbreakable on-line approach towards sol-gel capillary microextraction

In this work a novel unbreakable sol-gel-based in-tube device for on-line solid phase microextraction (SPME) was developed. The inner surface of a copper tube, intended to be used as a high performance liquid chromatography (HPLC) loop, was electrodeposited by metallic Cu followed by the self assembled monolayers (SAM) of 3-(mercaptopropyl) trimethoxysilane (3MPTMOS). Then, poly (ethyleneglycol) (PEG) was chemically bonded to the -OH sites of the SAM already covering the inner surface of the copper loop using sol-gel technology. The homogeneity and the porous surface structure of the SAM and sol-gel coatings were examined using the scanning electron microscopy (SEM) and adsorption/desorption porosimetry (BET). The prepared loop was used for online in-tube SPME (capillary microextraction) of some selected polycyclic aromatic hydrocarbons (PAHs), as model compounds, from the aquatic media. After extraction, the HPLC mobile phase was used for on-line desorption and elution of the extracted analytes from the loop to the HPLC column. Major parameters affecting the extraction efficiency including the sample flow rate through the copper tube, loading time, desorption time and sample volume were optimized. For investigating the sorbent efficiency, four loops based on the copper tube itself, the copper tube after electrodeposition with Cu and the tubes with the SAMs and SAMs-sol-gel coating were made and compared. The SAMs-sol-gel coated loop clearly shows a prominently lead of at least 20-100 times of higher efficiency. The linearity for the analytes was in the range of 0.01-500 μg L(-1). Limit of detection (LOD) was in the range of 0.005-0.5 μg L(-1) and the RSD% values (n=5) were all below 8.3% at the 5 μg L(-1) level. The developed method was successfully applied to real water samples while the relative recovery percentages obtained for the spiked water samples were from 90 to 104%. The prepared loop exhibited long life time due to its remarkable solvent and mechanical stability. Different solvents such as methanol, acetonitrile and acetone were passed through the loop for many days and it was also used for more than 100 extractions/desorption of the selected analytes and no decrease in the peak areas was observed.