Bis Methyl Research Articles

Smart valve: Polymer actuator to moisture soil control

The adequate use of water for irrigation in agriculture is a widespread concern. In this study, we developed an autonomous smart system consisting of a new hydrogel into a valve, which regulates the flow of water according to soil moisture. The main objective was to find an alternative to avoid waste of water. Yet, hydrogel development and study of the quantitative relationship between its properties and soil moisture were also important to achieve this aim. The hydrogel was synthesized from tris[(hydroxymethyl) methyl]acrylamide (NAT) copolymerized with methyl methacrylate (MMA) and crosslinked with N,N′-methylene bis(acrylamide) (BIS). The use of cellulose (2% w/v) avoids hydrogel breakage during swelling-deswelling. The relation between swelling ratio, force of expansion and moisture was evaluated for the novel hydrogel. It was found that as soil moisture increases, the gel swells, while expansion force diminishes. These properties showed linear relationship in the range studied. The three-dimensional network formed by flexible chains has the attribute of exerting a great force when it expands (≅15N for a hydrogel disc of 1cm2). When the material was put in contact with the ground, it swelled and deswelled without breaking. The hydrogel within the valve was able to open and close the passage of water. The valve prototype was tested during four months with a plant. During this period, only three liters of irrigation water were used monthly, instead of about half a liter daily. Hence, an autonomous actuator capable of controlling soil moisture was developed based on a new hydrogel.

Poly(N‐vinyl pyrrolidone)‐block‐Poly(N‐vinyl carbazole)‐block‐poly(N‐vinyl pyrrolidone) triblock copolymers: Synthesis via RAFT/MADIX process, self‐assembly behavior, and photophysical properties

ABSTRACTPoly(N‐vinyl pyrrolidone)‐block‐poly(N‐vinyl carbazole)‐block‐poly(N‐vinyl pyrrolidone) (PVP‐b‐PVK‐b‐PVP) triblock copolymers were synthesized via sequential reversible addition‐fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process. First, 1,4‐phenylenebis(methylene)bis(ethyl xanthate) was used as a chain transfer agent to mediate the radical polymerization of N‐vinyl carbazole (NVK). It was found that the polymerization was in a controlled and living manner. Second, one of α,ω‐dixanthate‐terminated PVKs was used as the macromolecular chain transfer agent to mediate the radical polymerization of N‐vinyl pyrrolidone (NVP) to obtain the triblock copolymers with various lengths of PVP blocks. Transmission electron microscopy (TEM) showed that the triblock copolymers in bulks were microphase‐separated and that PVK blocks were self‐organized into cylindrical microdomains, depending on the lengths of PVP blocks. In aqueous solutions, all these triblock copolymers can self‐assemble into the spherical micelles. The critical micelle concentrations of the triblock copolymers were determined without external adding fluorescence probe. By analyzing the change in fluorescence intensity as functions of the concentration, it was judged that the onset of micellization occurred at the concentration while the FL intensity began negatively to deviate from the initial linear increase with the concentration. Fluorescence spectroscopy indicates that the self‐assembled nanoobjects of the PVP‐b‐PVK‐b‐PVP triblock copolymers in water were capable of emitting blue/or purple fluorescence under the irradiation of ultraviolet light. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1852–1863

ChemInform Abstract: Novel Approaches to Pharmacology‐Oriented and Energy Rich Organic Nitrogen—Oxygen Systems

AbstractReview: [79 refs.

Blood compatibility of heparin-inspired, lactose containing, polyureas depends on the chemistry of the polymer backbone

Sulfated glycopolymers were synthesized from diisocyanates and lactose containing diamines. Blood compatibility assays indicated highly sulfated glycopolymers with methylene bis(4-cyclohexyl isocyanate) backbones result in prolonged clotting times.

ChemInform Abstract: Synthesis of Allenyl Esters by Horner—Wadsworth—Emmons Reactions of Ketenes Mediated by Isopropylmagnesium Bromide.

The synthesis of conjugated allenyl esters (tri-substituted allenes) was achieved by magnesium(II)-mediated Horner–Wadsworth–Emmons reaction of methyl bis(2,2,2-trifluoroethyl)phosphonoacetate with disubstituted ketenes. In addition, a novel access to α-fluorinated allenyl carboxamides (tetrasubstituted allenes) is presented.

Human mesenchymal stem cell behavior on segmented polyurethanes prepared with biologically active chain extenders.

