Emulsion Surface Research Articles

Preparation and characterization of styrene acrylate emulsion surface sizing agent modified with rosin

AbstractA series of core‐shell type cationic soap‐free latex were prepared by using styrene(St), butyl acrylate(BA), and methyl methacrylate(MMA) as main materials and introducing rosin as the functional monomer. Cationic starch (CS‐8), which has low relative viscosity, was used as the emulsifier and dispersant. The influencing factors of the reaction were studied and the optimal conditions were achieved. Then the products were characterized by scanning electron microscope (SEM), FT‐IR, laser particle sizer, and particle charge detector (PCD). The results showed that the excellent performance and good sizing effects of SAE were achieved when the reaction conditions were as follows: the starch amount was 8 wt %, the charge of the initiator (APS) was 0.5%, and the amount of rosin was 2 wt %. Under these conditions, the particle size of the latex was around 100 nm and had a narrow distribution, and the charge density of latex was 0.61 mmol L−1. The water‐resistant performance of paper was improved significantly when SAE was modified with rosin, and the Cobb value decreased by 46.8% compared to that of the paper sized by SAE without rosin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Preparation and Characterization of Styrene Acrylate Emulsion(SAE) Surface Sizing Agent with Rosin as Functional Monomer

A series of core-shell type cationic soap-free latex were prepared by using styrene(St), butyl acrylate(BA) and methyl methacrylate(MMA) as main materials and introducing rosin as the functional monomer. In this reaction, starch(CS-8), which has low relative viscosity , was used as the emulsifier and dispersant. The influencing factors of the reaction were especially studied and the optimum conditions were got. Then the products were characterized by using scanning electron microscope (SEM), FT-IR, laser particle sizer, particle charge detector(PCD). The results show that the excellent performance and good sizing effects of SAE are achieved when the reaction conditions are as follows: the starch amount is 8%(wt), the charge for the initiator(APS) is 0.5%, and the amount of rosin is 2%(wt). And the water-resistant performance of paper is improved significantly when the rosin is chosen as the functional monomer.

A submicron lipid emulsion coated with amphipathic polyethylene glycol for parenteral administration of paclitaxel (Taxol).

Paclitaxel is a promising anticancer agent with poor solubility in water and requires a suitable formulation for intravenous administration. Presently paclitaxel is formulated for clinical use in ethanol and Cremophor EL (Diluent 12), a solvent system associated with severe adverse effects. In this study paclitaxel was entrapped in lipid emulsion droplets with triolein as oil core and dipalmitoyl phosphatidylcholine as the principal emulsifier. The emulsion was further stabilized with polysorbate 80 and polyethylene glycol-dipalmitoyl phosphatidylethanolamine. The drug-emulsion droplets (diameter about 40 nm) were physically and chemically stable during several months at 4 degrees C. Lyophilized preparations in 5% glucose were completely restored by distilled water. Studies of the integrity of the drug-emulsion showed a release of the drug from emulsion globules and surface transfer was found to be the major mechanism for cellular uptake. The in-vitro antiproliferative activity of paclitaxel against T-47D cells was retained by the drug-emulsion with an ID50 value of 7 nM compared to 10 and 35 nM for paclitaxel in liposomes and Diluent 12, respectively. Long-circulating submicron lipid emulsions may prove useful, not only for replacement of the more toxic Cremophor EL vehicle, but also by improving the distribution of the drug to the tumour.

