Tunable Nanoporous Network Polymer Nanocomposites having Size‐Selective Ion Transfer for Dye‐Sensitized Solar Cells

Nanoporous network polymer nanocomposites with tunable pore size for size‐dependent selective ion transport are successfully prepared via the surface‐induced cross‐linking polymerization of methyl methacrylate (MMA) and 1,6‐hexanediol diacrylate (HDDA) on the surfaces of nanocrystalline TiO₂ particles. The morphologies of the porous network polymer layer and nanopores were investigated by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE‐SEM), and Brunauer–Emmett–Teller (BET) experiments. The porous layer size‐selectively screened the ions that contacted the nanocrystalline TiO₂ particles, as demonstrated by ion conductivity measurements, electrochemical impedance spectroscopy (EIS), and transient absorption spectroscopy (TAS).     

Graft copolymerization of methyl methacrylate onto Bombyx mori initiated by semiconductor-based photocatalyst

Methyl methacrylate (MMA) was graft copolymerized onto Bombyx mori fibre (natural silk). The graft copolymerization was carried out by photopolymerization of MMA using semiconductor particles (CdS) as photocatalyst in the presence of visible light. The effect of additives like triethylamine (Et(3)N) and ethylene glycol on graft copolymerization was studied. We have achieved 2-10% graft conversion with 10-20% homopolymer formation. After removal of the homopolymer, the graft copolymer (grafted fibre) was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC). The chemical resistance of grafted fibre was compared with virgin one.     

Preparation and copolymerization of a novel carbohydrate containing monomer

A novel carbohydrate containing monomer was prepared by simple reaction of 2-vinyl-4,4′-dimethylazlactone (VDMA) and 1,2;5,6-diisopropylidene--d-glucofuranose (DAG). The monomer was easily homopolymerized as well as copolymerized with methyl methacrylate (MMA) to give high molecular weight polymers using free radical conditions. Upon removal of the isopropylidene groups from the polymer, water contact angles decreased for polymeric films of the material, indicating a more hydrophilic surface. The addition of a carbohydrate moiety to MMA copolymers increases its hydrophilicity and allows for potential use of the new polymer as a biomaterial in a variety of applications.     

Stimuli-responsive surfactant/phospholipid stabilized colloidal dispersions and their film formation

Methyl methacrylate (MMA) and n-butyl acrylate (nBA) were copolymerized into stable colloidal particles in the presence of micelle forming sodium dioctyl sulfosuccinate (SDOSS) and liposome forming 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) in aqueous media that serve as thermodynamically stable loci for lipophilic monomers and nanostructured templates. These studies show for the first time that hollow colloidal particles may coalesce to form polymeric films and the combination of SDOSS and DLPC dispersing agents provides a stimuli-responsive environment during film formation through which individual surface stabilizing components can be driven to the film-air (F-A) or film-substrate (F-S) interface. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) of p-MMA/nBA colloidal dispersions revealed preferential and enhanced mobility of SDOSS and DLPC lipid rafts to the F-A and F-S interfaces in response to thermal, ionic, and enzymatic stimuli.     

New hybrid latexes from a soybean oil-based waterborne polyurethane and acrylics via emulsion polymerization

A series of new waterborne polyurethane (PU)/acrylic hybrid latexes have been successfully synthesized by the emulsion polymerization of acrylic monomers (butyl acrylate and methyl methacrylate) in the presence of a soybean oil-based waterborne PU dispersion using potassium persulfate as an initiator. The waterborne PU dispersion has been synthesized by a polyaddition reaction of toluene 2,4-diisocyanate and a soybean oil-based polyol (SOL). The resulting hybrid latexes, containing 15-60 wt % SOL as a renewable resource, are very stable and exhibit uniform particle sizes of 125 +/- 20 nm as determined by transmittance electronic microscopy. The structure, thermal, and mechanical properties of the resulting hybrid latex films have been investigated by Fourier transform infrared spectroscopy, solid state 13C NMR spectroscopy, dynamic mechanical analysis, extraction, and mechanical testing. Grafting copolymerization of the acrylic monomers onto the PU network occurs during the emulsion polymerization, leading to a significant increase in the thermal and mechanical properties of the resulting hybrid latexes. This work provides a new way of utilizing renewable resources to prepare environmentally friendly hybrid latexes with high performance for coating applications.     

