Monomer Concentration Ratio Research Articles

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

Correlation of polymerization conditions with drag reduction efficiency of poly(1-hexene) in oil pipelines

High molecular weight with long linear side branches are frequently used in oil pipelines as one of the main classes of drag reducer agents (DRAs). We studied the effects of polymerization conditions, including reaction temperature, monomer concentration and cocatalyst concentration ratio (Al/Ti), on the polymerization yield and molecular weight of the resultant poly(1-hexene) made by Ziegler–Natta catalyst and their consequent effects on the drag reduction efficiency in a loop test. The experimental results verified that the catalyst activity increased from 115 to 220 kgPH/molTi.atm, while the molecular weight of poly(1-hexene) dropped from 2100 to 1030 kDa, as the reaction temperature was increased from 0 to 50 °C. The loop test results also revealed that the highest pressure drop was achieved using the polymer synthesized at 0 °C and by subsequent increase in reaction temperature the pressure drop decreased. Furthermore, the catalyst activity increased from 143 to 262 kgPH/molTi.atm by increasing Al/Ti ratio, while the molecular weight increased up to a maximum level of 1500 kDa at Al/Ti = 143 and decreased at higher cocatalyst contents. Similarly, the results showed the maximum pressure drop of 20 % at Al/Ti = 143. Finally, by increasing monomer concentration, the catalyst activity and polymer molecular weight increased from 75 to 262 kgPH/molTi.atm for the former, and from 700 to 1800 kDa for the latter which resulted in maximum pressure drop by 25 %. Moreover, the pressure drop for each utilized poly(1-hexene) was increased proportionately with DRA’s concentration, and interestingly enough, DRAs were further effective at more turbulent flows with higher Reynolds numbers.

EFFECT OF MONOMER CONCENTRATION ON PROPERTIES OF POLY (METHYL METHACRYLATE/BUTYL ACRYLATE/VINYL SILICA) EMULSION NANO-COMPOSITE

Poly (methyl methacrylate-co-butyl acrylate) as shell and vinyl silica nano-particles as core were prepared by in situ seed emulsion polymerization. The monomer concentration ratio of butyl acrylate (BuA), and methyl methacrylate (MMA) was changed. The ratio of the monomers MMA/BuA were 60/40, 70/30, 40/60 and 30/70 at constant dose of vinyl silica nano-particles 5% (based on total monomer ratio). The prepared nano emulsions were characterized using thermal analyses, HRTEM, FTIR and Zeta potential. The results have shown that monomer concentration ratio had a significant influence on glass transition temperature (Tg). Thermo gravimetric analysis showed that the systems with higher BuA fraction had better thermal stability than systems with higher (MMA) fraction.

Developed Hybrid Model for Propylene Polymerisation at Optimum Reaction Conditions.

A statistical model combined with CFD (computational fluid dynamic) method was used to explain the detailed phenomena of the process parameters, and a series of experiments were carried out for propylene polymerisation by varying the feed gas composition, reaction initiation temperature, and system pressure, in a fluidised bed catalytic reactor. The propylene polymerisation rate per pass was considered the response to the analysis. Response surface methodology (RSM), with a full factorial central composite experimental design, was applied to develop the model. In this study, analysis of variance (ANOVA) indicated an acceptable value for the coefficient of determination and a suitable estimation of a second-order regression model. For better justification, results were also described through a three-dimensional (3D) response surface and a related two-dimensional (2D) contour plot. These 3D and 2D response analyses provided significant and easy to understand findings on the effect of all the considered process variables on expected findings. To diagnose the model adequacy, the mathematical relationship between the process variables and the extent of polymer conversion was established through the combination of CFD with statistical tools. All the tests showed that the model is an excellent fit with the experimental validation. The maximum extent of polymer conversion per pass was 5.98% at the set time period and with consistent catalyst and co-catalyst feed rates. The optimum conditions for maximum polymerisation was found at reaction temperature (RT) 75 °C, system pressure (SP) 25 bar, and 75% monomer concentration (MC). The hydrogen percentage was kept fixed at all times. The coefficient of correlation for reaction temperature, system pressure, and monomer concentration ratio, was found to be 0.932. Thus, the experimental results and model predicted values were a reliable fit at optimum process conditions. Detailed and adaptable CFD results were capable of giving a clear idea of the bed dynamics at optimum process conditions.

