Composition Of Monomer Mixture Research Articles

Copolymers of N-Vinylpyrrolidone with N-(p-Acetoxy)phenylmaleimide and Its Oxime: Synthesis and Sorption Properties

Radical copolymerization of N-vinylpyrrolidone with N-(p-acetoxy)phenylmaleimide and its oxime in the bulk and in a dimethylformamide solution was studied. Irrespective of the medium, copolymerization of N-vinylpyrrolidone with N-(p-acetoxy)phenylmaleimide yields copolymers with high tendency of comonomer units to alternation. Copolymerization of N-vinylpyrrolidone with N-(p-acetoxy)phenylmaleimide oxime in the bulk yields random copolymers. In the curve of the copolymer composition vs. the initial monomer mixture composition, there is an azeotropic point in the region of 45 mol % oxime. The kinetic relationships of the reactions were studied, and the structure of the copolymers obtained was determined. The ability of the copolymers to take up Cu(II) and Ni(II) ions from acidic and alkaline solutions was studied. The copolymers quantitatively take up Ni(II) and Cu(II) from ammonia solutions and can find use as sorbents for wastewater treatment to remove copper and nickel ions.

Controlled Synthesis of Polymers on the Basis of Stearyl Methacrylate and Their Use as Depressor Additives

The controlled synthesis of poly(stearyl methacrylate) and stearyl methacrylate–acrylonitrile copolymers is conducted using a catalytic system consisting of copper(I) bromide, tris[(2-pyridyl)methyl]amine as a ligand, and isopropylamine as an activating agent. Effects of activator concentration and monomer mixture composition on the molecular-weight characteristics of the (co)polymers are estimated. It is shown that the products of synthesis may be used as depressor additives lowering the cloud point, pour point, and cold filter plugging point of diesel fuel.

Copolymerization of Methacryloylguanidine Trifluoroacetate with Styrene in Acetone and Dimethylsulfoxide at High Conversions

Radical copolymerization of methacryloylguanidine trifloroaceatate with styrene has been studied in acetone and dimethylsulfoxide in a wide range of the monomer mixture compositions. For the first time, copolymers (with the yield up to 90%) have been obtained from monomer mixtures with a high total concentration of comonomers (up to 1.7 mol/L). The preliminary biological tests have shown sufficiently high biocide and fungicide activity of the synthesized copolymers.

P‐227: Late‐News Poster: Topology‐enhanced Electro‐optical Performance of Reverse‐mode Polymer Stabilized Cholesteric Shutters for Volumetric 3D Devices

Topology‐enhanced electro‐optic performance of reverse‐mode polymer stabilized cholesteric shutters (R‐PSCT) with mixture of two reactive monomers, is experimentally demonstrated. Significantly distinct morphology of polymer network generated by two reactive monomers provides a unique combination of high optical contrast and low driving voltage along with excellent electromechanical stability that ensures longer life time of the shutters without any loss in electro‐optical performance, which has been main concern in R‐PSCT shutters. We demonstrate a R‐PSCT with optimum composition of reactive monomer mixture for electro‐mechanically sustained polymer network with 150K switching cycles for its application in optical shutters used in volumetric 3D devices.

Aqueous‐Phase Copolymerization of N‐Vinylpyrrolidone and N‐Vinylformamide

AbstractAqueous‐phase batch free‐radical copolymerization of NVP and NVF is studied at 60 and 85 °C with varying initial monomer mixture compositions and monomer to water ratios. The rate of monomer conversion is found to increase with increasing NVP molar fraction and with decreasing total monomer concentration, in accordance with the expected behavior based on homopolymerization kinetics. The copolymer composition is equal to the initial comonomer composition, indicating monomer reactivity ratios to be unity. A terminal copolymerization model provides a good description of polymerization rate, copolymer composition, and polymer molar mass distributions using the same kinetic rate coefficients as used to previously describe the homopolymerization of the two monomers.

