Solubilization Of Styrene Research Articles

Role of Acetone in the Formation of Highly Dispersed Cationic Polystyrene Nanoparticles

Abstract A modified emulsion polymerisation synthesis route for preparing highly dispersed cationic polystyrene (PS) nanoparticles is reported. The combined use of 2,2′-azobis[2-(2-imidazolin- 2-yl)propane] di-hydrochloride (VA-044) as the initiator and acetone/water as the solvent medium afforded successful synthesis of cationic PS particles as small as 31 nm in diameter. A formation mechanism for the preparation of PS nanoparticles was proposed, whereby the occurrence of rapid acetone diffusion caused spontaneous rupture of emulsion droplets into smaller droplets. Additionally, acetone helped to reduce the surface tension and increase the solubility of styrene, thus inhibiting aggregation and coagulation among the particles. In contrast, VA-044 initiator could effectively regulate the stability of the PS nanoparticles including both the surface charge and size. Other reaction parameters i.e. VA-044 concentration and reaction time were examined to establish the optimum polymerisation conditions.

Solubilities of Diethyl Phthalate, Dicyclopentadiene, and Styrene in Ionic Liquid 1-Ethyl-3-methylimidazolium Acetate

Solubilities of diethyl phthalate (DEP), dicyclopentadiene (DCPD), and styrene in ionic liquid 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) were measured in the temperature range T = (283.15–353.15) K and at atmospheric pressure (101.3 kPa) the corresponding temperature–composition phase diagrams were obtained. Solubilities of DEP and DCPD in [Emim][OAc] increase with temperature but the solubility of styrene in [Emim][OAc] decreases with temperature. The ternary liquid–liquid equilibrium data for the system of styrene + glycerol + [Emim][OAc] were also determined at temperatures of 298.15, 308.15, 318.15, and 328.15 K, and the results indicate that the addition of glycerol can significantly reduce the solubility of styrene in [Emim][OAc]. For the ternary system, when the amount of glycerol is enough, the solubility of styrene in [Emim][OAc] increases with temperature. The experimental data were correlated by the nonrandom two-liquid activity coefficient model and the binary interaction parameters we...

Preparation of hemispherical polymer particles via phase separation induced by microsuspension polymerization

Micrometer-sized, hemispherical polystyrene (PS) particles were successfully prepared by microsuspension polymerization of homogeneous styrene/hexadecane (HD) droplets dispersed in polyoxyethylene nonylphenyl ether (Emulgen 931) aqueous solution, followed by rapid removal of HD from formed PS/HD particles with a “Janus” structure. It was important for the formation of the morphology of Janus particles in thermodynamically stable state to carry out the polymerization slowly. The formation of by-product small PS particles by emulsion polymerization was suppressed by the additions of CuCl2 as a water-soluble inhibitor and NaCl to decrease the solubility of styrene in the aqueous phase.

Effect of Sodium dodecyl sulfate on the Mass Transfer Rate between Styrene and Water

AbstractSummary: The effect of sodium dodecyl sulfate (SDS) on the mass transfer rate between styrene and water has been investigated. SDS increases the solubility of styrene in water even below the critical micelle concentration (CMC) and therefore increases the thermodynamic driving force for the mass transfer. The mass transfer coefficient however is not altered by SDS, even if the interface is almost saturated with emulsifier.

Polystyrene latex synthesized in presence of ultrasonic initiation

AbstractThe low water solubility of styrene (St) monomer increase the need for a good initiator system to speed up the emulsion polymerization and remove unreacted monomers. Polymerization of styrene monomer in water was performed at 30, 50, and 70°C under ultrasonic irradiation using sodium dodecyl sulfate as surfactant and ammonium persulfate as initiator. Ultrasonic energy was used as a tool to speed up the polymerization. Combining ultrasonic and ammonium persulfate led to a higher conversion and higher rate of polymerization. Ultrasonic energy has an effect on the particle size distribution. The particle size distribution increases with an increase in the monomer conversion of styrene for ultrasonic polymerization, whereas the particle size distribution did not change with an increase in the monomer conversion compared with the conventional thermal polymerization results. Higher molecular weights were obtained under ultrasonic irradiation. FE‐SEM and TEM pictures show different morphology with changing temperature polymerization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The solubility of styrene in supercritical carbon dioxide

Possible reasons for the existing differences in styrene solubilities in supercritical carbon dioxide obtained using the dynamic (flow) method are analyzed. The results of an experimental study of the solubility of styrene in supercritical CO2 with the use of the static method of measurements and an improved dynamic cell are given. The influence of styrene polymerization under experimental conditions on measurement results at elevated pressures is analyzed. A mathematical formulation for the description of solubility data with the use of the Peng-Robinson equation and three adjustment parameters is presented. The experimental data on the solubility of styrene in supercritical carbon dioxide are described.

