Marta Grochowicz

Synthesis and characterization of nanostructural polymer–silica composite: Positron annihilation lifetime spectroscopy study

The swelling of poly(TRIM) spherical particles in TEOS is assessed as a potential way for obtaining polymer-silica nanocomposite materials. Silica deposition was achieved by simply stirring of swollen polymer particles in acidic hydrochloric-water solution. This procedure leads to spherical composite particles with dispersed silica gel within the polymer matrix. The resulting material exhibits the same morphology as the initial polymer. Nanocomposite particles are silica rich (about 17 wt.%). Characterization of the nanocomposites was performed using scanning electron microscopy, FT-IR spectroscopy, (29)Si CP MAS NMR spectroscopy and thermogravimetry. Moreover, the use of positron annihilation lifetime spectroscopy PALS to characterize the structural properties of the nanocomposites is presented. This technique gave more realistic pieces of information about the pore structure of the investigated samples in contrast to nitrogen adsorption studies.

Effect of some parameters on the synthesis and the physico-chemical properties of new amphiphilic starch-g-copolymers.

The detailed studies on the graft copolymerization of phenyl methacrylate onto gelatinized potato starch in water using potassium persulfate as radical initiator were presented. The different reaction parameters such as effect of initiator concentration, starch to monomer ratio, reaction temperature and reaction time were studied in terms of grafting efficiency, grafting percent and percent homopolymer formation. It was found that grafting process of aromatic methacrylate monomer onto potato starch backbone allowed obtaining new amphiphilic copolymers with different physicochemical properties as compared to non-modified starch. The influence of the copolymer structure on the swelling behavior in polar and non-polar solvents, moisture absorbance, gelatinization properties, acid and base resistance, surface morphology and thermal properties was discussed.

Diels–Alder Reaction as a Tool to Modify the Surface of Polymeric Microspheres

The study describes the synthesis of glycidyl methacrylate microspheres cross-linked with ethylene glycol dimethacrylate. With the use of suspension–emulsion polymerization, microspheres with different degrees of cross-linking were prepared. Their chemical modification involved several steps: at the beginning, the epoxide ring was opened using sodium cyclopentadienide; in the next step, materials with grafted cyclopentadiene fragments were then subjected to Diels–Alder reaction with maleic anhydride; in the last step, the anhydride groups were turned into carboxylic groups. To confirm the attachment of cyclopentadiene to the microspheres surface, the material obtained was treated with fluorescence marker N-(1-pyrene) maleimide. The resulting material has fluorescent properties in the UV wavelength of 366 nm. Moreover, to confirm the chemical structure of modified materials, attenuated total reflection-Fourier transform infrared spectroscopy analysis was performed. Thermal stability in inert atmosphere of prepared microspheres was determined. It was found that chemical modification of the microspheres surface improves their thermal resistance. On the basis of this study, it can be assumed that the Diels–Alder reaction is an expedient tool to obtain microspheres having carboxyl and hydroxyl groups, which can be an interesting option as stationary phases in chromatography.

Polymer-amino-functionalized silica composites for the sustained-release multiparticulate system

This study presents an interesting and promising strategy for producing an oral multiparticulate formulation of the sustained-release of diclofenac sodium (DS) consisting of subunits closed inside hard gelatin capsules (each capsule contains ~50mg of diclofenac sodium). The subunits in the form of beads were produced through the encapsulation of diclofenac sodium dispersed within a nondisintegrating polymer carrier by a silica gel functionalized with the 3-aminopropyl groups. The hybrid silica gel, which plays the role of enteric coating, was fabricated by the gelation of the liquid silica precursors mixture (i.e. tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES)) in the vapor phase of ammonia. The conducted studies reveal that the introduction of the hybrid silica gel into the solid DS dispersion facilitates prolonged release in the neutral environment of the intestine. Since the ability of the multiparticulate formulation to control the release of the drug depends on the properties of its subunits, studies involving the low temperature N2 sorption, DSC analysis together with spectroscopic techniques (XRD, SEM, 29Si MAS NMR) were conducted.

