Molar Ratio Of Monomer Research Articles

Poly(diphenylamine-co-aniline) copolymers for supercapacitor electrodes

Polyaniline, polydiphenylamine, and two copolymers with precursor monomers molar ratios of 1:1 and 3:1 (anilinium dodecyl sulfate (P1):diphenylamine) were synthesized via oxidative polymerization in a water/ethanol interfacial system. The morphology characterization and physicochemical properties showed that the copolymers share polyaniline or polydiphenylamine characteristics, depending on the monomer molar ratio. The electroactivity characterization indicated that the polydiphenylamine (PDPA) repeating units provided the copolymers with better cycling stability, whereas PAni repeating units reduced resistance and improved storage capacity, generating a synergistic interaction. Particularly, the copolymer with the highest content of P1, showed a specific capacitance of 341.93 F g−1, with a 74.5% capacitance retention after 500 cycles, which suggests a feasible application in electrodes for supercapacitor design.

Preparation and flash sintering of MgTiO3 nanopowders obtained by the polyacrylamide gel method

Using a polyacrylamide gel method, phase pure and well-dispersed MgTiO3 nanopowders were prepared at 800 °C for 2 h. It was found that a high mole ratio of monomers to precursors resulted in low formation temperature of MgTiO3, due to the highly mixing homogeneity and smaller particle sizes of precursors. Sintering behaviors of MgTiO3 nanopowders under DC electric field from 500 to 800 V/cm were investigated. Nearly full dense MgTiO3 ceramics can be prepared in 30 s. An abrupt and simultaneous increase in current density and power dissipation were observed in sintering process, which are characteristics of flash sintering. The power dissipation for the flash sintering was found to be 82 mW/mm3. The densities and average grain sizes of samples increase with the increase of the electrical field strength. It was suggested that Joule heating was the main mechanism of flash sintering of MgTiO3 ceramics. Our work provides a useful route for the fabrication of dense MgTiO3 ceramics at low temperature in short time.

Tuning poly(p-phenylene) nano-size for enhancing electrical conductivity based on surfactant templates and doping

Nanoparticles play a vital role in the material property improvement. For conductive polymers, nanoparticles have been known to affect various electrical properties. This work reports the size-controlled synthesis of poly(p-phenylene) (PPP) nanoparticles using benzene, AlCl3, and CuCl2 as a monomer, catalyst, and oxidant respectively, incorporated with a surfactant template and subsequently doped with various doping agents to increase the electrical conductivity. The effects of surfactant types namely Span65, Tween80, and TritonX100 and surfactant concentrations were investigated. The PPP structure was confirmed by NMR, FT-IR, and XPS techniques. SEM images showed different undoped-PPP (uPPP) morphologies: irregular shape, coral reef shape, spherical shape, and worm-like shape with the particle sizes between ∼30 and ∼120 nm not previously reported. The electrical conductivity of the uPPP with a surfactant was higher than that without a surfactant due to the smaller particle size. From the doping, the electrical conductivity of the doped-PPP (dPPP) increased with the doping agent to monomer mole ratio up to 50:1. The dPPP doped with HClO4 (dPPP/HClO4) at the doping agent to monomer mole ratio of 50:1 exhibited the highest electrical conductivity of 74.34 S cm−1 along with the long term stability in air.

Isolation of sinapic acid from broccoli using molecularly imprinted polymers.

A molecularly imprinted polymer was synthesized for the purpose of sinapic acid isolation from Egyptian nutraceutical Botrytis italica, L. (broccoli) due to its prominent medicinal and wide pharmacological activities. A computational study was first developed to determine the optimal template to functional monomer molar ratio. Based on the computational results, five polymers were synthesized using a bulk polymerization method with sinapic acid as the template molecule. Evaluation of the synthesized polymers binding performance was carried out using batch rebinding assay, which revealed that the molecularly imprinted polymer of molar ratio (1:4:20), template to functional monomer (4-vinyl pyridine) to crosslinker (ethylene glycol dimethacrylate) was of optimum performance, thus, this polymer was applied for sinapic acid isolation from closely related analogues. This represents a more practical approach to isolate sinapic acid from different natural extracts selectively.