Understanding the enhanced aqueous solubility of styrene by terrestrial dissolved organic matter using stable isotope mass balance and FTIR

We present a new stable isotope mass balance method for measuring the enhanced aqueous solubility of specific organic compounds in the presence of natural dissolved organic matter (DOM). It involves interfacing a standard dissolved organic carbon (DOC) analyzer with a stable isotope ratio monitoring system, is applicable to a wide range of model organic compounds and can be tuned to provide maximum precision for a given range of compound solubility and initial natural DOC concentration. Using 13C-labeled styrene as a model compound, we applied the method to investigate the reactivity of Dismal Swamp DOM as a function of season, nominal molecular size and chemical composition as determined using Fourier Transform Infrared Spectroscopy (FTIR). The solubility enhancement of styrene ranged from 23% to 118% relative to deionized water, while DOC-normalized enhancements varied from about 0.04 to 0.35 μM styrene/μM DOC as a function of season and nominal molecular weight. Statistical analysis of FTIR spectra reveals a strong positive correlation between the styrene concentration and the carboxyl content of the natural DOM. Reactivity differences between high molecular weight (HMW), low molecular weight (LMW) and total DOM samples are consistent with potential variations in their higher order structures.

A Further Study on the Solubilization Behavior of Styrene in the Cationic Microemulsion Media by Means of NMR

In this study, we further investigated the solubilization of styrene in a cationic CTAB/n‐butanol/water/styrene microemulsion by means of NMR. It was found that the solubilization behavior of styrene in the cationic was quite different from that in anionic microemulsion media. In a cationic microemulsion system, the solubilization site of styrene was mainly in the palisade layer of the microemulsions and less of styrene was located in the inner core. Meanwhile, due to the steric hindrance effect styrene molecules can hardly distribute near the N‐CH3 group of CTAB, and the content of styrene was gradually decreased from the outer to inner along the hydrocarbon chain of CTAB.

Free-radical polymerization of styrene in worm-like micelles

The solubilization of styrene in wormlike micelles of the cationic surfactant, cetyltrimethylammonium tosilate (CTAT), and its polymerization is examined here by UV spectroscopy, oscillatory rheometry, small angle X-ray scattering, polarizing light microscopy, and transmission electron microscopy. At low CTAT concentrations, the polymerization of styrene yields small and rigid rods in coexistence with wormlike micelles that form from the excess surfactant after the polymerization process. At high CTAT concentrations, polymeric rods (of large aspect ratio), spheroid polymer particles, and wormlike micelles coexist. The polymerization rate is second order, indicating that polymerization reactions end mainly by bimolecular termination.

Polystyrene nanoparticles based on poly(butyl methacrylate-g-methoxypoly(ethylene glycol)) and poly(methyl methacrylate-g-methoxypoly(ethylene glycol)) graft copolymers

The solubilization of styrene by poly(butyl methacrylate-g-methoxypoly(ethylene glycol)) and poly(methyl methacrylate-g-methoxypoly(ethylene glycol)) graft copolymers has been examined. From turbidity measurements the solubility limit of the monomer in the micelles was obtained and the distribution coefficients were evaluated. Dynamic light scattering revealed that below the solubility limit, solubilization leads to a slight increase in micelle size, while above the solubility limit, there is a dramatic increase in particle size and turbidity as oil-in-water emulsions are formed through coalescence of monomer-swollen micelles. Polymerizations carried out below the solubility limit using the graft copolymer micelles as templates resembled microemulsion polymerizations in nature and led to very fine sterically stabilized polystyrene latex particles. Through careful control of the monomer concentration and the polymerization temperature it was possible to obtain spherical nanosize latex particles with similar size to those of the micelle precursors (10 nm) up to 11% monomer by weight. Polymerizations above the solubility limit, on the other hand, showed similarities with emulsion polymerizations and resulted in larger particles with higher polydispersity.