Sensitivity of ASTM D7000 Sweep Test to Emulsion Application Rate and Aggregate Gradation

Presented in this paper are the effects of emulsion application rate and aggregate gradation on the performance of chip seal samples prepared and tested according to the ASTM D7000 Standard Test Method for Sweep Test of Bituminous Emulsion Surface Treatment Samples (sweep test). Aggregate loss of the samples was used as a performance indicator for chip seals. Limestone and granite aggregates were tested, and each aggregate type was tested with two gradations. Tests were carried out with three emulsion types: CRS-2, HFRS-2L, and HFRS-2. Each emulsion was tested at three application rates. Samples were tested at two different curing times, 2 h and 6 h. Statistical analysis of the chip loss results revealed that the current sweep test was not sensitive to emulsion application rate in the range tested. Results showed that gradation was a statistically significant factor. Coarse-graded aggregates resulted in high aggregate loss compared with fine-graded aggregates. From the overall results of the study, it is concluded that the current sweep test protocol is not suitable for use as a chip seal design tool because of its insensitivity to emulsion application rate. The test, however, is very sensitive to the combination of emulsion type, aggregate mineralogy, and gradation. It is recommended that the procedure be changed to use aggregate gradations representative of field aggregate. It is also recommended that the sweep test, with minor modifications, be used for evaluating compatibility between emulsions and aggregates and for estimating curing times required.

The effect of addition of flaxseed gum on the emulsion properties of soybean protein isolate (SPI)

The effect of addition of flaxseed gum on the emulsion properties of soybean protein isolate (SPI) were investigated in this study. Flaxseed gum with 0.05–0.5% (w/v) concentration was used together with 1% (w/v) SPI to emulsify 10% (v/v) soybean oil. The emulsion was analyzed for emulsion activity (turbidity), stability, particle size, surface charge, and rheological properties. The turbidity and absolute zeta-potential values decreased initially by the addition of flaxseed gum and subsequently increased with further increase in the gum concentration to reach their peak around 0.35% (w/v) gum. The particle size of the emulsion decreased and reached a minimum value at 0.1% (w/v) gum concentration. Any increase in gum concentration beyond this value resulted into increase in the particle size. This study would help to widen the application of SPI and flaxseed gum mixture, and also contribute to the understanding of protein–gum interaction in emulsion.

Presence of Apolipoprotein C‐III Attenuates Apolipoprotein E‐Mediated Cellular Uptake of Cholesterol‐Containing Lipid Particles by HepG2 Cells

Apolipoprotein C-III (apoC-III) decreases the apolipoprotein E (apoE)-mediated uptake of lipoprotein remnants by the liver, and a high plasma concentration of apoC-III in VLDL is associated with hypertriglyceridemia and the risk of coronary heart disease. In this study, we prepared lipid emulsions containing triolein, phosphatidylcholine and cholesterol as model particles of lipoproteins, and examined the roles of apoC-III in apoE-mediated uptake of emulsions by HepG2 cells. Cholesterol in emulsion particles enhanced the apoE-mediated uptake via heparan sulfate proteoglycan and LDL receptor-related protein pathways. The amount of apoE bound to emulsion particles was increased by the presence of cholesterol at the particle surface, whereas cholesterol had no effect on the binding amount of apoC-III. Surface cholesterol alleviated the inhibitory effect of apoC-III on apoE incorporation into the emulsion surface. However, ApoC-III almost completely inhibited the apoE-mediated uptake of cholesterol-containing emulsions despite sufficient binding of apoE to emulsions. These findings suggest that apoC-III attenuates the binding of apoE to the lipoprotein surface and apoE-mediated cellular uptake of lipoprotein remnants. Furthermore, cholesterol may affect these functions of apoC-III and apoE involved in the clearance of lipoprotein remnants.

Destabilization of protein-based emulsions by diglycerol esters of fatty acids – The importance of chain length similarity between dispersed oil molecules and fatty acid residues of the emulsifier

Destabilizing effects of diglycerol mono-esters of different saturated or one mono-unsaturated fatty acids (DF) on protein-based emulsions prepared with various types of oil were examined by visual observations and particle size analyses. By diglycerol esters of oleic acid (DO), a hexadecane-in-water emulsion was more obviously destabilized than an octadecane-in-water emulsion or food oil-in-water emulsions. Interfacial tension measurements indicated that the adsorbed protein on oil droplet surfaces of hydrocarbon emulsions can be more easily displaced by DO compared to the case of food oil emulsions. The degree of hydrocarbon emulsion destabilization by DO varied with the chain length of hydrocarbon molecules. From the results of combination tests of five hydrocarbons varying in chain length in oil phase and five DF having different mono-fatty acid residue, we described a possibility that DF could effectively destabilize the hydrocarbon emulsion when the chain length of fatty acid residue of DF was similar to that of hydrocarbon molecules.

