Effect of nanoclay and macroinitiator on the kinetics of atom transfer radical homo- and copolymerization of styrene and methyl methacrylate initiated with CCl3-terminated poly (vinyl acetate) macroinitiator

Effect of nanoclay on the kinetics of atom transfer radical bulk homo- and copolymerization of styrene (St) and methyl methacrylate (MMA) initiated with CCl₃-terminated poly (vinyl acetate) macroinitiator at 90 °C was investigated. CuCl/PMDETA was used as a catalyst system. Results showed that nanoclay significantly enhances the homopolymerization rate of MMA. It was attributed to the activated conjugated CC bond of MMA monomer via interaction between the carbonyl group of MMA monomer and the hydroxyl moiety (AlOH) of nanoclay as well as to the effect of nanoclay on the dynamic equilibrium between the active (macro)radicals and dormant species. Homopolymerization rate of St (a noncoordinative monomer with nanoclay) decreased slightly in the presence of nanoclay. It could be explained by inserting of a portion of macroinitiator into the clay galleries, where no sufficient St monomer exists due to the low compatibility or interaction of St monomer with nanoclay to react with the macroinitiator. Controlled/living characteristic of all the reactions were confirmed by GPC results. More reliable reactivity ratios of the St and MMA in the presence of nanoclay were calculated by using the cumulative average copolymer composition at the moderate to high conversion to be r_St = 0.290 ± 0.082, r_MMA = 0.443 ± 0.093 (extended Kelen-Tudos method) and r_St = 0.293 ± 0.071, r_MMA = 0.447 ± 0.080 (Mao-Huglin method). Results indicated that the rate of incorporation of MMA comonomer into the copolymer increases in the presence of nanoclay, verifying the existence of interaction between the carbonyl group of MMA comonomer and the hydroxyl moiety of nanoclay. It was found that in the presence of nanoclay, tendency of the random copolymerization of St and MMA toward an alternating copolymerization increases.     

Free radical copolymerization of 1-vinyl naphthalene with styrene,methyl methacrylate,and acrylonitrile

Investigations on free radical copolymerization of 1-vinyl naphthalene (1-VNph, monomerM ₂) with styrene (St), methyl methacrylate (MMA) and acrylonitrile (AN) (monomersm ₁) in bulk at 60°C with AIBN as initiator are presented. Relative reactivity ratios were calculated by the Kelen-Tüdös method yielding:r _st=0.70 ±0.23 andr _1–VNph=2.02 ±0.40 for system St/1-VNph;r _MMA=0.32 ±0.10 andr _1–VNph=0.57 ±0.07 for system MMA/1-VNph andr _AN=0.11 ±0.03 andr _1–VNph=0.45 ±0.09 for system AN/1-VNph.Q, e values for 1-VNph according to Alfrey, Price scheme were calculated toQ _1–VNph=1.02,e ₁–VNph=–0.62.     

Homopolymer and copolymers of 4-nitro-3-methylphenyl methacrylate with glycidyl methacrylate: Synthesis, characterization, monomer reactivity ratios and thermal properties

The novel methacrylic monomer, 4-nitro-3-methylphenyl methacrylate (NMPM) was synthesized by reacting 4-nitro-3-methylphenol dissolved in ethyl methyl ketone (EMK) with methacryloyl chloride in the presence of triethylamine as a catalyst. The homopolymer and copolymers of NMPM with glycidyl methacrylate having different compositions were synthesized by free radical polymerization in EMK solution at 70 ± 1 °C using benzoyl peroxide as free radical initiator. The homopolymer and the copolymers were characterized by FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The solubility tests were tested in various polar and non-polar solvents. The molecular weight and polydispersity indices of the copolymers were determined using gel permeation chromatography. The glass transition temperature of the copolymers increases with increase in NMPM content. The thermogravimetric analysis of the polymers performed in air showed that the thermal stability of the copolymer increases with NMPM content. The copolymer composition was determined using ¹H NMR spectra. The monomer reactivity ratios were determined by the application of conventional linearization methods such Fineman-Ross (r₁ = 1.862, r₂ = 0.881), Kelen-Tudos (r₁ = 1.712, r₂ = 0.893) and extended Kelen-Tudos methods (r₁ = 1.889, r₂ = 0.884).     

