Radical Copolymerization Of Styrene Research Articles

On the Absence of Cyclic Structures in Branched Polystyrenes Synthesized by Living Three-Dimensional Radical Polymerization in the Medium of a Deteriorating Thermodynamic Quality Solvent

Branched polystyrenes are synthesized by the radical copolymerization of styrene and divinylbenzene with reversible inhibition (in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl) under deteriorating thermodynamic quality of the solvent. The resulting polymers are studied by size-exclusion chromatography combined with static light scattering, ozonolysis, NMR spectroscopy, and differential scanning calorimetry. The branched polymers synthesized by living radical polymerization are characterized by lower intrinsic viscosity values than their linear analogs. Kuhn–Mark–Houwink parameters for these polymers in a tetrahydrofuran solution (а = 0.29) confirm the nonlinear architecture of macromolecules and a high content of pendant double bonds comparable in the order of magnitude with their theoretical content in the absence of the cyclization reaction indicate their branched structure. The glass transition temperature of the branched polystyrenes is 20–35°С lower than the glass transition temperature of the linear polystyrene.

Scalable and facile synthesis of acetal covalent adaptable networks with readily adjustable properties

Covalent adaptable networks (CANs) were rapidly developed to address the recycle issue of thermosets; however, facile and scalable synthesis of CANs is still a challenge. Here, we report the preparation of the acetal-based CANs with commercially available raw materials by a one-pot method without solvent, which can achieve zero atom loss over the whole process. The CANs were synthesized through a radical copolymerization of styrene (or 2-ethylhexyl methacrylate) and 2-hydroxyethyl methacrylate and an addition reaction of the hydroxyl from 2-hydroxyethyl methacrylate and a divinyl ether in one pot. The CANs could be recycled by hot-press reprocessing, and could also be degraded and regenerated into networks to achieve closed-loop recycling. In addition, the thermal and mechanical properties could be readily regulated by changing the monomers for the preparation. This work provides a scalable method to prepare acetal-based CANs, which will shorten the scientific research of CANs to industrialization.

Visual Ozone Sensor: Structural Color Change of Pendant Selenium-Containing Maleimide Polymers via Oxidation.

Pendant selenium-containing maleimide polymers with different selenium contents are synthesized via a radical copolymerization of styrene and N-butylmaleimide phenyl selenide. The polymer structures are characterized by nuclear magnetic resonance, gel permeation chromatography, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and scanning electron microscopy with an energy-dispersive spectrometer, which results in the desired structures and selenium contents. The refractive indices of the polymers, which change as a function of different contents of selenium and oxidative stimuli by H2 O2 or O3 , are investigated. Finally, a photonic crystal (PC) is prepared based on the selenium-containing polymer. The visible color changes of the PC are investigated as a function of different concentrations and contact times of O3 .

Effect of HMDS-modified silica aerogel nanoparticles on ATRP of styrene and methyl methacrylate: Kinetics and thermal studies

Surface of pristine silica aerogel nanoparticles was hydrophobically modified with hexamethyldisilazane (HMDS). Then, the resultant modified nanoparticles were used for in situ atom transfer radical copolymerization of styrene and methyl methacrylate. Surface area and structural characteristics of the HMDS-modified silica aerogel nanoparticles (H-SANs) were examined by nitrogen adsorption/desorption isotherm. Evaluation of size distribution and morphological studies were also performed by scanning electron microscopy and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas chromatography and size exclusion chromatography, respectively. Adding of H-SAN by 3 wt% results in decrement of conversion from 98% to 79%. In addition, molecular weight of copolymer chains decreases from 20,372 g·mol−1 to 16,487 g·mol−1. However, polydispersity index values increases from 1.38 to 1.76. Linear increase of ln( M0/ M) with time for all the samples shows that polymerization proceeds in a living manner. Increasing thermal stability of the nanocomposites is demonstrated by thermal gravimetric analysis. Differential scanning calorimetry shows a decrease in glass transition temperature from 67.4°C to 59.8°C by the addition of 3 wt% of the H-SAN.

