Effect of γ-dose rate and total dose interrelation on the polymeric hydrogel: A novel injectable male contraceptive

Functional necessity to use a particular range of dose rate and total dose of γ-initiated polymerization to manufacture a novel polymeric hydrogel RISUG^® (reversible inhibition of sperm under guidance) made of styrene maleic anhydride (SMA) dissolved in dimethyl sulphoxide (DMSO), for its broad biomedical application explores new dimension of research. The present work involves 16 irradiated samples. They were tested by fourier transform infrared spectroscopy, matrix assisted laser desorption/ionization–TOF, field emission scanning electron microscopy, high resolution transmission electron microscopy, etc. to see the interrelation effect of gamma dose rates (8.25, 17.29, 20.01 and 25.00 Gy/min) and four sets of doses (1.8, 2.0, 2.2 and 2.4 kGy) on the molecular weight, molecular weight distribution and porosity analysis of the biopolymeric drug RISUG^®. The results of randomized experiment indicated that a range of 18–24 Gy/min γ-dose rate and 2.0–2.4 kGy γ-total doses is suitable for the desirable in vivo performance of the contraceptive copolymer.     

Iron hydroxide nanoparticles coated with poly(ethylene glycol)-poly(aspartic acid) block copolymer as novel magnetic resonance contrast agents for in vivo cancer imaging

PEG-coated β-FeOOH nanoparticles were prepared through electrostatic complex formation of iron oxide nanoparticles with poly(ethylene glycol)-poly(aspartic acid) block copolymer [PEG-P(Asp)] in distilled water. By dynamic light scattering (DLS) measurement, the nanopaticle size was determined to be 70 nm with narrow distribution. The FT-IR and zeta potential experimental results proved that PEG-PAsp molecules bound to the surface of the iron oxide nanoparticles via the coordination between the carboxylic acid residues in the PAsp segment of the block copolymer and the surface Fe of the β-FeOOH nanoparticles. The PEG-coated nanoparticles revealed excellent solubility and stability in aqueous solution as well as in physiological saline. In vivo MRI experiments on tumor-bearing mice demonstrated that the PEG-coated nanoparticles prepared by the current approach achieved an appreciable accumulation into solid tumor, suggesting their potential utility as tumor-selective MRI contrast agents.     

Hybrid micelle formation from poly(ethylene oxide-b-sodium 2-acrylamido-1-propanesulfonate-b-styrene) and Fe3+ ion in aqueous solution

Organic–inorganic nanohybrid particles are prepared in aqueous solution from poly(ethylene oxide-b-sodium 2-acrylamido-1-propanesulfonate-b-styrene) (PEO-b-PAMPS-b-PS) triblock copolymer and ferric ions. The hybrid micelles were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy, and zeta-potential measurements. The hydrodynamic diameter of the hybrid micelles ranges from 68 to 118 nm depending on the concentration of the polymer and the amount of ferric ions loaded on the polymer. Zeta-potential measurements revealed that the micelles are assembled mainly by electrostatic interaction between the ferric ions and the negatively charged PAMPS block in the PEO-b-PAMPS-b-PS.     

表面包覆保护的离子电池新型正极材料LiFeBO3电化学性能

以偏硼酸锂和草酸亚铁为原料,采用固相反应,合成了用于动力锂离子电池新型正极材料LiFeBO<,3>,并用乙丙共聚物(EPM)对该材料进行包覆保护处理;采用XRD、SEM和元素分析等测试技术对样品进行表征.实验表明.LiFeBO<,3>具有较高的放电重量比容量,而且包覆EPM后的硼酸铁锂具有更好的电化学性能,5%EPM包覆的硼酸锂首次放电容量达190 mA·h/g,0.5 C下充放电循环50次后容量衰减只有4.2%.     