The development of elastomeric, bioresorbable and biocompatible segmented polyurethanes (SPUs) for use in tissue-engineering applications has attracted considerable interest because of the existing need of mechanically tunable scaffolds for regeneration of different tissues, but the incorporation of osteoinductive molecules into SPUs has been limited. In this study, SPUs were synthesized from poly (ε-caprolactone)diol, 4,4'-methylene bis(cyclohexyl isocyanate) using biologically active compounds such as ascorbic acid, L-glutamine, β-glycerol phosphate, and dexamethasone as chain extenders. Fourier transform infrared spectroscopy (FTIR) revealed the formation of both urethanes and urea linkages while differential scanning calorimetry, dynamic mechanical analysis, X-ray diffraction and mechanical testing showed that these polyurethanes were semi-crystalline polymers exhibiting high deformations. Cytocompatibility studies showed that only SPUs containing β-glycerol phosphate supported human mesenchymal stem cell adhesion, growth, and osteogenic differentiation, rendering them potentially suitable for bone tissue regeneration, whereas other SPUs failed to support either cell growth or osteogenic differentiation, or both. This study demonstrates that modification of SPUs with osteogenic compounds can lead to new cytocompatible polymers for regenerative medicine applications.

Fire behaviour and morphology of epoxy matrices designed for composite materials processed by infusion

The present work is about the investigation of the fire behavior of epoxy networks designed for structural composite materials used in aeronautics. Two high-Tg, infusion-suitable epoxy systems were studied. A model system was based on tetraglycidyl(diaminodiphenyl)methane (TGDDM) as an epoxy prepolymer, and 4,4′ methylene bis(2,6-diethylaniline) (MDEA) as a curing agent. A second system was based on a commercial aeronautic formulation specially designed for the infusion process. The triSilanolPhenyl POSS (POSSOH) was chosen as an additive due to the presence of phenyl groups and silanol functions that could possibly react with the network compounds. In this perspective, an aluminium salt (aluminium tri(acetylacetonate)) was introduced in presence of POSSOH in order to enhance the reaction of the additive with the epoxy monomer. The study of the morphology revealed intricate structures, with an overall good dispersion of the POSSOH in the epoxy networks. In terms of fire behaviour, same tendencies were observed for both epoxy networks, i.e. the combined presence of POSSOH and the aluminium-based additive brought significant improvements with a substantial and effective intumescent-like behaviour.

Removal of safranine T and brilliant cresyl blue dyes from water by carboxy methyl cellulose incorporated acrylic hydrogels: Isotherms, kinetics and thermodynamic study

Polymer hydrogels having numerous functional groups can efficiently remove the low concentration of an industrial dye from water. This kind of functional adsorbent can be prepared by integrating a low cost polymer obtained from a naturally occurring polysaccharide such as sodium carboxy methyl cellulose (CMC) with a synthetic polymer like acrylic polymers. In the present work acrylic acid (AA)/N'N, methylene bis acrylamide(MBA), sodium acrylate/MBA and comonomers AA /hydroxyl ethyl methacrylate (HEMA)/MBA were free radical polymerized in an aqueous solution of CMC to produce several composite hydrogels. The swelling and dye adsorption properties of the hydrogels increased with an increase in the wt% of CMC. The hydrogels prepared with sodium polyacrylate and 6 wt% of CMC showed the highest swelling in water and also the highest adsorption (mg/g gel)/removal% of 9.45/94.5 and 9.89/98.9,respectively for 10 mg/L of Safranine T and brilliant cresyl blue dye, respectively, from water.

SYNTHESIS AND CHARACTERIZATION OF NATURAL FIBRE REINFORCED POLYURETHANE COMPOSITES BASED ON CARDANOL

In recent studies importance has been given to the use of natural products from renewable resources due to the decrease in the supply and price escalations of petroleum raw materials. Cardanol based resole type phenolic resin has been synthesized by condensing cardanol with furfural in a particular mole ratio using dicarboxylic acid catalyst such as phthalic acid. Polyurethane sheets were prepared by treating cardanol furfural resin with 4,41 – methylene bis(cyclohexyl isocyanate) and the catalyst dibutyltin dilaurate. Natural fibres are prospective reinforcing materials and their use until now has been more traditional than technical. Among the various fibres sisal is of particular interest in that its composites have high impact strength besides having moderate tensile and flexural properties compared to other fibres. Fibre reinforced polyurethane composites have been prepared by treating sisal fibre (10%) into polyurethane. The physico chemical, spectral and thermal properties of polyurethane and fibre reinforced polyurethane composites have been studied.