Aluminum triflate-cocatalyzed radical copolymerization of styrene and ethyl acrylate

Various random copolymers, poly(styrene-co-ethyl acrylate), were synthesized by free radical bulk copolymerization cocatalyzed by aluminum triflate (Al(OTf)3). The experimental conditions for the polymerization reactions, which include the amount of cocatalyst, polymerization time and ratio of styrene to ethyl acrylate, were investigated. The copolymer molecular weights were determined by gel permeation chromatography coupled to multi-angle laser light scattering. Compositional analysis was performed using proton nuclear magnetic resonance spectrometry. Electron paramagnetic resonance spectroscopy was also used to study the radical species which form in the presence or absence of Al(OTf)3. Kinetic studies were performed by determining monomer conversions as a function of time on gas chromatography. It was found that Al(OTf)3 accelerated the rate of polymerization significantly while also increasing the polymer molecular weights for a given conversion compared to the reactions where the triflate was absent. Al(OTf)3 can be a significantly more cost-effective and abundant alternative polymerization cocatalyst compared to some of the rare lanthanide triflates.

Formation of Proton-Conducting Polymer Additives Based on Sulfonated Crosslinked Polystyrene in Nafion Membranes

A method for the in situ modification of Nafion perfluorinated proton-conducting membranes with a polyelectrolyte based on sulfonated crosslinked polystyrene has been developed. The method is based on the radical copolymerization of styrene with divinylbenzene in situ in the transport channels of Nafion and subsequent sulfonation. The use of a mixed dimethyl sulfoxide–isopropanol solvent, which provides, on one hand, an effective swelling of the Nafion membrane and, on the other hand, the diffusion of nonpolar monomers into the hydrophilic transport channels of the membrane, makes it possible to obtain samples with a uniform distribution of the polyelectrolyte throughout the membrane thickness. The developed method provides a significant increase in the charge carrier concentration and the proton conductivity of the membranes.

Hydrodynamic characteristics of branched polystyrenes with varying content of a highly branched fraction

The branched polymers containing different amounts of the highly branched fraction are synthesized by the radical copolymerization of styrene and divinylbenzene under conditions of the reversible inhibition by 2,2,6,6-tetramethylpiperidine-1-oxyl. The branched polystyrenes are studied by size-exclusion chromatography combined with static light scattering, viscometry, and pulsed-field gradient nuclear magnetic resonance. The branched polymers prepared by living radical polymerization (in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl) feature reduced intrinsic viscosities and increased self-diffusion coefficients compared with their linear analogs. As the content of the highly branched fraction in the synthesized polymers grows, the Zimm contraction factor in toluene solution decreases to g′ = 0.13. The Kuhn-Mark-Houwink parameters for these polymers in toluene solution (a = 0.43) confirm the nonlinear architecture of macromolecules.

A nanocomposite consisting of carbon nanotubes and gold nanoparticles in an amphiphilic copolymer for voltammetric determination of dopamine, paracetamol and uric acid

The amphiphilic copolymer poly(vinylbenzyl thymine-co-styrene-co-maleic anhydride) (PSVM) was synthesized by radical copolymerization of styrene, vinylbenzyl thymine, and maleic anhydride. Its chemical structure was proven by using 1H nuclear magnetic resonance spectroscopy. PSVM was used as a host to prepare a composite consisting of carbon nanotubes and gold nanoparticles by in-situ reduction. The morphology of the nanocomposites was studied by transmission electron microscopy. A glassy carbon electrode coated with this composite is shown to be a viable sensor for the determination of dopamine (DA), paracetamol (PAT) (both at a pH value of 7), and uric acid (UA) (at pH 6). Two linear relationships exists between amperometric current and analyte concentrations. For DA, the linear analytical ranges are from 0.1 to 200 μM and from 200 to 1000 μM. For PAT, the ranges are from 0.1 to 200 μM and from 200 to 1000 μM. For UA, the ranges are from 0.05 to 1000 μM. The respective limits of detection (for S/N = 3) are 56, 27 and 50 nM. The sensor is highly sensitive, stable, reproducible, and selective.

