Continuous Organic Phase Research Articles

Mathematical modeling and analysis of an interfacial polycarbonate polymerization in a continuous multizone tubular reactor

A detailed mathematical model is presented to describe the steady state behavior of a continuous multizone tubular reactor for the synthesis of aromatic polycarbonate by interfacial polycondensation mechanism. In this process, bisphenol‐A dissolved in a dispersed aqueous phase reacts with phosgene dissolved in a continuous organic phase and hence, the reaction initiates at the interface of the two phases. A liquid‐liquid mass transfer process is incorporated into a reaction kinetic model to calculate the reaction rates and polymer molecular weight distribution. The kinetic model has also been used in developing a steady state multizone tubular reactor model for continuous production of polycarbonate. The model simulations are compared with proprietary plant data and excellent agreement has been obtained. POLYM. ENG. SCI., 58:438–446, 2018. © 2017 Society of Plastics Engineers

Particle agglomeration studies in a slurry bubble column due to liquid bridging: Effects of particle size and sparger design

Particle agglomeration can occur in heavy oil upgrading hydroprocessors due to the formation of carbonaceous mesophase, a secondary liquid phase which results from an increased rate of thermal cracking relative to the hydrogenation rate. A cold-flow slurry bubble column operated at atmospheric pressure with an internal diameter of 0.152m was used to examine particle agglomeration behavior and the overall fluid dynamics in a gas-liquid-liquid-solid system. The experimental system consisted of biodiesel (organic continuous phase), aqueous glycerol solutions (immiscible secondary phase), glass beads and nitrogen. The impacts of the secondary liquid loading, secondary liquid viscosity, and particle diameter on the fluid dynamics were established. Particle agglomeration was studied by measuring the axial solid holdup profiles while varying the superficial gas velocity and secondary liquid loading. Enhanced particle agglomeration was observed when increasing the secondary liquid loading, based on the increased solid holdups at the bottom of the column. Three sparger designs (six-legged spider sparger, perforated plate and conical perforate plate) were compared. Following the glycerol addition, the spider sparger was less effective based on the particle sedimentation at lower liquid/solid ratios when compared to the other sparger designs. A Revolution Powder Analyzer (RPA) was also used for complementary measurements to examine whether operational difficulties due to particle agglomeration can be anticipated using a simplified system.

Microcapsules for Enhanced Cargo Retention and Diversity.

Prevention of undesired leakage of encapsulated materials prior to triggered release presents a technological challenge for the practical application of microcapsule technologies in agriculture, drug delivery, and cosmetics. A microfluidic approach is reported to fabricate perfluoropolyether (PFPE)-based microcapsules with a high core-shell ratio that show enhanced retention of encapsulated actives. For the PFPE capsules, less than 2% leakage of encapsulated model compounds, including Allura Red and CaCl2 , over a four week trial period is observed. In addition, PFPE capsules allow cargo diversity by the fabrication of capsules with either a water-in-oil emulsion or an organic solvent as core. Capsules with a toluene-based core begin a sustained release of hydrophobic model encapsulants immediately upon immersion in an organic continuous phase. The major contribution on the release kinetics stems from the toluene in the core. Furthermore, degradable silica particles are incorporated to confer porosity and functionality to the otherwise chemically inert PFPE-based polymer shell. These results demonstrate the capability of PFPE capsules with large core-shell ratios to retain diverse sets of cargo for extended periods and make them valuable for controlled release applications that require a low residual footprint of the shell material.

Nanogels based on alginic aldehyde and gelatin by inverse miniemulsion technique: synthesis and characterization.

Nanogels were developed from alginic aldehyde and gelatin by an inverse miniemulsion technique. Stable inverse miniemulsions were prepared by sonication of noncontinuous aqueous phase (mixture of alginic aldehyde and gelatin) in a continuous organic phase (Span 20 dissolved in cyclohexane). Cross-linking occurred between alginic aldehyde (AA) and gelatin (gel) in the presence of borax by Schiff's base reaction during the formation of inverse miniemulsion. The effects of surfactant (Span 20) concentration, volume of the aqueous phase and AA/gel weight ratio on the size of the alginic aldehyde-gelatin (AA-gel) nanoparticles were studied. Nanogels were characterized by DLS, FT-IR spectroscopy, TGA, SEM and TEM. DLS, TEM and SEM studies demonstrated nanosize and spherical morphology of the nanogels. Hemocompatibility and in vitro cytocompatibility analyses of the nanogels proved their nontoxicity. The results indicated the potential of the present nanogel system as a candidate for drug- and gene-delivery applications.

