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Objectives The currently available commercial dental resin composites have limitations in use owing to the high viscosity and water sorption of Bisphenol A glycidyl methacrylate (BisGMA). The objective of this study was to obtain a BisGMA analog with reduced viscosity and hydrophilicity for potential use as an alternative to BisGMA in dental resin composites. Methods The targeted chlorinated BisGMA (Cl-BisGMA) monomer was synthesized via the Appel reaction. The structural modification was confirmed via 1H- and 13C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and mass spectrometry. Five resin mixtures (70:30 wt.%: F1 = BisGMA/TEGDMA; F2 = Cl-BisGMA/TEGDMA; F3 = Cl-BisGMA only; F4 = Cl-BisGMA/BisGMA; F5 contained 15% TEGDMA with equal amounts of BisGMA and Cl-BisGMA) were prepared. The viscosity, degree of double-bond conversion (DC), water sorption (WSP), and solubility (WSL) were tested. Cell viability and live/dead assays, as well as cell attachment and morphology assessments, were applied for cytotoxicity evaluation. Results Cl-BisGMA was successfully synthesized with the viscosity reduced to 7.22 (Pa s) compared to BisGMA (909.93, Pa s). Interestingly, the DC of the F2 resin was the highest (70.6%). By the addition of equivalence concentration of Cl-BisGMA instead of BisGMA, the WSP was decreased from 2.95% (F1) to 0.41% (F2) with no significant change in WSL. However, the WSL increased with high Cl-BisGMA content. Biological tests revealed that all the resins were biocompatible during CL1 incubation. Significance The experimental resins based on Cl-BisGMA exhibited improved properties compared with the control samples, e.g., biocompatibility and lower viscosity, indicating that Cl-BisGMA can be considered as a potential monomer for application in dental resin composites.

The objective of this work was to investigate the advantages of using dichloro bisphenol A-glycidyl methacrylate (dCl-BisGMA) as a potential matrix for dental resin composites. A series of model composites containing 65 wt% resin (urethane dimethacrylate/triethylene glycol dimethacrylate/BisGMA as 1:3:1) and 35 wt% silanated silica were prepared. Thus, BisGMA was replaced by dCl-BisGMA as 0, 25, 50, and 100 wt% to obtain UTBC0, UTBC25, UTBC50, and UTBC100, respectively. The composites’ rheological properties, degree of double-bond conversion (DC), water sorption (WSP), and water solubility (WSL) were examined. The data revealed a statistically significant reduction in the complex viscosity of composites containing dCl-BisGMA, compared with UTBC0. No significant differences between DCs were detected (p &lt, 0.05). A significant enhancement in the reduction of the dCl-BisGMA composite WSP was also detected, and conversely, WSL was increased. Although the viscosity, DC, and WSP characters were enhanced, a WSL increase is an undesirable development. However, WSL is supposedly caused by cyclization of small flexible chains, which is more likely to occur in the presence of hydrophobic monomers such as dCl-BisGMA and more prone to leaching than are crosslinked networks. We concluded that dCl-BisGMA is a monomer that could potentially be used as an alternative or in combination with traditional monomers, including BisGMA, in resin-based dental composites, and it deserves further investigation.

This study aimed to synthesize new bisphenol A-glycidyl methacrylate (BisGMA) derivatives, targeting a reduction in its viscosity by substituting one of its OH groups, the leading cause of its high viscosity, with a chlorine atom. Hence, this monochloro-BisGMA (mCl-BisGMA) monomer was synthesized by Appel reaction procedure, and its structure was confirmed using Fourier transform infrared spectroscopy, 1H and 13C-nuclear magnetic resonance spectroscopy, and mass spectroscopy. The viscosity of mCl-BisGMA (8.3 Pa&middot, s) was measured under rheometry conditions, and it was found to be more than 65-fold lower than that of BisGMA (566.1 Pa&middot, s) at 25 &deg, C. For the assessment of the viscosity changes of model resins in the presence of mCl-BisGMA, a series of resin matrices, in which, besides BisGMA, 50 wt % was triethylene glycol dimethacrylate, were prepared and evaluated at 20, 25, and 35 &deg, C. Thus, BisGMA was incrementally replaced by 25% mCl-BisGMA to obtain TBC0, TBC25, TBC50, TBC75, and TBC100 blends. The viscosity decreased with temperature, and the mCl-BisGMA content in the resin mixture increased. The substantial reduction in the viscosity value of mCl-BisGMA compared with that of BisGMA may imply its potential use as a dental resin matrix, either alone or in combination with traditional monomers. However, the various properties of mCl-BisGMA-containing matrices should be evaluated.