Polystyrene supramolecular networks based on DA-AD hydrogen bonds

Then polystyrene supramolecular networks were prepared by radical copolymerization of styrene with monomers containing donor–acceptor (DA) moieties methacrylamide (MAAM) or 2-methacrylamidopyridine (MAP). The molar percentages of MAAM and MAP in the copolymers were, respectively, 2–20% and 6–40%. The glass transition temperatures (Tgs) of these copolymers have been modeled by the Kwei equation showing secondary interactions due to intermolecular hydrogen bonds. The DA-AD association constants (K) have been calculated by 1H NMR spectroscopy of MAAM and MAP. These constants were, respectively, 6.75 and 16.75 M−1. Dynamic mechanical analyses by frequency and temperature sweep tests, were carried out in the molten state. Styrene–MAP or styrene–MAAM copolymers had higher moduli than neat polystyrene but the MAP influences the materials’ properties distinctively from the MAAM. MAP copolymers had a second G′ plateau that appeared at 150 °C, thus showing the formation of a supramolecular network.

Ambient temperature living radical copolymerization of styrene and methyl methacrylate with sodium hypophosphite as reducing agent

A facile, safe and economical reducing agent, sodium hypophosphite (NaH2PO2·H2O), has been successfully employed for ambient temperature living radical copolymerization of styrene (St) and methyl methacrylate (MMA). Such effective reducing agent significantly improved the reactivity of low reactive St monomers during the copolymerization, where the reactivity ratios of St and MMA were determined to be 0.50 and 0.36 by Finemann-Ross method. Thus the copolymerizations proceeded fast and showed typical living/controlled features, as evidenced by pseudo first-order kinetics of polymerization, linear increase in molecular weight versus monomer conversion, and low polydispersity index values. Effects of the concentration of reducing agent and the monomer feed ratio on the copolymerization were investigated in detail. Furthermore, gel permeation chromatography and 1H-NMR analyses as well as chain extension experiments confirmed the high chain-end functionality of the resultant copolymer.

Copper mediated controlled radical copolymerization of styrene and 2-ethylhexyl acrylate and determination of their reactivity ratios.

Copolymerization is an important synthetic tool to prepare polymers with desirable combination of properties which are difficult to achieve from the different homopolymers concerned. This investigation reports the copolymerization of 2-ethylhexyl acrylate (EHA) and styrene using copper bromide (CuBr) as catalyst in combination with N,N,N′,N″,N″- pentamethyldiethylenetriamine (PMDETA) as ligand and 1-phenylethyl bromide (PEBr) as initiator. Linear kinetic plot and linear increase in molecular weights vs. conversion indicate that copolymerization reactions were controlled. The copolymer composition was calculated using 1H NMR studies. The reactivity ratio of styrene and EHA (r1 and r2) were determined using the Finemann–Ross (FR), inverted Finemann–Ross (IFR), and Kelen–Tudos (KT) methods. Thermal properties of the copolymers were also studied by using TGA and DSC analysis.

Synthesis of branched polymers via radical copolymerization under oxygen inflow

Branched and highly-branched polymers were prepared through radical copolymerization of styrene (St) and divinylbenzene (DVB) in the presence of dissolved molecular oxygen (AIBN, 95°С). The gel point (Cg) was found to depend on DVB/St ratio and oxygen concentration in liquid phase ([O2]). Our data of size-exclusion chromatography (SEC) coupled to a multi-angle laser light scattering detector (MALLS) and differential refractive index detector (DRI) suggest that thus synthesized products are a mixture of primary polymer chains (PPCs) and branched macromolecules whose relative amount grows on approaching to Cg. Polymers with a largest amount of highly-branched macromolecules ωHBP≈40wt% were obtained in the vicinity of Cg. Synthesized polymers contain pendant double bonds [CC]≈1×10−3mol/g and some amount of peroxide groups [OO]=(0.1–0.5)×10−3mol/g.

“Nascent” Fe(0)-mediated living radical copolymerization of styrene and acrylonitrile

AbstractIn this work, we reported the synthesis of copolymers of poly(styrene-co-acrylonitrile) via single-electron transfer-living radical polymerization using CCl4 as an initiator and Zn(0)/2,2′-bipyridine (Bpy)/FeCl2 as catalyst complexes. The polymerization was carried out at 25°C. The polymerization proceeded in a living fashion based on “nascent” Fe(0) as the source of the transition metal, which was prepared by Zn(0)/FeCl2 in situ. The kinetic experimental results showed that the copolymerization is first-order kinetics. The molecular weights increased linearly with respect to monomer conversion, and narrow polydispersity index values were obtained. The effect of the molar ratio of [Zn(0)]0/[FeCl2]0 on polymerization was investigated. In addition, the polymerization carried out in different solvents was also investigated. The obtained random copolymer was characterized by 1H NMR and gel permeation chromatography. The living characteristic was demonstrated by chain extension experiment.