Synthesis, Characterization, and Electrospinning of Calcium-Containing Polyurethane Urea

Calcium-containing segmented polyurethane urea was synthesized using a calcium salt of p-aminobenzoic acid, polytetramethylene glycol, and 4,4′-methylene bis(cyclohexyl isocyanate) and thereafter fabricated into three-dimensional scaffolds for the use in biomedical applications. Biocompatibility evaluation of the polymer showed that this newly developed metal-containing polyurethane urea demonstrated good cytocompatibility and hemocompatibility. The fabricating ability of the metal-containing polymer was studied by the electrospinning process. The effect of various parameters such as polymer concentration, applied voltage, and flow rate on the electrospinning process, morphology, and diameter of the resultant fibers was investigated. The findings indicate that increasing the concentration and flow rate of the solution increases the fiber diameter. It was also demonstrated that increasing the applied voltage decreases the fiber diameter. Mechanical property evaluation of the scaffolds showed that the strength of the scaffold depends on both the diameter and morphology of the fibers. As the fiber diameter increases from 1.6 to 3.02 μm, the tensile strength enhanced from 3 to 7 MPa.

Synthesis and characterization of an ultra-soft poly(carbonate urethane)

A high performance, thermoplastic polyurethane elastomer was synthesized with methylene bis(4-cyclohexylisocyanate), 1,4-butanediol as a chain extender and a polycarbonate polyol containing 1,6-hexanediol and 3-methyl-1,5-pentanediol. SAXS data evidences an interdomain “center-to-center” distance of 45Å. DSC traces evidence one glass transition temperature and weak melting region. Surprisingly, the material is ultra-soft with a Shore A hardness of 64, but does not undergo any blocking. DMA analysis reveals a low temperature secondary relaxation and the glass to rubber transition followed by a rubbery plateau. In tensile set experiments strain recovery averaged 96–98%. The PCPU exhibits partial self-healing after rupture without the addition of additives or imbedded healing agents. Self-healing is attributed to interdiffusion and hydrogen bonding mechanism, where rehealing is possible. FTIR measurements characterize hydrogen bonding.

Synthesis of Allenyl Esters by Horner–Wadsworth–Emmons Reactions of Ketenes Mediated by Isopropylmagnesium Bromide

The synthesis of conjugated allenyl esters (tri-substituted allenes) was achieved by magnesium(II)-mediated Horner–Wadsworth–Emmons reaction of methyl bis(2,2,2-trifluoroethyl)phosphonoacetate with disubstituted ketenes. In addition, a novel access to α-fluorinated allenyl carboxamides (tetrasubstituted allenes) is presented.

Temperature-responsive poly(N-vinylcaprolactam-co-hydroxyethyl methacrylate) nanogels for controlled release studies of curcumin

A series of nanogels (NGs) were developed from N-vinylcaprolactam and hydroxyethyl methacrylate through free radical emulsion polymerization using methylene bis acrylamide as cross-linker. Curcumin, an anticancer agent was successfully loaded into these NGs via equilibrium in situ method. These NGs were characterized by Fourier transform spectroscopy (FTIR), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and dynamic light-scattering experimental (DLS) techniques. The formation of co-polymeric NGs was confirmed by FTIR analysis. DSC results reveal that the drug was molecularly dispersed in the NG networks. TEM results indicate the formation of NGs, in a spherical shape, with the size of 150 nm. The DLS results also support the formation and size of NGs. An in vitro release study indicates that the NGs may be potentially useful for targeted drug delivery applications.

Stimuli-responsive polymers. 11. Highly adaptive poly(urea-amide)s that display solvent, light and heat modulated chiroptical behavior

Commercially available 4,4′-methylene bis(phenyl isocyanate), when copolymerized with the atropisomeric monomer S-(-)-1,1′-binaphthyl-2,2′-diamine, provides convenient access to urea-linked polymers that exhibit exceptional levels of solvent-dependent chiroptical behavior. The use of different solvent media affords a high degree of control over both the sign and magnitude of the optical rotations that are ultimately displayed by these conformationally dynamic systems. The polarity of the solvent environment appears to play a role in shaping polymer responses. A number of related poly(urea-amide) constructs fitted with azobenzene backbone segments are also sensitive to the application of light and heat, ultimately providing for highly adaptive material systems with chiroptical outputs that can be dynamically modulated in real-time by a combination of different input signals.

Syntheses and Structures of [CH2(NCnH2n)2]Mo(CO)4 (n = 4,5) Complexes with Bis(cycloamine) Ligands Easily Prepared from CH2Cl2

Dipyrrolidylmethane, CH2(pyr)2, and dipiperidylmethane, CH2(pip)2, are synthesized via the condensation of their respective secondary amine precursors and dichloromethane at room temperature in the absence of light. Their use as chelating ligands is shown by the isolation and complete characterization of [CH2(pyr)2]Mo(CO)4 and [CH2(pip)2]Mo(CO)4 complexes. X-ray analysis reveals the methylene bis(cycloamines) to possess a sharp bite angle between 61° and 63° and a strong steric impact on the surrounding carbonyl ligands as a result of their ring conformations.

