Determination Of Reactivity Ratios Research Articles

Reactivity ratio determination of styrene and 2-ethylhexyl acrylate by least squares methods

The reactivity ratios of styrene (STY) and 2-ethylhexyl acrylate (EHA) synthesized by bulk copolymerization method, were determined by ordinary least square (OLS) and generalized least square (GLS) approaches according to Inverted Finemann - Ross (IFR), Yezrielev - Brokhina - Roskin (YBR), Kelen - Tudős (KT) methods. Composition results were summarized and the 95 % individual confidence limits were determined and compared with each other and Error - in - Variables - Model (EVM) approach. Based on the copolymer compositions, the calculated reactivity ratios of STY and EHA through the GLS approach show acceptable percentage deviation with the well-known EVM method, which proves GLS approach, is the best linear estimator program for determining the monomer reactivity ratios. The reactivity ratios of EHA and STY are equal to 0.292 and 0.980 in IFR technique through the generalized least squares (GLS) approach which is closer to the point estimated from Error-in-variables model (EVM) and also r EHA and r STY are equal to 0.292 and 0.979 in EVM method, respectively. The present paper shows an estimation integral method for investigating the reactivity ratios of styrene and 2-ethylhexyl acrylate in Eviews software and the estimated values are discussed in terms of two regression approaches and compared with EVM method.

Monomer Reactivity Ratios and Chain Segment Distribution for AM/2-EHA Copolymer

A new copolymer of acrylamide (AM) and Isobutane-Ethylhexyl acrylate (2-EHA) was synthesized as profile control agent by free radical copolymerization. The copolymer composition obtained by element analysis method led to determination of reactivity ratio by employing YBR calculative method. The result indicated that the reactivity ratios of AM and 2-EHA were 0.856and 0.592 respectively. The chain segment distribution of copolymer was investigated from reactivity ratio and the microstructure of copolymer molecule was analyzed. The results showed that the ratios in feed can hardly change the chain segment distribution. The proportion of 1M1 decreased with the increase of AM in feed. AM and 2-EHA had a tendency to alternate in copolymer chain when f1=0.286~0.375. The monomer which had a low ratio in feed inserted in copolymer chain with 1M chain segment and the other monomer was separated evenly. It can help to study copolymerization for AM and 2-EHA for industrial production in mass.

Photo-induced controlled/living copolymerization of styrene and acrylic acid and determination of reactivity ratios

A controlled/living photopolymerization of styrene (St) and acrylic acid (AA) mediated by FeCl3·6H2O/tetramethylethylenediamine (TMEDA) was performed in N,N-dimethylformamide using 4-bromomethylbenzophenon (4-BMBP) as photoinitiator at room temperature under UV irradiation. 4-BMBP was first used as ATRP initiator and photoinitiator. A well-defined poly(styrene-co-acrylic acid) with predetermined molecular weight and narrow molecular weight distribution was obtained. The kinetic rule of controlled free radical photopolymerization of St and AA was studied. The kinetic results showed that the obtained random poly(St-co-AA) copolymers produced narrow polydispersity (PDI) within the range of 1.25–1.32 when the conversion was beyond 16.5 %, which was characterized by GPC. The plots of number average molecular weight versus conversion and ln([M]0/[M]) versus time were linear, indicating a controlled/living photopolymerization process. The system proceeded under mild and environmentally friendly conditions. The effects of initiator, catalyst, ligand, and vitamin C(VC) concentrations on polymerization process were investigated. The copolymers were characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR). The methods of Mayo-Lewis (ML), Kelen-Tudos (KT), and Yzrielev-Brokhina Roskin (YBR) were used to calculate the monomer reactivity ratios of controlled/living photopolymerization of St and AA at low conversions under selected conditions. The monomer reactivity ratios of St and AA were calculated to be r St = 0.82 and r AA = 0.30, respectively in this system. The living characteristics were demonstrated by chain extension experiment.