Two poly(&delta, valerolactone)/poly(ethylene-co-vinylalcohol)/beta-tricalcium phosphate (PEVAL/PDVAL/&beta, TCP) composites containing an equal ratio of polymer and filled with 50 and 70 wt% of &beta, TCP microparticles were prepared by the solvent casting method. Interconnected pores were realized using the salt leached technique, and the porosity of the resulted composites was evaluated by the scanning electron microscopy (SEM) method. The homogeneity of the hybrid materials was investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The prepared materials&rsquo, SEM images showed interconnected micropores that respond to the conditions required to allow their uses as scaffolds. The porosity of each scaffold was determined from micro computed tomography (micro-CT) data, and the analysis of the mechanical properties of the prepared materials was studied through the stress-strain compressive test. The proliferation test results used human mesenchymal stem cells (MSCs) to grow and proliferate on the different types of prepared materials, reflecting that the hybrid materials were non-toxic and could be biologically acceptable scaffolds. The antibacterial activity test revealed that incorporation of amoxicillin in the specimens could inhibit the bacterial growth of S. aureus. The in vitro study of the release of amoxicillin from the PEVAL/PDVAL/amoxicillin and PEVAL/PDVAL/&beta, TCP/amoxicillin drug carrier systems in pH media 7.4, during eight days, gave promising results, and the antibiotic diffusion in these scaffolds obeys the Fickian model.

Graphene and graphene oxide based nanomaterials have attained immense significance in research because of their matchless physiochemical characteristics. Although potential biomedical applications of graphene have been extensively studied, however, dentistry related applications were rarely explored. This study aimed to investigate the effect of various percentages of surface modified reduce graphene oxide (S-rGO) in combination with SiO2 nanoparticles (bulk filler) on numerous physio-mechanical characteristics of acrylate-based (BisGMA/TEGDMA: 1:1 by wt.) composites. BisGMA/TEGDMA reinforced with 30 wt.% surface modified fumed-silica (S-A200) was considered as control group (base composite). Various concentrations (0, 0.5, 1, 2, 4 wt.%) of S-rGO were incorporated into the base composite via solution casting and high-speed mixing. The obtained composites were characterized for rheological properties before curing by using Rheometer (Anton Paar, USA) in the oscillatory mode under a frequency sweep over a range of angular frequency of 0.1&ndash, 100 rad/s at 25 &deg, C. The degree of conversion (DC) was measured by using Fourier transform infrared spectroscopy (FTIR). A Nano-indentation test was carried out to obtain nano-hardness and elastic modulus. The surface roughness was measured by optical microscope (Bruker&reg, ), 3D non-contact surface profilometer. The structural and morphological properties were studied by using Scanning Electron Microscopy (SEM). The mean and standard deviation were calculated and a simple mean comparisons test was performed for comparison using SPSS. The results revealed that the addition of a tiny proportion of S-rGO considerably increased the nano-indentation hardness, elastic modulus and DC. Conversely, a gradual reduction in viscosity was observed with increasing S-rGO concentration. The study demonstrates that a small fraction of S-rGO in combination with SiO2 could enhance physical, mechanical and rheological properties of acrylate based composites. Thus S-rGO/SiO2 combination could be used as a potential hybrid filler for dental nanocomposites.