Synthesis of Graft Copolymers for Green Composite Films and Optimization of Reaction Parameters using Taguchi (L16) Orthogonal Array

Oleic acid was graft copolymerized onto barley husk (BH) using a redox initiator. Samples of natural and grafted BH were characterized by fourier transform infrared spectroscopy, scanning electron microscopy (SEM), x-ray diffraction, thermal analysis, swelling (%) and moisture absorption (%). SEM analysis revealed that the surface of the BH became rough after grafting. Reaction time, temperature, amount of solvent, monomer concentration and initiator molar ratio were optimized using conventional as well as Taguchi L16 (orthogonal array) design to get maximum percentage graft yield. At optimized conditions, the maximum graft yield was 55.3% by conventional method, whereas it was 56.82% by Taguchi method. Analysis of variance revealed that the reaction temperature and reaction time were the most and the least influential factors, respectively. Swelling (%) and moisture absorption (%) decreased with the increase in percentage graft yield. Grafted BH showed more chemical and thermal resistance as compared to natural BH. Synthesized graft copolymers were used as reinforcing material in poly vinyl alcohol composite films and rendered higher mechanical properties.

Silica-particle-supported zwitterionic polymer monolith for microcolumn liquid chromatography.

A silica-particle-supported zwitterionic polymeric monolithic column, shortened as supported column (S-column), was prepared by the in situ polymerization of methacrylic acid, ethylene dimethacrylate, and 2-(dimethylamino)ethyl methacrylate in the presence of a ternary porogenic solvent containing water, methanol, and cyclohexanol in a 250 μm id fused-silica capillary prepacked with 5 μm bare silica particles. In the S-column, a thin layer of the polymers was formed around the silica particles in the form of nanoglobules, leaving the interstitial spaces between the particles free for liquid flow. The effects of the preparation conditions on the morphology of the monolith were investigated by scanning electron microscopy and backpressure measurements. The selected volumetric ratio of porogens, monomer concentration, polymerization time, and temperature are 1:1:8 (water/methanol/cyclohexanol), 25% v/v, 5 h, and 60°C, respectively. The S-column was evaluated by comparison with its conventional organic counterpart in terms of morphology, mechanical stability, permeability, swelling-shrinking behavior, capacity, and efficiency. The results demonstrate that the S-column is superior to its counterpart in all the terms with the exception of permeability. The above merits and zwitterionic property of the S-column were further confirmed by separate separations of four inorganic anions and three organic cations.

One-pot synthesis of poly(methacrylic acid)-b-poly(2,2,2-trifluoroethyl methacrylate) diblock copolymers via RAFT polymerization

In this work, the reversible addition-fragmentation chain transfer (RAFT) polymerization was utilized to synthesize the amphiphilic diblock copolymers of poly(methacrylic acid)-b-poly(2,2,2-trifluoroethyl methacrylate) (PMAA-b-PTFEMA) via one-pot two-step reaction protocol. The controlled radical polymerization of MAA monomer was first carried out in pure water by using 4-cyanopentanoic acid dithiobenzoate (CADB) as chain transfer agent. Subsequently, the as-synthesized PMAA homopolymers with dithiobenzoate end-groups were employed as macro-CTA and chain-extended in situ with the hydrophobic TFEMA monomer. The reactions were carried out in 1,4-dioxane/water medium. Both the polymerization of PMAA and PTFEMA blocks showed the well controllability on the molecular weighs and distributions. It was found that the amphiphilic diblock copolymers formed the stable spherical particles via the polymerization-induced self-assembly. Meanwhile, the effect of various parameters, such as the concentration ratio of TFEMA monomer over PMAA macro-CTA, the solvent condition (different ratio of 1,4-dixane/water), and the pH, on the RAFT polymerization of TFEMA monomer were investigated in detail. Their kinetic results suggested that the propagation of TFEMA monomer on the macro-CTA was performed at the particle/water interfaces. The concentration of chain transfer agents at the interfaces determined the polymerization rate. Finally, the stability of the fluorinated polymer dispersions was also evaluated in this work.