Copolymerization of novel reactive fluorinated acrylic monomers with styrene: reactivity ratio determination

The radical copolymerization of three polymerizable surfactants with styrene was investigated by NMR spectroscopy to assess their compositions. The reactivity ratios of these monomers were calculated according to the methods of Fineman–Ross and Kelen–Tudos. Consequently, Q and e values were deduced by the Alfrey and Price method. The results indicated the positive effect of the fluorine chain on the reactivity of monomers bearing a long spacer between the ammonium head and the acrylic function. These monomers exhibit high e values which are in favor of an intramolecular conformation of the surfactant where the ester carbonyl function of the polymerizable group interacts with the onium nitrogen atom via a compact six-sided structure.

Reactivity Ratio Estimation in Radical Copolymerization: From Preliminary Estimates to Optimal Design of Experiments

An error-in-variables-model (EVM) framework is presented for the optimal estimation of reactivity ratios in copolymerization systems. This framework consists of several sequential steps and practical prescriptions that can yield reliable and statistically correct reactivity ratio values. These steps include: (a) screening experiments for estimating preliminary reactivity ratios, (b) optimal design of experiments, (c) full conversion range experiments and estimation of optimal reactivity ratios, and if necessary, (d) design of sequentially optimal experiments and re-estimation of reactivity ratios and diagnostic checks. This complete methodology should become common practice for determining reactivity ratios with the highest possible level of confidence. The performance of this framework is verified experimentally with data from the controlled nitroxide-mediated copolymerization of 9-(4-vinylbenzyl)-9H-carbazole (VBK) and methyl methacrylate (MMA), a novel and largely unstudied copolymer system.

Synthesis via RAFT polymerization of thermo- and pH-responsive random copolymers containing cholic acid moieties and their self-assembly in water

Here we report the design and synthesis of polymers containing cholic acid pendant groups, a major bile acid synthesized in the liver from cholesterol. Random copolymers derived from 2-(methacryloyloxy)ethyl cholate (MAECA) with polyethylene glycol methyl ether methacrylate (PEGMA) and N,N-dimethylaminoethyl methacrylate (DMAEMA) have been synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. Compositions of co-monomers in the copolymers were determined by 1H NMR spectroscopy, which were further used to determine reactivity ratios of the monomers using the extended Kelen–Tudos method at high conversions. Copolymers from MAECA with PEGMA (P(MAECA-co-PEGMA)) series displayed lower critical solution temperatures (LCSTs) up to 23% MAECA content in the copolymer, which was studied by UV-visible spectroscopy. Both thermo- and pH-responsiveness were observed for the P(MAECA-co-DMAEMA) copolymers with an MAECA unit in the copolymer up to 11.8%. The critical aggregation concentration (CAC) of water soluble copolymers was determined by fluorescence spectroscopy. Self-assembly of random copolymers was investigated by 1H NMR spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM) and scanning electron microscopy (SEM), which indicated micellar structures in water from cholic acid based random copolymers. The polymeric aggregates were further explored for their drug encapsulation capabilities in aqueous medium using nile red as a hydrophobic model compound.

High‐Throughput Method for RAFT Kinetic Investigations and Estimation of Reactivity Ratios in Copolymerization Systems

AbstractA new high‐throughput experimental technique, namely automated parallel freeze‐evacuate‐thaw degassing method, is applied for the facile, rapid and reliable determination of reactivity ratios in copolymerization systems. The approach allowed carrying out a detailed kinetic investigation of the reversible addition‐fragmentation chain transfer (RAFT) copolymerization of methyl acrylate (MA) with vinyl acetate (VAc) monomers in 2‐methyl‐2‐butanol at 60 °C. Thereafter, the reactivity ratios of this copolymerization system were estimated utilizing the obtained kinetic data and a computer program based on the visualization of the sum of residual space method. The obtained reactivity ratios of the system (rMA = 8.2 and rVAc = 0.17) are comparable to values previously reported in the literature, which demonstrates the utility of this approach.

