Methylene blue as a retarder of free radical polymerization: 1. Polymerization of acrylonitrile,methyl methacrylate and styrene

Methylene blue (MB), a redox dye, in monomeric form significantly retards the free radical polymerization of styrene (ST) and acrylonitrile (AN) in N,N-dimethyl formamide solvent. The effect is small in methyl methacrylate (MMA) polymerization. Partly reduced MB is found to be a stronger retarder than MB. The rate constants for the oxidation of the polymer radicals by MB at 60°C follows the order ST>AN>MMA. The results cannot be explained when only taking into consideration the reactivity and polarity parameters of the radicals and the substrate, as is done in the Q-e scheme. The low rate constant with the PMMA radical is attributed to steric effects. The current work has shown that single molecules of MB are effective chain terminators and this is in sharp contrast with the conclusion reached by Chen who postulated that only the aggregates of MB are the chain terminators in the polymerization of acrylamide in water.     

An interesting contrast: effects of maleic acid and styrene on the synthesis of functional poly(methyl methacrylate) microspheres

The effects of maleic acid and styrene on the polymerization of methyl methacrylate (MMA) have been studied. Both comonomers play a considerable role in terms of particle size and MMA conversion. The polymerization of MMA in the presence of maleic acid can result in larger particles and a higher MMA conversion. However, in the presence of styrene, the polymerization process yields smaller particles and low MMA conversion. This can be related to the different properties of maleic acid and styrene. Maleic acid, a hydrophilic and electron‐withdrawing comonomer, can play a positive role in stabilizing the particles and increasing MMA activation. However, for styrene, these effects are reversed due to its opposite properties. The change in particle size may be caused by the change in particle stabilization. The change of MMA conversion can be kinetically attributed to the effects of maleic acid and styrene on the activation process. Copyright © 2004 Society of Chemical Industry     

Photoinitiator‐free UV grafting of styrene,a weak donor,with various electron‐poor vinyl monomers to polypropylene film

This study investigated the possibility of using styrene, a weak donor forming donor(D)/acceptor(A) pairs with electron‐poor (EP) vinyl monomers, for initiating spontaneous photopolymerization and photografting of the copolymers onto polypropylene. Maleic anhydride (MA), methyl methacrylate (MMA), methyl acrylate (MAC), dimethyl maleate (DMMA), acrylonitrile (AN) and acrylic acid (AA) were the EP monomers used. Grafting yields together with FTIR analyses were used to confirm the presence of grafting. Styrene/MMA and styrene/AN systems achieved significant grafting, but such levels of grafting were not observed in the styrene/MAC and styrene/DMMA systems. No grafting was observed for styrene/AA or styrene/MA systems, but the latter system underwent photopolymerization. The effect of solvents on grafting was evaluated on styrene/MMA and styrene/AN systems and dimethylformamide (DMF) was found to retard grafting of both D/A systems. In contrast, chloroform and methanol enhanced grafting of the styrene/AN system although these two solvents had no significant effect on the grafting of the styrene/MMA system. Copyright © 2004 Society of Chemical Industry     

Effect of compatibilizer in acrylonitrile‐butadiene‐styrene toughened nylon 6 blends: Ductile–brittle transition temperature

The ductile–brittle transition temperatures were determined for compatibilized nylon 6/acrylonitrile‐butadiene‐styrene (PA6/ABS) copolymer blends. The compatibilizers used for those blends were methyl methacrylate‐co‐maleic anhydride (MMA‐MAH) and MMA‐co‐glycidyl methacrylate (MMA‐GMA). The ductile–brittle transition temperatures were found to be lower for blends compatibilized through maleate modified acrylic polymers. At room temperature, the PA6/ABS binary blend was essentially brittle whereas the ternary blends with MMA‐MAH compatibilizer were supertough and showed a ductile–brittle transition temperature at ?10°C. The blends compatibilized with maleated copolymer exhibited impact strengths of up to 800 J/m. However, the blends compatibilized with MMA‐GMA showed poor toughness at room temperature and failed in a brittle manner at subambient temperatures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2643–2647, 2003     

Densimetry for on-line conversion monitoring in emulsion homo- and copolymerization

The use of on-line densimetry to monitor conversion in batch emulsion polymerization reactors are investigated. Some characteristics of the sampling circuit connecting the reactor to the densitometer, which allow one to obtain reliable on-line estimations of monomer conversion in the whole range of conversion, are discussed in detail. Moreover, the amount of collected data provides a practically continuous monitoring of the system evolution in time, which allows one to estimate directly the rate of conversion as a function of time. The technique has been applied both to homopolymerization systems [i.e., styrene (STY) and methyl methacrylate (MMA)] as well as to copolymerization systems [i.e., STY–MMA, acrylonitrile (ACN)–MMA, vinyl acetate (VAC)–MMA]. In the latter case, the density measurements are combined with a reliable model which provides for polymer composition as a function of conversion, in order to obtain accurate measurements of monomers conversion. © 1993 John Wiley & Sons, Inc.     