Hydrophilic and hydrophobic copolymer systems based on acrylic derivatives of pyrrolidone and pyrrolidine

This article deals with the synthesis of hydrophilic methacrylic monomers derived from ethyl pyrrolidone [2‐ethyl‐(2‐pyrrolidone) methacrylate (EPM)] and ethyl pyrrolidine [2‐ethyl‐(2‐pyrrolidine) methacrylate (EPyM)] and their respective homopolymers. For the determination of their reactivity in radical copolymerization reactions, both monomers were copolymerized with methyl methacrylate (MMA), the reactivity ratios being calculated by the application of linear and nonlinear mathematical methods. EPM and MMA had ratios of r_EPM = 1.11 and r_MMA = 0.76, and this indicated that EPM with MMA had a higher reactivity in radical copolymerization processes than vinyl pyrrolidone (VP; r_VP = 0.005 and r_MMA = 4.7). EPyM and MMA had reactivity ratios of r_EPyM = 1.31 and r_MMA = 0.92, and this implied, as for the EPM–MMA copolymers, a tendency to form random or Bernoullian copolymers. The glass‐transition temperatures of the prepared copolymers were determined by differential scanning calorimetry (DSC) and were found to adjust to the Fox equation. Total‐conversion copolymers were prepared, and their behavior in aqueous media was found to be dependent on the copolymer composition. The swelling kinetics of the copolymers followed water transport mechanism case II, which is the most desirable kinetic behavior for a swelling controlled‐release material. Finally, the different states of water in the hydrogels—nonfreezing water, freezing bound water, and unbound freezing water—were determined by DSC and found to be dependent on the hydrophilic and hydrophobic units of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 395–407, 2003     

Characterization and optimization of poly(glycidyl methacrylate-co-styrene) synthesized by atom transfer radical polymerization

Styrene (S) and glycidyl methacrylate (GMA) copolymers were synthesized by atom transfer radical polymerization (ATRP) under different conditions. The effect of initiators, ligands, solvents, and temperature to the linear first-order kinetics and polydispersity index (PDI) was investigated for bulk polymerization. First-order kinetics was observed between linearly increasing molecular weight versus conversion and low polydispersities (PDI) were achieved for ethyl 2-bromo isobutyrate (EBiB) as an initiator and N,N′,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA)/CuBr as a catalyst. The copolymers with different compositions were synthesized using different in-feed ratios of monomers. Copolymers composition was calculated from ¹H NMR spectra which were further confirmed by quantitative ¹³C{¹H} NMR spectra. The monomer reactivity ratios were obtained with the help of Mayo-Lewis equation using genetic algorithm method. The values of reactivity ratios for glycidyl methacrylate and styrene monomers are r_G = 0.73 and r_S = 0.42, respectively.     

The influence of molecular interactions on polymerization—IV: Copolymerization of 2-naphthyl methacrylate and methyl methacrylate in solvents with different dielectric constants

The copolymerization of 2-naphthyl methacrylate (2-NM) with methyl methacrylate (MMA) initiated by 2,2′-azoisobutyronitrile in carbon tetrachloride, chloroform, benzene, acetone and acetonitrile was investigated. The reactivity ratios determined by the methods of Fineman-Ross and Kelen-Tüdős are: in carbon tetrachloride—r_2-NM = 2.46 ± 0.25, r_MMA = 0.61 ± 0.06; chloroform—r_2-NM = 2.71 ± 0.30, r_MMA = 0.60 ± 0.06; benzene—r_2-NM = 2.62 ± 0.44, r_MMA = 0.63 ± 0.11; acetone—r_2-NM = 4.13 ± 0.45, r_MMA = 0.60 ± 0.06 and acetonitrile—r_2-NM = 3.70 ± 0.30, r_MMA = 0.62 ± 0.05.The dependence of the reactivity ratios on the solvent is explained on the basis of formation of complexes between the electron-donating naphthalene rings and the electron-accepting methacrylic double bonds, as indicated by NMR studies.     