Injectable polymeric microspheres with X-ray visibility. Preparation,properties, and potential utility as new traceable bulking agents

The copolymer of methyl methacrylate (MMA) and 2-[2',3',5'-triiodobenzoyl]oxoethyl methacrylate (1), ratio 3:1 (mass:mass), was prepared via a free-radical polymerization in bulk. The copolymer (M(w) = 97.8 kD and M(n) = 41.5 kD) was dissolved in chloroform and subsequently transformed into beads with a diameter in the micrometer range, using a solvent evaporation technique. The resulting microbeads were characterized by different techniques, including NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography, and scanning electron microscopy. The latter technique was used as the basis for statistical analysis of the bead size. Typically, an average diameter of 96 microm and a standard deviation of 21 microm were obtained. The beads were also subjected to some preliminary tests regarding cytotoxicity. The copolymer of MMA and 1 contains covalently bound iodine. Therefore, the material is intrinsically radiopaque, i.e., capable of absorbing X-radiation while no contrast additive is needed. Our interest in these microspheres stems primarily from their possible utility as injectable and afterward traceable (radiopaque) bulking agents, e.g., for use in urology for the treatment of female stress incontinence due to sphincter deficiency. As a first test into this direction, a sample of the microbeads was mixed with ethylene glycol, and the resulting suspension was studied with respect to injectability and radiopacity. The results suggest that the radiopaque microbeads may provide access to improved bulking agents. Further modification of the surface may be necessary in order to suppress the migratory aptitude of the radiopaque polymeric microspheres in vivo.     

Morphological,biochemical and kinetic properties of lipase from Candida rugosa immobilized in zirconium phosphate

Zirconium phosphate (ZrP), a low-cost inorganic material with well-defined physicochemical properties, was successfully used as support for immobilizing Candida rugosa lipase by covalent bonding. The immobilized derivative showed high catalytic activity in both aqueous and non-aqueous media. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy measurements demonstrated that the ZrP fulfilled the morphological requirements for use as a matrix for immobilizing lipases. The free and immobilized lipases were compared in terms of pH, temperature and thermal stability. The immobilized lipase had a higher pH optimum (7.5) and higher optimum temperature (50°C) than the free lipase. Immobilization also increased the thermal stability. The hydrolysis of p-nitrophenyl palmitate (pNPP) by immobilized lipase, examined at 37°C, followed Michaelis–Menten kinetics. Values for K_m=1.18 µM and V_max=325Umg^?1 indicated that the immobilized system was subject to mass transfer limitations. The immobilized derivative was also tested under repetitive reaction batches in both ester hydrolysis and synthesis.     

Syntheses and characterisation of graft copolymers of maize starch and methacrylonitrile

Grafting of methacrylonitrile (MAN) onto dried maize starch using ceric ammonium nitrate (CAN) as an initiator has been studied gravimetrically under nitrogen atmosphere in aqueous medium. The percentage grafting is favoured by increasing monomer concentration and reaction time but is affected by higher concentration of initiator and high temperature. No grafting was observed beyond 45°C. The optimum conditions established for grafting were: [CAN]=0.002 mol/l which was added in molar nitric acid; [MAN]=0.755 mol/l; reaction time, 180 min; and temperature, 35°C. The graft copolymers were analyzed by infrared spectroscopy and acid hydrolysis. The grafting of methacrylonitrile onto starch does not alter the thermal stability of starch. The crystalline region of starch was also involved in grafting. Scanning electron microscopy showed a thick polymer coating of grafted PMAN on the starch surface.     