FTIR characterization of tropical wood–polymer composites

Wood–polymer composites (WPC) of Geronggang (Cratoxylon arborescens), a light tropical hardwood, impregnated with methyl methacrylate (MMA), methyl methacrylate-co-acrylonitrile (1 : 1; MAN), and styrene-co-acrylonitrile (3 : 2; STAN), were prepared by in situ polymerization using gamma radiation or the catalyst–heat treatment. The FTIR spectra of the three types of WPC, with polymer loadings ranging from 10 to 70%, were compared with that of the wood itself and the respective polymers. Characteristic peaks due to C?O vibration of MMA, C?N stretching of acrylonitrile, and ring stretching and bending of styrene monomers, were prominent in the samples that had higher polymer loadings. For the copolymeric systems, quantitation of the FTIR spectra of these characteristic peaks enabled calculations of incorporated acrylonitrile and styrene monomers in the composites to be made. The FTIR spectra of the residues remaining, after exhaustive extraction to remove homopolymer, showed that graft copolymerization of wood components with acrylonitrile and styrene monomers was possible, but not with MMA. Composites prepared by the two methods, gamma radiation and the catalyst–heat treatment, were shown to be chemically very similar.     

Towards a one‐pot synthesis of a polystyrene–PMMA block copolymer via atom‐transfer radical polymerization

The solution atom‐transfer radical copolymerization of styrene and methyl methacrylate in butyl acetate at 110 °C in the presence of Cu(II) bromide and 2,2′‐bipyride was investigated. Polystyrene was polymerized by atom‐transfer radical polymerization using benzyl bromide as initiator and MMA was then added to the system. Block copolymers were formed when MMA was added at ≤90% styrene conversion. Molecular weight distributions (M_w/M_n) of the block copolymers were ≤1.5. The possibility of end‐capping the polystyrene precursor as a means of improving its initiating efficiency towards MMA was also investigated but did not improve the system. © 2002 Society of Chemical Industry     

Organotin polymers—XVII. Azeotropy in terpolymerization reactions of tri-n-butyltin 4-acryloyloxybenzoate wit alkyl acrylates or styrene and acrylonitrile

Ternary copolymerizations of tri-n-butyltin 4-acryloyloxybenzoate (ABTB) with acrylonitrile (AN) and alkyl acrylates [methyl (MA), ethyl (EA) or butyl acrylate (BA)], methyl methacrylate (MMA) or styrene (ST) were carried out in solution at 70°C in the presence of free radical initiator. Experimental terpolymerization data agreed well with calculations based on the Alfrey-Goldfinger equation. The determination of unitary, binary and ternary azeotropies of various systems studied was easily handled by a computer program. The results obtained show that there is no ternary azeotropic composition for any terpolymer, system studied. Selective unitary and binary azeotropic compositions were polymerized and the results obtained show good agreement between the theoretical and experimental terpolymer composition for each case.     

UV and fluorescence characterization of styrene and methyl methacrylate polymerization

Polymerization of styrene and methyl methacrylate (MMA) were studied by UV and fluorescence spectroscopic techniques. Using a sharp decrease in the extinction coefficient at 250 nm and the fluorscence quantum yield at 308 nm of styrene following polymerization, styrene conversion in solution polymerization by UV and fluorescence measurements were found to correlate well with IR results monitoring the disappearance of vinyl groups, at three different temperatures (65, 70, and 75°C). The activation energy of about 6 kcal/mol was obtained. Using the decrease in UV absorbance of MMA during polymerization, solution polymerization of MMA was studied and compared with IR results. Due to the solvent absorbance, the UV method underestimates the conversion to a certain extent. When a small amount of styrene is added in MMA polymerization as a reactive extrinsic comonomer, the conversion of styrene measured by fluorescence is found to be faster than MMA, due to the characteristic reactivity ratios of MMA and styrene. The correlation curve could be used to estimate MMA conversion from styrene fluorescence, providing a method more sensitive than the viscosity-dependent fluorescence probe technique. Bulk polymerization of styrene was studied by bifurcated fiber-optic fluorescence. Due to self-quenching, little fluorescence of styrene is observed up to 75% conversion, but increases sharply from 75 to 85% conversion, followed by a drastic decrease during the last 15% conversion. In comparison to other methods of following vinyl polymerization such as refractive index, density, and gel permeation chromatography, these spectroscopic techniques provide real-time in situ capability as well as better sensitivity, especially in the later stages of polymerization. © 1995 John Wiley & Sons, Inc.     

