Search

Poly(2-hydroxyethylmethacrylate-graft-ibuprofen) (IpGH) of different ibuprofen (Ibu) contents was prepared by grafting of Ibu groups on poly(2-hydroxyethyl methacrylate) (PHEMA) in an esterification reaction route. The resulted copolymers were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, thermal gravimetric analysis, X-ray diffraction, and scanning electron microscope analysis. The cytotoxicity test and the free radical scavenging ability of this material were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium (MTT) and 1,1-diphenyl-2-picryl-hydrazyl assay methods, respectively. Thein vitrorelease study of Ibu through a retro-esterification reaction of IpHG material during 3 days reveals that the release dynamic depends on the initial Ibu grafted, pH media, and the swelling degree of PHEMA. It was also revealed that the water solubility of Ibu easily reached a maximum of 0.216 mg mL−1. The diffusion of Ibu through the polymer matrix obeys the Fickian model. The estimated distribution of the cumulative drug released in different simulated digestive organs reveals that the IpHG7 containing 6.69 mol% of Ibu content showed the best performance. [ABSTRACT FROM AUTHOR]

A series of poly(ethylene-co-vinyl alcohol)/poly(ε-caprolactone) blends with different compositions were prepared using solvent casting. The miscibility of this pair of polymers was investigated using differential scanning calorimetry (DSC), and proved by a negative Flory interaction parameter value calculated from the Nishi–Wang equation. The miscibility of this blend was also confirmed by scanning electronic microscopy (SEM). The thermal behaviors of the obtained materials were investigated by DSC, thermogravimetric analysis, and direct analysis in real-time–time-of-flight mass spectrometry and the results obtained were very relevant. Furthermore, the crystalline properties of the obtained materials were studied by DSC and X-ray diffraction where the Ozawa approach was adopted to investigate the non-isothermal crystallization kinetics. The results obtained revealed that this approach described the crystallization process well. [ABSTRACT FROM AUTHOR]

The release dynamics of aspirin(ASP), used as a drug model, from the poly(ethylene-co-vinyl alcohol)/poly(δ-valerolactone) (PE-co-VAL/Pδ-VL) hydrogel blend was controlled by varying the blend's degree of swelling through a gradual loading of Pδ-VL (hydrophobic polymer) in this copolymer matrix. To achieve this goal, a series of PE-co-VAL/Pδ-VL blends with different ratios was prepared through the solvent casting method, and the miscibility of this polymer blend was evaluated by using Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and scanning electronic microscopy methods. The tests of cell adhesion and growth on the PE-co-VAL/Pδ-VL specimens were performed using the 3-(4,5-demethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and the results obtained were the best performance in terms of cell viability, cell adhesion, and growth of the PE-co-VAL/Pδ-VL50 material. The dynamic mechanical properties of the prepared material were also examined by dynamic mechanical analysis; the results obtained showed a material having intermediary mechanical properties between those of the two components. On the basis of these characterizations, the blend showing the best performance, such as the PE-co-VAL/Pδ-VL50 system, was chosen as a carrier to study the in vitro control of the release dynamics of ASP from the ASP/PE-co-VAL/Pδ-VL drug-carrier system when administered orally, in which the influences of the ASP content and the degree of swelling of the PE-co-VAL/Pδ-VL blend were investigated. Based on the data obtained and the gastrointestinal transit time reported by Beltzer et al., it was possible to estimate the distribution of the in vitro cumulative ASP released in different digestive system organs regardless of the actions of any enzymes and microorganisms and select the best-performing drug-carrier system. [ABSTRACT FROM AUTHOR]

Titanium dioxide/poly(δ-valerolactone) (TiO2/Pδ-VL) nanohybrid material containing interconnected pores with sizes in the range 80–150 μm were prepared by the solvent casting and polymer melting routes, and the dispersion of the TiO2 nanofiller in the Pδ-VL matrix and its adhesion were characterized by X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy. A significant depression in the glass transition temperature (Tg) and melting temperature (Tm) values were revealed for the polymer nanocomposites prepared by the solvent casting technique. For the potential application of the prepared materials in the biomedical domain, complementary analyses were performed to examine the dynamic mechanical properties, and cell adhesion (using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay), and the results obtained for the samples prepared by the two methods were compared. Interconnected pores were successively produced in the new material by employing naphthalene microparticles as a porogen for the first time, and the results obtained were very promising. [ABSTRACT FROM AUTHOR]