Effects of chemical structure and composition of the polymer matrix on the morphology and electro-optical performance of polymer-dispersed liquid crystal films

Polymer-dispersed liquid crystal (PDLC) systems on the basis of nematic liquid crystal E7 and amphiphilic binary copolymers of acrylic acid (AA) with such acrylates as 2-ethylhexyl acrylate (EHA), n-butyl acrylate (BA), and methyl acrylate (MA) are investigated. It is shown that the liquid crystal (LC) drops in the copolymer EHA–AA have submicrometre sizes, and their dependence on the composition of the photo-curable monomer mixture is described by a parabolic curve. The highly oriented domain structure in the same system is first revealed when electric field is applied. The threshold voltage for all systems begins to increase with some critical composition of a monomer mixture in which the longer the hydrocarbonic radical in an acrylate molecule, the higher the content of AA. The PDLC system based on the BA–AA copolymer with 30 wt% LC exhibits the least value of the driving voltage, 1 V μm–1, and the lowest memory effect.

Precipitation Copolymerization of Vinyl‐Imidazole and Vinyl‐Pyrrolidone, 1 – Experimental Analysis

AbstractThe precipitation copolymerization of two water‐soluble monomers, vinyl‐imidazole and vinyl‐pyrrolidone, carried out in butylacetate is investigated for the first time. Compared to classical solution polymerization it is found that much larger molecular weights are obtained. Such large polymer chains are formed by a crosslinking reaction occurring in the precipitated polymer particles. The dependence of the reaction kinetics on operating parameters such as monomer mixture composition (from vinyl‐imidazole homopolymer to the 50/50 copolymer), monomer mixture holdup, initiator amount, and stirring rate has been elucidated. Notably, it is found that the polymerization kinetics is independent of the particle size distribution (PSD). Therefore, the polymerization mechanism and the morphology of the precipitating particles can be investigated separately. The final PSD is broad and bimodal, with a first mode at around 10 µm, corresponding to clusters of nucleated primary particles, and a second larger mode at around 100 µm, corresponding to aggregates of such clusters. The smaller clusters show fractal geometry, with a fractal dimension of ∼2.5, corresponding to quite compact aggregates. The size of the two peaks, the ratio between the two modes and the time evolution of the PSD are all depending on the aggregation/breakage processes in the reactor, which are affected by operational parameters like the copolymer composition and the shear rate.magnified image

Effect of monomer mixture composition on structure and chromatographic properties of poly(divinylbenzene- co-ethylvinylbenzene- co-2-hydroxyethyl methacrylate) monolithic rod columns for separation of small molecules

Porous poly(divinylbenzene- co-ethylvinylbenzene- co-2-hydroxyethyl methacrylate) monoliths were synthesized via thermally initiated free-radical polymerization in confines of surface-vinylized glass columns (150 mm × 3 mm i.d.) and applied to the reversed-phase separation of low-molecular-weight aromatic compounds. In order to compensate for the polymer shrinkage during the synthesis and prevent the monolith from detachment from the column wall, polymerization was conducted under nitrogen pressure. The reaction proceeded at 60 °C for 22 h. 2,2′-Azo- bis-isobutironitrile was used as the initiator and 1-dodecanol was used as the porogen. A series of monoliths with different monomer ratios were obtained. All the monoliths had high specific surface areas ranging from 370 to 490 m 2/g. In the studied range of monomer mixture compositions, the mechanical stability of the stationary phase in water/acetonitrile eluents was found to be high enough and practically insensitive to the fraction of 2-hydroxyethyl methacrylate (HEMA). Increasing the molar fraction of HEMA from 10.5% to 14.7% resulted in the decrease of column permeability by two orders of magnitude (from 1.1 × 10 −12 to 1.8 × 10 −14 m 2) and led to weaker retention of alkylbenzenes. The higher HEMA content was shown to reduce the plate height of the columns in the separation of small molecules from 160–490 μm to 40–76 μm. This was attributed mainly to the decrease of the domain size of the monoliths leading to lower eddy dispersion and mass transfer resistance in the column.

Kinetics of pseudoliving free-radical copolymerization of styrene and methyl methacrylate by the reversible addition fragmentation chain-transfer mechanism

The kinetics of copolymerization of styrene with methyl methacrylate in the presence of tert-butyl dithiobenzoate as a reversible addition fragmentation chain-transfer agent has been studied. Formation of radical intermediates has been investigated. In a wide range of monomer mixture compositions, the kinetic features of pseudoliving radical copolymerization of this monomer pair in the presence of both a low-molecular-mass reversible addition fragmentation chain-transfer (RAFT) agent and a polymer RAFT agent being formed are close to the corresponding features of the homopolymerization of styrene.