Electrosyntheses of Poly(selenophene-co-3-methylthiophene) with Improved Thermoelectric Property in Boron Trifluoride Diethyl Etherate

Novel poly (selenophene-co-3-methylthiophene) was successfully achieved by directly electrochemical oxidation of the monomer mixtures of selenophene and 3-methylthiophene (3MeT) in boron trifluoride diethyl etherate. The effect of monomer concentration ratios on the copolymerization were investigated by cyclic voltammetry. The structures of as-prepared copolymers were characterized by UV-vis and infrared spectroscopy. The conductivity and thermoelectric measurements revealed the incorporation of 3MeT into the polyselenophene (PSe) chain improved significantly the conductivity and thermoelectric property of PSe.

Cellulose Nanofiber-Supported Polyaniline Nanocomposite Conductive Film and its Conductive Properties

As a conducting polymer, polyaniline (PANI) have found wide applications including electrode material, sensors and supercapacitors, which is attributed to a combination of the advantages for both organic semiconductors and nanomaterials. This article concentrates on the preparation of bacteria cellulose-polyaniline (BC/PANI) conducting nanocomposite films via in situ polymerization of anailine onto bacteria cellulose (BC) scaffold. A series of nanocomposites were prepared with different anailine concentration, doping acid concentration and molar ratio of monomer and oxidant. The as-prepared conducting nanocomposites were characterized by conductivity measurement, scanning electronic microscope (SEM), fourier transform infrared spectroscopy (FT-IR), thermogravimetric analyser (TGA), etc, to find out the best preparation conditions. The results indicated that PANI coated on the surface of nanofibers of bacterial cellulose, the nanoconductive path formed and the conductivity of the film ranged from 2.0×10-8to 0.24 S·cm-1. In addition, the method of combining organic and inorganic acids can solve the de-doped problem caused by using traditional inorganic small molecule acid, such as HCl.

Cure Depth of Photo‐Polymerized Gels

Cure depth of photo‐polymerized gels is theoretically analyzed. The critical point in a frontally photo‐polymerized sample is determined by the critical degree of polymerization, which is derived by the concentration ratio of monomer and initiator. While the total polymer depth or gel depth weighed by the monomer conversion depends on both radiation energy and light intensity, the averaged cure depth around the critical point depends on radiation energy only. The profile is consistent with experimental results. This is a practical formulation of the cure depth of photo‐polymerized gels without any empirical parameter.

Environmentally friendly preparation of a strong basic anion exchange fibers and its application in sugar decolorization

An efficient route for the synthesis of a strong basic anion exchange fibers is described. In this synthesis route, the commercially available p-chloromethylstyrene was directly grafted onto a polypropylene fiber substrate, which eliminated the need of the highly carcinogenic chloromethyl methyl ether in the chloromethylation of grafting fiber. Several interdependent parameters such as monomer concentration, bath ratio and the influence of solvents on the grafting copolymerization were investigated. The removal efficiency of sugar colorants by the anion exchange fibers was evaluated. The results show that simultaneous irradiation and grafting p-chloromethylstyrene onto polypropylene fiber can obtain a good grafting level under appropriate conditions. The optimal monomer concentration and bath ratio are 40% and 1:30 for a moderate grafting degree and the suitable solvent is toluene. The grafted fiber changed from flexible to rigid. And the prepared material maintains stable before 134.5°C. The static ion exchange capacity of the synthesized anion exchange fiber is up to 4.72mmolg−1 and the fiber possesses better ability to remove sugar colorants. The experimental results indicate that the decolorization ratio of the product anion exchange fibers was greater than that of commercial material.

Pressure Induced Synthesis of EA Grafted Saccaharum cilliare Fibers

In view of recent technological significance of green cellulosic polymers in environmentally friendly materials, the present study is an attempt to synthesize Saccaharum cilliare-graft-poly (ethyl acrylate) (Saccaharum cilliare-g-PEA) copolymers via pressure-induced free-radical polymerization. The effect of pressure, time, ratio of monomer, solvent, and initiator concentrations were determined to get the premier percentage of grafting. It has been observed from this study that the physicochemical and thermal properties of the grafted cellulosic polymers have increased to a considerable extent and can be a potential material for a number of applications.