Solubilization of Styrene and Acrylamide Monomers in Microemulsions

Phase diagrams of sodium dodecyl sulfonate (DS)/n‐butanol/styrene/water systems with variable amounts of styrene were constructed at 40°C, and the effects of styrene on microemulsion stability were studied. The solubilization of styrene in these O/W microemulsion systems was investigated by 1H NMR methods. The results show that the solubilization site shifts from the palisade layer to the inner core of microemulsion droplets when the molar fraction of styrene reaches 0.312. The solubilization of acrylamide in cetyltrimethylmethyl ammonium bromide (CTAB)/n‐butanol/10% n‐octane/water reverse microemulsions (W/O) was studied with a 13C NMR method. It was found that the acrylamide was mainly solubilized in the Stern layer of droplets at low acrylamide levels. However, when the mole fraction of acrylamide approaches 0.428, the acrylamide penetrates into the palisade layer and is distributed along the hydrocarbon chain of the surfactant.

Interaction of Styrene with DODAB Bilayer Vesicles. Influence on Vesicle Morphology and Bilayer Properties

The solubilization of styrene in large unilamellar DODAB vesicles is investigated at a styrene to DODAB molar ratio of 2:1. The combination of various vesicle characterization methods allows a simultaneous look at vesicle morphology (cryo-TEM, DLS) and molecular interactions (micro-DSC, various fluorescence techniques) and gives a complete picture of the DODAB vesicles before and after the addition of styrene. Cryo-TEM and DLS results reveal that the addition of styrene does not break up the DODAB vesicles as an entity, but the peculiar angular DODAB vesicle morphology becomes smoother and the geometries tend to be more curved. The change in morphology is explained by an enhanced bilayer fluidity and the drastic depression of the phase transition temperature as determined from calorimetry and fluorescence experiments. Moreover, micro-DSC scans and fluorescence experiments with two different pyrene probes suggest a nonhomogeneous distribution and partial demixing of solute and bilayer for temperatures belo...

Solubilization of styrene in the catanionic system dodecyltrimethylammonium hydroxide- n ′-dodecanephosphonic acid

The solubilization of styrene in micelles of the catanionic surfactant dodecyltrimethylammonium hydroxide (DTAOH)–n-dodecane-phosphonic acid (DPA) was studied by UV–Vis. spectrometry, as a function of the DTAOH:DPA proportion in the surfactant mixture. The styrene molecules are adsorbed at the surface of the micelles, with the vinyl group closer to the hydrocarbon core than the aromatic ring, which is oriented to the water. In micelles with an excess of DTAOH, the dielectric constant of the water surrounding the micelles was strongly affected by the non-neutralized –N(CH3)+3 groups at the Stem layer. In micelles with an excess of DPA, the –PO3H2 groups which are not neutralized by –N(CH3)+3, remain almost unionized and hydrogen-bonded. The effect of the micellar surface on the surrounding water dielectric constant dropped sharply. The dielectric constant in the hydrogen-bonded polar layer is ∼65, rising to the value of pure water very close to the micellar surface.

Phase compositions of styrene oil-in-water microemulsions

The structure of oil-in-water microemulsions, consisting of styrene, water, 1-pentanol, and sodium dodecyl sulfate (SDS) was modeled in terms of three phases: oil (core) phase, membrane phase, and aqueous (continuous) phase. The composition of the oil and aqueous phases was determined using a diffusion method and partitioning measurements. The membrane phase was composed mainly of 1-pentanol and SDS. The solubilization of styrene in the hydrophobic region created by the SDS in the membrane phase was considered. The partitioning of styrene and 1-pentanol among oil, aqueous, and membrane phases was studied using a 13C NMR chemical shielding experiment. The results were self-consistent and showed that more than 60% of the 1-pentanol partitions into the interface. The partitioning of 1-pentanol into the oil phase increases with increasing amounts of styrene in the system. The radius of the microemulsion droplets was calculated to be 3 to 4 nm. The thickness of the interfacial layer was found to be 1 nm, and was constant regardless of composition in the range studied.