Sol Gel Dip Coated Yb and Tm Doped Indium Oxide Dye Sensitizrd Solar Cells

In2O3 thin films were deposited by the sol gel dip coating method adopting the following procedure. Clean ITO substrates were used for the deposition of the films. 10 ml of 0.33 M solution of Indium (III) nitrate was taken in a clean glass beaker. The solution was heated to 70˚C and the pH was brought to 9 by the addition of ammonia, then 1 gm of Acrylamide was added followed by the addition of 0.25 gm of N,N,bis methylene acrylamide. After 20 min, 5 mg ammonium persulphate initiator was added to this mixture. The solution became viscous. Cleaned microglass slides (2.5 cm x 7.5 cm) were immersed into the viscous solution and withdrawn at the rate of 1cm min-1. The film formed on the surface was dried in an air oven for about 15 min followed by annealing in air at different temperatures in the range of 350 - 500˚C for different durations in the range of 15 min to 90 min. Doping with Tm and Yb was done by adding 0.1 g of Yb(NO3)3 and 0.1 g of Tm(NO3)3 to the Indium nitrate solution before gelling. The doped and undoped films were dipped in N719 dye for 24 hours. a sandwich structure was formed by bonding the FTO substrate with dye coated In2O3 and a Pt counter electrode together through a hot-melt spacer, and a drop of electrolyte (0.60 M 1-butyl-3-methylimidazolium iodide (BMII), 0.03 M I2 was injected into the device through predrilled holes on the Pt counter electrode. DSSCs based on In2O3:Yb and In2O3:Tm were also fabricated via the same process. The XRD patterns of the In2O3, In2O3:Tm and In2O3:Yb. . All the patterns can be assigned to cubic phase standard card (JCPDS 06-0416) without any additional diffraction peaks. The UV–vis absorption spectra of the doped and undoped In2O3 exhibit the absorption peak of the pure In2O3 about 3.85 eV, which is consistent with the results published, and it icreases to 3.93 eV and 4.00 eV respectively as Tm and Yb are doped into In2O3. The J-V characteristics of the doped and undoped Indium oxide films indiacted that the Voc increased from 410 mV for undoped films increased to 530 mV and 630 mV for Tm and Yb doped films respectively. The Jsc increased from 2.45 mA cm-2 for the undoped films increased to 3.50 mA cm-2 and 4.25 mA cm-2 for Tm and Yb doping respectively.IPCE measurements indicated that for doped films the PCE was higher than that of undoped films. The fill factor of the films increased by doping with Tm and Yb. The larger Voc obtained with Yb doping can be explained on theb basis that the conduction band edge of Yb doped films is higher than that of undoped and Tm doped Indium oxide.

Stimulus-Responsive, Biodegradable, Biocompatible, Covalently Cross-Linked Hydrogel Based on Dextrin and Poly(N-isopropylacrylamide) for in Vitro/in Vivo Controlled Drug Release.

A novel stimulus-sensitive covalently cross-linked hydrogel derived from dextrin, N-isopropylacrylamide, and N,N'-methylene bis(acrylamide) (c-Dxt/pNIPAm), has been synthesized via Michael type addition reaction for controlled drug release application. The chemical structure of c-Dxt/pNIPAm has been confirmed through Fourier transform infrared (FTIR) spectroscopy and (1)H and (13)C NMR spectral analyses. The surface morphology of the hydrogel has been studied by field emission scanning electron microscopic (FE-SEM) and environmental scanning electron microscopic (E-SEM) analyses. The stimulus responsiveness of the hydrogel was studied through equilibrium swelling in various pH media at 25 and 37 °C. Rheological study was performed to measure the gel strength and gelation time. Noncytotoxicity of c-Dxt/pNIPAm hydrogel has been studied using human mesenchymal stem cells (hMSCs). The biodegradability of c-Dxt/pNIPAm was confirmed using hen egg lysozyme. The in vitro and in vivo release studies of ornidazole and ciprofloxacin imply that c-Dxt/pNIPAm delivers both drugs in a controlled way and would be an excellent alternative for a dual drug carrier. The FTIR, powder X-ray diffraction (XRD), and UV-vis-near infrared (NIR) spectra along with the computational study predict that the drugs remain in the matrix through physical interaction. A stability study signifies that the drugs (ornidazole ∼97% and ciprofloxacin ∼98%) are stable in the tablet formulations for up to 3 months.