Vacuum evaporation of surfactant solutions and oil-in-water emulsions

Vacuum evaporation of surfactant solutions and oil-in-water (O/W) emulsions at laboratory-scale set-up was investigated. Experiments were performed with surfactant solutions and model emulsions formulated with a base oil (85–15% (w/w) mixture of a synthetic poly-α-olefin and a trimethylol propane trioleate ester, respectively) and the following surfactants: Brij-76 (polyethylene glycol octadecyl ether, non-ionic), CTAB (hexadecyltrimethyl ammonium bromide, cationic), or Oleth-10 (glycolic acid ethoxylate oleyl ether, anionic). Evaporation rates are strongly influenced by operating pressure and temperature. Surfactants enhance oil emulsification in water and increase the evaporation temperature and the water evaporation rate, especially at low pressures. Surfactant concentration effects depend on the type of surfactant. For surfactant solutions the evaporation rate is mainly controlled by the boundary layer which is formed at the solution surface, primarily by surfactants. For the O/W emulsions, the transfer of water to the liquid–vapour interface and the development of an oil boundary layer at the emulsion surface are also controlling steps. The chemical oxygen demand (COD) of the evaporation condensate was lower than 2% with respect to the original O/W emulsion/surfactant solution, which permits to recycle water in the closed-loop process.

Pickering Emulsions Stabilized by a Lipophilic Surfactant and Hydrophilic Platelike Particles

Liquid paraffin-water emulsions were prepared by homogenizing oil phases containing sorbitan oleate (Span 80) and aqueous phases containing layered double hydroxide (LDH) particles or Laponite particles. While water-in-oil (w/o) emulsions are obtained by combining LDH with Span 80, the emulsions stabilized by Laponite-Span 80 are always o/w types regardless of the Span 80 concentration. Laser-induced fluorescent confocal micrographs indicate that particles are absorbed on the emulsion surfaces, suggesting all the emulsions are stabilized by the particles. The difference of the particle-stabilized emulsion type may be explained by comparing particle contact angles and the oil-water interfacial tensions, indicating that more Span 80 molecules are adsorbed on the LDH particles than on Laponite. Apparently, the LDH particles are rendered more hydrophobic by Span 80, resulting in the formation of w/o emulsions. The long-term stability of the emulsions was also compared. Emulsions stabilized by Span 80 alone completely separate into two bulk phases of oil and water after 3 months. However, emulsion stability is greatly enhanced with the addition of LDH or Laponite particles. This synergism was accounted for by an increase of the dilational viscoelasticity modulus of the oil-water interface after particles were added to the aqueous phase. This increase indicates that the gel-like particle layer stays at the oil-water interface and resists emulsion coalescence. Scanning electron microscope (SEM) images display the presence of a firm layer surrounding the emulsion droplets and a three-dimensional particle network which extends into the bulk phase aiding emulsion stability.

Controllable Synthesis of New Polymerizable Macrosurfactants via CCTP and RAFT Techniques and Investigation of Their Performance in Emulsion Polymerization