Radical copolymerization of vinylidene fluoride with perfluoroalkylvinyl ethers

The radical copolymerization of perfluoromethylvinyl ether (PMVE) and perfluoropropylvinyl ether (PPVE) with vinylidene fluoride (VDF), initiated by tertiobutyl peroxypivalate (TBPPI) and ditertiobutyl peroxide (DTBP), respectively, are presented. The kinetics of copolymerization were investigated for each monomer from series of at least eight reactions for which the initial [VDF]₀/[fluorinated vinyl ether]₀ molar ratios ranged between 20/80 and 80/20. The copolymer compositions of these random-type copolymers were calculated by means of ¹⁹F NMR spectroscopy and allowed one to quantify the respective amounts of each monomeric unit in the copolymer. According to the Tidwell and Mortimer method, the reactivity ratios (r_i) of both comonomers for each type of copolymerization were obtained : r_VDF = 3.40 ± 0.40 and r_PMVE = 0 at 74 °C; and r_VDF = 1.15 ± 0.36 and r_PPVE = 0 at 120 °C. Moreover, the glass transition temperatures (T_g’s) of poly(VDF-co-PMVE) and poly(VDF-co-PPVE) copolymers containing different amounts of VDF and PMVE or PPVE, were determined and the theoretical glass transition temperatures of poly(PMVE) and poly(PPVE) homopolymer were deduced.     

Use of the NiBr2(PPh3)2/Zn catalytic system for homo- and copolymerization of styrene and methyl methacrylate

The regularities of methyl methacrylate and styrene (co)polymerization in the presence of catalytic systems based on a Ni(II) complex combined with zinc and an aryl halide have been studied. The effects of temperature and catalytic system components on conversion are established. The molecular masses of the polymers linearly increase with monomer conversion, thus suggesting the controlled character of the polymerization. Reactivity ratios are calculated for methyl methacrylate-styrene copolymerization (r _MMA = 0.45, r _styrene = 1.70) in the presence of NiBr₂(PPh₃)₂/Zn/PhI. The rate of copolymerization is shown to decrease with an increase in methyl methacrylate concentration. The scheme of the process is proposed based on an analysis of the experimental and literature data.     

Preparation and degradation of copolymers of methyl methacrylate with alkali metal methacrylates—I. Copolymerization parameters for the systems methyl methacrylate-lithium methacrylate,methyl methacrylate-sodium methacrylate and methyl methacrylate-potassium methacrylate

Copolymerizations of methyl methacrylate with the Li, Na and K salts of methacrylic acid have been studied in methanol solution at 60°. Reactivity ratios have been calculated by the methods due to Mayo and Lewis, Fineman and Ross and Peckham. The rate of copolymerization decreases as the size of the metal cation increases, in contrast to the behaviour in the homopolymerization of the alkali metal methacrylates. The systems have the following reactivity ratios (MMA as monomer-1): Li salt r₁ = 0.59, r₂ = 0.073; Na salt r₁ = 3.97, r₂ = 0·126; K salt r₁ = 5.65, r₂ = 0.143. The MMA-LiMA system shows azeotropic copolymerization for a mole fraction of MMA in the feed equal to 0.7. This system shows a strong tendency towards alternation (r₁r₂ = 0.044). The differences in the reactivity ratios are discussed in relation to steric and electrostatic effects.     

Photodegradation in solution of copolymers of methyl vinyl ketone and methyl isopropenyl ketone with methyl methacrylate

Copolymers of methyl vinyl ketone (MVK) and methyl isopropenyl ketone (MIK) with methyl methacrylate (MMA), have been prepared covering the whole composition range. Reactivity ratios have been estimated as follows: MMA/MVK, r_MMA = 0·63 ± 0·2, r_MVK = 0·53 ± 0·2; MMA/MIK, r_MMA = 0·98 ± 0·2, r_MIK = 0·69 ± 0·2. Number average molecular weights have been measured during the course of photodegradation under 253·7 nm radiation in methyl acetate solution and rates of chain scission calculated. In each system the copolymers are less stable than the corresponding homopolymers, the rate passing through a maximum at 20–30% ketone content. These results have been discussed from a mechanistic point of view.     