Microgels formed by electrostatic and hydrophobic interaction of naphthaleneacetic acid with β-cyclodextrin-grafted polyethyleneimine

Microgels were prepared by physically cross-linking β-cyclodextrin-grafted polyethyleneimine (βCD-PEI) using a hydrophobic acidic compound, naphthaleneacetic acid (NAA). Under a strong acidic condition (e.g., pH 3.0), fibrous microgels were observed on a scanning electron microscope (SEM) possibly due to the intermolecular electrostatic interaction of NAA with PEI. In the range of pH 4.0 to pH 8.0, globular microgels were found possibly because an intramolecular electrostatic interaction prevails over an intermolecular interaction. At pH 9.0 and pH 10.0, neither fibrous nor globular microgels were observed due to lack of the electrostatic interaction and the hydrophobic interaction of NAA with βCD-PEI. The release of fluorescein isothiocyanate-dextran (FITC-dextran; M.W., 10,000) from the microgels increased with increasing pH. At pHs higher than pH 3.0, not only the diffusion of the solute, but also the dissolution of the microgels could contribute to the release.     

Reverse atom transfer radical random copolymerization of styrene and methyl methacrylate in the presence of diatomite nanoplatelets

Diatomite nanoplatelets were used for in situ random copolymerization of styrene and methyl methacrylate by reverse atom transfer radical polymerization to synthesize different well‐defined nanocomposites. Inherent features of the pristine diatomite nanoplatelets were evaluated by Fourier transform infrared spectroscopy, nitrogen adsorption/desorption isotherm, scanning electron microscope, and transmission electron microscope. Gas and size exclusion chromatography was also used to determine conversion and molecular weight determinations, respectively. Considerable increment in conversion (from 81% to 97%) was achieved by adding 3 wt% diatomite nanoplatelets in the copolymer matrix. Moreover, molecular weight of random copolymer chains was increased from 12 890 to 13 960 g·mol⁻¹ by addition of 3 wt% diatomite nanoplatelets; however, polydispersity index (PDI) values increases from 1.36 to 1.59. Proton nuclear magnetic resonance spectroscopy was used to evaluate copolymers composition. Thermal gravimetric analysis results indicate that thermal stability of the nanocomposites is improved by adding diatomite nanoplatelets. Differential scanning calorimetry shows an increase in glass transition temperature from 66°C to 71°C by adding 3 wt% of diatomite nanoplatelets.     

Degradation of EPDM seal used for water supplying system

Degradation of ethylene-propylene-diene (EPDM) rubber seal used for supplying water system was investigated through spectroscopic techniques. The EPDM seal was utilized at 20-45 °C for about 3 years. It was characterized by solid state nuclear magnetic resonance spectroscopy equipped with field gradient fast magic angle spinning probe and Fourier transform-infrared spectroscopy. Morphology of the EPDM seal was observed by scanning electron microscopy, focused ion beam scanning electron microscopy and electron probe micro-analysis. The hardness and crosslink density of EPDM seal were reduced by a factor of one-half after using for supplying water system, even though it contains little amount of carbon-carbon double bond. Surface of the EPDM seal was significantly damaged by water. The degradation of EPDM seal was associated with chain scission and oxidation of EPDM.     

Synthesis and biocompatibility of phosphoryl polymer and relationship between biocompatibility and water structure

A series of copolymers, poly(methylmethacrylate-co-2-methacryloyloxyethyl phosphorylcholine), with various compositions of methyl methacrylate (MMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) were synthesized by radical copolymerization in a mixed solvent of ethanol and chloroform. The structures of the copolymers were confirmed by proton nuclear magnetic resonance and elemental analysis. The properties and morphologies of the copolymers were characterized by differential scanning calorimeter, scanning electron microscopy, and optical microscope. The adsorption of bovine serum albumin (BSA) and the adhesion of platelet on the surfaces of the copolymer membrane significantly decreased with increasing the MPC composition. The copolymers containing MPC above 18% showed excellent biocompatibility. Moreover, the relationship between the water structure and the biocompatibility was illustrated by changing quantity of the MPC in copolymers. The result showed that the amount of free water affected the platelet compatibility of the copolymer.     