Silylation of Al13-intercalated montmorillonite with trimethylchlorosilane and their adsorption for Orange II

The grafting reactions between trimethylchlorosilane (TMCS) and Al13-intercalated montmorillonite were investigated using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and nitrogen adsorption–desorption isotherms. The influence of solvent on the grafting process is discussed. The grafting amount of TMCS was roughly controlled by choosing different solvents. The product prepared in anhydrous ethanol has a high specific surface area and a large pore volume but a low degree of grafting modification; by comparison, the product prepared in cyclohexane has a high loading amount of silane but a low surface area. These organic–inorganic montmorillonites have an excellent adsorption capability for the removal of the anion dye, Orange II. Orange II exists in the interlayer region, not only through the electrostatic interactions between the anionic sulfonic acid groups of Orange II and the interlayer Al polycations, but also through the hydrophobic interactions between Orange II molecules and grafted silane. With particular emphasis on the absorbents prepared in cyclohexane, the removal rate of Orange II remains at 98.7% when the initial concentration is 1000mgl−1. A continuous organic phase is formed in the interlayer space of the products prepared in cyclohexane. The removal of Orange II with this adsorbent is based on both the adsorption on the interface and the partition between the water and the interlayer organic phases.

Microfluidics-Assisted Diffusion Self-Assembly: Toward the Control of the Shape and Size of Pectin Hydrogel Microparticles

We demonstrated the generation of pectin hydrogel microparticles having complex shapes either by combining the phenomenon of gelation and water diffusion-induced self-assembly in microfluidic channels (on-chip) or by the deformation of the pregelled droplets outside the channels (off-chip) at a fluid-fluid interface. We proved that by tuning the mode of pectin cross-linking (CaCl2 vs CaCO3) and the degree of shrinking (water content in the dimethyl carbonate (DMC) organic continuous phase) we can control the shape of the final particle. Sphere, doughnut, oblate ellipsoid, or mushroom-type morphologies were thus produced, demonstrating the ability to control the formation of anisotropic biopolymer-based hydrogel microparticles using microfluidics. Shape changes were explained by the redistribution of calcium ions in combination with the local Peclet number experienced by the microdroplets during the on-chip process. Moreover, during the off-chip process, the interplay between elastic and viscous forces for microdroplets entering the CaCl2-DMC interface caused deformation of the pregelled droplets to occur and therefore resulted in the formation of microparticles with a mushroom-like morphology.

Creating polymer templates and their use in the in-situ synthesis of biodegradable composite networks

A biodegradable polyethyleneoxide–polycaprolactone–polyethyleneoxide (PEO–PCL–PEO or PECE) triblock polymer was synthesized as a structure-directing agent for high-surface area silica formation. Systematic end-group functionalization of the triblock polymer, prior to its use as a structure-directing agent for high-surface area silica growth, imparts an additional reactive function that is exploited to grow a continuous organic phase within and around the silica particles. Hence, the biodegradable triblock also acts as a macromer whose dual function leads to in-situ generation of intimately mixed biopolymer/nanoporous–silica composite networks. This composite can be both biodegradable and biocompatible, and the modulus is comparable to other non-biodegradable materials.