This work aims to study the role of bentonite, Na+ montmorillonite (Na+MMT), as a filler to design a new poly(vinyl alcohol) (PVA)-based membrane for the pervaporation of an azeotropic water/ethanol mixture to enhance its separation efficiency. PVA/Na+MMT nanocomposite membranes, containing different ratios of Na+MMT (i.e., 1, 5, 10, 15, and 20 wt%), were prepared using the solvent casting method and crosslinked with maleic acid. The interactions between the PVA polymer and MMT were determined using Fourier transform infrared spectroscopy. Structural characterization by X-ray diffraction and scanning electron microscopy (SEM) analysis showed that the nanoclay structure was well-exfoliated and distributed in the crosslinked PVA matrix. To determine the thermal stability of different membranes, thermogravimetric analysis and differential scanning calorimetry were used. The mechanical properties of pure PVA and the intercalated polymer material were studied. Of note, in this study, the membranes showed a simultaneous increase in the permeation flow and selectivity depending on the montmorillonite filling charge.

A polystyrene sulfonic acid-functionalized mesoporous silica (SBA-15-PSSA) catalyst was synthesized via an established multistep route, employing 2-bromo-2-methylpropionyl bromide as initiator of atom transfer radical polymerization. Fourier-transform infrared spectroscopy, thermogravimetric/differential thermal, Brunauer&ndash, Emmett&ndash, Teller, and transmission electron microscopy analyses revealed outstanding structural characteristics of the catalyst, including highly ordered mesopores, high surface area (726 m2/g), and adequate estimated concentrations of active sites (0.70 mmol H+/g). SBA-15-PSSA&rsquo, s catalytic performance was evaluated in the esterification of acetic acid and n-heptanol as a model system at various temperatures (50&ndash, 110 &deg, C), catalyst loads (0.1&ndash, 0.3 g), and reaction times (0&ndash, 160 min). The conversion percentage of acetic acid was found to increase with the temperature, catalyst load, and reaction time. Furthermore, results indicated a fast conversion in the first 20 min of the reaction, with remarkable conversion values at 110 &deg, C, reaching 86%, 94%, and 97% when the catalyst load was 0.1, 0.2, and 0.3 g, respectively, notably, at this temperature, 100% conversation was achieved after 60 min. At 110 &deg, C, the reaction conducted in the presence of 0.3 g of catalyst displayed more than 6.4 times the efficiency of the uncatalyzed reaction. Such activity is explained by the concomitant presence in the polymer of strong sulfonic acid moieties and a relatively high hydrophobic surface, with adequate numbers of active sites for ester production.

In order to improve the cell adhesion on poly(&epsilon, 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.

A series of poly(ethylene‐co‐vinylalcohol)(PE‐VOL)/poly(D,L‐lactic‐co‐glycolic acid(PD,L‐LGA) blends with different compositions was prepared by solution casting, and its miscibilitywas proved through viscosimetry and differential scanning calorimetry (DSC) methods through apositive value of &alpha, (San et al. Eq.) and negative value of &chi, 1,2 (Nishi&ndash, Wang Equation). XRD analysisof the PE‐VOL/PD,L‐LGA system revealed a homogeneous distribution of PE‐VOL moleculesaggregated in the PD,L‐ LGA matrix and the crystalline structure of the semi crystalline copolymerwas conserved in the blend in aggregated form. It also revealed that the amorphous copolymerdispersed in the blend acted as a weak nucleating agent. The non‐isothermal crystallization kineticsof neat semi‐crystalline copolymer and the blend was used to describe the crystallization processusing the Ozawa approach. The thermal stability of these materials was investigated by the thermalgravimetry analysis. The isothermal decomposition of copolymers and their blend were carried outby high resolution mass spectrometry using direct‐analysis‐in‐real‐time method. Relevant resultsthat could highlight the miscible character of this blend are revealed through comparison of thedifferent fragments resulting from the decomposition of the blend with those of the purecomponents.

