Hybrid Emulsion Research Articles

Hybrid oil-in-water emulsions applying wax(lecithin)-based structured oils: Tailoring interface properties

This study addressed the impact of fruit wax(lecithin)-based oleogels as dispersed phase in formation and stability of oil-in-water emulsions. These hybrid emulsions were prepared above the melting point of the oleogels, using Tween 80 (T80) or whey protein isolate (WPI) as emulsifiers. Both mono- and mixed-component oleogels comprised of fruit wax (FW) or FW + lecithin (FWLEC), respectively, were studied as lipid phases. After hot-homogenization, emulsions were submitted to quiescent cooling and stored over 14 days at 5 or 25 °C, in such temperatures supposed to assist or hinder oleogelation, respectively. Time course promoted a slight decrease in zeta potential only for WPI-stabilized emulsions and particle size distribution was shifted to larger size values, but showing a lesser extent to those stored at 5 °C. The presence of oleogels improved kinetic stability of emulsions compared to liquid oil at both temperatures, disclosing the role of the combined effects of the type of emulsifier and oleogelator(s)-emulsifier interactions. These outcomes are associated with the interfacial activity played by both oleogelators, but mainly lecithin that led to lower values of interfacial tension. In addition FWLEC combined with WPI showed the lowest complex modulus from dilational rheology, which can be related with WPI-LEC complex formation. Overall, results suggest that oleogelators migrated to the O/W interface of dispersed droplets, no longer reflecting oleogel bulk properties and showing a more complex behavior. However, the formation of more complex structures at the interface favored greater stability of the emulsions. Thus, the new perspective of oleogel-inspired fat droplets in hybrid systems can expand the conventional approach of oil structuring to create mixed interfaces tailoring oil-in-water emulsions properties.

Poly (methyl methacrylate-co-butyl acrylate)/nano-silica composite emulsions as efficient retanning agent for chrome-tanned leather

Retanning process aims at filling up of the meatuses of the already tanned leather through the incorporation of vegetable or synthetic tannins or polymer (resins) with the aim of giving more fullness and improving to the final product. In this research, poly(methyl methacrylate-co-butyl acrylate) emulsion was prepared in situ with nano-silica in order to be used as a modern retanning agent of chrome tanned leather to totally replace chrome salt and to enhance physical, thermal shrinkage, and mechanical properties of the final tanned leather as well as to reduce the environmental impact of chrome tanning effluent. Polymer/nano-silica hybrid emulsions were prepared via in situ seed emulsion polymerisation. The prepared polymers were characterised for solid content, molecular weight, viscosity, drying time, minimum film-forming temperature (MFFT) and microstructures (via TEM). The mechanical, shrinkage, thermal and surface morphological (by SEM) properties of the treated samples were also investigated. The influence of the increase in the content of organic nano-silica on the properties of the retanned leather were also discussed.