Phosphomolybdic acid functionalized graphene loading copper nanoparticles modified electrodes for non-enzymatic electrochemical sensing of glucose

A sensitive non-enzymatic glucose electrochemical biosensor (Cu/PMo₁₂-GR/GCE) was developed based on the combination of copper nanoparticles (CuNPs) and phosphomolybdic acid functionalized graphene (PMo₁₂-GR). PMo₁₂-GR films were modified on the surface of glassy carbon electrode (GCE) through electrostatic self-assembly with the aid of poly diallyl dimethyl ammonium chloride (PDDA). Then CuNPs were successfully decorated onto the PMo₁₂-GR modified GCE through electrodeposition. The morphology of Cu/PMo₁₂-GR/GCE was characterized by scanning electron microscope (SEM). Cyclic voltammetry (CV) and chronoamperometry were used to investigate the electrochemical performances of the biosensor. The results indicated that the modified electrode displayed a synergistic effect of PMo₁₂-GR sheets and CuNPs towards the electro-oxidation of glucose in the alkaline solution. At the optimal detection potential of 0.50 V, the response towards glucose presented a linear response ranging from 0.10 μM to 1.0 mM with a detection limit of 3.0 × 10⁻² μM (S/N = 3). In addition, Cu/PMo₁₂-GR/GCE possessed a high selectivity, good reproducibility, excellent stability and acceptable recovery, which indicating the potential application in clinical field.     

Poly (caprolactone)/poly (ethylene glycol) pervaporation blend membranes: Synthesis,characterization, and performance

Poly (caprolactone) membranes with addition of different poly (ethylene glycol) concentrations were prepared for separation of water/isopropanol azeotropic mixture by pervaporation process. Different characterization tests including Fourier transform infrared, scanning electron microscopy, water contact angle, and thermogravimetric analysis were carried out on the prepared membranes. In addition, the effect of poly (ethylene glycol) PEG content on the swelling degree and the performance of the prepared membranes in pervaporation process were investigated. According to the obtained results, all the membranes were water selective and the blend membrane containing 3 wt% PEG exhibited the best pervaporation performance with a water flux of 0.517 kg/m² hour and separation factor of 1642 at the ambient temperature. Hydrophilicity improvement of the blend membranes was confirmed by constant decrease in water contact angle of the membranes as PEG content increased in the casting solution. Scanning electron microscopy cross‐sectional images indicated that the blend membranes containing PEG had a closed cellular structure. Furthermore, mechanical and thermal properties of the membranes decreased by adding PEG.     

Controllable synthesis and micelles preparation of tri-block copolymers from 2,2-dimethyl-trimethylene carbonate and ethylene glycol

Amphiphilic triblock copolymer of poly(2,2-dimethyl-trimethylene carbonate)–poly(ethylene glycol)–poly(2,2-dimethyl trimethylene carbonate) (PDTC–PEG–PDTC) was synthesized by dihydroxyl capped PEG with molecular weight of 1,000, 4,000, and 6,000 in the presence of rare earth tris(2,6-di-tert-butyl-4-methylphenolate)s. The rare earth phenolates/PEG system could prepare triblock copolymer with predictable molecular weights with narrow molecular weight distribution. The polymers were characterized by nuclear magnetic resonance spectroscopy, gel permeation chromotography, and differential scanning calorimetry to confirm the structure. The micelles formed from the amphiphilic triblock copolymer were determined by fluorescence spectrophotometer and dynamic light scattering. The critical micelle concentrations fell in the range of 1.67∼5.25 mg/L. Transmission electron microscopy pictures showed that the micelles possess spherical morphology, and the diameters of micelles in number averaged scale ranged from 20–70 nm. The micelles formed from triblock amphiphilic copolymers were explored as carrier for indomethacin (IND), and they could enhance IND solubility in water dramatically.     