Novel Schiff bases of metformin hydrochloride and (ortho)para-nitrobenzaldehyde were synthesized by employing two efficient environmentally friendly methods, namely, stirring and microwave-assisted methods using water as the solvent. The advantage of microwave irradiation over the other methods was represented in the reduction of reaction time and wastes, and good yields, however, water in both methods plays the role of eco-friendly solvent. The structural properties of the (ortho)para-isomer products were analyzed by elemental analysis, Fourier transform infrared (FTIR) spectroscopy, UV-Visible (UV-Vis) spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, 13C NMR spectroscopy, mass spectroscopy, and differential scanning calorimetry (DSC). The newly synthesized compounds were screened for their antibacterial activity against selected Gram-positive (ATCC 25923, ATCC 43300, and ATCC 29212) and Gram-negative (ATCC 25922, ATCC 27853, and ATCC 700603) bacteria using the agar well diffusion method. Compared with the standard drug streptomycin, both Schiff bases exhibited moderate bactericidal activity against the tested bacteria with higher values of ortho-nitro compared with the para-nitro isomer, however, no effect on ATCC 43300 and ATCC 27853 was observed under the experimental conditions employed.

The catalytic system of azo-bis-isobutyronitrile (AIBN) combined with (SiMes)Ru(PPH3)(Ind)Cl2 [M20] 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/M20 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/M20initiating system under the same conditions. Keywords: Catalytic effectiveness, Azobis-isisobutyronitrile/[(SiMes)Ru(PPh3)(Ind)Cl2] initiating system, Living radical, Polymerization conditions, Stereo-structure, Molecular weight distribution, Kinetics of polymerization

A series of poly(acrylic acid)/poly(methyl vinyl ketone) (PAA/PMVK) blends with different compositions were prepared by the solvent casting method. The miscibility of this pair of polymers was investigated by differential scanning calorimetry(DSC), Fourier transform infra-red (FTIR) and X-Ray diffraction (XRD) techniques. An in-vitro cytotoxicity test of the drug-carrier system via MTT (3-(4,5-demethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed no significant cytotoxic effects at concentrations up to 100 µg· ml−1. The STX/PAA-50 drug carrier systems were also prepared by solvent casting of solutions containing the sulfamethoxazole (STX) used as drug model and PAA/PMVK blend in N.N-dimethylformamide then crosslinked with acidified ethylene glycol. The release dynamic of STX from the prepared hydrogels was investigated in which the diffusion through the polymer matrix, the enhancement of the water solubility of STX, the influence of the initial drug concentration, the pH of the medium, and the effect of the degree of swelling of the polymer matrix on the release dynamic was evaluated. According to the total gastrointestinal transit time estimated by Belzer, the estimate distribution of STX released in the different organs indicated that the performance is obtained with the drug – carrier-system containing equal ratios of polymer and 10 wt% of STX (STX-10/PAA-50).

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. The in vitro release 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. T...

The adsorption of methyl orange (MO) from aqueous solutions onto a KOH-activated polypyrrole-based adsorbent (PACK) was investigated using batch and fixed-bed column techniques. The structural, thermal, and morphological properties of the PACK, analyzed by various methods, support its applicability as an adsorbent. An adsorption kinetic study revealed a preferably pseudo-second-order (R2 = 0.9996) and rate-limiting step controlled by both film and intra-particle diffusions. The thermodynamic adsorption tests resulted in negative &Delta, G&deg, &Delta, H&deg, and &Delta, S&deg, values, which decreased as the temperature and concentration increased, indicating the spontaneous and exothermic adsorption over 25&ndash, 45 &deg, C. The adsorption isotherms fit the experimental data in the order of Langmuir &asymp, Freundlich &gt, Temkin, with evidence of adsorption operating well via the monolayer physical adsorption process, and maximum monolayer adsorption ranging from 520.8 to 497.5 mg/g. The breakthrough curve of the fixed-bed column experiment was modeled using the Thomas, Yoon&ndash, Nelson, and Hill models, resulting in an equilibrium capacity of 57.21 mg/g. A 73% MO recovery was achieved, indicating the possibility of column regeneration. Compared to other adsorbents reported, PACK had comparable or even superior capacity toward MO. For cost-effectiveness, similar nitrogen-containing polymeric wastes could be exploited to obtain such excellent materials for various applications.