Radical polymerization of trifluoromethyl-substituted methyl methacrylates and their application for use in pressure-sensitive paint

Three CF3-substituted methyl methacrylates (MMAs), 2,2,2-trifluoroethyl methacrylate (TFEMA), 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (HFIPMA) and nonafluoro-tert-butyl methacrylate (NFTBMA), were polymerized by conventional radical polymerization to give oxygen-permeable polymers for application in pressure-sensitive paint (PSP). The radical copolymerizations of styrene with TFEMA, HFIPMA, or NFTBMA were carried out to examine the effect of CF3 groups on the polymerizability. The e values increased in the order of MMA (0.40) < TFEMA (0.76) < HFIPMA (1.19) < NFTBMA (1.31). The homopolymers of TFEMA, HFIPMA and NFTBMA (PTFEMA, PHFIPMA, and PNFTBM, respectively) were examined as polymers for use in PSP using 5,10,15,20-tetrakis(pentafluorophenyl)porphinato platinum(II) (PtTFPP). The PSP consisting of PNFTBMA and PtTFPP exerted very high pressure sensitivity and very low temperature sensitivity. In the absence of oxygen, the temperature sensitivity decreased in the order of PTFEMA > PHFIPMA > PNFTBMA = PMMA, which corresponds to the order of glass transition temperatures (Tg). However, the activation energies of the overall process of the luminescence quenching by oxygen were found to be 16.8 (PMMA), 13.0 (PTFEMA), 6.8 (PHFIPMA), and 4.3 kJ mol−1 (PNFTBMA). Therefore, the low temperature sensitivity of PNFTBMA was attributed to its high degree of substitution with CF3 groups and to its relatively high Tg value. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 963–972

Study on Synthesis and Characterization of Styrene-Maleic Anhydride Random Copolymer by Xylene

Radical copolymerization of styrene (St) and maleic anhydride (MA) were typically alternating copolymerization, which generated copolymer styrene-maleic anhydride (SMA). The copolymer was synthesized by solution polymerization method,with benzoyl peroxide (BPO) as initiator and xylene as solvent, and using the yield of copolymer as evaluation criteria, the reaction conditions were researched. The maleic anhydride of molar fraction was 45% in the copolymer measured by chemical titration, combined with the theoretical that the synthesis of styrene-maleic anhydride copolymer was confirmed to be the alternating copolymer. The structure and character of the copolymer was also confirmed by IR. The glass-transition temperature of the alternating copolymer was tested by DSC.

Porphyrin derivatives act as vinylene monomers in TEMPO‐mediated radical copolymerization with styrene

AbstractIn this article, we offer clear evidence for the radical copolymerizability of porphyrin rings in 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO)‐mediated radical copolymerizations with styrene. The radical copolymerizations of styrene with 5,10,15,20‐tetrakis(pentafluorophenyl)porphyrin (H2TFPP) was conducted using 1‐phenyl‐1‐(2,2,6,6‐tetramethyl‐1‐piperidinyloxy)ethane as an initiator. The refractive index (RI) traces for the size‐exclusion chromatography of the resulting copolymers were unimodal with narrow molecular weight distributions. The RI traces shifted toward higher molecular weight regions as the polymerization progressed, and the number‐average molecular weights were close to those calculated on the basis of the feed compositions and monomer conversions. These features were in good agreement with a TEMPO‐mediated mechanism. The traces recorded by the ultraviolet‐visible (UV‐vis) detector (430 nm) were identical to those obtained by the RI detector, indicating a statistical copolymerization of styrene with H2TFPP. This also indicated that H2TFPP acted as a monomer and not as a terminator or a chain‐transfer agent under the conditions used. A benzyl radical addition to H2TFPP was conducted as a model reaction for the copolymerization using tributyltin hydride as a chain‐transfer agent, affording a reduced porphyrin, 2‐benzyl‐5,10,15,20‐tetrakis(pentafluorophenyl)chlorin 1, via radical addition to the β‐pyrrole position. The UV‐vis spectrum of 1 was fairly similar to that of poly(styrene‐co‐H2TFPP), indicating that H2TFPP polymerized at its β‐pyrrole position in the TEMPO‐mediated radical polymerization. TEMPO‐mediated radical copolymerizations of styrene with several porphyrin derivatives were also demonstrated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Synthesis and characterization of positively charged, alumina‐coated silica/polystyrene hybrid nanoparticles via pickering miniemulsion polymerization