New poly (δ-valerolactone)/titanium dioxide (PDVL/TiO2) nanocomposites with different TiO2 nanoparticle loadings were prepared by the solvent-casting method and characterized by Fourier transform infra-red, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy, and thermogravimetry analyses. The results obtained reveal good dispersion of TiO2 nanoparticles in the polymer matrix and non-formation of new crystalline structures indicating the stability of the crystallinity of TiO2 in the composite. A significant increase in the degree of crystallinity was observed with increasing TiO2 content. The non-isothermal crystallization kinetics of the PDVL/TiO2 system indicate that the crystallization process involves the simultaneous occurrence of two- and three-dimensional spherulitic growths. The thermal degradation analysis of this nanocomposite reveals a significant improvement in the thermal stability with increasing TiO2 loading. [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphene oxide sheets (N-GOs) are prepared by employing N-containing polymers such as polypyrrole, polyaniline, and copolymer (polypyrrole-polyaniline) doped with acids such as HCl, H2SO4, and C6H5-SO3-K, which are activated using different concentrations of KOH and carbonized at 650 °C; characterized using SEM, TEM, BET, TGA-DSC, XRD, and XPS; and employed for the removal of environmental pollutant CO2. The porosity of the N-GOs obtained were found to be in the range 1–3.5 nm when the KOH employed was in the ratio of 1:4, and the XRD confirmed the formation of the layered like structure. However, when the KOH employed was in the ratio of 1:2, the pore diameter was found to be in the range of 50–200 nm. The SEM and TEM analysis reveal the porosity and sheet-like structure of the products obtained. The nitrogen-doped graphene oxide sheets (N-GOs) prepared by employing polypyrrole doped with C6H5-SO3-K were found to possess a high surface area of 2870 m2/g. The N-GOs displayed excellent CO2 capture property with the N-GOs; PPy/Ar-1 displayed ~1.36 mmol/g. The precursor employed, the dopant used, and the activation process were found to affect the adsorption property of the N-GOs obtained. The preparation procedure is simple and favourable for the synthesis of N-GOs for their application as adsorbents in greenhouse gas removal and capture. [ABSTRACT FROM AUTHOR]

This paper is concerned with the improvement of dye-sensitized solar cell (DSSC) efficiency upon MgO post-treatment of the TiO 2 electrode. A simple sol–gel technique, involving magnesium acetate as precursor, ethanol as solvent and nitric acid as stabilizer, is applied to prepare a solution of suspended MgO nanoparticles. A single drop of MgO sol at 0.1 M precursor concentration was spin-coated at 3000 rpm for 30 s onto the TiO 2 electrode and sintered at 500 K for 1 h. Dye-loading using N3-dye was applied for 6 h. An increase in the average efficiency of the DSSC from 2.5% to 3.9% (over 50% enhancement) was recorded. Measurements of the dark I – V characteristics, the open circuit voltage decays, the SEM images and the dye absorbance spectra, for both uncoated and MgO-coated electrodes were examined. The improvement of the DSSC efficiency was attributed to an upward shift of the TiO 2 flat band energy and a reduction of the rate of back-transport and recombination. [ABSTRACT FROM AUTHOR]

Titanium dioxide/poly(δ-valerolactone) (TiO₂/Pδ-VL) nanohybrid material containing interconnected pores with sizes in the range 80⁻150 μm were prepared by the solvent casting and polymer melting routes, and the dispersion of the TiO₂ nanofiller in the Pδ-VL matrix and its adhesion were characterized by X-ray diffraction, differential scanning calorimetry, and scanning electron microscopy. A significant depression in the glass transition temperature ( T g ) and melting temperature ( T m ) values were revealed for the polymer nanocomposites prepared by the solvent casting technique. For the potential application of the prepared materials in the biomedical domain, complementary analyses were performed to examine the dynamic mechanical properties, and cell adhesion (using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay), and the results obtained for the samples prepared by the two methods were compared. Interconnected pores were successively produced in the new material by employing naphthalene microparticles as a porogen for the first time, and the results obtained were very promising., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analysis, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.