Nanoporous Nonwoven Fibril-Like Morphology by Cooperative Self-Assembly of Poly(ethylene oxide)-block-Poly(ethyl acrylate)-block-Polystyrene and Phenolic Resin

Cooperative self-assembly of block copolymers with (in)organic precursors effectively generates ordered nanoporous films, but the porosity is typically limited by the need for a continuous (in)organic phase. Here, a network of homogeneous fibrous nanostructures (≈20 nm diameter cylinders) having high porosity (≈ 60%) is fabricated by cooperative self-assembly of a phenolic resin oligomer (resol) with a novel, nonfrustrated, ABC amphiphilic triblock copolymer template, poly(ethylene oxide)-block-poly(ethyl acrylate)-block-polystyrene (PEO-b-PEA-b-PS), via a thermally induced self-assembly process. Due to the high glass transition temperature (Tg) of the PS segments, the self-assembly behavior is kinetically hindered as a result of competing effects associated with the ordering of the self-assembled system and the cross-linking of resol that suppresses segmental mobility. The balance in these competing processes reproducibly yields a disordered fibril network with a uniform fibril diameter. This nonequilibrium morphology is dependent on the PEO-b-PEA-b-PS to resol ratio with an evolution from a relatively open fibrous structure to an apparent poorly ordered mixed lamellae-cylinder morphology. Pyrolysis of these former films at elevated temperatures yields a highly porous carbon film with the fibril morphology preserved through the carbonization process. These results illustrate a simple method to fabricate thin films and coatings with a well-defined fiber network that could be promising materials for energy and separation applications.

Preparation of protein loaded chitosan microparticles by combined precipitation and spherical agglomeration

Abstract Combined precipitation and spherical agglomeration was carried out in the non-miscible region of ethyl acetate–ethanol–water ternary solvent system. At first, w/o type quasi emulsion was prepared by sequential introduction of aqueous solutions of human serum albumin (HSA), chitosan (CS), and poly(4-styrenesulfonate) (PSS) into an ethyl acetate–ethanol solvent mixture. HSA was used to model a protein type drug, while CS and PSS served as matrix material in the obtained composite particles. PSS also served as chemical precipitation agent for both of the HSA and CS. The solubility of all these substances was reduced by introduction of additional amounts of ethyl acetate–ethanol mixture and/or ethanol as poor solvents. Due to the counter-diffusion of the good and poor solvents between the water rich droplets and the ethyl acetate–ethanol rich continuous phase, the aqueous phase gradually disappeared and partial agglomeration of the precipitated solids and their transfer to the continuous organic phase took place. The paper gives a report on the effect of several process variables on the quality of the obtained microparticles, such as their shape and stability against disintegration. The effects of the composition of the ternary solvent mixture, the route of its variation, the feeding method and composition of the added poor solvents, the stirring rate and the duration of agitation were studied.

Inverse Miniemulsion Periphery RAFT Polymerization: A Convenient Route to Hollow Polymeric Nanoparticles with an Aqueous Core

The recently developed [Chem. Commun. 2012, 48, 11103−11105] inverse miniemulsion periphery RAFT polymerization (IMEPP) approach to prepare hollow polymeric nanoparticles (∼200 nm) with an aqueous core has been explored in detail. The method is based on an amphiphilic macroRAFT agent acting as stabilizer of water droplets in an organic continuous phase while also mediating cross-linking chain growth in a controlled/living manner on the outer periphery of the droplets. The macroRAFT agent comprised a hydrophilic block of poly(N-(2-hydroxypropyl)methacrylamide) and a hydrophobic block of either polystyrene or poly(methyl methacrylate), and the cross-linked shell was formed on polymerization of styrene/divinylbenzene or methyl methacrylate/ethylene glycol dimethacrylate, respectively. The effects of various reaction parameters on the resulting hollow nanoparticles have been systematically investigated, and it has been demonstrated that the shell thickness can be tuned based on initial stoichiometry and monom...

Peleg and Weibull models for water absorption of copolymer gels crosslinked on polyethylene glycol dimethacrylates

In this study, the super-absorbent copolymer gels were obtained from the aqueous solution of monomers dispersed in a continuous organic phase. The inverse suspension polymerization was accomplished with the use of aqueous solutions of partly neutralized acrylic acid with a predetermined crosslinker agent, polyethylene glycol dimethacrylates (PEGDMA)/monomer ratio in cyclohexan. The copolymer gels synthesized using PEGDMA crosslinker with three different molecular weights (PEGDMA330, PEGDMA550, and PEGDMA750) were characterized by infrared spectroscopy and scanning electron microscopy. Water absorption capacities of the copolymer gels were determined. The water absorption capacity of 1 g copolymer gels in water was respectively obtained as 232, 255, and 316 g water/g polymer gel for PEGDMA330, PEGDMA550, and PEGDMA750, respectively. The Peleg and Weibull models were used to describe the water absorption behavior of the copolymer gels. The highest values of R 2 and the lowest values of χ 2 and RMSE for copolymer gels were observed with the Weibull model.