Latex particle nucleation in emulsion polymerization

Although it has been generally accepted for the past 45 years that the latex particles which are the principal locus of the emulsion polymerization reaction are nucleated from monomer solubilized in emulsifier micelles, conclusive evidence to support this supposition has been lacking. Twenty years ago it became apparent that in the case of monomers such as methyl methacrylate and vinyl acetate which have significant solubility in water, latex particles are nucleated by precipitation of oligomeric radicals formed in aqueous solution. Then it was found that even styrene, which has a very low solubility in water, could be polymerized in emulsion without an emulsifier or below the critical micelle concentration of the emulsifier when the latex particles must also be nucleated by oligomeric precipitation. However, such ‘emulsifier-free emulsion polymerization’ proves impossible with p-tert-butyl styrene which has only one tenth of the water solubility of styrene. Subsequently much evidence has been published to show that the ultimate latex particles are formed by coalescence of unstable precursor particles. It is argued that in the case of water-insoluble monomers, precursor particles may be formed by coalescence of monomer-swollen micelles destabilized by polymerization.

Styrene and polystyrene microemulsions. I. Solubility in the W/O system

AbstractThe solubility of styrene, its oligomers, and different molecular weight polymers was determined in W/O microemulsions stabilized by sodium dodecyl sulfate and pentanol. The results showed a complex pattern due to the interactions with pentanol, surfactant, and associated structures.

Topochemical features of the emulsion polymerization of styrene and chloroprene in the presence of hydroxyethylated cetyl alcohols

A study was made of the solubilization of styrene and chloroprene in aqueous solutions of cetyl alcohols with varying degrees of hydroxyethylation, and the kinetic principles of the polymerization of these monomers were investigated. The results show the dissimilarity of the mechanism of latex particle formation in the presence of non-ionic emulsifiers compared with analogous processes where ionogen emulsifiers are used.

The concentration‐dependent diffusion of styrene in ethyl cellulose

AbstractThe diffusion of styrene vapor in ethyl cellulose film has been studied as a function of styrene solubility in the film at 50°C. Methods and data are presented for determining the equilibrium solubility of styrene in ethyl cellulose as a function of vapor pressure at 50°C. The permeation rates of styrene vapor through 3‐mil film were determined under steady state conditions for various pressures of pure styrene vapor on one side of the film and vacuum on the other side. From a plot of permeation rates versus styrene solubility the diffusion coefficient was calculated as a function of concentration. Measurements made over a concentration range of 0 to 0.7 g. styrene/cm.3 of unswollen film show that the diffusion coefficient first increases rapidly with concentration, then goes through a maximum, and finally levels off at 10−7 cm.2/sec. In the limited range of 0.06 to 0.10 g./cm.3 the diffusion coefficient varies exponentially with concentration as has been reported for other systems in a similar range. However, such a functionality does not represent the present system over a broad concentration range. These results, if generally applicable to other systems, indicate that the nature of the diffusion process for organic vapors in polymers may be considerably more complicated than formerly supposed.

Mechanism of emulsion polymerization of styrene with persulfate as activator in the absence and presence of mercaptan and a retarder

AbstractWith the use of persulfate containing radioactive sulfur it is shown that the termination reaction of the polymerization of styrene is a coupling of the free radical chains. In the presence of m‐dinitrobenzene as a retarder evidence has been presented that the termination reaction is a disproportionation and not a combination of two free radical chains. Mercaptan in the emulsion polymerization of styrene acts solely as a chain transfer agent. Any chemical reaction between persulfate and mercaptan does not contribute to the initiation. In the presence of detergent the rate of initiation of the polymerization of styrene is equal to the rate of thermal dissociation of persulfate: Thus, any reaction between persulfate with monomer and detergent does not contribute to the initiation. The much smaller rate of initiation in the absence of detergent is attributed to the slight solubility of styrene, the concentration of the monomer being so small that it cannot capture all the free radicals. The effect of the detergent is a physical one, by its solubilizing action it increases the solubility of the monomer in the water layer to such an extent that the “activator” now becomes 100% efficient.

Polymerization of styrene in soap solutions

AbstractA turbidimetric method has been developed for determining the styrene content in water and soap solution. The solubility of styrene in distilled water was 0.022% while in 2.0% potassium oleate solution it was 0.65 to 0.88%. The course of the polymerization of a saturated solution of styrene in 2% potassium oleate was followed by a colorimetric analysis based on reaction with dilute potassium permanganate. The rate of polymerization decreased rapidly after 50% conversion. The activation energy was estimated to be 17,000 kcal., somewhat less than in solution. The molecular weight of the polymer produced was 200,000. Occasional erratic results were ascribed to possible influence of various amounts of air sealed in the polymerization mixtures.