Synthesis of N-vinylpyrrolidone/Acrylic acid nanoparticles for drug delivery: Method optimization

There are various approaches to deliver therapeutic agents to the preferred target. Polymeric nanoparticles were found to have pleasing suitability as a drug carrier. The goal of this research was to optimize the synthesis method to obtain the desirable %yield and particle properties of the new biocompatible polymer-based nanoparticles. The non-toxic polymer, N-vinyl pyrrolidone (NVP) and a widely used hydrophilic biocompatible acrylic acid (AA) monomer were used to form the drug nanocarriers. The synthesis method was optimized by changing the types of initiator (KPS or V50) and the monomers molar ratio (NVP:AA). It was found that by varying both the monomer molar ratio and the type of reaction initiator, did not have significant effect on the physicochemical characteristics of the nanocarriers. The FTIR spectra of all products exhibited the peaks of carboxylic acid, carbonyl, and tertiary amine functional group vibration. The particle size of the nanocarriers was in the range of 173.6 ± 18.4 to 201.4 ± 17.1 nm with negative surface charge. However, the yield obtained increased as the initiator was altered from KPS to V50, and when the acrylic acid molar ratio was increased from 1:1 to 1:3. In conclusion, changing the initiator and monomer molar ratio may affect the physicochemical properties of the nanocarriers and the %yield of the nanocarrier product. Further investigations are essential to obtain the favorable drug nanocarriers for drug delivery.

Synthesis and properties of polylactide terpolymers P(LLA‐TMC‐GA) catalyzed by zirconium (IV) acetylacetonate

A series of L‐lactide (LLA), 1,3‐trimethylene carbonate (TMC) and glycolide (GA) terpolymers (LTG) of different monomer molar ratios were synthesized by using ring‐opening copolymerization. An effective and low‐toxic zirconium (IV) acetylacetonate Zr(Acac)4 was used as catalyst. The viscosity‐average molecular weights (Mη) of obtained polymers were all above 2.2×104 g/mol. The chemical structure and viscosity of terpolymers were confirmed by Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1HNMR), 13C nuclear magnetic resonance (13CNMR) and an Ubbelohde viscometer. The thermal and mechanical properties were investigated by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X‐ray diffraction (XRD) and stress‐strain measurements. Results suggested that all terpolymers were amorphous and showed good thermal stability. Also it was found that elongation increased with the decreasing of LLA unit. More importantly, terpolymers displayed shape memory property when deformation temperatures were 14‐15 °C above Tg.

Rapid and efficient removal of heavy metal and cationic dye by carboxylate-rich magnetic chitosan flocculants: Role of ionic groups

A multifunctional carboxylate-rich magnetic chitosan flocculant (Mag@PIA-g-CS) was prepared through surface graft copolymerization on magnetite particles. The effect of monomer molar ratio, initiator and pre-neutralized degree on polymerization rate was determined. Various analytical methods were applied to characterize Mag@PIA-g-CS, exhibiting the successful grafting of polymers, good magnetic feature and core-shell structure. The kinetic process of Ni(II) and malachite green (MG) flocculation by Mag@PIA-g-CS reached equilibrium within <60min with the optimal uptake rate of 98.3% and 87.4%, and exhibited satisfactory removal effect in wide pH range (4.0–8.0 for Ni(II), 5.0–10.0 for MG). Mag@PIA-g-CS exhibited superior flocculation performance over chitosan magnetic flocculant (Mag@CS). The pH-dependent behavior, rapid responsiveness and sensitivity to ionic strength in batch flocculation tests indicated the distinct effect of ionic groups. Moreover, sweeping action of linear molecular chains facilitated further flocculation. Mag@PIA-g-CS showed high stability in extreme environments, and can be easily regenerated and separated.

Synthesis of PAA-PAMPS-PNaSS Terpolymers as Ultraviolet-Tagged Scale Inhibitor for Industrial Water Cooling System

Carboxylated polymer can be used as an anti-scaling agent in circulating water cooling systems. Poly(acrylic acid) and homopolymer have some drawbacks such as slight solubility in water and low calcium tolerance leading difficulty to determine the remaining quantity of polymer in water. This research is mainly focused on synthesis and ability of poly(acrylic acid-co-2-acrylamido-2-methylpropane sulfonic acid) (PAA-PAMPS) for scale inhibition. These terpolymers varied in mole ratios of monomers were prepared via solution polymerization. The obtained polymers are then characterized by FT-IR, 1H-NMR, TGA, turbidity, and UV-visible spectroscopy. For a scale inhibition test, GB/T 16632-2008 standard is applied. The scale inhibition efficiency for 100% was found in PAA-PAMPS copolymer (7:3). Afterwards this polymer was chosen for synthesizing an ultraviolet-tagged PAA-PAMPS-PNaSS terpolymer. UV-visible spectroscopy was used to monitor benzene sulfonate structure in sodium styrene sulfonate of the polymer chain at 224 nm.