Studies on photocrosslinkable copolymers of 4-methacryloyloxyphenyl-3′,4′-dimethoxystyryl ketone and methyl methacrylate

Copolymers with various contents of 4-methacryloyloxyphenyl-3′,4′-dimethoxystyryl ketone (MPDSK) and methyl methacrylate (MMA) were prepared in methyl ethyl ketone solution using benzoyl peroxide as a free radical initiator at 70 °C. Characterization of the resulting polymers was done by UV, FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The copolymer compositions were determined by ¹H NMR analysis. The monomer reactivity ratios were calculated using linearisation methods such as Finemann-Ross (r₁ = 0.4283 and r₂ = 0.3050), Kelen-Tudos (r₁ = 0.4264 and r₂ = 0.2606), and extended Kelen-Tudos (r₁ = 0.4022 and r₂ = 0.2704) methods as well as by a non-linear error-in-variables model (EVM) method using the computer program RREVM (r₁ = 0.4066 and r₂ = 0.2802). The molecular weights ( and ) and the polydispersity index of the copolymers were determined by gel permeation chromatography. The thermal stability of the copolymers increases with increase in concentration of MPDSK. Glass transition temperatures were determined by differential scanning calorimeter under nitrogen atmosphere. The photoreactivity of the copolymers having pendant chalcone moieties was studied in chloroform solution.     

Atom transfer radical copolymerization of glycidyl methacrylate and allyl methacrylate, two functional monomers

Bi-functional statistical copolymers, based on allyl methacrylate (AMA) and glycidyl methacrylate (GMA), were synthesized via atom transfer radical polymerization (ATRP). The polymerization reactions were carried out in a diphenyl ether solution at low temperature, 50 °C, using ethyl 2-bromoisobutyrate (EBrIB) as an initiator, and copper chloride with N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) as the catalyst. Different aspects of the copolymerization, such as the kinetic behaviour, crosslink density and gel fraction were studied. The sol fractions of the synthesized copolymers were characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. The reactivity ratios were calculated from the copolymer composition, determined by ¹H NMR, and using the extended Kelen-Tüdös method. Values of 0.82 ± 0.04 and 1.22 ± 0.03 were obtained for AMA and GMA, respectively. The copolymer composition as a function of conversion degree for the different monomer molar fractions in the feed agreed with the theoretical values calculated from the Mayo-Lewis terminal model (MLTM).     

Graft copolymerization of 2-hydroxyethyl methacrylate and methyl methacrylate onto hide powder

Graft copolymerization of 2-hydroxyethyl methacrylate(HEMA) and mixtures of HEMA with methyl methacrylate (MMA) onto hide powder was attempted using ceric ammonium nitrate as initiator, with a view to optimize the conditions for graft copolymerization. Percent grafting and grafting efficiency were calculated for various variables such as monomer concentration, initator concentration and mole ratio of HEMA to MMA. R_p, R_g and R_h (rates of polymerization, grafting and homopolymerization respectively) were also evaluated. It was observed that R_p increased linearly with increasing concentration of MMA except at very low concentrations of the monomer. An explanation is given for the effect of variables on extent of grafting and grafting efficiency.     

Ferrocene-containing polymers. II. Radiation-induced copolymerizations of ferrocenylmethyl methacrylate with styrene,methyl methacrylate,and ethyl acrylate

Ferrocenylmethyl methacrylate (FMMA) was copolymerized with styrene (St), methyl methacrylate (MMA), and ethyl acrylate (EA) in benzene solution at 25°C by γ radiation. The reactions proceeded by a free radical mechanism, and monomer reactivity ratios were derived by the Tidwell–Mortimer method for St(M₁)–FMMA(M₂), r₁ = 0.35 and r₂ = 0.46; for MMA(M₁–FMMA)(M₂), r₁ = 0.85 and r₂ = 1.36; for EA(M₁)–FMMA(M₂), r₁ = 0.36 and r₂ = 3.03. The Q and e values of FMMA determined from copolymerization with St were 0.97 and 0.55, respectively. Terpolymerization of a MMA–FMMA–EA system based on the Alfrey–Goldfinger equations was studied. This is a typical terpolymerization system in which reactivities of the monomers obey the Q–e scheme. Comparing the results obtained here with those previously reported for other monomers, we concluded that FMMA is one of the most highly reactive monomers among alkyl methacrylates.     

