Catalytic effectiveness of azobisisobutyronitrile/[SiMes)Ru(PPH3)(Ind)Cl2 initiating system in the polymerization of methyl methacrylate and other vinylic monomers

The catalytic system of azo-bis-isobutyronitrile (AIBN) combined with (SiMes)Ru(PPH3)(Ind)Cl-2 [M-20] was investigated for the controlled radical polymerization of methyl methacrylate (MMA) in solution. Various factors that may influence the catalytic polymerization process, such as the aging time of the initiating system, AIBN/M-20 ratio, concentration of monomer, polymerization time, temperature, and the nature of solvent were examined. The results showed that the yield, molecular weight, and molecular distribution are practically unaffected by these parameters; however, the syndiotactic stereo-structure tendency that characterizes the produced poly(methyl methacrylate) (PMMA) varied with temperature. The optimum conditions for PMMA synthesis were determined to produce an essentially syndiotactic material with uniformly high molecular weights. It was also revealed that the kinetics of MMA polymerization is of first order with respect to the concentration of monomer. A comparison was also made for some vinylic polymers synthesized either with the AIBN alone or with the AIBN/M-20 initiating system under the same conditions

Synthesis of Poly (Citric Acid-Co-Glycerol) and Its Application as an Inhibitor of CaCO3 Deposition

This investigation determined a feasible route to prepare hyperbranched polyesters involving citric acid (CA) and glycerol (GLC) monomers (CA-co-GLC) using a thermal polycondensation method. The synthesized copolymer was characterized using Fourier transform infrared spectroscopy (FT-IR), carbon-13 nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The ability of CA-co-GLC to inhibit deposition of inorganic scales such as calcium carbonate was investigated under varying temperature and pH medium. The evaluation of inhibition efficiency (IE) was conducted using the static scale inhibition method. The mechanism of the inhibitor’s action was investigated via growth solution analysis, measurement conductivity, and analysis of CaCO3 using FT-IR and scanning electron microscopy. The results obtained showed that the CA-co-GLC had good IE at an elevated temperature reaching 75% at 100 °C, pH 7.5, and 10 ppm copolymer dose. Using the same dose, the IE reached 66% at 50 °C and pH 10. The CA-co-GLC did not chelate Ca2+ in water, but led to a change in polymorphism, making it brittle and able to slip easily from the surface. Its action principally prevented the adhesion of calcium carbonate onto the surface

New Method Based on Direct Analysis in Real-Time Coupled with Time-of-Flight Mass Spectrometry (DART-ToF-MS) for Investigation of the Miscibility of Polymer Blends

The miscibility of a series of binary blends such as polystyrene/poly(methyl methacrylate) (PS/PMMA), polystyrene/poly(vinyl chloride)(PS/PVC), poly(vinyl chloride)/poly(polymethyl methacrylate)(PVC/PMMA) and poly(ethylene-co-vinyl alcohol)/poly(lactide-co-glycolide acid) PEVAL/PLGA with equal ratios and poly(ethylene oxide)/poly(hydroxyl propyl methyl cellulose) (PEO/PHPMC) containing 30 and 70 wt% PEO, which were randomly chosen among the widely systems reported in the literature, was investigated by a new method based on a direct analysis in real-time coupled with time-of-flight mass spectrometry (DART-ToF-MS). To reach this goal these pairs of polymers and copolymers were prepared by solvent casting method. As a first step, the DSC technique was undertaken in this work to highlight the published results on the miscibility of these binary systems. The thermogravimetry analysis (TGA) was used to define the optimum decomposition temperature of these blends programmed for the study of miscibility using the DART-ToF-MS technique. The results obtained by this method based on the comparison of the nature of the fragments resulting from the isothermal decomposition of the blend with those of their pure components have been very effective in demonstrating the character of miscibility of these systems. Indeed, it was found that the PS/PMMA-50 and PS/PVC-50 blends were immiscible, PVC/PMMA-50 and PEVAL/PLGA-50 miscible, and the PEO/PHMC partially miscible. This method, which is rapid and uses a very small amount of sample (1–2 mg) can be extended in its application to other blends whose other methods used have shown their limits due to the intrinsic properties of the polymers involved

Preparation and Characterization of Poly(δ-Valerolactone)/TiO₂ Nanohybrid Material with Pores Interconnected for Potential Use in Tissue Engineering