Bimetallic Co–Ni based complex catalyst for hydrogen production by catalytic hydrolysis of sodium borohydride with an alternative approach

Hydrogen is a clean energy carrier and is expected to be one of the main energy sources in the 21st century. The basic aim of this study is to develop a feasible new catalyst system for the hydrogen generation by catalytic hydrolysis of NaBH4. The method is an alternative approach for the hydrogen production with metal catalysts. Ni–Co bimetallic complex catalysts with different Co–Ni contents were derived from 4-4′-methylene bis (2,6-diethyl)aniline-3,5-di-tert-butylsalisilaldimin ligand and their catalytic performances were investigated with hydrogen generation by catalytic hydrolysis of NaBH4. Experimental results showed that the Co–Ni contained catalysts exhibited much higher activity than the monometallic complex catalyst. The optimal mixture percentage of Co–Ni complex catalyst was 80:20. It was found that a combination of 2.5 wt% NaBH4 solution concentration and 5 wt% NaOH yields the highest performance for the hydrogen generation. The catalysts were characterized by XRD, FT-IR and SEM techniques.

A Novel Europium Chelate Coated Nanosphere for Time-Resolved Fluorescence Immunoassay.

A novel europium ligand 2, 2’, 2’’, 2’’’-(4, 7-diphenyl-1, 10-phenanthroline-2, 9-diyl) bis (methylene) bis (azanetriyl) tetra acetic acid (BC-EDTA) was synthesized and characterized. It shows an emission spectrum peak at 610 nm when it is excited at 360 nm, with a large Stock shift (250 nm). It is covalently coated on the surface of a bare silica nanosphere containi free amino groups, using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-Hydroxysuccinimide. We also observed an interesting phenomenon that when BC-EDTA is labeled with a silica nanosphere, the chelate shows different excitation spectrum peaks of about 295 nm. We speculate that the carboxyl has a significant influence on its excitation spectrum. The BC-EDTA/Eu3+coated nanosphere could be used as a fluorescent probe for time-resolved fluorescence immunoassay. We labeled the antibody with the fluorescent nanosphere to develop a nanosphere based hepatitis B surface antigen as a time-resolved fluorescence immunoassay reagent, which is very easy to operate and eliminates potential contamination of Eu3+ contained in the environment. The analytical and functional sensitivities are 0.0037 μg/L and 0.08 μg/L (S/N≥2.0) respectively. The detection range is 0.08-166.67 μg/L, which is much wider than that of ELISA (0.2-5μg/L). It is comparable to the commercial dissociation-enhanced lanthanide fluoro-immunoassay system (DELFIA) reagents (0.2-145μg/L). We propose that it can fulfill clinical applications.

Experimental and theoretical studies of hydrolysis of nerve agent sarin by binuclear zinc biomimetic catalysts

A complex (ZnL1) of 2,2-(2-hydroxy-5-methyl-1,3-phenylene)bis(methylene)bis ((pyridin-2-ylmethyl)azanediyl)diethanol (this ligand is named by L1) functionalized with two Zn(II) centers, has been previously suggested to be a structural model for binuclear zinc phosphotriesterases (PTEs) and proven to be an effective catalyst for the hydrolysis of bis(2,4-dinitrophenyl)phosphate (BDNPP). In this paper, ZnL1 was further found to have a high catalytic activity for the hydrolysis of isopropyl methylphosphonofluoridate (sarin, GB) with kcat/Km=0.051s−1M−1 at 303K, examined by on-site NMR analysis. The subsequent density functional theory (DFT) calculations indicate that a terminal alkoxide (Ot) bound by Zn may work as a general base to activate a water molecule and then a hydroxide derived from the latter performs the initial nucleophilic attack on the phosphor in GB. Inspired by this mechanism, a new biomimetic catalyst was designed and synthesized by replacing the two pyridines of ZnL1 by hydroxyls, i.e. a complex of two Zn(II) with 2,6-bis((bis(2-hydroxyethyl)amino)methyl)-4-methylphenol (the ligand is named by L2). This replacement was expected to increase the Ot basicity, thereby facilitating the nucleophilic attack and the overall hydrolysis of GB. It was shown that ZnL2 had a very high catalytic efficiency for the hydrolysis of GB, with kcat/Km=0.11s−1M−1 at 303K and about 90% conversion in 30min. The following DFT calculations proposed a detailed reaction mechanism of ZnL2 and gave an energy barrier (5.8kcalM−1) very close to the experimental activation energy (5.6kcalM−1). In this study, a mechanism-inspired design strategy has been demonstrated to be successful in developing biomimetic catalyst.