We reported herein the synthesis of poly(methacrylic acid)-b-poly(butyl acrylate) (PMAA-b-PBA) block copolymers (surfmers) and their performance as novel polymerizable macrosurfactants in emulsion polymerization. The surfmers bearing terminal unsaturated carbon-carbon double bonds were first successfully designed and sythesized via catalytic chain transfer polymerization (CCTP) and radical addition-fragmentation polymerization (RAFT) techniques. The structures of surfmers were characterized by Raman spectra, nuclear magnetic resonance ((1)H NMR), and gel permeation chromatography (GPC). The critical micelle concentration of surfmers was determined. Subsequently, the surfmers were used as emulsifier to prepare polyacrylate latexes (PA-surf). The influence of the surfmer concentration as well as PMAA and PBA chain segment ratios of surfmer on their performance in emulsion polymerization was discussed thoroughly. The particle size, amount of coagulum, and stability against electrolyte solutions of the latexes were evaluated. Also, the relations between monomer conversion in emulsion polymerization, polymerization rate, emulsion particle size, surface tension, and reaction time were investigated, which showed some interesting information for the probable mechanism underlying this emulsion polymerization system. Atomic force microscopy (AFM) and attenuated total reflection Fourier transform infrared spectra (ATR FT-IR) were performed to investigate the surface morphology and component distribution of the latex films. The results show high efficiency of these surfmers in emulsion polymerization, suggesting that the resultant PMAA-b-PBA block copolymers act not only as the emulsifier but also as the stabilizer of monomer droplets as well as the so-called comonomer.

“Supramolecular” Amphiphiles Created by Wrapping Poly(styrene) with the Helix‐Forming β‐1,3‐Glucan Polysaccharide

We have demonstrated that giant polymer micelles with a uniform diameter (ca. 200 nm) can be fabricated by "supramolecular wrapping" of poly(styrene) (PS) with the beta-1,3-glucan polysaccharide, with the beta-1,3-glucan fastening the PS chains together in a noncovalent fashion to facilitate the formation of a supramolecular polymer network on the O/W emulsion surface. Various spectroscopic and microscopic investigations have revealed that the inner cores of the micelles are comprised of a hydrophobic PS network, whereas the surfaces consist of a hydrophilic beta-1,3-glucan layer. Accordingly, functional guest molecules can easily be encapsulated inside the cavity through hydrophobic interactions. The encapsulated molecules can simply be released from the micelle cores by peeling off the beta-1,3-glucan shell in a supramolecular manner. As functional groups can be introduced into the glucose side-chain unit in a straightforward manner by chemical modification, the micellar surface can acquire further functions useful for molecular recognition. These results show that the micelles obtained could have applications as novel soft nanoparticles, which would be indispensable not only for nanotechnologies, but also for biotechnologies aimed at gene or drug delivery systems.

Synergistic stabilization of emulsions by poly(oxypropylene)diamine and Laponite particles

Liquid paraffin–water emulsions were prepared which were stabilized by Laponite particles in situ modified with poly(oxypropylene)diamines in the absence of electrolytes. First, the characteristics of the Laponite dispersions in the presence of increasing concentrations of diamines were studied in detail. Infrared absorption spectra and zeta potential measurements confirm the adsorption of diamines on the Laponite particles. Adsorption isotherms further indicate highly affinitive L-type behaviors and the diamine molecules are deduced to lie with both end groups anchored on the particle surface and the poly(oxypropylene) chain exposed to the aqueous solution. Then, emulsions were prepared using the diamine-modified particles. Diamines and Laponite particles alone are ineffective emulsifiers, but a strong synergism is exhibited between them. Laser-induced fluorescent confocal micrographs and TEM observations demonstrate the arrangement of the particles on the emulsion surfaces and also reveal the stability mechanisms. The emulsion stability was also explored with optical microscopy and droplet size measurements. As the diamine concentration increases, the extent of emulsion creaming decreases and the droplet size correspondingly decreases. At a certain low diamine concentration, the extent of emulsion creaming decreases down to a minimum and the corresponding droplet size is the smallest. This optimal emulsion state is unchanged when the diamine concentration is further increased.