Fabrication of self-assembled polyaniline tubes and their electrorheological characteristics

Polyaniline (PANI) nanotube (NT) particles possessing a rectangular shape were fabricated by self-assembly via a chemical soft template technique with citric acid as the dopant acid at an organic dopant acid to aniline monomer molar ratio of 1:4. Morphology of the PANI NTs was examined by scanning electron microscope and transmission electron microscope, while their chemical structure was tested by FT-IR spectroscopy and X-ray diffraction. PANI NTs were suspended in silicone oil for electrorheological (ER) characterization, and their fibrillation phenomenon under an induced electric field caused by their highly polarizable characteristics was observed directly by an optical microscope. Their rheological behaviors under different electric fields were tested using a rotational rheometer, exhibiting increased ER effects with an input electrical field strength. Frequency dependence of the dielectric spectra was also obtained using a LCR meter and well related with the ER effect.

Copolymerization of Norbornene and Norbornadiene Using a cis-Selective Bimetallic W-Based Catalytic System.

The bimetallic cluster Na[W2(μ-Cl)3Cl4(THF)2]·(THF)3 ({W2}, {W 3 W}6+, a′2e′4), which features a triple metal-metal bond, is a highly efficient room-temperature initiator for ring opening metathesis polymerization (ROMP) of norbornene (NBE) and norbornadiene (NBD), providing high-cis polymers. In this work, {W2} was used for the copolymerization of the aforementioned monomers, yielding statistical poly(norbornene)/poly(norbornadiene) PNBE/PNBD copolymers of high molecular weight and high-cis content. The composition of the polymer chain was estimated by 13C CPMAS NMR data and it was found that the ratio of PNBE/PNBD segments in the polymer chain was relative to the monomer molar ratio in the reaction mixture. The thermal properties of all copolymers were similar, resembled the properties of PNBD homopolymer and indicated a high degree of cross-linking. The morphology of all materials in this study was smooth and non-porous; copolymers with higher PNBE content featured a corrugated morphology. Glass transition temperatures were lower for the copolymers than for the homopolymers, providing a strong indication that those materials featured a branched-shaped structure. This conclusion was further supported by viscosity measurements of copolymers solutions in THF. The molecular structure of those materials can be controlled, potentially leading to well-defined star polymers via the “core-first” synthesis method. Therefore, {W2} is not only a cost-efficient, practical, highly active, and cis-stereoselective ROMP-initiator, but it can also be used for the synthesis of more complex macromolecular structures.

Glass–Metal Adhesive Polymers from Copper(I)‐Catalyzed Azide–Alkyne Cycloaddition

Cu(I)‐catalyzed azide–alkyne cycloaddition is shown here to be an efficient method to create adhesive materials in situ between glass and copper surfaces. Twelve formulations show adhesive strengths greater than a commercial product under comparable conditions, with the best combination of monomers the same as that previously developed for copper–copper adhesion. Strong adhesion is also achieved under water, an environment in which the commercial glue fails. Brass, iron, and stainless steel could also be adhered to glass using different formulations, but aluminum could not. The concentration and molar ratio of monomers, curing temperature, prefunctionalization of the glass surface, and the incorporation of flexibility‐inducing components all have significant effects on adhesive performance. image

Voltammetric Determination of Valaciclovir Using a Molecularly Imprinted Polymer Modified Carbon Paste Electrode

AbstractA molecularly imprinted polymer (MIP) was rationally synthesized with the aid of computer based studies. The computational studies were used to screen for the most suitable template to functional monomer molar ratio. Two functional monomers were involved in the study (methacrylic acid and 4‐vinylpyridine). Four MIP ratios were synthesized in accordance with the results of the computational studies and their performance was evaluated using equilibrium rebinding assays. The MIP with the best performance was used as an additive in carbon paste electrodes for the voltammetric determination of valaciclovir (VCV). Following the optimization of voltammetric parameters, a linear response was obtained in the range of 1.0x10−6–7.0x10−4M with a limit of detection at 4.45x10−7M. The MIP modified carbon paste electrode was successfully applied for the determination of VCV in pure solutions and dosage form.