Polymerization kinetics of indene, methyl methacrylate and acrylonitrile and characterization of their terpolymer

The free radical terpolymerization of indene (In), methyl methacrylate (MMA) and acrylonitrile (AN) has been investigated. The rate of polymerization of all the binary systems involved has been measured dilatometrically for the homogeneous polymerization. The reactivity ratios of the three binary systems were calculated and were found to be equal to 0.031 and 0.397 for In/AN copolymers and 0.02 and 3.82 for In/MMA copolymers and finally 0.152 and 1.20 for AN/MMA copolymers. The rate of terpolymerization in bulk has been measured as well as the relationship between the monomer mixture composition and the obtained terpolymer in order to construct the compositional triangle. Also the effect of initiator concentration on the rate of terpolymerization was investigated. The activation energy of terpolymerization was determined. The terpolymers were characterized by spectral and thermo-gravimetric analyses. The data indicates that polyindene improves the thermal stability of the prepared terpolymers.

Polydispersity of Hyperbranched Polyesters Based on 2,2-Bis(hydroxymethyl)propanoic Acid: SEC/MALDI−TOF MS and 13C NMR/Kinetic-Recursive Probability Analysis

The absolute average molar masses and polydispersity index of a series of polyesters based on 2,2-bis(hydroxymethyl)propanoic acid (BMPA, AB2-type monomer), 2,2-bis(hydroxymethyl)-1,3-propanediol (PE, B4-type monomer), and 1,1,1-tris(hydroxymethyl)propane (TMP, B3-type monomer) were determined by SEC/MALDI−TOF off-line coupling. The M̅w/M̅n values, in the 1.8−3.1 range, were surprisingly very close to those found by SEC using the conventional linear polystyrene calibration method, but dramatically lower than those calculated from conversion and composition of initial monomer mixture assuming equal reactivity of functional groups. The mol ratios of the various monomer units in final polyesters were determined by 13C NMR. The kinetic-recursive probability approach assuming first-shell substitution effects was then applied to calculate the branching factors and the average molar masses of these polyesters from their final composition. The AB- and B-branching factors were significantly lower than expected for random polymerizations, reflecting the existence of both negative A−B and B−B substitution effects, i.e. lower reaction rate of a given A or B group after reaction of the other groups present on the same monomer unit. The calculated values of M̅w and M̅w/M̅n were reasonably close to the experimental ones for all hyperbranched polyesters. Intramolecular esterifications and intermolecular etherifications side reactions were taken into account in the calculations with some simplifying assumptions and found to marginally broaden MW distributions.

First Shell Substitution Effects in Hyperbranched Polymers: Kinetic−Recursive Probability Analysis

The kinetic−probability approach taking into account first shell substitution effects (FSSE) is applied to hyperbranched condensation polymerizations. Simple explicit relationships giving the mass-average molar mass ( ) and mass-average degree of polymerization ( ) as a function of conversion, of initial monomer mixture composition and of polymer architecture at a given reaction time are derived using the “in−out” recursive probability approach. Three experimentally available parameters, the A-, B-, and AB-branching factors (δA, δB, and δAB) are introduced to describe polymer branching. δB generalizes Frey's degree of branching to polymerizations involving any type of monomer mixture and can directly be used to calculate polymer . δAB characterizes the substitution effects induced on A-group reactivity by the reaction of B-groups (and vice versa). This effect, generally neglected in hyperbranched polymerization studies, may exert a dramatic influence on hyperbranched polymer dispersity ( / ). Two systems,...

Using 1H‐NMR spectroscopy for the kinetic study of the in situ solution free‐radical copolymerization of styrene and ethyl acrylate

AbstractThe free‐radical copolymerization of styrene and ethyl acrylate in benzene‐d6 as the solvent in the presence of benzoyl peroxide as an initiator at 70°C was studied by online 1H‐NMR spectroscopy. The chemical composition of the copolymer at different reaction times was calculated from the conversion of the monomers to the copolymer, and then the reactivity ratios of styrene and ethyl acrylate were determined at both low and high conversions. Data for the overall monomer conversion versus the time were used to estimate the ratio kpkt−0.5 for different compositions of the initial feed (kp is the propagation rate constant, and kt is the termination rate constant). kpk increased with an increasing molar fraction of ethyl acrylate in the initial feed. The monomer mixture and copolymer compositions versus the overall monomer conversion were calculated with the data of 1H‐NMR spectra. The incorporation of the styrene monomer into the copolymer structure was more favored than that of the ethyl acrylate monomer. Reducing the molar fraction of styrene in the initial feed intensified this. Drawing the molar fraction of styrene (or ethyl acrylate) in the copolymer chains versus that in the initial feed showed a tendency of the system toward random copolymerization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Kinetic Study of Radical Polymerization VIII. A Comprehensive Study of Solution Copolymerization of Vinyl Acetate and Methyl Acrylate by 1H‐NMR Spectroscopy