Rheological Properties of Aqueous Dispersions of Xanthan Gum Containing Different Chloride Salts Are Impacted by both Sizes and Net Electric Charges of the Cations

Xanthan gum (XG) is one of the most effective thickener agents used worldwide. In foods products, one of the factors affecting its physical properties is the ionic strength of the medium. Though it is well known that XG rheological properties in aqueous media depend on both type and concentration of electrolytes, correlations between such dispersion properties and molecular aspects of dispersed XG chains are still to be more deeply studied. Thus, in the present study, aqueous XG dispersions [200 mg?(100 mL)^?1] added of Na, K, Mg or Ca chlorides (ionic strength 50 mM or 100 mM) were rheologically characterized, and the corresponding results were explained based on different physicochemical analyses. Comparing to the control (unsalted XG dispersion), KCl and CaCl₂ tended to produce a more drastic decrease of apparent viscosities of XG dispersions than NaCl and MgCl₂. In dynamic-oscillatory assays, the predominance of elastic character over viscous character was more evident for XG dispersions containing KCl and CaCl₂, in particular at frequencies > 0.1 Hz. XG dispersions containing KCl or CaCl₂ also presented smaller pH and |ζ-potentials| values, as well as greater densities and average hydrodynamic diameters of dispersed XG chains, when compared to respective counterparts containing NaCl or MgCl₂. As the decreasing order of the cations radii is K⁺?>?Ca²⁺ ≈ Na⁺?>?Mg²⁺, our results allowed deducing that not only the net electric charges of the cations, but also their sizes, should be considered when analyzing the effect of chloride salts on rheological properties of XG aqueous dispersions, according to the desired for this hydrocolloid (weak thickener, strong thickener or pro-gelling agent).     

Grafted megaporous materials as ion‐exchangers for bioproduct adsorption

Megaporous chromatographic materials were manufactured by a three‐step procedure, including backbone synthesis, chemical grafting, and introduction of ion‐exchange functionality. The backbone of the adsorbent cylindrical bodies was prepared by polymerization of methacrylic acid and poly(ethylene glycol) diacrylate at sub‐zero temperatures. Grafting was performed employing glycidyl methacrylate and a chemical initiator, cerium ammonium nitrate. The degree of grafting was adjusted by modifying the concentration of the initiator in the reaction mixture to a range of values (23, 39, 62, 89, and 105%). Further, the pendant epoxy‐groups generated by the previous step were reacted to cation‐ and anion‐exchanging moieties utilizing known chemical routes. Infrared spectroscopy studies confirmed the incorporation of epoxy and ion‐exchanger groups to the backbone material. Optimized materials were tested for chromatography applications with model proteins; the dynamic binding capacity, as recorded at 10% breakthrough and 2.0 × 10^?4 m/s superficial velocity, were 350 and 58 mg/g for the cation‐exchanger and the anion‐exchanger material, respectively. These results may indicate that long tentacle‐type polymer brushes were formed during grafting therefore increasing the ability of the megaporous body to efficiently capture macromolecules. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29: 386–393, 2013     

Synthesis, characterization and optical properties of tin oxide nanoclusters prepared from a novel precursor via thermal decomposition route

As a new precursor, [bis(2-hydroxy-1-naphthaldehydato)tin(II)]; ([Sn(HNA)₂]), complex was used in thermal decomposition process for the synthesis of tin oxide (SnO₂) nanoclusters. The steric hindrance of the precursor raises the need of using co-surfactant, therefore oleylamine (C₁₈H₃₇N) was applied as the only surfactant of the reaction. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. Also the novel precursor was thermal treated in solid-state reaction in different temperature, 400, 500, and 600 °C. Synthesized tin dioxide nanoclusters with tetragonal phase, have average size of 1.5-4 nm. Finally, optical properties of the products were examined and investigated by photoluminescence spectra.     