Novel tanning agent based on silica-nanocomposite emulsion polymers

PurposeThe purpose of this paper is devoted to application of the emulsion polymer of poly(methyl methacrylate-co-butyl acrylate) prepared with in situ nano-silica as a novel tanning agent of hide to partly or totally replace chrome salt and to improve physical, thermal and mechanical properties of the tanned leather and to reduce the environmental impact of chrome tanning effluent.Design/methodology/approachPolymer/nano-silica hybrid emulsions were prepared via in situ seed emulsion polymerisation. The prepared polymers were characterised for solid content, molecular weight, viscosity, drying time, minimum film-forming temperature (MFFT) and microstructures (via transmission electron microscopy). The mechanical, thermal and surface morphological (by scanning electron microscope) properties of the treated samples were also investigated. The influences of the increase in the content of organic nano-silica on the properties of the tanned leather are discussed.FindingsIt was found that the viscosity, the particle size and the solid content of the prepared polymers increased as the content of the nano-silica increased while gloss and drying time of the resulting polymer film decreased. Tanning buffalo hide by Polymer F (containing a high content of nano-silica) gave desirable properties in terms of tensile strength, thermal stability and shrinkage temperature.Research limitations/implicationsThis paper discusses the preparation and the characterisation of emulsion polymers with in situ nano-silica and their application in tanning process to enhance and improve the leather quality, as well as reduce the use of chrome tanning materials and consequently chrome tanning waste.Practical implicationsThe tanned leather showed an improvement of physico-mechanical properties and enhancement of thermal stability. Furthermore, the tanned leather has uniform colour, softness and firmness of grain. All these promising results provide evidence to support the applicability of the prepared co-polymer/nano-silica emulsions as an efficient tanning agent that also provides lubricating properties for leather.Originality/valueSince May 2015, REACH Annex XVII restricts Cr(VI) in leather articles or leather parts of articles that come into contact with skin to a concentration of less than 3 mg/kg. Cases of discovery of Cr(VI) in leather papers have been reported by the European rapid alert system on dangerous consumer products (RAPEX). The emulsion poly (methyl methacrylate-co-butyl acrylate) with in situ nano-silica that has been developed via the study reported in this paper is one of the better technologies for the reduction of chromium ratio used in tanning industry.

Evaluation of Potential Skin Sensitization of Humans Receiving Bright and Firm Hybrid Emulsion I

OBJECTIVES: The aim of this study was to evaluate potential skin sensitization of human receiving Bright and Firm Hybrid Emulsion I. MATERIAL AND METHODS: 130 subjects were recruited and the human repeated insult patch test (HRIPT) was used to assess the skin sensitization potential of the Bright and Firm Hybrid Emulsion I. The test article container was 0.2 g and the size per patch test was 2x2 cm2. The placebo patch tests were applied on normal skin at the right scapula area and Bright and Firm Hybrid Emulsion I patch tests were applied on the left scapula area. In the induction phase, subjects applied patch tests on Monday, Wednesday, and Friday for three consecutive weeks. All of the patch tests were removed 24 hours (h) after being applied and the HRIPT score was evaluated. After the induction phase, a single challenge patch was applied to a naive site of normal skin. The challenge phase is scored 24, 48, and 72 h after application and the experiment was monitored at the 72 h HRIPT score reading. RESULT: All 130 subjects completed the study. The age of subjects ranged between 19 to 33 years old (mean age 21.45 ± 1.45 years). The HRIPT scoring scale was measured for to the induction and challenge phase, edema, papules, vesicles, and bullae of the subjects who applied Bright and Firm Hybrid Emulsion I. The results were not significantly different when compared to the placebo patch test group. CONCLUSION: This study shown that Bright and Firm Hybrid Emulsion I is a low skin sensitization potential among subjects.

Embedded polyhedral SiO2/castor oil-based WPU shell-core hybrid coating via self-assembly sol-gel process

An embedded polyhedron SiO2/castor oil-based waterborne polyurethane (CWPU) shell-core hybrid coating was designed and successfully prepared via a self-assembly sol-gel process. The morphologies of the particles in hybrid emulsions and the dispersion stability of the emulsion as well as the surface, thermal, and mechanical properties of the hybrid films were characterized. The results showed that the introduction of 3-(methacryloxy)propyl trimethoxy silane (γ-MPS) contributed to the formation of nano-silica shells on the surface of CWPU colloidal particles and covalently connecting CWPU with silica in films. When the mass ratios of γ-MPS:tetraethyl orthosilicate (TEOS) were 1:0, 1:1 and 1:4, the shell-core hybrid structure could be observed in the TEM (transmission electron microscope) images. In addition, the introduction of silica component inhibited the aggregation of particles and retained the good dispersion stability of the emulsion. Besides, silica component also shifted the wettability of CWPU films and significantly improved water resistance, thermal and mechanical properties of the CWPU films.