Fluorinated oligo(ethylene glycol) methacrylate-based copolymers: Tuning of self assembly properties and relationship with rheological behavior

A series of thermo-responsive oligo(ethylene glycol) methacrylate (OEGMA, Mn = 300 g/mol)-pentafluorostyrene (PFS) copolymers was prepared, and the effect of composition on polymer conformation changes and size of the self-assembled particles in solution was studied. Furthermore, the relationship between self-aggregation mechanistic steps in water and rheological properties is reported. Water-soluble OEGMA-PFS copolymers were synthesized at different molar ratios via free radical polymerization, and their phase transition behavior was investigated in detail by dynamic light scattering (DLS), 1H NMR, simultaneous rheometry-FTIR spectroscopy, and transmission electronic microscopy (TEM). All copolymers exhibited sharp and reversible LCST in water. LCST and particle size of the self-assemblying copolymers can be precisely tuned by varying monomer molar ratio. Simultaneous rheometry-FTIR spectroscopy showed that above the LCST, copolymers with higher OEGMA content form micron-sized and hydrated particles, resulting in a pseudo-hydrogel structure. When the hydrophobic character increases, a more significant dehydration of OEGMA side chains leads to a strengthening of polymer chain interactions, resulting in the formation of nanosized and phase-segregated particles. These results are also relevant with a view of using these structures as a template for the preparation of chemically or physically stabilized nanoparticles to be employed for a variety of applications, such as immobilization, controlled release and flocculation in water treatment.

Synthesis and curing process of TMA-MDI polyamide-imides

The influence of molecular ratio of monomers, reaction time, reaction temperature and solid content on the molecular weight of polyamide imides(PAI), heating rate, temperature and time on tensile properties of PAI film was investigated in detail. The results showed that when monomer molar ratio (MDI: TMA)R >1, PAI is an isocyanate terminated, intrinsic viscosity increases with the increase of R, reaches maximum value at R=1.06, then it decreases obviously. Contrarily, when R <1, PAI is terminated with anhydride, intrinsic viscosity increases with the decrease of R, its maximum value at R= 0.97, then it decreases with the decrease of R. The relation between intrinsic viscosityof PAI and reaction temperature, reaction time, solid content all follows the parabolic law. The optimal reaction temperature,reaction time, solid content is 140°C, 120 min, 30%. Therefore, the best synthesis process of the PAI is reacting for 120 min at 140°C when 30% solid content and R=1.06. Tensile strength and elongation increase with the increase of heating rate, curing temperature and curing time, after peak value, they decrease with the increase of heating rate, curing temperature andcuring time. The best curing process of the PAI is curing for 2h at 260°C and heating rate 100°C/h.

Random copolymer gels of N-isopropylacrylamide and N-ethylacrylamide: effect of synthesis solvent compositions on their properties

Random copolymer gels of N-isopropylacrylamide (NIPAM) and N-ethylacrylamide (NEAM) were synthesized using 1 : 1 monomer molar ratio in different methanol–water mixtures. (xm = 0, 0.06, 0.13, 0.21, 0.31 0.43, 0.57, 0.76, where xm = mole fraction of methanol) (xm = 0, 0.06, 0.13, 0.21, 0.31, 0.43, 0.57, 0.76, where xm = mole fraction of methanol).

Ratiometric fluorescence for sensitive and selective detection of mitoxantrone using a MIP@rQDs@SiO2 fluorescence probe

Molecularly imprinted polymer coated quantum dots (MIP@rQDs@SiO2) fluorescence probe combined with ratiometric fluorescence technique has been applied to the selective and sensitive detection of mitoxantrone (MIT) for the first time. The MIP@rQDs@SiO2 fluorescence probe was synthesized with the mole ratio of template, monomer and cross-linker at 1:4:12. The proposed method can quickly detect mitoxantrone in human serum and urine samples at pH 6.5 within 10min. The linear range for MIT concentrations was 0.2μM–2.0μM, and the detection limit was as low as 0.067μM. The MIP@rQDs@SiO2 ratiometric fluorescence probe, which integrated the high selectivity of MIP and high sensitivity of the ratiometric fluorescence probe, possesses greater sensitivity and reliability than a single quantum dot MIP fluorescence probe.