Nonlinear Method for Determining Reactivity Ratios of Ring-Opening Copolymerizations

A nonlinear errors-in-variables-model (EVM) regression method was used to determine reactivity ratios for enzyme-catalyzed ring-opening copolymerizations of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL). The cumulative copolymer composition model accurately described the experimental data, indicating that conventional models can be used to describe enzyme-catalyzed copolymerizations. Reactivity ratios were calculated from Raman spectroscopic data collected in situ and the model of monomer feed drift over the course of copolymerization. The analysis was combined for multiple experiments to improve the estimate. For the lipase-catalyzed copolymerization, the calculated reactivity ratios were rε-CL = 0.27 and rδ-VL = 0.39. Compared to conventional linearization techniques, the EVM method reduced the experimental work required and reduced the measurement error, as indicated by the 95% joint confidence region. In addition, the EVM method is influenced less by the apparent induction period of δ-VL. The conventional methods rely on low conversion data where the induction period is significant. The EVM method presented here determines reactivity ratios rapidly, saving both time and material waste.

Quantitative NMR Spectroscopy and Determination of Polymer Microstructure of Ethylene‐Styrene and Ethylene‐Isobutylene Co‐Polymers

AbstractSummary: Quantitative 13C NMR spectroscopy is used to determine reactivity ratios and end group and branching frequency of ethylene‐styrene and ethylene‐isobutylene co‐polymers synthesized at a temperature T = 205 °C and pressure p = 1650 bar at different levels of co‐monomer fraction. In the forefront of the studies quantitative 13C NMR conditions have to be investigated. Optimum conditions are achieved using a relaxation agent Chromium(III) acetylacetonate (Cr(acac)3) at measurement temperature T = 100 °C and a delay time d1 = 7 s with a 90° pulse and inverse‐gated decoupling. The analysis of conversion dependence of co‐monomer content shows an increase in conversion with increasing co‐monomer content for the ethylene‐styrene co‐polymerization, whereas conversion decreases with rising isobutene fraction in the co‐polymer. Reactivity ratios for ethylene‐styrene as well as for ethylene‐isobutylene co‐polymerization system are determined with values rES = 0.09 ± 0.007 and rSE = 2.3 ± 7.0 and rEIB = 3.3 ± 0.6 and rIBE = 6.3 ± 4.2. Frequency on methyl end groups, end‐of‐chain contributions caused by transfer to propionic aldehyde and butyl branches are gained. For the ethylene‐styrene co‐polymer system a decrease in frequency is observed, whereas for the ethylene‐isobutylene co‐polymer system the opposite occurs. Influence of the co‐monomers on the polymerization reaction steps as transfer to chain transfer agent and backbiting reaction is discussed.

Preparation of Organic/Inorganic Hybrid Materials Using Agregates of Poly{2-methyl-N-[2-(phenylthio)phenyl] Acrylamide-co-2-(Trimethylsyloxy)Ethyl Methacrylate} as Precursor and Vibrational Investigation of the Polymerization

Acrylamide based monomer, 2-methyl-N-[2-(phenylthio)phenyl]acrylamide (MPPA) was synthesized by reacting 2-(phenylthio) aniline with methacryloylchloride. The copolymerization of MPPA, with 2-(trimethylsyloxy)ethyl methacrylate(TSEM) was carried out with different monomer-to-monomer ratios in the feed. All the compounds were characterized by IR, Raman and 1H- and 13C-NMR techniques and SEM analysis. The elemental analysis of the copolymer composition led to the determination of reactivity ratios employing Fineman-Ross, Kelen-Tüdös and Extended Kelen-Tüdös linearization methods. These parameters were also estimated using a non-linear computational fitting procedure, known as reactivity ratio errors in variable model. The molecular weights and polydispersity index of polymers was determined by gel permeation chromatography. Thermal stability of the copolymers were found to increase with increasing mole fraction of MPPA from thermogravimetric analysis. The vibrational analysis of MPPA and poly(MPPA) were also performed to explain the vibrational spectra and to confirm the polymerization on the basis of a theoretical and experimental aproach.