2‐(4‐Ethoxy phenyl)‐4‐phenyl quinoline organic phosphor for solution processed blue organic light‐emitting diodes

This paper reports the synthesis and characterization of 2‐(4‐ethoxyphenyl)‐4‐phenyl quinoline (OEt‐DPQ) organic phosphor using an acid‐catalyzed Friedlander reaction and the preparation of blended thin films by molecularly doping OEt‐DPQ in poly(methyl methacrylate) (PMMA) at different wt%. The molecular structure of the synthesized phosphor was confirmed by Fourier transform infra‐red (FTIR) spectroscopy and nuclear magnetic resonance spectra (NMR). Surface morphology and percent composition of the elements were assessed by scanning electron microscopy (SEM) and energy dispersive analysis of X‐rays (EDAX). The thermal stability and melting point of OEt‐DPQ and thin films were probed by thermo‐gravimetric analysis (TGA)/differential thermal analysis (DTA) and were found to be 80°C and 113.6°C, respectively. UV–visible optical absorption spectra of OEt‐DPQ in the solid state and blended films produced absorption bands in the range 260–340 nm, while photoluminescence (PL) spectra of OEt‐DPQ in the solid state and blended thin films demonstrated blue emission that was registered at 432 nm when excited at 363–369 nm. However, solvated OEt‐DPQ in chloroform, tetrahydrofuran or dichloromethane showed a blue shift of 31–43 nm. Optical absorption and emission parameters such as molar extinction coefficient (ε), energy gap (E_g), transmittance (T), reflectance (R), refractive index (n), oscillator energy (E₀) and oscillator strength (f), quantum yield (φ_f), oscillator energy (E₀), dispersion energy (E_d), Commission Internationale de l'Éclairage (CIE) co‐ordinates and energy yield fluorescence (E_F) were calculated to assess the phosphor's suitability as a blue emissive material for opto‐electronic applications such as organic light‐emitting diodes (OLEDs), flexible displays and solid‐state lighting technology.     

The single source preparation of rod-like mercury sulfide nanostructures via hydrothermal method

High-quality and high-yield rod-like HgS dendrites with cubic structure was synthesized by a wet chemical route, without using any surfactant and organic solvents at 180 °C for 5 h, by using Hg(NO₃)₂·H₂O and thioglycolic acid (TGA) as starting reagents. The obtained HgS with different morphologies and sized were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). The effects of reaction parameters, such as temperature, precursor concentration and reaction time on the morphology and particle size of products were investigated. Our experimental results showed that temperature reaction played key role in the final morphology of HgS. The morphology of HgS nanostructures could be changed from rod-like dendrites to nanoparticles by only decreased temperature reaction to 110 °C. In the present study the possible mechanism of HgS nanoparticles growth to dendrites in the aqueous solution was also discussed and the optical properties rod-like HgS dendrites were investigated by ultraviolet-visible (UV-Vis) spectroscopy.     

Identification of covalent binding sites of ethyl 2-cyanoacrylate,methyl methacrylate and 2-hydroxyethyl methacrylate in human hemoglobin using LC/MS/MS techniques