Kinetic investigation of the reversible addition-fragmentation chain transfer polymerization of 1,3-butadiene

Reversible addition-fragmentation chain transfer (RAFT) polymerization of 1,3-butadiene using a trithiocarbonate chain transfer agent, S-1-dodecyl-S′-(r,r′-dimethyl-r″-acetic acid)trithiocarbonate (DDMAT), was investigated. For the first time, comprehensive kinetic study of solution RAFT polymerization of 1,3-butadiene is reported. Effect of some factors such as RAFT agent and initiator concentration and initial molar ratio of monomer to both RAFT agent and initiator on the rate of polymerization and molecular weight distribution (MWD) were examined experimentally and discussed quantitatively. The validity of quasi-steady state approximation (QSSA) was shown and the rate of polymerization’s equation was obtained. Good compatibility with the experimental and theoretical values of molecular weights was obtained. Also, polybutadiene samples with narrow molecular weight distribution were synthesized.

Rapid synthesis of graft copolymers from natural cellulose fibers

Cellulose is the most abundant natural polysaccharide polymer, which is used as such or its derivatives in a number of advanced applications, such as in paper, packaging, biosorption, and biomedical. In present communication, in an effort to develop a proficient way to rapidly synthesize poly(methyl acrylate)-graft-cellulose (PMA-g-cellulose) copolymers, rapid graft copolymerization synthesis was carried out under microwave conditions using ferrous ammonium sulfate–potassium per sulfate (FAS–KPS) as redox initiator. Different reaction parameters such as microwave radiation power, ratio of monomer, solvent and initiator concentrations were optimized to get the highest percentage of grafting. Grafting percentage was found to increase with increase in microwave power up to 70%, and maximum 36.73% grafting was obtained after optimization of all parameters. Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA/DTA/DTG) analysis were used to confirm the graft copolymerization of poly(methyl acrylate) (PMA) onto the mercerized cellulose. The grafted cellulosic polymers were subsequently subjected to the evaluation of different physico-chemical properties in order to access their application in everyday life, in a direction toward green environment. The grafted copolymers demonstrated increased chemical resistance, and higher thermal stability.

Electrosynthesis and characterization of viologen cross linked thiophene copolymer

Electrochemical copolymerization of 3-octyloxy-4-methylthiophene (OOT) and 1-[6-[(4-methyl-3-thienyl) oxy] hexyl]-4-cyanopyridinium bromide (HOT-CNP) was carried out using tetrabutylammonium hexafluorophosphate and acetonitrile (TBAPF6/ACN) as electrolyte. The cyanopyridine functionalized HOT-CNP undergoes further electrochemical reductive coupling to viologen. Both polymer (POOT) and copolymer P(OOT-co-HOT-CNP) were characterized by cyclic voltammetry (CV), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and in situ UV–vis spectroscopy. The effect of the monomer concentration ratio and the scan rate on the electrochemical properties of the copolymer was studied by the CV technique. The electrochemical redox response of the copolymer together with FTIR analysis further confirms the formation of viologen. The surface morphology was studied using SEM analysis. The polymer POOT revealed color changes between violet and bright blue, whereas the copolymer showed the most vivid change of color between purple and greenish blue in its fully reduced and oxidized states respectively. The results showed that copolymerization is a valuable approach in order to achieve desired electrochromic and redox properties.

Synthesis of poly(aniline-co-3-amino-4-hydroxybenzoic acid) and its enhanced redox activity under highly basic conditions

Poly(aniline-co-3-amino-4-hydroxybenzoic acid) was synthesized using cyclic voltammetry. The monomer concentration ratio and applied potential strongly affect the copolymerization rate and electrochemical properties of the copolymer. The results from the infrared spectrum (IR) and X-ray photoelectron spectroscopy (XPS) of the copolymer demonstrate that 3-amino-4-hydroxybenzoic acid units are incorporated into the copolymer chain and that SO42− ions can be doped into the copolymer film during the electrochemical copolymerization. The scanning electron microscopy (SEM) micrograph proves that the copolymer film has a nanostructured network of mass interwoven fibers with a diameter of 10–50nm. The copolymer obtained at the optimum conditions exhibits excellent redox activity in a 0.30M Na2SO4 aqueous solution (pH 11.0), which is superior to that of polyaniline itself. The improvement can be attributed to the synergistic effect of the COOH and OH functional groups in the copolymer chain.