Evaluation of the Antioxidant Activity, Collagen Synthesis and Stability of Bright and Firm hybrid emulsion I

Evaluation of the Antioxidant Activity, Collagen Synthesis and Stability of Bright and Firm hybrid emulsion I

Hybrid polysiloxane/polyacrylate/nano-SiO2 emulsion for waterborne polyurethane coatings

A hybrid polysiloxane/polyacrylate/nano-SiO2 emulsion, as a component in the formula of waterborne polyurethane coatings, was synthesized by multi-step modification. The hybrid emulsion was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), particles size distribution analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The water absorption and hardness of films were investigated. The results showed that the initial decomposition temperature of polysiloxane polyacrylate emulsion (PSPAE) film was increased by 9% (from 335 °C of PAE to 365 °C of PSPAE) and the water absorption of the film was 1.7%. With the addition of polysiloxane pre-polymer, the contact angle of PSPAE films increases from 76.3° to 96.7°, suggesting that the PSPAE has excellent hydrophobicity. TEM images illustrated the PSPAE particle was well-dispersed and had a clear core-shell structure. Due to the addition of modified SiO2 nanoparticles, the hybrid emulsion film had better mechanical properties and waterproof. The test results showed that the hardness of hybrid emulsion film was 4 H when 2% modified SiO2 nanoparticles were added.

Polyurea-acrylic hybrid emulsions: Characterization and film properties

A polyurea macromer (PUM) nanodispersion acted as a reservoir of stabilizing agent for a thermally initiated acrylic emulsion polymerization process to form binders characterized by a highly phase separated core-shell morphology. The synthesized binders (referred to as PUM-Binders) exhibited distinct dried film mechanical properties that were tied to both the state of hydration and morphology. Films from PUM-Binders exhibited higher König hardness and storage modulus when compared to films from blends of traditional acrylic latex with PUM nanodispersion at the same PUM level. König hardness and modulus increased with increasing levels of PUM for both approaches, however the closed cell foam morphology of the PUM-binder films exhibited optimal hardness and modulus retention. A separate set of PUM-Binders was prepared with varying levels of butyl acrylate (BA) and methyl methacrylate (MMA). Mechanical properties of the resulting transparent films were evaluated by dynamic mechanical analysis (DMA) and by tensile strength measurements. It was found that both tensile strength and elongation decreased with increasing BA. Increasing levels of BA were hypothesized to lead to higher degrees of phase separation between PUM and acrylic. Finally, a specific PUM/acrylic blend zone in the shell is assigned and attributed to the property differences observed.

Preparation and characterization of dimer fatty acid epoxy-acrylate resin hybrid emulsion for photocurable coatings

UV-curable epoxy acrylate oligomer was synthesized via one-pot and two-step method by the ring-opening reaction of bisphenol-A epoxy resin (DGEBA) with dimer acid (DA) and acrylic acid (AA) in this paper. The molecular chain was firstly extended with DA. Then, AA, as a blocking agent, played the role in introducing unsaturated bonds to the chain. The water-based dispersion of epoxy acrylate was fabricated by subsequent phase-inversion emulsification in the presence of methacryloxypropyl silsesquioxane (MASQ). Compared with the traditional UV-curable epoxy acrylate, emulsions contain much less volatile organic compounds (VOC), which are more widely used in the coating industry. Because of the introduction of unsaturated bonds, MASQ participated in free-radical polymerization when incurred by UV, resulting in a better compatibility with epoxy acrylate. The cured samples were characterized with dynamic thermomechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and contact angle measurement (CA). The results indicated that the thermal property, flexibility, and water resistance all improved with the increasing proportion of DA, which may contribute to the long hydrophobic chain. Besides, the organic-inorganic and cage-like structure of MASQ also contributed to the enhancement of thermal property, water resistance, glass transition temperature, and storage modulus. With the above favorable properties and performances, the dimer fatty acid epoxy-acrylate resins will demonstrate promising applications in waterborne coatings.