Biodegradable graphene oxide nanosheets/poly-(butylene adipate-co-terephthalate) nanocomposite film with enhanced gas and water vapor barrier properties

Poly-(butylene adipate-co-terephthalate) (PBAT) has captured significant interest by dint of its biodegradability, superb ductility, promising processing properties and good final properties, but the insufficient barrier performance limits its application, especially in packaging field. In the present work, improved barrier properties of PBAT films were obtained by introducing an extremely low amount of graphene oxide nanosheets (GONS). O₂ and water vapor permeability coefficients were decreased by more than 70% and 36% at the GONS loading of 0.35 vol%, respectively. The enhanced barrier performance was ascribed to the outstanding impermeability and well dispersion of GONS as well as the strong interfacial adhesion between GONS and PBAT matrix. Furthermore, tensile strength and Young's modulus of GONS/PBAT nanocomposite rise up to 27.8 MPa and 72.2 MPa from 24.6 MPa to 58.5 MPa of neat PBAT, respectively, showing a prominent increase of mechanical properties compared to neat PBAT. The incorporation of GONS also endowed PBAT matrix with an excellent thermal stability. These findings provide a significant guidance for fabricating high barrier films on a large scale.     

The Use of Microporous Divinyl Benzene Copolymer for Yeast Cell Immobilization and Ethanol Production in Packed-Bed Reactor

Microporous divinyl benzene copolymer (MDBP) was used for the first time as immobilization material for Saccharomyces cerevisiae ATCC 26602 cells in a bed reactor and ethanol production from glucose was studied as a model system. A very homogenous thick layer of yeast cells were seen from the scanning electron micrographs on the outer walls of biopolymer. The dried weight of the cells was found to be approximately 2 g per gram of cell supporting material. Hydrophobic nature of polymer is an important factor increasing cell adhesion on polymer pieces. The dynamic flow conditions through the biomaterial due to its microporous architecture prevented exopolysaccharide matrix formation around cells and continuous washing out of toxic metabolites and dead and degraded cells from the reactor provided less diffusional limitations and dynamic living environment to the cells. In order to see the ethanol production performance of immobilized yeast cells, a large initial concentration range of glucose between 6.7 and 300 g/l was studied at 1 ml/min in continuous packed-bed reactor. The inhibition effect of glucose with increasing initial concentration was observed at above 150 g/l, a relatively high substrate concentration. The continuous fluid flow around the microenvironment of the attached cells and mass transferring ability of cell immobilized on MDBP can help in decreasing the inhibition effect of ethanol accumulation and high substrate concentration in the vicinity of the cells.     

Competitive heavy metal removal by poly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid‐co‐itaconic acid)

The competitive removal of Pb²⁺, Cu²⁺, and Cd²⁺ ions from aqueous solutions by the copolymer of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and itaconic acid (IA), P(AMPS‐co‐IA), was investigated. Homopolymer of AMPS (PAMPS) was also used to remove these ions from their aqueous solution. In the preparation of AMPS–IA copolymer, the molar percentages of AMPS and IA were 80 and 20, respectively. In order to observe the changes in the structures of polymers due to metal adsorption, FTIR spectra by attenuated total reflectancetechnique and scanning electron microscopy (SEM) pictures of the polymers were taken both before and after adsorption experiments. Total metal ion removal capacities of PAMPS and P(AMPS‐co‐IA) were 1.685 and 1.722 mmol Me²⁺/g_polymer, respectively. Experimental data were evaluated to determine the kinetic characteristics of the adsorption process. Competitive adsorption of Pb²⁺, Cu²⁺, and Cd²⁺ ions onto both PAMPS and P(AMPS‐co‐IA) was found to fit pseudo‐second‐order type kinetics. In addition, the removal orders in the competitive adsorption of these metal ions onto PAMPS and P(AMPS‐co‐IA) were found to be Cd²⁺ > Pb²⁺ > Cu²⁺ and Pb²⁺ > Cd²⁺ > Cu²⁺, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