Acrylates are used in vast quantities, for instance in paints, adhesive glues, molding. They are potent contact allergens and known to cause respiratory hypersensitivity and asthma. Here we study ethyl 2-cyanoacrylate (ECA), methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA). There are only limited possibilities to measure the exposure to acrylates, especially for biological monitoring. The aim of the present study was to investigate the chemical structures of adducts formed after reaction of hemoglobin (Hb) with ECA, MMA, and HEMA. This information may be used to identify adducted Hb peptides for biological monitoring of exposure to acrylates. Hb-conjugates with ECA, MMA, and HEMA were synthesized in vitro. The conjugates were digested by trypsin and pronase E. Adducted peptides were characterized and analyzed by liquid chromatography and nano electro spray/hybrid quadrupole time-of-flight mass spectrometry (MS) as well as tandem quadrupole MS. The search for the adducted peptides was facilitated by visualizing the MS data by different computer programs. The results showed that ECA binds covalently to cysteines at the 104 position in the α and the position 112 in the β-chains in Hb. MMA and HEMA bound to all the cysteines in both chains, Cys¹⁰⁴ in the α-chain and Cys⁹³ and 112 in the β-chain. The full-length spectra of in un-digested Hb confirmed this binding pattern. There was no reaction with N-acetyl-l-lysine at physiological pH. The adducted peptides were possible to measure using LC/MS/MS in selected reaction monitoring mode. These peptides may be used for biological monitoring of exposure to ECA, MMA and HEMA.     

Improvement of decay resistance of wood via combination treatment on wood cell wall: Swell-bonding with maleic anhydride and graft copolymerization with glycidyl methacrylate and methyl methacrylate

Poplar wood (Populus ussuriensis Kom) was modified by a novel combined two-step treatment to improve its decay resistance. Maleic Anhydride (MAN) was first employed to swell and bond to wood cell wall, and then mixed monomers of glycidyl methacrylate/methyl methacrylate (GMA/MMA) were used to graft copolymerization within wood cell lumen. The swelling and bonding of cell wall by MAN, interfacial compatibility between resultant polymer from GMA/MMA monomers and wood cell wall, and decay resistance of all composites were tested and analyzed by Scanning electron microscopy–Energy dispersive X-ray (SEM–EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) apparatus. The results indicate that the volume of poplar wood treated by MAN swells about 9% with about 15% of weight percent gain, and MAN chemically bonds to the cell wall through substitution reaction with hydroxyl group, and the grafting adduct mainly remains as an amorphous form. The resultant Poplar-MAN shows improved decay resistance of 69.79% against brown fungus (Gloeophyllum trabeum (Pers. ex Fr.) Murr.) and 81.42% against white fungus (Phanerochaete chrysosporium Burdsall.) over those of untreated Poplar, respectively. After the combined two-step treatment, GMA and MMA are copolymerized within wood cell lumen, and the resultant polymer is also grafted onto wood cell wall, resulting in the improvement of interfacial compatibility between polymer and wood substance without obvious gaps. The decay resistance of the resultant composite from the combined two-step treatment against the brown decay fungus and the white decay fungus is improved by 97.64% and 99.17%, respectively, compared with those of untreated poplar wood; and also more excellent than those of MMA treated wood, GMA/MMA monomers treated wood, organic 3-Iodo-2-Propynyl Butyl Carbamate (IPBC) treated wood and inorganic boron compounds treated wood, respectively.     

Morphological, biochemical and kinetic properties of lipase from Candida rugosa immobilized in zirconium phosphate

Zirconium phosphate (ZrP), a low-cost inorganic material with well-defined physicochemical properties, was successfully used as support for immobilizing Candida rugosa lipase by covalent bonding. The immobilized derivative showed high catalytic activity in both aqueous and non-aqueous media. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy measurements demonstrated that the ZrP fulfilled the morphological requirements for use as a matrix for immobilizing lipases. The free and immobilized lipases were compared in terms of pH, temperature and thermal stability. The immobilized lipase had a higher pH optimum (7.5) and higher optimum temperature (50°C) than the free lipase. Immobilization also increased the thermal stability. The hydrolysis of p-nitrophenyl palmitate (pNPP) by immobilized lipase, examined at 37°C, followed Michaelis-Menten kinetics. Values for K_m=1.18 µM and V_max=325Umg^-1 indicated that the immobilized system was subject to mass transfer limitations. The immobilized derivative was also tested under repetitive reaction batches in both ester hydrolysis and synthesis.     