Preparation and properties of a novel waterborne fluorinated polyurethane–acrylate hybrid emulsion modified by long aliphatic chains

Waterborne fluorinated polyurethane–acrylate hybrid emulsion modified by long aliphatic chains (WFPUA) is prepared by two steps, which include that the stearyl alcohol (SA)-blocked (end-capped) polyurethanes (SPU) are carried out in the mixtures of vinyl monomers, and then, the WFPUA is prepared via the free radical polymerization after the pre-emulsification of the said system. The characteristic of the reaction is the phase-inversion polymerization. The results show that the emulsifiability of SPU is firstly improved then decreased with the continuous increase in SA content. When the molar ratio of SA to 2-hydroxyethyl methacrylate (HEA) in the SPU is 1:1, the stability, zeta potential, viscosity and particle sizes of the WFPUA emulsion have the best results. The mechanical properties of WFPUA hybrid films deteriorate with the increase in SA content at 20 °C, but the mechanical properties of WFPUA films with more SA content achieve better results at 80 °C. The fluorinated groups migrated to the surfaces more easily with more SA content. In order to form the liquid crystalline-like structure on the WFPUA’s surface, the gradient heating treatment to an elevated temperature (i.e., 120 °C) to properly orient the fluorinated chains is necessary.

Tailoring the morphology and properties of waterborne polyurethanes by incorporation of acrylic monomers

A series of waterborne polyurethane-acrylate (WPUA) hybrid emulsions in the presence of organic silicon were synthesized by the reaction of isophorone diisocyanate, polytetramethylene ether glycol, double hydroxyl terminated polydimethylsiloxane, methyl methacrylate, and butyl acrylate as mainly raw materials. Three WPUA dispersions with differently internal structures (core-shell, inverse core-shell and semi-interpenetrating network (semi-IPN)) were designed in this study. The morphological analysis was carried out by transmission electron microscopy (TEM) and showed that the designed structures were obtained by changing synthesis method. The mobility of silicon, which affects the water resistance of the films, is determined by the structure of the WPUA and was evaluated by X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurements. The degree of silicon migration and water resistance were the highest for the WPUA with the semi-IPN structure. The WPUA with the core-shell structure had the highest tensile strength and the best thermal stability. The WPUA with the inverse core-shell structure had the worst mechanical property. Scanning electron microscopy (SEM) results showed that the WPUA with semi-IPN structure had the highest degree of phase separation.

Self‐assembled polyurea macromer nanodispersion and resulting hybrid polyurea‐acrylic emulsions and films

ABSTRACTA polyurea macromer (PUM) was synthesized and dispersed in basic conditions to form self‐assembled nanoparticles (<20 nm dispersions, up to 30 wt % aq. soln.). These nanoparticles enabled surfactant‐free emulsion polymerization to form hybrid polyurea‐acrylic particles despite the absence of a measureable water‐soluble fraction. The Tg of the starting PUM material was a strong function of the PUM's extent of neutralization and hydration (varying between 100 °C and >175 °C) due to changes in hydrogen and ionic bonding. Two separate hybrid polyurea‐acrylic emulsion systems were prepared: one by direct polymerization of (meth)acrylic monomers in the presence of the nanodispersion and a second by a physical blend of PUM nanodispersion with an acrylic latex control. The direct polymerization method resulted in a hybrid emulsion particle size that developed by a mechanism resembling conventional emulsion polymerization and was unlike that described for seeded polyurethane dispersion systems. Film hardness was shown to increase with increasing coating thickness for the hybrid film prepared by direct polymerization. The resulting mechanical properties could be explained by applying mechanical models for a composite foam structure. These results were unprecedented for normal elastomer films. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1373–1388

High performances polyurethane-urea polyacrylate hybrid emulsion coatings with multiple crosslinking structures