Synthesis and dispersion of colloidal silver nanoparticles on microcellular polyHIPE support

Highly open-cell polyHIPE solid foam was prepared by polymerization of continuous organic phase of a high internal phase emulsion (HIPE) containing styrene (St), acrylonitrile (AN), divinelybenzene (DVB), and Span 80 as emulsifier. The cross-linked SAN copolymer foam was reinforced by adding 1 and 3wt% organoclay, i.e. Cloisite30B (C30B), into its emulsion organic phase in order to improve the compression properties of the resulting foam. Scanning electron micrographs indicated a typical highly open-cell structure of the neat and reinforced copolymer foams. The introduction of 1wt% C30B inside the emulsion foam significantly decreased the weighted-average cell diameter from 62 to 16.1μm, and the mean intercellular pore size from 17.9 to 4.2μm. On the other hand, the above organoclay level considerably improved the crush strength of the foam by about 271%. The surface of the foams was then coated by colloidal silver nanoparticles (SNPs) previously generated by a reduction of silver ions (Ag+) using sodium borohydride (NaBH4) as the reducing agent and polyvinyl alcohol (PVA) as the stabilizing agent. The colloidal SNPs were characterized by ultraviolet–visible (UV) spectroscopy, dynamic laser light scattering, and X-ray diffraction (XRD) techniques. The effect of PVA molecular weight, reduction temperature, and foam organoclay level on the mean size and dispersion state of SNPs dispersed on polyHIPE support has been investigated. The results showed that the SNPs prepared using low-molecular PVA at higher reduction temperature dispersed well on the support surface. A more uniform SNP dispersion as singlet was observed for the copolymer foam reinforced by organoclay.

Estudio de separación de fases en sistemas líquido-líquido usando LIX 984N en fase orgánica

In this work we studied the sedimentation and coalescence phenomena in liquid-liquid dispersion without chemical reaction, the aqueous electrolyte consisted of 0.25 M sodium sulfate and an organic phase characteristic organic extractant for copper (LIX 984N) diluted in a commercial solvent (Shellsol 24 AR). The phenomena that dominate the phase separation have been studied by several researchers, which proposed a number of models to predict sedimentation and coalescence profiles. In this work we applied a semi-empirical model to describe the phenomena involved, varying the following experimental conditions: percentage of extractant in organic phase (5 - 30 % v / v), continuous phase (aqueous and organic), time and stirring speed (30 - 1800 s and 400 - 1200 rpm respectively). The main results show that from the 800 rpm of agitation this variable has no influence on primary breakup time, in the same way for 180 seconds of stirring produces the same effect. The fraction of dispersed phase in the packing zone found was 0.74. For higher levels of percentage of extractant in organic phase increased the phase separation time as when the organic phase was used as the continuous phase relative to the aqueous phase. We found a partial adjustment of the experimental data in relation to the simulated values , which is attributable to two factors: the initial inertia of the system once the agitation stopped and the existence of different times of inflection points of the curves of sedimentation and coalescence. In the different articles found in literature assume that the above phenomena occur simultaneously.

Suspension catalysis in a liquid–liquid capillary microreactor

Suspended catalyst particles in two phase slug flow could be an alternative technique for using heterogeneous catalysts in microreactors, which has so far mainly been restricted to immobilised solid catalysts, either in micro-fixed-beds or catalytically coated wall reactors. The hydrodynamic and particle behaviour in slug flow was analysed using fluorescent particles and particles of typical catalyst supports in various biphasic liquid–liquid systems. Typically, the circulations only encompassed the anterior section of the slug and depended on the properties of the liquid–liquid system and, in particular, on the slug velocity. Silicon dioxide or aluminum oxide particles suspended in the aqueous phase follow the internal circulation streamlines almost exactly, while carbon-based particles suspended in the continuous organic phase formed a contiguous cap around the rear end of the dispersed aqueous slug. The principle of suspension catalysis was demonstrated experimentally for a heterogeneous catalytic transfer hydrogenation of m-nitrotoluene with aqueous potassium formate.