Synthesis, Antimicrobial Activity and Semi-conducting Properties of Novel 2-(4-Chloro-1-Naphtyloxy)-2-Oxoethyl Methacrylate with 2-(Diethylamino)Ethyl Methacrylate Copolymers

The free-radical initiated copolymerization of 2-(4-chloro-1-naphtyloxy)-2-oxoethyl methacrylate (ClNOEMA) with 2-(diethylamino) ethyl methacrylate (DEAEMA) was carried out in 1,4-dioxane solution at 70 ± 1°C using 2,2′-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios (ranging from 0.15 to 0.85) in the feed. The copolymer composition obtained by elemental analysis led to the determination of reactivity ratios employing Fineman-Ross (F-R) and Kelen-Tüdös (KT) linearization methods. These parameters were also estimated using a non-linear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). The prepared homo and copolymers were tested for their antimicrobial activity against bacteria and yeast. These copolymers have been converted into novel salts by reaction with the iodemethane (CH3I). The copolymers and the corresponding salts have been characterized fully by a range of spectroscopic analysis techniques. The electrical conductivity dependence of temperature of the polymers were measured and the polymers exhibit the semi-conducting behavior, confirming that the electrical conductivity increases with increasing temperature. The poly(CINOEMA-co-DEAEMA) polymer doped by CH3I for 15 min shows the highest conductivity. The optical band gap, activation energy and room temperature conductivity values of these polymers were obtained. These electronic parameters suggest that the poly(CINOEMA-co-DEAEMA)s doped by CH3I for 15 min is an organic semiconductor with the thermally activated conduction mechanism.

Copolymerization of a dendronized monomer with styrene and different acrylates: Determination of reactivity ratios

AbstractThe reactivity ratios for the copolymerization of a first‐generation dendronized monomer with styrene and different acrylates are determined. The obtained ratios as well as the copolymer compositions that can be expected are discussed in detail. The influence of the dendron on the polymerization potential of the monomer is estimated by comparing its reactivity to those of linear systems as well as using higher generations of the dendronized monomer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Percipitation copolymerization of acrylamide and acrylic acid: Determination of reactivity ratio by various methods

AbstractCopolymers of acrylamide ( AM ) and acrylic acid ( AA) were prepared by precipitation polymerization method at 65 °C in the ethyl acetate as solvent. Copolymer composition was determined by elemental analysis. Monomer reactivity ratios were determined in low conversions. Mayo-Lewis, Finemann-Ross, Inverted Finemann-Ross, Ezrielev-Brokhina-Roskin, Kelen-Tudos, Extended Kelen-Tudos and Mao-Huglin methods, as linear methods, and Tidwell-Mortimer, as nonlinear method, were applied to calculate rAM and rAA r reactivity ratios. Monomer reactivity ratios of AM and AA were obtained 0.46 and 0.28, respectively. Comparing of reactivity ratios of AM and AA in this work by other solvents showed that hydrogen bonding and ionic strength are important parameters that can affect the reactivity ratios of monomers. Moreover, microstructure of copolymers was determined using reactivity ratios and conditional probability based on the kinetic model for free-radical polymerization.

Poly(isobornyl methacrylate-co -methyl acrylate): Synthesis and stereosequence distribution analysis by NMR spectroscopy