In this article, polyurethane-urea polyacrylate hybrid emulsions were synthesized via emulsion copolymerization of acrylate monomers, vinyltriethoxysilane (VTES) and anionic polyurethane-urea prepolymer with acrylate groups as the reactive emulsifier. Using waterborne polycarbodiimide as the crosslinker, room temperature multiple crosslinking hybrid coatings were fabricated successfully. Besides the crosslinking between polycarbodiimide and carboxyl groups, the polymerization crosslinking between polyurethane-urea and polyacrylate and the crosslinking of polyacrylate by VTES were confirmed by analyzing the crosslinking degree, FT-IR spectra and DSC curves. As more polycarbodiimide was used to consume hydrophilic carboxyl groups within the coatings, the water resistance increased considerably as well as the improvement in tensile strength. At polypropylene glycol and polyether amine molar ratio of 1:2, strengthening and toughening phenomenon were observed in tensile test of the hybrid films. At which the hybrid coatings demonstrated high impact strength and flexibility. However, higher weight ratios of methyl methacrylate and butyl acrylate resulted in brittle coatings.

Rheological approach to select most suitable associative thickener for water-based polymer dispersions and paints

In the 1980s, a new class of thickeners, i.e., associative thickener (AT), was introduced for water-based coatings to improve their rheology. Principally, they work by associating with polymer particles present in the paint. Manufacturers of ATs provide some generic guidelines to choose them based on economy, regulatory restrictions, and polymer type; however, it is very difficult to choose suitable ATs until and unless their interactions with polymer particles are studied by rheology. This article focuses on developing a rheological approach to identify a suitable AT for a paint formulation. In this approach, a rheology viscosity curve was used on AT–emulsion polymer mix and AT–emulsion polymer–surfactant mix to short-list a suitable AT. Subsequently, the shortlisted ATs were tested in the paint formulation to study their efficacy. Commonly used, hazardous air pollutants (HAPs)-free, commercially available ATs, viz. hydrophobically modified ethoxylated urethane thickener (HEUR) and hydrophobically modified poly(acetal- or ketal-polyether) thickener (HMPE), were selected to study their interaction with a unique surfactant-stabilized acrylic–polyurethane hybrid emulsion. A range of acrylic–polyurethane hybrid emulsions were prepared by increasing the polyurethane content in the emulsion. As the polyurethane content increased in the emulsion polymer, the thickening efficiency of AT decreased.

Effects of the molecular structure on the vibration reduction and properties of hyperbranched waterborne polyurethane–acrylate for damping coatings

ABSTRACTA series of hyperbranched waterborne polyurethane–acrylate (HWPUA) hybrid emulsions were prepared with isocyanate‐terminated PU prepolymers, hyperbranched polyol (HP), and acrylate monomers. The HP as crosslinker was synthesized with isophorone diisocyanate, dimethylol propionic acid, and diethanol amine. The influence of the HP content on the chemical structure, particle size, morphology, damping properties, and thermal stability of the HWPUA hybrid emulsions and films were investigated by Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, dynamic mechanical analysis (DMA), and thermogravimetric analysis, respectively. The results show that the addition of HP obviously improved the damping and thermal properties of the HWPUA films. However, the addition of excessive HP had a detrimental impact on the performance of films. The DMA curves indicated that when the HP content was 1%, tan δ was 0.3 or greater and spanned the broadest temperature range, with a maximum value of 0.65. The HWPUA hybrid emulsions could be used as damping coatings. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47733.

Development of a Polyacrylate/Silica Nanoparticle Hybrid Emulsion for Delaying Nutrient Release in Coated Controlled-Release Urea

Polyacrylate/silica hybrid emulsions were prepared by blending aqueous silica nanoparticles with polyacrylate emulsion, which were used for coating urea granules. After incorporating 1.0 wt.% silica nanoparticles into polyacrylate emulsion, preliminary solubility of CRU was decreased from 38.3% to 2.2%, and the release duration was extended from 8 to 27 days. The hybrid coating remarkably delayed the release of urea via improving wear-resistance due to the enhanced hardness, reducing water vapor permeability because of the tortuous diffusion pathway, and less breakage of CRU granules resulted from higher glass transition temperature. Meanwhile, the processibility was improved, which prevented particle agglomeration during coating. Therefore, aqueous silica nanoparticles have potential application in polymer emulsion coated controlled-release fertilizers.