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

Synthesis of New Hydrogels Involving Acrylic Acid and Acrylamide Grafted Agar-Agar and Their Application in the Removal of Cationic Dyes from Wastewater

Polyacrylic Acid grafted Agar-agar (AAc-graf-Agar), and polyacrylamide grafted Agar-Agar (AAm-graf-Agar) have been synthesised by free radical polymerisation route initiated by ammonium peroxodisulphate (APS), the grafted polymers were characterised by FTIR, TGA and SEM methods. The swelling properties were studied in deionised water and saline solution at room temperature. The prepared hydrogels were examined by removing cationic methylene blue (MB) dye from the aqueous solution, in which the adsorption kinetics and isotherms models were also investigated. It was found that the pseudo-second-order and Langmuir equations are the most suitable for the different sorption processes. The maximum dye adsorption capacity was 1035.96 mg∙g−1 for AAc-graf-Agar in pH medium 12 and 1015.7 mg∙g−1 for AAm-graf-Agar in neutral pH medium. This indicates that the AAc-graf-Agar hydrogel could be an excellent adsorbent for removing MB from aqueous solutions

Thermal Properties and Non-Isothermal Crystallization Kinetics of Poly (δ-Valerolactone) and Poly (δ-Valerolactone)/Titanium Dioxide Nanocomposites

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

Preparation and Characterization of Poly(ethylene-co-vinyl alcohol)/poly(ε-caprolactone) Blend for Bioscaffolding Applications

In order to improve the cell adhesion on poly(ε-caprolactone) (PCL) scaffolds, poly(ethylene-co-vinyl alcohol) (E-VAL) which has hydroxyl groups capable of developing hydrogen bonds with celling was blended with this polymer. To reach this goal, a series of E-VAL/PCL blends with different compositions were prepared by the solvent casting method. The miscibility of the polymer blend was proved by differential scanning calorimetry and Fourier-transform infrared spectroscopy spectrometry. Furthermore, the mechanical properties of the polymer blends were assessed in their wet state by dynamic mechanical analysis. The surfaces wettability of blends and their components were examined through static contact angle measurements. The pore interconnections in the resulted scaffolds were achieved by the incorporation of naphthalene microparticles which were used as porogen and then removed in its gas state by sublimation under reduced pressure. The presence of pores interconnected inside the polymeric materials and their surface morphologies was examined by scanning electron microscopy. The in-vitro cytotoxicity and cell adhesion on the prepared materials were examined by an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay

Naproxen-Loaded Poly(2-hydroxyalkyl methacrylates): Preparation and Drug Release Dynamics

Poly(2-hydroxyethylmethacrylate)/Naproxen (NPX/pHEMA) and poly (2-hydroxypropyl methacrylate)/Naproxen (NPX/pHPMA) composites with different NPX content were prepared in situ by free radical photopolymerization route. The resulted hybrid materials were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning Electron microscopy (SEM), and X-ray diffraction (XRD). These composites have been studied as drug carrier systems, in which a comparison of the in vitro release dynamic of NPX between the two drug carrier systems has been conducted. Different factors affecting the performance of the release dynamic of this drug, such as the amount of Naproxen incorporated in the drug carrier system, the pH of the medium and the degree of swelling, have been investigated. The results of the swelling study of pHEMA and pHPMA in different media pHs revealed that the diffusion of water molecules through both polymer samples obeys the Fickian model. The “in vitro” study of the release dynamic of Naproxen from NPX/pHEMA and NPX/pHPMA drug carrier systems revealed that the higher percentage of NPX released was obtained from each polymer carrier in neutral pH medium, and the diffusion of NPX trough these polymer matrices also obeys the Fickian model. It was also found that the less the mass percent of NPX in the composites, the better its release will be. The comparison between the two drug carrier systems revealed that the pHEMA leads to the best performance in the release dynamic of NPX. Regarding Naproxen solubility in water, the results deducted from the “in vitro” study of NPX/pHEMA10 and NPX/pHPMA10 drug carrier systems revealed a very significant improvement in the solubility of NPX in media pH1 (2.33 times, 1.43 times) and 7 (3.32 times, 2.60 times), respectively, compared to those obtained by direct dissolution of Naproxen powder

Poly(ethylene-co-vinylalcohol)/ Poly(δ-valerolactone)/Aspirin Composite: Model for a New Drug-Carrier System

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