In this study, polypyrrole-based activated carbon was prepared by the carbonization of polypyrrole at 650 &deg, C for 2 h in the presence of four-times the mass of KOH as a chemical activator. The structural and morphological properties of the product (polypyrrole-based activated carbon (PPyAC4)), analyzed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and thermogravimetric analysis, support its applicability as an adsorbent. The adsorption characteristics of PPyAC4 were examined through the adsorption of lead ions from aqueous solutions. The influence of various factors, including initial ion concentration, pH, contact time, and adsorbent dose, on the adsorption of Pb2+ was investigated to identify the optimum adsorption conditions. The experimental data fit well to the pseudo-second-order kinetic model (R2 = 0.9997) and the Freundlich isotherm equation (R2 = 0.9950), suggesting a chemisorption pathway. The adsorption capacity was found to increase with increases in time and initial concentration, while it decreased with an increase in adsorbent dose. Additionally, the highest adsorption was attained at pH 5.5. The calculated maximum capacity, qm, determined from the Langmuir model was 50 mg/g.

2-hydroxyethyl methacrylate, methylmethacrylate, ethylene glycol dimethyl methacrylate, and lignocaine (drug) were mixed together and the monomers were copolymerized at 60 &deg, C through a free radical polymerization in the presence of &alpha, &alpha, &prime, Azoisobutyronitrile in tetrahydrofuran. A series of copolymer/drug composites with different monoacrylate monomer compositions were prepared by solvent evaporation and characterized by different methods such as nuclear magnetic resonance, differential scanning calorimetry, Fourier transform infrared, X-ray diffraction, and mechanical and optical testing. The water content in the copolymers and the cell viability test on the samples were also examined in this investigation. The results of the analyses of the properties of this drug-carrier system are promising, indicating that this material may be a potential candidate for contact lens applications. The release dynamic of this medication from the prepared drug-carrier systems was investigated in neutral pH media. The results obtained revealed that the diffusion of lignocaine through the copolymer matrix obeys the Fick model and the dynamic release can be easily controlled by the methyl methacrylate content in the copolymer.

Titanium dioxide/poly(&delta, valerolactone) (TiO2/P&delta, VL) nanohybrid material containing interconnected pores with sizes in the range 80&ndash, 150 &mu, m were prepared by the solvent casting and polymer melting routes, and the dispersion of the TiO2 nanofiller in the P&delta, 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.

New poly (&delta, 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.

Poly(eugenyl-2-hydroxypropyl methacrylate) (PEUGMA), poly(methyl methacrylate) (PMMA) and poly(eugenyl-2-hydroxypropyl methacrylate-co-methyl methacrylate) (PEUGMA-co-MMA) were synthesized by a free radical polymerization route in the presence of azobisisobutyronitrile. EUGMA was synthesized by etherification of the eugenol phenolic hydroxyl group with glycidyl methacrylate. Polymers and copolymers were characterized using size exclusion chromatography, Fourier transform infrared, and nuclear magnetic resonance. The effects of the encumbering substituent on the thermal behavior of the polymers and copolymers were studied by differential scanning calorimetry, thermogravimetry (TG) and direct analysis, using real-time, time-of-flight mass spectroscopy (DART-ToF-MS) methods. The results obtained revealed that for PEUGMA, the average molecular weight was 1.08 &times, 105, and increased slowly with the decrease in the EUGMA content in the copolymer. The order of the distribution of dyads comonomer units in the copolymer chains estimated by the Igarashi method based on the reactivity ratio does reveal a random distribution with a tendency toward alternation. The glass transition temperature of PEUGMA (46 &deg, C) increased with the MMA content in the copolymer, and those of the copolymer fit well with the Johnston&rsquo, s linearized expression. The TG analysis of pure PEUGMA revealed a significantly high thermal stability compared to that of PMMA. During its degradation, the preliminary decomposition was at 340 &deg, C, and decreased as the MMA units increased in the copolymer. The DART-ToF-MS analysis revealed that the isothermal decomposition of PEUGMA led to a regeneration of raw materials such as EUGMA, GMA and EUG, in which the maximum amount was achieved at 450 &deg, C.