Biodegradation of cellulose by β-glucosidase and cellulase immobilized on a pH-responsive copolymer

Biodegradation of cellulose involves synergistic action of the endoglucanases, exoglucanases and β-glucosidases in cellulase. However, the yield of glucose is limited by the lack of β-glucosidase to hydrolyze cellobiose into glucose. In this study, β-glucosidase as a supplemental enzyme along with cellulase are co-immobilized on a pHresponsive copolymer, poly (MAA-co-DMAEMA-co-BMA) (abbreviated P_MDB, where MAA is α-methacrylic acid, DMAEMA is 2-dimethylaminoethyl methacrylate and BMA is butyl methacrylate). The thermal and storage stabilities of PMDB with immobilized enzymes are improved greatly, compared with those of free cellulase. Biodegradation of cellulose is carried out in a pH-responsive recyclable aqueous two-phase system composed of poly (AA-co- DMAEMA-co-BMA) (abbreviated P_{ADB 3.8}, where AA is acrylic acid) and P_MDB. Insoluble substrate and P_MDB with immobilized cellulase and β-glucosidase (Celluclast 1.5L FG and Novozyme 188, respectively) were biased to the bottom phase, while the product was partitioned to the top phase in the presence of 40 mM (NH₄)₂SO₄. When the degradation reaction of cellulose is carried out with PMDB containing immobilized cellulase and β-glucosidase, the concentration of glucose reaches 4.331 mg/mL after 108 h. The yield of glucose is 50.25% after P_MDB containing the immobilized enzymes is recycled five times.     

Influence of β-cyclodextrin on the Properties of Norfloxacin Form A

Cyclodextrins are able to form host–guest complexes with hydrophobic molecules to result in the formation of inclusion complexes. The complex formation between norfloxacin form A and β-cyclodextrin was studied by exploring its structure affinity relationship in an aqueous solution and in the solid state. Kneading, freeze-drying, and physical mixture methods were employed to prepare solid complexes of norfloxacin and β-cyclodextrin. The solubility of norfloxacin significantly increased upon complexation with β-cyclodextrin as demonstrated by a solubility isotherm of the A_L type along with the results of an intrinsic dissolution study. The complexes were also characterized in the solid stated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffractometry, scanning electron microscopy (SEM), and solid-state nuclear magnetic resonance (ssNMR) spectrometry. The thermal analysis showed that the thermal stability of the drug is enhanced in the presence of β-cyclodextrin. Finally, the microbiological studies showed that the complexes have better potency when compared with pure drug.KEY WORDS: bioassay, complexation, intrinsic dissolution, norfloxacin, β-cyclodextrin     

Demystification of luminescence properties and the near imperceptible thermal quenching of Sm3+-doped tungstate phosphors

Ultra-high thermally stable Ca₂MgWO₆:xSm³⁺ (x = 0.5, 0.75, 1, 1.25, and 1.5 mol%) double perovskite phosphors were synthesized through solid-state reaction method. Product formation was confirmed by comparing the X-ray diffraction (XRD) patterns of the phosphors with the standard reference file. The structural, morphological, thermal, and optical properties of the prepared phosphor were examined in detail using XRD, Fourier transform infrared spectra, scanning electron microscopy, diffused reflectance spectra, thermogravimetric analysis (TGA), photoluminescence emission, and temperature-dependent PLE (TDPL). It was seen that the phosphor exhibited emission in the reddish region for the near-ultraviolet excitation with moderate Colour Rendering Index values and high colour purity. The optimized phosphor (x = 1.25 mol%) was found to possess a direct optical band gap of 3.31 eV. TGA studies showed the astonishing thermal stability of the optimized phosphor. Additionally, near-zero thermal quenching was seen in TDPL due to elevated phonon-assisted radiative transition. Furthermore, the anti-Stokes and Stokes emission peaks were found to be sensitive toward the temperature change and followed a Boltzmann-type distribution. All these marked properties will make the prepared phosphors a suitable candidate for multifield applications and a fascinating material for further development.