A cost-effective anionic flocculant prepared by grafting carboxymethyl cellulose and lignosulfonate with acrylamide

How to efficiently utilize most abundant biomass of cellulose, lignin and their derivatives has become an emerging challenge as the anticipative oil depletion. In this paper, the ternary anionic copolymer of carboxymethyl cellulose-acrylamide-lignosulfonate (CAL) was successfully prepared by hydrothermal polymerization. Based on the flocculation characteristics of cationic methylene blue, the optimal polymerization process was confirmed as the raw material ratio of 1:1:1, initiator dosage of 0.9 wt %, the reaction time was 5 h and the reaction temperature was 55 °C. The results showed that the decolorization ratio was 87.5% at the CAL dosage of 600 mg/L for the 500 mg/L methylene blue simulated wastewater. The CAL achieved fast flocculation kinetics and super color removal ratios in the wide ranges of environmental pH, temperature and salt concentration. The flocculation mechanism is single charge neutralization. Moreover, the estimated treatment cost of CAL is 68.3% lower than that of commercial anionic PAM. The prepared anionic CAL flocculant has the characteristics of environmental safety, excellent flocculation performance and cost-effectiveness, which shows great potential in the field of dye wastewater treatment, and also provides a feasible way for the effective utilization of biomass resources.

     

Separation and purification of aloe polysaccharides by a combination of membrane ultrafiltration and aqueous two-phase extraction

A two-step process was developed for the purification of polysaccharides from the pulp of Aloe varavia using aqueous two-phase system (ATPS) extraction and a novel copolymer ultrafiltration membrane. The first step was ATPS under optimal separations conditions using a total composition of 18% PEG2000, 25% ammonium sulfate, pH 3.0, and 0.3 M NaCl. To form the copolymer membrane, poly(acrylonitrile-acrylamide-styrene) was prepared by solution polycondensation using azoisobutyronitrile as initiator. Then, membranes were formed from the dissolved copolymer by the phase inversion method. Copolymer structure was investigated by infrared spectrum and thermogravimetric analysis (TGA). The copolymer membrane surface and cross section were observed by scanning electron microscopy. The water flux of this membrane was 26.33 mL/(cm² h), and retention was 96% for bovine serum albumin and 34% for dextran T40000. The separation and purification of aloe polysaccharide were carried using this copolymer membrane following ATPS. The TGA of aloe polysaccharide demonstrated a high purity of the polysaccharide. By gas chromatographic analysis, it was shown that mannose is the main monosaccharide in the aloe polysaccharide, and only a few glucose residues are present.     

Synthesis of a copolymer with filter aid,dihydration, and scale inhibition abilities and its application to wet phosphoric acid

A new type of multifunction copolymer PAMA having filter aid, dihydration, and dynamic scale inhibition properties was synthesized using acrylamide (AM) and a homemade polyoxyethylene octylphenol ether acrylic ester (AOP) as the feedstock and persulfate as the initiator in an aqueous solution. The structure of the copolymer was characterized using FTIR and ¹H NMR spectroscopy. Scanning electron microscopy and the software Matlab 7.0 were used to investigate the influence of the copolymer on filter aid and scale inhibition. The results indicated that the copolymer consists of AM and AOP. The filtration rates of the phosphogypsum slurry increased 3.8 times compared to the blank group, and the water content of the phosphogypsum cake was reduced by 10.42% with the addition of 10 ppm of PAMA. The dynamic scale inhibition rate of sodium fluorosilicate and potassium fluorosilicate can reach up to 53.5% when the experiment runs continuously for 12 h. The experiments related to mechanism indicate that PAMA has a strong adsorbability and high bridge effect on the phosphogypsum crystals. Concurrently, PAMA can efficiently improve the microstructure of a filter cake and remove the scale layer of sodium fluorosilicate and potassium fluorosilicate adhering to the wall of a stainless steel pipe, which is beneficial for increasing the filter rate, decreasing the moisture content of the filter cake, and preventing scale layer formation on the filter.     