Synthesis of thiophene-based polymeric semiconductor with high aromatic density and its application in organic thin-film transistors

A new p-type polymer, poly(3,3″‴-didodecyl sexythiophene) (PST), was synthesized via FeCl3 oxidative coupling reaction. The mole ratio of FeCl3 and monomer (4:1), and keeping room temperature for polymerization were very important to obtain soluble polymer with regulated molecular weight. The photoluminescence (PL) maxima of the polymer are found at 500 and 562 nm for the solution and at 656 nm for the film. The low density of side chains enables substantial torsional deviations of the thienylene units, thereby inducing a relatively low highest occupied molecular orbital (HOMO) level (~ -5.22 eV). X-Ray diffraction analysis showed that PST forms a highly interdigitated structure due to the low density of side chains. PST were introduced as the active layers of organic thin-film transistors, and the resulting device showed field-effect mobilities of 0.12 cm2/Vs (on/off ratio=1.7×105) in air. The intrinsic mobility of PST measured by using the time of flight technique also supports a high conductance of 4×10-4 cm2/Vs.

Self‐driven graft polymerization of vinyl monomers on poultry chicken feathers in the absence of initiator/catalyst

ABSTRACTAn efficient and simple method for graft copolymerization of powdered chicken feather (CF) with vinyl monomers without any free radical initiator is reported. Various vinyl monomers such as glycidyl methacrylate (GMA), styrene (S), and methyl methacrylate (MMA); (20–60 wt % with respect to CF) were successfully grafted to chicken feather (CF) by using sodium dodecyl sulfate (SDS, 0.086–0.5 mmol) in the absence of any catalyst or initiator. Most likely, the hydrophilicity, hydrophobicity, and complex forming properties of chicken feather keratin with surfactant molecules were responsible for efficient grafting of polymers on CF surface. The effect of polymerization conditions, such as monomer concentration, temperature, and time of reaction, on the grafting parameters such as monomer conversion, grafting efficiency, and molar grafting ratio were studied. The described method showed a good potential of using low cost, easily accessible poultry chicken feathers as grafting material and self catalyzing agent for graft copolymerization with vinyl monomers to produce low cost commodity plastic for various end uses. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44645.

Preparation of covalently cross-linked sulfonated polybenzimidazole membranes for vanadium redox flow battery applications

A series of polybenzimidazole copolymers with varied content of pendant amino groups have been synthesized by condensation polymerization of 4,4′-dicarboxydiphenyl ether (DCDPE), 5-aminoisophthalic acid (APTA) and 3,3′-diaminobenzidine (DAB) in polyphosphoric acid at 190°C for 20h. The resulting copolymers undergo post-sulfonatation in fuming sulfuric acid at 100°C yielded the highly sulfonated polybenzimidazoles (SOPBI-NH2(x/y), ‘x/y’ refers to the monomer molar ratio of DCDPE to APTA). A series of covalently cross-linked membranes (CSOPBI-NH2(x/y)) with good mechanical properties are fabricated by solution cast technique using bisphenol A epoxy resin as a cross-linker. The CSOPBI membranes show 3–4 orders of magnitude lower VO2+ permeability and 6–30 times higher ion diffusion selectivity (proton vs. VO2+) than Nafion117. The charge-discharge behaviors of the vanadium redox flow batteries (VRBs) assembled with the CSOPBI-NH2(x/y) membranes and Nafion 117 are investigated and compared. The VRBs assembled with the CSOPBI membranes exhibit significantly higher columbic efficiency and lower self-discharge rate than that assembled with Nafion 117 owing to the extremely lower vanadium cations crossover of the former. The VRB assembled with the CSOPBI-NH2(9/1) membrane exhibits fairly high energy efficiency (~85% at 60mAcm−2) and little decay in performance is observed after 300 charge-discharge cycles.

Low temperature synthesis and characterization of YAG nanopowders by polyacrylamide gel method

Yttrium aluminum garnet (YAG, Y3Al5O12)nanopowders were synthesized by a polyacrylamide gel method at a much lower temperature of 900°C than using the traditional methods. This synthesis process was thoroughly investigated including an examination of the phase transformation, the particle size and agglomeration degree at different molar ratios of monomer to the precursor salt and the calcination temperature. A high mole ratio of monomer to the precursor salt led to low formation temperature of YAG, resulting from the high homogeneity and reduced particle size of the precursor. Consequently, weak-agglomerated YAG nanopowder with an average particle size of 35nm can be prepared at a calcination temperature of 900°C for 2h. The as-prepared YAG nanopowder showed excellent sinter-ability.