Radical copolymerization reaction of vinyl acetate (VA) and methyl acrylate (MA) was performed in a solution of benzene‐d6 using benzoyl peroxide (BPO) as the initiator at 60°C. Kinetic studies of this copolymerization reaction were investigated by on‐line 1H‐NMR spectroscopy. Individual monomer conversions vs. reaction time, which was followed by this technique, were used to calculate the overall monomer conversion, as well as the monomer mixture and the copolymer compositions as a function of time. Monomer reactivity ratios were calculated by various linear and nonlinear terminal models and also by simplified penultimate model with r 2(VA)=0 at low and medium/high conversions. Overall rate coefficient of copolymerization was calculated from the overall monomer conversion vs. time data and k p . k t −0.5 was then estimated. It was observed that k p . k t −0.5 increases with increasing the mole fraction of MA in the initial feed, indicating the increase in the polymerization rate with increasing MA concentration in the initial monomer mixture. The effect of mole fraction of MA in the initial monomer mixture on the drifts in the monomer mixture and copolymer compositions with reaction progress was also evaluated experimentally and theoretically.

Optimization of Alkyl Methacrylate Terpolymer Properties as Lubricating Oil Rheology Modifier

Solution terpolymerization processes of methyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate using bifunctional 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane or monofunctional tert-butylperoxy-2-ethylhexanoate initiator were investigated. The first set of terpolymerizations was performed in 2 M xylene solutions, isothermally at 91, 100, 105, and 115 °C. The terpolymerization kineticsconcentrations of molecular species, kinetic chain length, molar mass averages as functions of the reaction timewas modeled by the Villermaux−Blavier tendency kinetic model for radical polymerization. Complete monomer conversions and high molar masses of terpolymers were achieved in a simple batch process with bifunctional initiator. The second set of polymerization reactions was performed in 2 M mineral base oil solutions, under isothermal conditions at 115 and 120 °C, using the bifunctional initiator. By varying the monomer mixture composition and concentrations of the initiator and chain transfer agent, n-dodecyl mercaptan, the terpolymers of different composition and molar mass were obtained. The solution properties of alkyl methacrylate terpolymers as lubricating oil rheology modifierskinematic viscosity, viscosity index, shear stability, and pour pointwere established. A strong correlation between molar mass distribution of synthesized polymers and rheological properties of polymer solutions was revealed by an applied optimization procedure.

Optimization of in-situ monolithic synthesis for immunopreconcentration in capillary

Poly(glycidyl methacrylate-co-ethylene dimethacrylate) monoliths have been synthetized in fused-silica capillary. The monomer mixture composition, initiation mode and porogen composition were optimized in order to provide a monolith with an homogeneous morphology and able to generate an electroosmotic flow via the incorporation of a small percentage of monomers possessing sulfonate group. Anti-ochratoxin A antibodies were immobilized through a single step on the epoxy groups leading to a miniaturized immunoextraction column. In order to evaluate the specificity of the analyte–antigen interaction on this immunosorbent, the retention of ochratoxin A was examined on this support but also on two complementary sorbents: one constituted by the non-bonded monolith and another one bonded with non-specific antibodies. Only the monolith bonded with anti-ochratoxin A antibodies lead to retention, showing the specificity of the interactions involved. This affinity phase based on a monolithic polymer support exhibits a high potential for specific preconcentration of small molecules.