Copolymerization of isobornyl methacrylate and methyl acrylate (I/M) is performed by atom transfer radical polymerization using methyl-2-bromopropionate as an initiator and PMDETA/CuBr as catalyst under nitrogen atmosphere at 70 °C. The copolymer compositions determined from 1H NMR spectra are used to determine reactivity ratios of the monomers. The reactivity ratio determined from linear Kelen–Tudos method and non-linear error-in-variable method, are rI = 1.25 ± 0.10, rM = 0.84 ± 0.08 and rI = 1.20, rM = 0.82, respectively. 1D, distortion less enhancement by polarization transfer and 2D, heteronuclear single quantum coherence, and total correlation spectroscopy NMR experiments are employed to resolve highly overlapped and complex 1H and 13C{1H} NMR spectra of the copolymers. The carbonyl carbon of I and M units and methyl carbon of I unit are assigned up to triad compositional and configurational sequences, whereas β-methylene carbons are assigned up to tetrad compositional and configurational sequences. Similarly, methine carbon of I unit is assigned up to triad level. The couplings of carbonyl carbon and quaternary carbon resonances are studied in detail using 2D hetero nuclear multiple bond correlation spectra. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Synthesis and characterization of new copolymers from glycidyl methacrylate and tetrahydrofurfuryl acrylate: Determination of reactivity ratios

The new copolymers from different feed compositions of glycidyl methacrylate (GMA) and tetrahydrofurfuryl acrylate (THFA) were synthesized using free radical polymerization in toluene at 70±1 °C using benzoyl peroxide (BPO) as initiator. The polymers were characterized by 1H NMR, 13C NMR and FTIR spectroscopic techniques. The polydispersities of the copolymers suggest a strong tendency for chain termination by disproportionation. The glass transition temperature of the copolymers increases with increase in GMA content. The thermal stability of the copolymers increases with increase in THFA content. The copolymer compositions were determined using 1H NMR analysis. Reactivity ratios for GMA and THFA as determined by the Mao-Huglin method were r1=0.379 and r2=0.266. The results showed that all these copolymerizations are strictly linear systems describable by the Mayo-Lewis equation based on the terminal model and that accurate reactivity ratio data can be obtained.

New functional copolymers of N-acryloyl-N′-methyl piperazine and 2-hydroxyethyl methacrylate: synthesis, determination of reactivity ratios and swelling characteristics of gels

Copolymers of N-acryloyl-N′-methylpiperazine (AcrNMP) and 2-hydroxyethyl methacrylate (HEMA) were synthesized by free radical solution polymerization in dioxane at 70 ± 1 °C, using 2,2′-azobisisobutyronitrile (AIBN) as initiator. The copolymer compositions were analyzed by the methods of FTIR spectroscopy and elemental analysis. Both the method of analysis yielded results that agreed reasonably well. The monomer reactivity ratios of the copolymerization were determined by the linearization methods of Finemann–Ross (FR) and Kelen–Tudos (KT). The reactivity parameter results derived using FTIR analysis showed that the copolymerization yielded mainly alternating structure with reactivity ratios, r1(AcrNMP) = 0.263 ± 0.011 and r2(HEMA) = 0.615 ± 0.097 by F–R method and r1 = 0.227 ± 0.074 and r2 = 0.53 ± 0.15 by KT method. Microstructure data calculated by the method of Igarashi also supports the alternating structure (tendency) of the copolymer. Crosslinked polymer gels of this system exhibited remarkably high swelling of more than 500% in water at ambient temperature.

Ambient temperature Atom Transfer Radical copolymerization of tetrahydrofurfuryl methacrylate and methyl methacrylate: Reactivity ratio determination

Tetrahydrofurfuryl methacrylate (THFMA), a heterocyclic monomer was polymerized by ambient temperature Atom Transfer Radical Polymerization (AT ATRP) using CuX/PMDETA/EBiB system. THFMA was found to undergo very rapid polymerization, in bulk. For a target DP > 200, bulk polymerization results in cross-linking as evidenced by (CH 2) n ,wag peaks (IR spectroscopy). Atom Transfer Radical copolymerization (ATRcP) of THFMA with MMA was performed and the reactivity ratios were calculated from the copolymer composition, as determined by 1H NMR, using Fineman–Ross and Kelen–Tudos methods. The reactivity ratios determined for ATRP were found to be significantly different from the literature values for conventional free radical polymerization (CFRP). This may be due to the coordination of copper catalytic system with the oxygen atom of the tetrahydrofurfuryl group that could lead to the variation in reactivity ratios. 1H NMR evidence for catalyst–monomer interaction is also provided.