Electromagnetic interference shielding performance of polyurethane composites: A comparative study of GNs-IL/Fe3O4 and MWCNTs-IL/Fe3O4 hybrid fillers

Water-borne polyurethane (WPU) based nanocomposites with graphene nanoplates (GNs)/Fe3O4 or multi-walled carbon nanotubes (MWCNTs)/Fe3O4 as hybrid nanofillers were fabricated by polymerizing hybrid emulsions, and their dielectric properties and electromagnetic interference shielding effectiveness (EMI SE) were carefully investigated. The carbon nanofillers showed good dispersion in the PU matrix due to cation-π interactions between carbon fillers and WPU end-capped by ionic liquid (IL) with amino groups. The results show that the PU/MWCNTs-IL composites provided better EMI SE and dielectric properties compared to PU/GNs-IL composites because of the one-dimensional geometry of MWCNTs and their better tendency to form a conductive network. Magnetic Fe3O4 nanoparticles can enhance the EMI SE of PU/GNs-IL/Fe3O4. However, they inhibit the EMI SE of PU/MWCNTs-IL/Fe3O4 because the two-dimensional geometry of GNs can restrain the strong magnetic attraction interaction between Fe3O4 and weaken the aggregation of GNs.

Preparation and characterization of soybean oil-based waterborne polyurethane/acrylate hybrid emulsions for self-matting coatings

This work aims to explore the feasibility of self-matting coatings based on soybean oil.

Effects of the reagent ratio on the properties of waterborne polyurethanes-acrylate for application in damping coating

Hybrid emulsions of waterborne polyurethanes-acrylate (WPUA) were synthesized using isophoronediisocyanate (IPDI), polytetramethylene glycol (PTMG), and an acrylate monomer as the main materials. The influence of the NCO/OH ratio (R value) and PU/PA ratio on different properties of the WPUA hybrid emulsions and films was investigated using dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), contact angle measurements, mechanical tests and dynamic mechanical analysis (DMA). DLS and TEM results showed that all WPUA latex particles display regular spheres and excellent stability. DMA indicated that when the PU/PA ratio was 30/70 and the R value was 1.2, the loss factor (tanδ) was ≥0.3 spanning a temperature range of 75℃ with a maximum value of 1.2. The WPUA films could be used as materials for damping applications.

Polyacrylate/silica nanoparticles hybrid emulsion coating with high silica content for high hardness and dry-wear-resistant

Polyacrylate/silica nanoparticles hybrid emulsion (PSHE) with high silica content was produced and used in the preparation of high hardness and dry-wear-resistant coating via a facile and environment-friendly method. Specifically, the surface of alkaline silica sol nanoparticles was modified by cationic polyacrylamide (CPAM), which was then added in an emulsifier-free polymerization system comprised of methyl methacrylate (MMA) and butyl acrylate (BA). Through electrostatic attractions, hydrogen bonds, and van der Waals force, the positive charged silica nanoparticles aggregate around polyacrylate emulsion particles to improve the hardness and dry-wear-resistant of PSHE coating. Our results confirmed an average size of the PSHE particles only 58.6 nm. A bimodal molecular weight distribution (MWD) and consequently two different glass transition temperatures (Tg) were found in such PSHE polyacrylate resin. Due to the presence of modified silica nanoparticles, a reduced polymerization degree of MMA monomer in the aqueous phase of core emulsion leads to a decreased first Tg and the high molecular weight fraction with highly compacted molecular structure, and the improved mechanical properties of the PSHE coating. The chains of relatively low molecular weight fraction of polyacrylate move more easily during film formation, which prevents the structural voids in the coatings. Better adhesion as well as higher hardness, impact resistance, dry-wear-resistance, and thermal stability are found when compared with its pure polyacrylate emulsion (PPE) coating counterparts. Although having high silica content, the PSHE coating still retains 90% transparency rate in visible light range.