Preparation of highly open porous styrene/acrylonitrile and styrene/acrylonitrile/organoclay polymerized high internal phase emulsion (PolyHIPE) foams via emulsion templating

AbstractHighly open porous crosslinked styrene/ acrylonitrile (SAN) polymerized high internal phase emulsion (PolyHIPE) foams containing various amounts of acrylonitrile (AN) were prepared by the polymerization of the continuous organic phase of high internal phase emulsions with an 85 vol % aqueous internal phase. The mean diameter of voids varied in the range 12.4–19.8 μm. The void diameter increased up to 10% AN, but beyond this limit, the diameter decreased. To improve the mechanical properties of the copolymer foams, the organic phase of the emulsion containing 20% AN was reinforced with organomontmorillonites with different surface modifiers. The effects of the organoclay on the equilibrium torque value of the emulsifying systems, as an approximate characteristic of the emulsion viscosity, and on the morphology and mechanical properties of the resulting foam were investigated. Scanning electron micrographs exhibited an open‐cell polyHIPE structure for all of the SAN/organoclay polyHIPE foams. The incorporation of organoclays within the emulsion copolymer foam significantly decreased the mean size of voids and intercellular pores compared with those of the copolymer foam without reinforcement. In fact, the presence of organoclay may have acted as a cosurfactant to improve the performance of the nonionic surfactant in the concentrated emulsions. The X‐ray diffraction patterns and transmission electron micrographs showed an intercalated nanocomposite structure for the organoclay‐reinforced copolymer foams. On the other hand, the addition of a more hydrophilic organoclay, that is, 3 wt % Cloisite30B, to the concentrated emulsion decreased the Young's modulus and significantly improved the crush strength of the emulsion copolymer foam. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Preparation of core-shell particle of disinfectant agent nanocapsules-skim rubber particles by the heterocoagulation technique

Sulphur-prevulcanised skim (SPVS) rubber particles were heterocoagulated on an aggregate of a disinfectant agent (chlorhexidine digluconate; CHD)-poly(methyl acrylate) (PMA) nanocapsules. The CHD-PMA nanocapsule stabilized by lecithin was prepared using the modified nanoprecipitation of PMA from an organic continuous phase onto nanodroplet containing the CHD aqueous solution. Cationic and anionic nanocapsules were produced by separately redispersing the nanocapsules into a water and 0.5% sodium dodecyl sulphate (SDS) aqueous solution, respectively. The largest aggregate, which was obtained from homocoagulation of the CHD-PMA nanocapsules with opposite charges, was selected as a core surrounded with SPVS shell particles. An interpolymer complex between poly(ethylene oxide) (PEO) moieties adsorbed on the aggregate and indigenous surfactant (protein-lipid) and/or SDS on the SPVS particle surface was the driving force for heterocoagulation. Data from the size, zeta potential measurements and TEM images of the heterocoagulated CHD-PMA/SPVS indicated the composite particle containing the CHD-PMA core.

Room temperature synthesis of titanium dioxide nanoparticles of different phases in water in oil microemulsion

We report the synthesis of crystalline titanium dioxide nanoparticles of two different phases (rutile and anomalous pseudobrookite) at room temperature by a novel microemulsion technique. In this method, one of the reactants (titanium tetrachloride) is dissolved in the continuous organic phase, whereas the second reactant (ammonium hydroxide) is added as an aqueous solution. The site of the reaction has been controlled by using two different addition methods for the second reactant. The size and the crystalline phase of the titanium dioxide nanoparticles varied according to the site of the reaction between the two reactants. Reaction in the aqueous core gives rutile titanium dioxide nanoparticles having an average size of 4.2 nm verified by X-ray diffraction and FTIR. The reaction in the organic phase gives rise to crystalline anomalous pseudobrookite titanium dioxide nanoparticles of much larger size (10–40 nm). This anomalous pseudobrookite structure is thermally unstable and converts to rutile on high temperature treatment.