Novel Copolymers of 4-Chloronaphthyl Methacrylate with Acrylonitrile: Determination of Monomer Reactivity Ratios and Antimicrobial Activity

Methacrylate based monomer, 4-chloronaphthyl methacrylate (4-CNMA) was synthesized by reacting 4-chloro naphthol with methacryloyl chloride in the presence of triethylamine (NR3) at 0–5°C. The free-radical initiated copolymerization of (4-CNMA), with acrylonitrile (AN) was carried out in 1,4-dioxane-dimethyl sulfoxide mixture (8:2) solution at 70 ± 1°C using 2,2′-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The monomer 4-CNMA, poly(4-CNMA) and copolymers were characterized by FT-IR and 1H-and 13C-NMR spectral studies. The copolymer composition obtained by elemental analysis led to the determination of reactivity ratios employing Fineman-Ross (F-R), Kelen-Tüdös (KT) and Extended Kelen-Tüdös (EKT) linearization methods. These parameters were also estimated using a non-linear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). The solubility of the polymers was tested in various polar and non-polar solvents. Gel permeation chromatography was employed to determine the molecular weights (Mw and Mn) and polydispersity index of polymers. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with increase in the mole fraction of 4-CNMA in the copolymers. The prepared homo and copolymers were tested for their antimicrobial activity against bacteria, fungi and yeast.

ANTIMICROBIAL ACTIVITY OF COPOLYMERS OF 2,4-DICHLOROPHENYL ACRYLATE WITH STYRENE: SYNTHESIS, CHARACTERIZATION AND REACTIVITY RATIOS

Some copolymers of 2,4-dichlorophenyl acrylate (2,4-DCPA) with styrene (St) of different feed compositions were prepared by free radical polymerization technique using 2,2′-azobisisobutyronitrile (AIBN) as an initiator, and the copolymers were characterized by IR spectroscopy. The copolymer composition obtained by UV-spectra led to determination of reactivity ratio by employing Fineman-Ross (F-R) and Kelen-Tudos (K-T) methods. Average molecular weight, as well as intrinsic viscosity, was obtained by vapor pressure osmometry (VPO) and Ubbleholde viscometer. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) of copolymers were carried out under nitrogen atmosphere. Antimicrobial effects of the homo and copolymers were also investigated against various microorganisms such as bacteria, fungi and yeasts.

Synthesis, characterization and antimicrobial activity of important heterocyclic acrylic copolymers

The acrylate monomer, 7-acryloyloxy-4-methyl coumarin (AMC) has been synthesized by reacting 7-hydroxy- 4-methyl coumarin, with acryloyl chloride in the presence of NaOH at 0-5°C. Copolymers of 7-acryloyloxy-4-methyl coumarin (AMC) with vinyl acetate (VAc) were synthesized in DMF (dimethyl formamide) solution at 70±1°C using 2,2'- azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The copolymers were characterized by Fourier transform infra red (FTIR) spectroscopy. The copolymer composition was evaluated by 1H-NMR (proton nuclear magnetic resonance) and was further used to determine reactivity ratios. The monomer reactivity ratios for AMC (M1)-VAc (M2) pair were determined by the application of conventional linearization methods such as Fineman-Ross (r1 = 0.6924; r2 = 0.6431), Kelen-Tudos (r1 = 0.6776; r2 = 0.6374) and extended Kelen-Tudos (r1 = 0.6657; r2 = 0.6256). Thermo gravimetric analysis showed that thermal decomposition of the copolymers occurred in single stage in the temper- ature range of 263-458°C. The molecular weights of the polymers were determined using gel permeation chromatography. The homo and copolymers were tested for their antimicrobial properties against selected microorganisms.