Kinetic Study of Radical Polymerization VI. Copolymer Composition and Kinetic Parameters for Coplymerization of Styrene‐Itaconic Acid by On‐Line 1H‐NMR

Free radical solution copolymerization of styrene (St) and itaconic acid (IA) in dimethylsulfoxide‐d6 (DMSO‐d6) as the solvent and the use of 2,2′‐azobisisobutyronitrile (AIBN) as the initiator at 78°C was investigated by an on‐line 1H‐NMR spectroscopy technique. Individual monomer conversion vs. reaction time, which was calculated from the 1H‐NMR spectra data, was used to study the drift in monomer mixture composition vs. conversion. It was found that in general, both monomers were incorporated almost equally into the copolymer. However, when the mole fraction of IA was low, the tendency of IA toward incorporation into the copolymer chain was somewhat higher than St and by increasing the mole fraction of IA in the reaction mixture, the inverse tendency was observed. Overall monomer conversion as a function of time was calculated from individual monomer conversion data and used for the estimation of kp /kt 0.5 for various monomer mixture compositions. This ratio was decreased with increasing the amount of IA in the initial feed, indicating a decrease in the rate of copolymerization. Changes in the copolymer composition vs. overall monomer conversion were investigated experimentally from the NMR spectra. This was in good agreement with the changes in monomer mixture composition vs. reaction progress. Plotting the copolymer composition vs. initial monomer feed showed tendency of the system toward alternating copolymerization.

Synthesis and Properties of CMPMI-Modified Graft-Type ACS Resin

Graft-type ACS was synthesized by suspension polymerization using N-(3-chloro-2-methylphenyl)maleimide (CMPMI) as a modifier. The effect of graft conditions such as initiator concentration and monomer mixture composition on graft efficiency (GE) were studied. The GE has maximum value when the initiator concentration is 0.05% of the monomer content, and increases with the increasing of CMPMI content at fixed initiator concentration. The effect of monomer mixture composition on the properties of the copolymers was also investigated. The results show that molecular weight ( and ), glass transition temperature (Tg), Vicat softening point (TVicat), and thermal degradation temperature (Td) of the copolymers increased with increasing CMPMI moieties in the copolymer. The mechanical properties (impact strength and tensile strength) are increased due to the feeding of CMPMI. The morphological structure of graft-type ACS resin was investigated by scanning electron microscopy (SEM).

Morphological and topographic effects on calcification tendency of pHEMA hydrogels

Poly(2-hydroxyethyl methacrylate) hydrogels were prepared in the presence of varying concentrations of water, or a co-monomer ethoxyethyl methacrylate at different strengths of crosslinking agent ethylene glycol dimethacrylate. Calcification tendency and its correlation with monomer mixture composition, topography and porosity of these materials were investigated. Scanning (SEM) and transmission electron microscopy (TEM) was used to study topography and porosity respectively. Calcification and calcium diffusion ability in to the hydrogels were investigated by light microscopy, SEM and energy dispersive analysis of X-rays (EDAX) after incubation of the materials in a metastable calcifying solution for 48 days. Polymer and solvent volume fractions were also studied to determine if a correlation existed between porosity and calcification. Most of the series of hydrogels showed surface irregularities. Internal structure showed evidence of a porous structure in one of the series. Calcification studies indicated diffusion of calcium ions in some of the series. The diffusion of calcium is limited to 30–40 μm in most calcified specimens. For hydrogels that exhibited substantial surface irregularities and micro channels, the infiltration of calcium up to 200 μm was observed. Attempts to detect porosity by electron microscopy failed in some of the hydrogels due to difficulty in sample processing and sectioning. However, collaboration of the results with different techniques used, indicated that surface defects are the major contributors to calcium deposition. Decrease in porosity reduces the amount of calcium deposits and infiltration with decreasing solvent volume fraction which is associated with crosslinking concentration and initial water content of the polymer.

Synthesis and Properties of N-cyclohexylmaleimide-Containing Graft-type MCS Resin

ABSTRACT N-cyclohexylmaleimide-containing Graft-type MCS resin was synthesized by suspension polymerization. Effects of graft conditions, such as initiator and monomer mixture composition, on graft efficiency (GE) were studied. GE has maximum value when the initiator concentration is 0.3% of the monomer content, and increases with increasing of cyclohexylmaleimide (ChMI) content at fixed initiator concentration. Effects of monomer mixture composition on the properties of the copolymers were also investigated. The results show that the molecular weight ( and ), Tg, TVicat, and degradation temperature of the copolymers increased with increasing ChMI moieties in the copolymer. The mechanical properties (impact strength and tensile strength) were increased due to the presence of ChMI. The apparent viscosity ηa and the non-newtonian flow parameter power n increase with increasing content of ChMI, and the melt is a pseudoplastic liquid. The morphological structure of graft-type MCS resin was investigated by scanning electron microscopy (SEM).