Controlled radical polymerization of methyl methacrylate in the presence of 2-bromoethanol

Summary The radical polymerization of methyl methacrylate (MMA) and styrene (St) initiated by 2,2’-azobis(isobutyronitrile) (AIBN) at 60 °C in the presence of haloalkyl alcohol are studied. The influence of structure and concentration of haloalkyl alcohol as a transfer agent are investigated. For the radical polymerization of MMA in the presence of large amount of 2-bromoethanol, controlled radical polymerization is proceeded. The 2-bromoethanol is, thus, one of the transfer agents for radical polymerization to control the molecular weight and the structure of poly(MMA).     

Poly(styrene)‐ and Poly(styrene‐co‐methyl methacrylate)‐graft‐hydrogenated natural rubber latex: Aspect on synthesis,properties, and compatibility

The undesirable properties of natural rubber (NR) can be improved via hydrogenation and graft copolymerization. Hydrogenated NR (HNR) latex was prepared via diimide reduction and then grafted with styrene (ST) or ST/methyl methacrylate (MMA) to form poly(ST)‐graft‐HNR (poly(ST)‐g‐HNR, GHNRS) or poly(ST‐co‐MMA)‐g‐HNR (GHNRSM), respectively. For the grafting of ST monomer onto HNR particles, the %monomer conversion and %grafting efficiency (%GE) were monitored as functions of %hydrogenation, monomer and initiator concentrations, temperature, and time. Under the optimum condition (HNR with 54.3% hydrogenation; 100 phr of ST, 1 phr of initiator at 50°C for 8 h), maximum %conversion and %GE of 44.6% and 36.9%, respectively, were achieved. Thermogravimetric analysis revealed that the HNR grafted with ST or ST/MMA had higher decomposition temperature than an ungrafted one. When these graft products were blended at 10% (w/w) with acrylonitrile‐butadiene‐styrene (ABS) resin, the GHNRS/ABS and GHNRSM/ABS composites exhibited the higher flexural strength and heat aging tolerance compared to the ungrafted HNR/ABS composite. Scanning electron microscopy (SEM) also showed the higher degree of homogeneity at the fractural surface, supporting the higher compatibility between the ABS and the GHNRS or GHNRSM phases in the blends. J. VINYL ADDIT. TECHNOL., 22:100–109, 2016. © 2014 Society of Plastics Engineers     

Graft polymerization of some vinyl monomers onto acrylic rubber. I. Chain transfer and grafting reaction

The grafting reactions of styrene (St), methyl methacrylate (MMA), and vinyl acetate (VAc) were investigated in the presence of n-butyl acrylate–acrylonitrile copolymer. Results showed that the nature of monomer and initiator were the major factors influencing the grafting activity. The grafting efficiency was 0.87 for St, 0.26 for MMA, and 0.18 for VAc under the most favorable conditions. Acrylic rubber reduced the rate of polymerization, and the retarding effect increased in the order St, MMA, VAc. The chain transfer constants for acrylic rubber were evaluated to be 4.8 × 10^?4 for St, 1.27 × 10^?3 for MMA, and 1.45 × 10^?3 for VAc. The rate of polymerization and the grafting efficiency decreased with increasing acrylonitrile content in acrylic rubber, while the chain transfer constant of St for acrylic rubber remained practically unchanged.     

Preparation of fine polymer particles containing metallocene derivatives

This article deals with preparations of fine particles of metallocene copolymers by emulsifierfree emulsion polymerization of vinylferrocene (VFc), ferrocenylmethyl methacrylate (FMMA), 1-ferrocenylethyl methacrylate (1-FEMA), 2-ferrocenylethyl methacrylate (2-FEMA), and 1-ruthenocenylethyl methacrylate (1-REMA) with acrylonitrile (AN), styrene (St), and methyl methacrylate (MMA) in water/ethanol medium. As a result, spherical copolymer particles containing metallocene derivatives have been successfully synthesized in the particle size of ca. 120 to 600 nm. The contents of ferrocenyl or ruthenocenyl groups in copolymer particles increased with increasing concentration of charged metallocene derivatives, while the amounts of metallocene derivatives incorporated into particles are much lower than the charged ratio. © 1994 John Wiley & Sons, Inc.     