Interactions between flaxseed gums and WPI-stabilized emulsion droplets assessed insitu using diffusing wave spectroscopy

Diffusing wave spectroscopy (DWS) was used to investigate the behavior of flaxseed gums when added to WPI-stabilized emulsions. The effect of different concentrations (0–0.33% (w/v)) of flaxseed gum, derived from two seed varieties, namely Emerson and McDuff, was studied at acidic and neutral pH. At pH 7.0 and low gum concentrations the dynamic and spatial characteristics of the system remained unchanged. While at gum concentrations from 0.075% to 0.20% a rapid phase separation was observed, at higher concentrations phase separation was retarded because of the increased background viscosity slowing down the mobility of the emulsion droplets. At pH 3.5, the difference in overall electrical charge between the gum (negative) and the protein on the emulsion surface (positive) led to electrostatic interactions. While at low concentration of flaxseed gum the general characteristics of the emulsions were not significantly different, at intermediate concentrations, bridging flocculation occurred. When sufficient flaxseed gum was present, the emulsion droplets mobility was arrested in a gel-like state. In spite of the compositional differences in the ratio of acidic and neutral fraction between the two polysaccharides extracted from different seed varieties, at both values of pH the behavior of the emulsions after addition of the polysaccharide was comparable.

High-speed analysis of nuclear emulsion films with the use of dry objective lenses

The extensive use of nuclear emulsions as precise tracking detectors in experimental physics has been made possible due to recent advances in the production of novel emulsion films and to the development of automatic scanning devices. The scanning speed of such systems has exceeded the level of 20 cm2 of emulsion surface per hour. High-speed automatic scanning systems, such as those developed by the OPERA Collaboration, are able to reconstruct particle tracks in nuclear emulsions with excellent accuracy. However, the high-magnification oil immersion objectives used in these systems assume deposition and removal of oil onto and from the emulsion films. This is a major technological obstacle in the automatization of the emulsion feeding to the microscope, as required for large scale use as in the case of the OPERA neutrino oscillation experiment. In order to overcome this problem, an innovative technique of nuclear emulsion films scanning with the use of dry objective lenses has been developed and successfully applied to the experiment.

Effect of Oil-in-Water Submicron Emulsion Surface Charge on Oral Absorption of a Poorly Water-Soluble Drug in Rats

The effect of oil-in-water submicron emulsion (SE) droplet surface charge on absolute bioavailability of a poorly water-soluble drug (griseofulvin, as model drug) after oral administration was studied in conscious rat. Positively, negatively, and neutrally charged SE were designed and characterized (size, polydispersity index, zeta potential, and pH). Three emulsion formulations, whose compositions included 40% oil phase and differed only in the nature of the emulsifying agent, were retained. Only the positively charged SE showed a higher area under the plasma concentration–time curve (AUC0 → ∞) in comparison with the tablet and with the other SE.

A polymorphism in the gene encoding procolipase produces a colipase, Arg92Cys, with decreased function against long-chain triglycerides

Type 2 diabetes mellitus is a multifactorial and polygenic disorder with increasing prevalence. Recently, a polymorphism in the gene encoding procolipase, a cysteine for arginine substitution at position 92, was associated with type 2 diabetes in two human populations. Because procolipase plays a critical role in dietary fat metabolism, polymorphisms that affect the function of procolipase could influence the development of type 2 diabetes. We hypothesized that the Arg92Cys polymorphism has functional consequences. To test our hypothesis, we expressed recombinant cysteine 92 (Cys92) procolipase in a yeast expression system and compared the function and stability of purified Cys92 with that of the more common arginine 92 (Arg92) procolipase. Cys92 fully restored the activity of bile-salt inhibited lipase with short- and medium-chain triglycerides but only had 50% of Arg92 function with long-chain triglycerides. After storage at 4 degrees C, Cys92 lost the ability to restore pancreatic triglyceride lipase activity with medium- and long-chain triglycerides. The loss of function correlated with the inability of Cys92 to anchor lipase on an emulsion surface and oxidation of the cysteine. No detectable degradation or intramolecular disulfide formation occurred in Cys92 after storage. Our findings demonstrate that the Arg92Cys polymorphism decreases the function of Cys92 colipase. This change may contribute to the development of type 2 diabetes.