Benzalkonium chloride/titanium dioxide as an effective corrosion inhibitor for carbon steel in a sulfuric acid solution

In this study, the corrosion performance of carbon steel samples in 0.5 M sulfuric acid by the addition of novel inhibitors, 200 ppm of (25% and 50%) titanium dioxide nanoparticles in benzalkonium chloride, was thoroughly investigated. Gravimetric measurements, cyclic and linear potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and hydrogen collection by water displacement evaluated inhibition performance. Analogously, TiO₂/ILB (50%), TiO₂/ILB (75%), and ILB inhibitors enhanced corrosion protection with over 80% inhibition efficiency in electrochemical tests. In addition, weight loss and hydrogen collection measurements reached comparable results. According to potentiodynamic polarization curves, inhibitors exhibited dual behavior, but cathodic protection was more predominant. Scanning electron microscopy (SEM) was employed to examine the surface morphology before and after immersion using corrosion tests. The correlation between electronic properties and inhibition efficiencies of tilted inhibitors was determined by simple linear regression. Electronic properties were calculated for neutral and protonated forms using a polarizable continuum model by the DFT method at the B3LYP/6-311+G (d, p) level of theory. The active adsorbed sites of HM1-HM3 on the metal surface were determined by analyzing their corresponding electrostatic surface potentials (ESP). Furthermore, molecular dynamics simulations were performed to illustrate the most conceivable adsorption configuration between the inhibitors and metal surfaces.     

Synthesis of MA/AA/MA-β-CD/SHP Quadripolymer and Its Performance Evaluation as Scale Inhibitor

A new scale inhibitor MA/AA/MA-β-CD/SHP was prepared from maleic anhydride, acrylic acid, sodium hypophosphite, and MA-β-CD via the method of free radical polymerization in aqueous solution. The MA-β-CD was obtained through the modification of β-cyclodextrin (β-CD) with maleic anhydride (MA). Results of performance evaluation showed that the synthesized copolymer has excellent scale inhibition effect for the calcium scale, and the resistance rate of silicon scale up to 79.81%. The structure, thermal property, and morphology of the copolymer were characterized by FTIR, TGA, and SEM. From crystallization data and morphology of the scale crystals it was found that the copolymer scale inhibitor can make the crystal lattice distortion, and has a good dispersing ability after addition of the scale inhibitor.     

New low-cost tubular ceramic microfiltration membrane based on natural sand for tangential urban wastewater treatment

In wastewater treatment, the development of low-cost separation methods is of significant importance. Low-cost membranes based on natural materials have become a highly active research topic in recent years. Herein, using low-cost natural Moroccan sand, new ceramic supports have been developed and characterized using different techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), along with scanning electron microscope (SEM). Plastic paste (average particle size ≤125 µm) was blended with organic additives and water, then the obtained paste was extruded into porous tubular supports. The support had a porosity of 43%, water permeability of 1928 L/h m² bar, excellent chemical and mechanical properties and an average pore diameter in the range of 8–15 µm after firing at 950 °C/2 h. As per SEM analysis, the tubular supports had a smooth and crack-free surface. The slip casting process was used to create a microfiltration layer from the same natural sand powder (average particle size ≤63 µm) using a mixture of powder sand, water, and polyvinyl alcohol solution. The water permeability of the microfiltration membrane sintered at 950 °C/2 h was 1052 L/h m² bar, the average pore size diameter was about 0.90 µm and 82% of pores had a diameter ≤1.00 µm. The obtained microfiltration membrane was tested for the treatment of urban wastewater. The membrane showed excellent separation performance in turbidity removal and chemical oxygen demand.