Synthesis of magnetic iron and iron oxide micrometre-sized composite particles of narrow size distribution by annealing iron salts entrapped within uniform porous poly(divinylbenzene) microspheres

This article describes a new simple approach to produce poly(divinylbenzene) and carbon micrometre-sized magnetic composite particles of narrow size distribution. For this purpose, uniform porous poly(divinylbenzene) microspheres were prepared by a single-step swelling of uniform polystyrene microspheres with divinylbenzene and benzoyl peroxide, followed by polymerization of the divinylbenzene within the swollen polystyrene particles. Uniform porous poly(divinylbenzene) microspheres were then formed by dissolution of the polystyrene part of the polystyrene–poly(divinylbenzene) composite particles. Iron salts, e.g., FeCl2·4H2O, dissolved in an organic continuous phase were then entrapped by vacuum within the pores of the cross-linked poly(divinylbenzene) microspheres. The obtained microspheres containing the iron salts were then annealed at 250 °C under ambient atmosphere. The formed magnetic microspheres were then annealed at 500 and 800 °C, respectively, under inert atmosphere. The annealing temperature allowed for control of the composition, crystallinity, size and size distribution and the magnetic properties of the obtained microspheres. Magnetic PDVB–α-Fe2O3 microspheres were obtained at 250 °C, while annealing of these microspheres at 500 and 800 °C under inert atmosphere leads to carbonization of the particles, and thereby the formation of C–Fe3O4 and air stable C–Fe microspheres, respectively. The magnetic moment of the C–Fe microspheres is notably high, 106.5 emu g−1. HR-TEM combined with STEM for elemental Fe mapping and imaging illustrated that by increasing the annealing temperature the size of the composite particles significantly decreased, while at the same time the size of the magnetic grains entrapped within the particles increased. Characterization of the various microspheres was also accomplished by other routine methods such as XRD, EDS, TGA, DSC, SQUID and Mossbauer spectroscopy.

Inverse emulsion polymerization for high molecular weight and electrically conducting polyanilines

The polyanilines were synthesized via an inverse emulsion polymerization path at 0 °C or room temperature using ammonium peroxydisulfate (APS) as oxidant and dodecylbenzene sulfonic acid (DBSA) as surfactant and dopant simultaneously for the resulting polyanilines. The influence of polymerization temperature, organic continuous phase type (xylene or hexane) and APS/aniline molar ratio on the polyaniline properties was investigated. Polyaniline–DBSA precipitates prepared at 0 °C showed high conductivity in the range of 1.0–4.0 S/cm. Polyanilines in emeraldine base form prepared at 0 °C and APS/aniline molar ratio of 0.4 had high intrinsic viscosities of 191 and 202 ml/g using xylene and hexane as the organic continuous phase of emulsion system, respectively. The polyaniline–DBSA precipitates obtained from the polymerization system using xylene as the organic continuous phase possessed nice fibrillar morphology.

Preparation and characterization superporous hydroxypropyl methylcellulose gel beads

Stearic acid monoglyceride as suspension agent, divinylsulfone (DVS) as the crosslinker, cyclohexane as the continuous organic phase and nano-calcium carbonate as the porogen were used to produce hydroxypropyl methylcellulose (HPMC) porous gels in bead form by inversing phase suspension crosslinking. Effects of porogen dosage on the gel surface and inner morphology, density, porosity, swelling kinetics have been studied. Results show that the interpenetrate pores can be formed in gel beads when the porogen dosage reached 70 wt% of the dry HPMC. The equilibrium swelling ratios of the gel beads increased from 30.1 (g/g) to 37.4 (g/g) when the fraction of CaCO 3 dosage increased from 0 to 100 wt% of the dry HPMC and the equilibrium swelling time of the gels decreased from about 400 to 20 min. The results also show that the gel re-swelling capability is related to the porous structure.