Rapid ambient temperature living radical polymerization of methyl methacrylate and styrene utilizing sodium hypophosphite as reducing agent

A facile, safe, and inexpensive reducing agent, sodium hypophosphite (NaH₂PO₂·H₂O), has been successfully used to perform ambient temperature living radical polymerizations of methyl methacrylate (MMA) and styrene (St). The rapid radical polymerizations were readily obtained at 25°C, i.e., MMA reached a conversion of ca 90% after 2.5 h, and St reached a conversion of ca 80% after 40 h. The polymerizations of MMA and St exhibited excellent living/controlled nature, as evidenced by pseudo first‐order kinetics of polymerization, linear evolution of molecular weights with increasing monomer conversions, and narrow molecular weight distributions. The various experimental parameters—ligand, solvent, and molar ratio of NaH₂PO₂·H₂O to CuSO₄·5H₂O—were varied to improve the control of polymerization, molecular weight, and molecular weight distribution. ¹H NMR analyses and chain‐extension reactions confirm the high chain‐end functionality of the resultant poly(methyl methacrylate) and polystyrene. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42123.     

Vinyl polymerization initiated with alkali metal adducts of triphenylamine and triphenylphosphine

The polymerizations of styrene, methyl methacrylate, isoprene, butadiene and acrylonitrile initiated with alkali metal adducts of triphenylamine or triphenylphosphine at 0°C in tetrahydrofuran take place by an anionic mechanism. Biphenyl alkali metal anion radical and alkali metal adducts of benzene, aniline and diphenylamine are formed in the reaction of triphenylamine with the alkali metal and it was shown that styrene was polymerized with both the anion radical and alkali metal adducts of benzene, whereas methyl methacrylate and acrylonitrile were polymerized by all anion species.     

Multiblock copolymers by polymeric initiators via free radical mechanism

Polymeric peroxycarbamate initiators containing polyazoester or polyethylene adipate blocks were synthesized. They can be used to prepare multiblock copolymers by radical polymerization in a procedure involving several steps. Bulk and solution polymerizations are suitable techniques in these steps. The polymerization of styrene with these initiators was investigated over a wide range of conversion. Longer polymerization times led to an expected decrease in peroxygen contents of the active polystyrenes. Styrene/methyl methacrylate/n-butyl methacrylate, polyethylene adipate/styrene/methyl methacrylate, polyethylene adipate/styrene/methyl methacrylate/n-butyl methacrylate and polyethylene adipate/styrene/methyl methacrylate/acrylonitrile multiblock copolymers were obtained in this way.     

Preparation of SBS/poly(styrene–methyl methacrylate) thermoplastic interpenetrating polymer network

SBS as polymer I, poly(styrene–methyl methacrylate) polymerized by atom transfer radical polymerization as polymer II, and a thermoplastic interpenetrating polymer network of SBS/poly(styrene–methyl methacrylate) were prepared by the sequential method. The effects of the polymerization temperature, the composition of the catalyst, the ratio of the monomers studied, and the kinetics at 90°C were also investigated. It was shown that when polymerization was initiated by a BPO/CuCl/bpy (BPO:CuCl:bpy = 1:1:3) system at 90°C, the mass averaged molecular weight of the poly(styrene–methyl methacrylate) increased with monomer conversion, and the polydispersities were kept very low. Fourier transform infrared spectroscopy and gel permeation chromatogram showed that poly(styrene–methyl methacrylate) with low polydispersities had been synthesized. Thus, a thermoplastic interpenetrating polymer network comprised of both narrow molecular‐weight‐distribution components was successfully prepared. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2007–2011, 2003     

Free radical terpolymerization of butyl acrylate/methyl methacrylate and alpha methyl styrene at high temperature

The free radical initiated terpolymerization of butyl acrylate (BA), methyl methacrylate (MMA) and alpha methyl styrene (AMS) has been examined. Kinetic studies focused on elevated reaction temperatures (115 and 140 °C). The studies were made over the full conversion range and examined the effect of reaction temperature, feed composition and initiator level on reaction rates. The composition of terpolymer products and their molecular weights were also analyzed with respect to monomer conversion levels.     

Modeling of the copolymerization,with depropagation,of α‐methyl styrene and methyl methacrylate at an elevated temperature

We propose a dynamic model for the copolymerization of α‐methyl styrene (α‐MS) and methyl methacrylate (MMA) in a batch reactor. The parameters are based on data from the literature and our own laboratories over the full conversion range. A two‐parameter model with constant reactivity ratios shows the most reasonable results. The dynamic model depicts the reaction kinetics and reactor behavior more clearly. Termination occurs mainly by the cross reaction of unlike radicals, and its rate increases with the molar ratio of α‐MS to MMA. The model enables us to predict the instantaneous and cumulative properties of the copolymer and also provides us with a basic tool for the optimization and control of industrial reactors. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 261–270, 2004