Organostibine mediated controlled/living random copolymerization of styrene and methyl methacrylate

The first example of organostibine mediated controlled/living random copolymerization of styrene (St) and methyl methacrylate (MMA) was achieved by heating a solution of St/MMA/organostibine mediator at 100 °C or St/MMA/organostibine mediator/AIBN with various monomer feed ratios at 60 °C. The addition of AIBN significantly decreased the reaction temperature and enhanced the rate of copolymerization. The structure of poly(St-co-MMA) was verified by ¹H NMR. The reactivity ratios at 60 °C were determined by the extended Kelen-Tüd?s method to be γ_St = 0.40 and γ_MMA = 0.44. The ln([M]₀/[M]) increased linearly with increasing reaction time. The number-average molecular weights of poly(St-co-MMA) increased linearly with conversion. Poly(St-co-MMA) with expected number-average molecular weight and low polydispersity index was formed. The living characteristic was further confirmed by chain-extension of poly(St-co-MMA) to form poly(St-co-MMA)-b-PMMA.     

Living radical polymerisation in heterogeneous conditions—suspension polymerisation

Transition metal mediated living radical polymerisation of butyl methacrylate has been demonstrated with a copper(I) halide N-alkyl-2-pyridylmethanimine ligands based catalyst. Optimum conditions were found to be with copper(I) chloride and N-octyl-2-pyridylmethanimine catalyst at 65 °C where conversions of 85% were achieved with polymers of M_n = 8900 g mol⁻¹ (theoretical = 8400 g mol⁻¹) and PDI = 1.23. Both non-ionic and ionic surfactants were employed which were also made by living radical polymerisation. The non-ionic surfactant was a block copolymer of PMMA from a polyethyleneglycol macroinitiator (total M_n = 7600 g mol⁻¹, PDI = 1.20) and the ionic surfactant PDMEAMA-PMMA (total M_n = 8000 g mol⁻¹, PDI = 1.21) with the PDMEAMA block quaternized with MeI (13.8%, 28.4%, 47.7% and 100%). A range of ligands were employed in the suspension polymerisation by varying the alkyl group on the ligand increasing the hydrophobicity (alkyl = propyl (PrMI), pentyl (PMI), octyl (OMI), dodecyl (DMI) and octadecyl (ODMI)). The more hydrophobic ligands were found to be more effective due to lower partitioning into the aqueous phase. Block copolymers of P(EMA)-P(BMA) and P(MMA)-P(BMA) were prepared by first preparing macroinitiators via living radical polymerisation (M_n = 1600 g mol⁻¹ (PDI = 1.23) for P(EMA) and M_n = 1500 g mol⁻¹ (PDI = 1.22) for P(MMA)) and using them for initiation of BMA in suspension polymerisation. Block copolymers had M_n between 12,800 and 13,700 g mol⁻¹ with PDI between 1.33 and 1.54. Block copolymer growth showed excellent linear first order kinetics wrt monomer and demonstrated characteristics expected of a living radical polymerisation. Particle sizes were measured by SEM and DLS with good agreement (1.4-2.8 μm) and SEM showed spherical particles were formed.     

Copolymerisation of 2-hydroxyethyl methacrylate with siloxanyl monomers

Acryloxymethylpentamethyldisiloxane (AMS) and methacryloxymethylpentamethyldisiloxane (MMS) have been prepared and purified chromatographically. Some physicochemical properties have been measured for these monomers as well as for highly purified 2-hydroxyethyl methacrylate (HEMA). Hydroxyl group analysis on copolymers of AMS with HEMA and of MMS with HEMA, obtained by free radical copolymerisation to low conversion, enabled monomer reactivity ratios to be determined by several procedures. The average values were r_HEMA = 0.86, r_AMS = 0.55 and r_HEMA = 0.97, r_MMS = 0.33. These values have been invoked in computing integral curves for the instantaneous copolymer composition throughout the whole range of conversion.     

