Małgorzata Maciejewska

Porosity evolution of VP-DVB/MCM-41 nanocomposite

The porous structure of nanostructured vinylpyrrolidone-divinylbenzene (VP-DVB)/MCM-41 composite was characterized using N(2) adsorption at 77K and positronium annihilation lifetime spectroscopy (PALS), atomic force microscopy (AFM) and Raman spectroscopy. Positron annihilation lifetime spectra were measured during outgassing procedure. The voids of differentiated dimensions were detected in the composite material. The number of free volumes and their dimensions depend on the degree of evacuation of volatile components from the samples.

A new application of micellar liquid chromatography in the determination of free ampicillin concentration in the drug–human serum albumin standard solution in comparison with the adsorption method

The determination of free drug concentration is a very important issue in the field of pharmacology because only the unbound drug fraction can achieve a pharmacological effect. Due to the ability to solubilize many different compounds in micellar aggregates, micellar liquid chromatography (MLC) can be used for direct determination of free drug concentration. Proteins are not retained on the stationary phase probably due to the formation of protein - surfactant complexes which are excluded from the pores of stationary phase. The micellar method is simple and fast. It does not require any pre-preparation of the tested samples for analysis. The main aim of this paper is to demonstrate a completely new applicability of the analytical use of MLC concerning the determination of free drug concentration in the standard solution of human serum albumin. The well-known adsorption method using RP-HPLC and the spectrophotometric technique was applied as the reference method. The results show that the free drug concentration value obtained in the MLC system (based on the RP-8 stationary phase and CTAB) is similar to that obtained by the adsorption method: both RP-HPLC (95.83μgmL(-1), 79.86% of free form) and spectrophotometry (95.71μgmL(-1), 79.76%). In the MLC the free drug concentration was 93.98μgmL(-1) (78.3%). This indicates that the obtained results are within the analytical range of % of free ampicillin fraction and the MLC with direct sample injection can be treated like a promising method for the determination of free drug concentration.

Studies on the Selectivity of Porous Methacrylate Polymers

Four types of porous methacrylate polymers were synthesized as stationary phases for gas chromatography. The influence of the chemical structure of the monomers used in the synthesis on the selectivities of the resulting polymers was studied. Two procedures were applied to determine the selectivities of the copolymers: the selectivity triangle and the general selectivity. Porapak Q, the least polar commercially available porous polymer, was used as a reference phase.

Testing of the Extended Tao-Eldrup Model on Porous VP-DVB Copolymers

Five samples of porous polymers were investigated using positron annihilation lifetime spectroscopy and liquid nitrogen sorption techniques. Temperature dependencies of o-Ps lifetime were used to estimate the ETE model parameters (R and Δ) for porous polymers. The value of the Δ parameter was found to be 0.13-0.15 nm. A significant difference between pore radii obtained by both techniques was found.

Study on Synthesis and Characterization of Porous Microspheres with Pendant Amine Groups

Porous microspheres of glycidyl methacrylate cross-linked with trimethylolpropane trimethacrylate were prepared with toluene as porogen by suspension–emulsion polymerization. With increasing molar ratio of the functional monomer to cross-linker, the epoxy group content increases significantly, whereas the parameters of porous structure (specific surface area and total pore volume) decrease. To obtain adsorbents bearing functional groups, the porous methacrylate network was modified by subsequent treatment with diethylenetriamine. Polymers capacity towards Cu(II), Zn(II), Pb(II) and Cd(II) was investigated.

Comparison of the Porous Structure of Polymeric Beads Obtained by Modified Suspension and Multi-step Swelling Polymerizations

The porous structures of the polymeric beads obtained by modified suspension and multi-step swelling polymerizations were studied. A porous styrene–divinylbenzene copolymer (ST–DVB) was synthesized in the modified suspension polymerization. In the multi-step polymerization, porous ST–DVB layers of the same chemical composition as obtained in the suspension polymerization were embedded onto polystyrene seed particles obtained in the first step. Three methods were used for investigating the porous structures generated. These were inverse exclusion chromatography, nitrogen adsorption and small X-ray scattering (SAXS). The former was used to characterize the polymer in the swollen state, whereas the latter two were employed with dry polymer samples. The results obtained showed that polystyrene seed particles are porous in the swollen state. However, such pores could not be detected either by nitrogen adsorption or SAXS methods.

Effect of Carbon Nanotubes Surface Modification on Structure of Forcibly Ordered Films of Filled Polystyrene

The effect of surface modification of multi-walled carbon nanotubes (MWCNTs) with different modifiers on the filler dispersibility in polystyrene and the influence of the external magnetostatic field on the structure of obtained composites have been studied. The surface modification of as-synthesised and oxidized carbon nanotubes was performed by treatment with hydrochloric acid or ammonia hydroxide solutions. The composite films were casted on glass plates with or without the influence of magnetostatic field at the desired directions of the magnetic lines. A combination of MWCNTs surface treatment and directed influence of the magnetostatic field was shown to be an effective route to change the structure of composites.