Effects of Membrane Structure on Apolipoprotein A-I Binding to Lipid

Interaction of apolipoproteins with lipid surfaces plays crucial roles in lipoprotein metabolism and cholesterol homeostasis. In this study, to understand the detailed mechanism by which apolipoprotein (apo) A-I associates with plasma membrane and lipoprotein particles, we investigated the effects of lipid composition and surface curvature on the lipid-apoA-I interactions. ApoA-I binding to lipid particles depends on membrane structure. Fluorescence and (13)C-NMR measurements revealed that apoA-I recognizes headgroup separation (hydrated space) between phospholipid molecules and displaces water molecules from the surface when it binds. At the surface monolayers of lipoprotein particles, interpenetration of core triglyceride molecules with phospholipid molecules appears to occur to alter the surface structure. ApoA-I binding to lipid membrane induces an increase in alpha-helical structure. This alpha-helix formation generates exothermic heat and promotes apoA-I binding to lipid. However, binding of apoA-I to small emulsions exhibited endothermic heat although apoA-I increases alpha-helical content. Taken together, these observations suggest that the presence of core triglyceride modifies the highly curved emulsion surface and thereby the thermodynamics of apoA-I binding in a manner that compensates for the exothermic heat generated by alpha-helix formation.

Capture of Airborne Particulate Using Surface Applied Emulsions: Potential for Postdetonation Dirty Bomb Cleanup

Recent research has proposed the use of asphalt and tall-oil-pitch emulsions for stabilizing radioactive contamination deposited on surfaces in urban areas. The objective of this project was to investigate whether surface applied emulsions could capture airborne radioactive particulate. Laboratory experiments included wind-blown particulate capture studies using an acrylic column and particulate retainment experiments using a wind box capable of producing wind speeds of 96 km∕h . A probe methodology was developed to relate particulate retainment to a tack force on the emulsion surface. Experiments were also performed to determine the potential for such emulsions to absorb particulate matter into their emulsion matrix. Tall-oil-pitch emulsions outperformed asphalt emulsions in terms of particulate retention, tack force, and the ability to absorb magnesium silicate. Both tall-oil-pitch and asphalt emulsions were capable of extracting 22–24 g m−2 of powder from particulate-laden airflow. Tall-oil-pitch emuls...

Preparation of CIM Feedstock of Al<sub>2</sub>O<sub>3</sub>-SiC Nanocomposite

The ceramic injection molding feedstock of Al2O3-SiC nanocomposite were prepared and studied in detail. Three ways of surface modification including surfactant pre-coating, surface emulsion polymerization and surface low temperature plasma polymerization were used to modify the surface of SiC powders in order to reduce the agglomeration, improve the dispersion and the compatibility with organic media. CIM feedstock with different SiC content and solid loading were prepared through mixing surface modified SiC powders with Al2O3 powders and organic binders. The effect of three ways of surface modification on the viscosity of CIM feedstock were studied and the way of surface emulsion polymerization developed the best action in increasing dispersion, reducing viscosity and improving the solid loading of CIM feedstock.

Alaska's Dense-Graded High-Float Emulsion Surface Treatments

Asphalt surface treatment (AST) pavements using high-float (HF) emulsions and dense-graded aggregates have been constructed on Alaska's low-volume roads for more than 20 years. These HF ASTs proved to be relatively inexpensive, were easy to construct, and provided good service for low-volume roads. However, the normally positive economics of these pavements have sometimes been offset by problems during or after construction. It was argued that most problems could be solved if a mix design method was devised to ensure optimum application rates of emulsion and aggregate. This paper presents a standardized laboratory mix design method for HF emulsion and dense-graded aggregates based on simple volumetric calculations. The method accounts specifically for aggregate maximum size, compaction characteristics, moisture content, and air voids. An outline of the design method and an example numerical application are presented, and reasons supporting each element of the design method are discussed. The paper addresses the variables that control the emulsion and aggregate contents of these mixes. New laboratory test methods are proposed for determining aggregate density. The proposed mix design method requires that 15% additional aggregate be added to the design amount determined through voids calculations. The paper also presents information that improves the constructability and long-term performance of HF pavements.