Preparation of poly(methyl methacrylate) microcapsules by in situ polymerization on the surface of calcium carbonate particles

Poly(methyl methacrylate) (PMMA) microcapsules were prepared by the in situ polymerization of methyl methacrylate (MMA) and N,N′-methylenebisacrylamide on the surface of calcium carbonate (CaCO₃) particles, followed by the dissolution of the CaCO₃ core in ethylenediaminetetraacetic acid solution. The microcapsules were characterized using fluorescence microscopy, atomic force microscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy. The average sizes of the CaCO₃ particles and PMMA capsules were 3.8 ± 0.6 and 4.0 ± 0.6 μm, respectively. A copolymer consisting of MMA and rhodamine B-bearing MMA was also used to prepare microcapsules for fluorescent microscopy observations. Fluorescein isothiocyanate-labeled bovine serum albumin was enclosed in the PMMA microcapsules and its release properties were studied.     

Emulsion copolymerization of styrene and methyl methacrylate

Chain transfer constants to monomer have been measured by an emulsion copolymerization technique at 44°C. The monomer transfer constant (ratio of transfer to propagation rate constants) is 1.9 × 10^?5 for styrene polymerization and 0.4 × 10^?5 for the methyl methacrylate reaction. Cross-transfer reactions are important in this system; the sum of the cross-transfer constants is 5.8 × 10^?5. Reactivity ratios measured in emulsion were r₁ (styrene) = 0.44, r₂ = 0.46. Those in bulk polymerizations were r₁ = 0.45, r₂ = 0.48. These sets of values are not significantly different. Monomer feed compcsition in the polymerizing particles is the same as in the monomer droplets in emulsion copolymerization, despite the higher water solubility of methyl methacrylate. The equilibrium monomer concentration in the particles in interval-2 emulsion polymerization was constant and independent of monomer feed composition for feeds containing 0.25–1.0 mole fraction styrene. Radical concentration is estimated to go through a minimum with increasing methyl methacrylate content in the feed. Rates of copolymerization can be calculated a priori when the concentrations of monomers in the polymer particles are known.     

Reactivity ratios and sequence structures of the copolymers prepared using photo‐induced copolymerization of MMA with MTMP

4‐Methacryloyl‐2,2,6,6‐tetramethyl‐piperidine (MTMP) was applied as reactive hindered amine piperidine. Photo‐induced copolymerization of methyl methacrylate (MMA, M₁) with MTMP (M₂) was carried out in benzene solution at ambient temperature. The reactivity ratios for these monomers were measured by running a series of reactions at various feed ratios of initial monomers, and the monomer incorporation into copolymer was determined using ¹H NMR. Reactivity ratios of the MMA/MTMP system were measured to be r₁ = 0.37 and r₂ = 1.14 from extended Kelen‐Tüdos method. The results show that monomer MTMP prefers homopolymerization to copolymerization in the system, whereas monomer MMA prefers copolymerization to homopolymerization. Sequence structures of the MMA/MTMP copolymers were characterized using ¹H NMR. The results show that the sequence structure for the main chain of the MMA/MTMP copolymers is mainly composed of a syndiotactic configuration, only with a little heterotactic configuration. Three kinds of the sequences of rr, rr′, and lr′ in the syndiotactic configuration are found. The sequence‐length distribution in the MMA/MTMP copolymers is also obtained. For f₁ = 0.2, the monomer unit of MMA is mostly separated by MTMP units, and for f₁ = 0.6, the alternating tendency prevails and a large number of mono‐sequences are formed; further up to f₁ = 0.8, the monomer unit of MTMP with the sequence of one unit is interspersed among the chain of MMA. Copyright © 2012 John Wiley & Sons, Ltd.