AbstractPositively charged, raspberry‐like hybrid nanoparticles, consisting of a polystyrene core and an alumina‐coated silica shell were successfully prepared in a surfactant free system via the radical copolymerization of styrene (St) and different comonomers (acrylic acid, methacrylic acid, and acrylamide) by using a cationic silica sol as the sole emulsifier in Pickering miniemulsion polymerization. The influence of different parameters like pH of the dispersion, comonomer content, and the amount and size of silica nanoparticles on the colloidal stability of the systems, prepared with different comonomers, was examined. The particles' morphology was observed via high‐resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The removal of free silica particles via centrifugation was proved by TEM and SEM, and the content of free and adsorbed silica was quantified via thermogravimetric analysis (TGA). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

One-step Preparation of Comb-like Surfactants Containing Poly(ethylene oxide) Methyl Ether and Linear Alkyl Grafts

Abstract The optimum one-step method for preparing comb-like surfactants with poly(styrene-co-maleic anhydride) (SMA) as backbone was investigated to achieve a commercial way for manufacture. The side chain molecule was introduced into reaction system while the radical copolymerization of styrene (St) and maleic anhydride (MA) in anhydrous inhibitor-free tetrahydrofuran (THF) was finished. The precipitation and purification process of SMA in traditional grafting-onto route was passed over. A series comb-like surfactants with various side chain, poly(styrene-co-maleic anhydride)-g-(poly(ethylene glycol) monomethyl ether) (SMA-M), poly(styrene-co-maleic anhydride)-g-(poly(ethylene glycol) monomethyl ether &amp; dodecane) (SMA-M+C12) and poly(styrene-co-maleic anhydride)-g-(dodecane) (SMA-C12), was prepared via this one step method respectively. The molecular weight of the products was measurement via gel permeation chromatography (GPC). The comb-like structures of the surfactants were confirmed by Infrared Spectroscopy (IR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). The equilibrium surface tension was measured to evaluate the surface activity of comb-like surfactants. The surface activity of the product could be improved by using C12 to carry out a hydrophobic modification. The surface activity of comb-like surfactants could be adjusted by using various side chains with different amphiphilic property.

PMMA‐AES Blends Prepared by in situ Polymerization

AbstractBlends of poly(methyl methacrylate) (PMMA) and poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene) (AES) were prepared by in situ polymerization. AES, a commercial elastomer obtained by radical copolymerization of styrene and acrylonitrile in the presence of ethylene‐propylene‐diene terpolymer (EPDM), was dissolved in methyl methacrylate and the in situ polymerization was conducted at 60 °C. The blends were characterized by CHN analysis, infrared spectroscopy (FTIR), carbon‐13 nuclear magnetic resonance (13C NMR), dynamic mechanical analysis (DMA) and transmission electron microscopy (TEM). These blends are immiscible and present complex phase behavior. Selective extraction of the blends’ components showed that a fraction of the material is crosslinked and grafting reactions on EPDM chains take place during MMA polymerization. Syndiotactic PMMA was obtained in the presence of AES and this syndiotactic‐specificity increased with increasing amount of AES. The morphology of polymerized specimens showed irregular domains of elastomeric phase and in some cases inclusions of PMMA could be observed.

Modeling of the Nitroxide‐Mediated Radical Copolymerization of Styrene and Divinylbenzene

AbstractA mathematical model for the copolymerization kinetics with crosslinking of vinyl/divinyl monomers in the presence of nitroxide controllers has been developed and validated using experimental data of TEMPO‐mediated copolymerization of styrene (STY) and divinylbenzene (DVB). Polymerization rate, molecular weight development, gelation point, evolution of sol and gel weight fractions, crosslink density, and copolymer composition, as well as concentrations of the species participating in the reaction mechanism can be calculated with the model. Diffusion‐controlled effects were assessed and found unimportant. The presence of nitroxide controllers seems to favor the production of more homogeneous polymer networks, but this effect decreases as the initial fraction of crosslinker is increased.magnified image