Synthesis of conducting poly(5-carboxyindole)/Au nanocomposite: Investigation of structural and nanoscale electrical properties

We report, herein, redox chemical synthesis of processible nanocomposite of carboxylic acid functionalized conducting polymer, poly(5-carboxyindole) (5C-PIn) and gold metal nanoparticles. The method involves a reaction between aqueous dispersion of carboxyindole monomer and aqueous solution of HAuCl4. The progress of the reaction is monitored by UV–visible spectroscopy and further nanocomposite is studied for structural, morphological, electrochemical and thermal properties. The concentration ratio of monomer and HAuCl4 is crucial to get desired morphology and uniformity of nanocomposite. The effect of the increasing concentration of gold salt is demonstrated with change in morphology and homogeneity of the nanocomposite. A uniform composite is formed using 1:2 mole ratio of HAuCl4 to monomer. Nanoscale electrical characterization of 5CPIn/Au nanocomposite is performed using current-sensing atomic force microscopy which exhibited a nonlinear and rectifying diode behavior with Al metal junction. Fluorescent spectral studies indicate that photoluminescence for the nanocomposite can be tuned from violet blue to yellow spectral range. The composite proves enormous potential in fabrication of nanoscale organic devices and organic optoelectronics.

Synthesis of Poly(o-phenylenediamine-co-o-aminophenol) via Electrochemical Copolymerization and its Electrical Properties

Poly(o-phenylenediamine-co-o-aminophenol) (PoPDoAP) was firstly synthesized via the electrochemical copolymerization of o-phenylenediamine (o-PD) and o-aminophenol (o-AP) in aqueous H2SO4 solution. The monomer concentration ratio strongly affected the electrochemical properties of the copolymer. The results from electrochemical impedance spectroscopy (EIS) indicated a copolymerization reaction took place between o-PD and o-AP. Compared to poly(o-phenylenediamine) (PoPD), the copolymer exhibited novel and improved electrical properties. The effect of the scan rate on the redox activity was also studied, indicating the electrochemical process of the copolymer is diffusion-controlled. A possible copolymerization mechanism was deduced from the IR spectrum of the copolymer.

Rapid Synthesis of MMA Grafted Pine Needles Using Microwave Radiation

Cellulose-graft-poly (methylacrylate) copolymers were prepared by microwave assisted free radical polymerization to develop an efficient rapid way to alter the surface properties of the cellulosic fibers. The effect of microwave radiation doses, ratio of monomer, solvent and initiator concentrations were determined to get the highest percentage of grafting. The graft copolymers were characterized by FTIR and SEM studies. The results clearly demonstrate that graft polymerization successfully occurred onto the cellulose backbone. The cellulose-graft-poly (methylacrylate) copolymers have been found to be more water- and moisture-resistant as well as also revealing enhanced chemical and thermal resistance.

Synthesis and characterization of hyperbranched polyurethanes via monomeric A2plus monomeric B3approach

The monomeric A2 plus monomeric B3 approach was employed to prepare hyperbranched polyurethanes (HBPUs) based on 4,4′-methylenediphenyl diisocyanate and trimethylolpropane with the molecular weights ranging from 20,000 to 59,800 g mol−1. Through controlling the concentration and stoichiometric ratio of monomers, gel was successfully prevented in the monomeric A2 plus monomeric B3 system. The structures of HBPUs were characterized by 13C NMR. Molecular weights of HBPUs were characterized by gel permeation chromatography. A gradual increase in HBPU molecular weight as well as degree of branching was observed when the stoichiometric ratio of A2 to B3 increased. It was exhibited that the solution concentration of the reaction had great effect on the gel point and cyclization of the monomeric A2 plus monomeric B3 system. This novel isocyanate terminated HBPUs are expected to be capable of modifying the curing performance of benzoxazine resin. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013