Thermal and spectral analysis of copolymers with sulphur groups

The paper presents the synthesis, structure and polymerization of S-phenyl 2-methylprop-2-enethioate (PSM). This compound was prepared in the reaction of thiophenol with methacryloyl chloride. The obtained PSM was purified on the chromatographic column. Chemical structure of the monomer was confirmed by spectroscopic methods (ATR–FTIR, GC–MS, 1H and 13C NMR). Next bulk polymerization of PSM with styrene (St) or methyl methacrylate (MMA) was performed. In this way, linear copolymers were obtained. The number and mass average molar mass of the obtained copolymers were determined by gel permeation chromatography (GPC). Additionally, crosslinked copolymers of the commercial monomer S,S′-thiodi-4,1-phenylene bis(thiomethacrylate) (DMSPS) under the same conditions were synthesized. The influence of thiol monomers on the physico-chemical properties of the obtained copolymers was determined. Thermal properties of the synthesized materials were investigated by means of DSC and TG/DTG.

Vapour-phase method in the synthesis of polymer-ibuprofen sodium-silica gel composites

The study discusses the synthesis of polymer-silica composites comprising water soluble drug (ibuprofen sodium, IBS). The polymers selected for this study were poly(TRIM) and poly(HEMA-co-TRIM) produced in the form of permanently porous beads via the suspension-emulsion polymerization method. The acid and base set ternary composites were prepared by the saturation of the solid dispersions of drug (poly(TRIM)-IBS and/or poly(HEMA-co-TRIM)-IBS) with TEOS, and followed by their exposition to the vapour mixture of water and ammonia, or water and hydrochloric acid, at autogenous pressure. The conducted analyses reveal that the internal structure and total porosity of the resulting composites strongly depend on the catalyst which was used for silica precursor gelation. The parameters characterizing the porosity of both of the acid set composites are much lower than the parameters of the base set composites. Moreover, the basic catalyst supplied in the vapour phase does not affect the ibuprofen sodium molecules, whereas the acid one causes transformation of the ibuprofen sodium into the sodium chloride and a derivative of propanoic acid, which is poorly water soluble. The release profiles of ibuprofen sodium from composites demonstrate that there are differences in the rate and efficiency of drug desorption from them. They are mainly affected by the chemical character of the polymeric carrier but are also associated with the restricted swelling of the composites in the buffer solution after precipitation of silica gel.

4-Vinylpyridine–Trimethylolpropane Trimethacrylate Composite Polymer Particles and Their Application as Adsorbents

The study describes the synthesis of microspheres of 4-vinylpyridine (4VP) and trimethylolpropane trimethacrylate (TRIM) with uniform diameters. Polymeric 4VP–TRIM microspheres were prepared by seed polymerization, using polystyrene beads as a shape template. Following polymerization, microspheres with average diameters of 10.2, 8.5 and 5.6 μm and coefficient of variation of approximately 7% were obtained. By changing the molar ratio of co-monomers, it was possible to prepare 4VP–TRIM materials with developed porous structure and specific surface area of up to 355 m2/g. 4VP–TRIM microspheres were synthesized with the intention to use them as polymeric stationary phases in high-performance liquid chromatography (HPLC). The Smith method was used to evaluate the chromatographic properties of polymeric packing. Using two retention index scales (alkylbenzenes and alkyl aryl ketones), the retention indices of test compounds with different chemical characters were calculated. Toluene had the highest retention index on the studied stationary phase, whereas 2-phenylethanol had the smallest retention. In the reversed phase-mode HPLC, isocratic separation of alkylbenzenes was achieved with satisfactory resolution on 100 times 4.6 mm i.d. column. Theoretical plate number exceeding 16,000 m−1 could be obtained with benzene as the analyte. The resolving power of the prepared column was maintained when the mobile phase flow rate was increased from 1 to 2 ml/minute.