Emulsifier-free Emulsion Research Articles

Influence of the composition of macromolecular diols on the rheology and water absorption of polyurethane acrylate emulsions

AbstractWaterborne modified polyurethane (PU) dispersions with different macromolecular diols as soft segments were prepared by the self‐emulsifying method, and then compounded with the acrylate monomers, the polyurethaneacrylate composite emulsion (PUA) with the core‐shell structure was prepared by emulsifier free emulsion polymerization. The effects of the type and ratio of macromolecular diols in the soft segment on the particle size and distribution, rheological properties, adhesion, water absorption and thermal properties of the PUA emulsion were studied. The results showed that the particle size of PUA decreased, and the shear resistance and heat resistance of PUA were enhanced with the addition of polypropylene glycol. According to the water absorption rate of PUA emulsion, it was found that adding poly‐1,4‐butanediol adipate glycol and poly(caprolactone) diol with more hydrophobic groups could improve the water resistance of PUA dry film, and the minimum water absorption value was 0.68%.

Emulsifier Free Emulsion as Fuel in a Common Rail Turbocharged Diesel Electric Generator

In present study, performance and emissions of a 100 kVA common rail turbocharged diesel engine electric generator installed with an emulsifier free emulsion fuel supply system, known as Real-Time Non-Surfactant Emulsion Fuel Supply System (RTES) was investigated experimentally. This system uses a novel mixing system design upgraded from previous RTES design, with an omission of ultrasonic agitator component. In this system, water was injected into an emulsification device where water and diesel fuel were mixed and supplied to the engine as an emulsion fuel. It was found that water-in-diesel emulsions produced from this system increased the engine's Brake Thermal Efficiency (BTE) to a maximum point of 42.7%, a marked increase of 28.6% from the base diesel. Furthermore, Brake Specific Fuel Consumption (BSFC) was reduced as water percentage increases. Additionally, Nitrogen Oxides (NO x ) emissions and smoke opacity was also reduced. However, water-in-diesel emulsion emitted increased carbon monoxide (CO) in lower to middle loads before a reduction was observed in higher loads. Meanwhile, unburned hydrocarbons (UHC) emission was reduced as 14% to 22% water percentage was achieved. In short, emulsifier free emulsion fuel produced by RTES was able to improve thermal efficiency and reduce fuel consumption and harmful emissions.

Peg-based temperature sensitive nanoparticle synthesis and their use in protein adsorption

In this study, temperature sensitive polymeric nanoparticles were prepared by emulsifier free emulsion polymerization. N-isopropylacrylamide (NIPA) has been used as main monomer to give temperature sensitivity and poly(ethyleneglycol) ethyl ether methacrylate (PEG-EEM) has been added to recipes as comonomer to aid in particle formation. The effect of NIPA, PEG-EEM and crosslinker content on particle size has been investigated. Temperature sensitivity or lower critical solution temperature (LCST) of the nanoparticles has been followed by Zeta Sizer as change in particle size. In order to determine the protein adsorption capacity of nanoparticles, adsorption experiments have been investigated as a function of temperature and PEG-EEM amount.

Synthesis and study of mechanical and fire retardant properties of (carboxymethyl cellulose -g-polyacrylonitrile)/montmorillonite biodegradable nanocomposite

Despite abundant researches on petroleum based polymer nanocomposites over micro and macro composites, these nanocomposites suffer from deprived biodegradability, highly inherent flammability and less mechanical strength. The present work describes the preparation of a biodegradable nanocomposite based on carboxymethyl cellulose-g-polyacrylonitrile (CMC-g-PAN) and montmorillonite (MMT) nanoclay by using ammonium persulfate (APS) as an initiator, methylene bis-acrylamide (MBA) as a crosslinker via emulsifier free emulsion polymerisation. The formation of the nanocomposites was confirmed by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and Transmission electron microscope (TEM) analysis. The formation of CMC-g-PAN copolymer was confirmed by means of proton nuclear magnetic resonance (1H NMR) spectra. The improvement in thermal stability of the nanocomposites over copolymer was outstanding. More importantly, incorporating MMT enables the nanocomposite to achieve a dramatically reduced peak heat release rate of 536 ± 03 kW m−2 shown in cone calorimetry tests and higher limiting oxygen index (LOI) value indicating improved fire retardancy. In addition, the tensile strength of the nanocomposite was also increased by around 41% with 5% w/v MMT contents. This is explained on the basis of strong interfacial adhesion between CMC and MMT through PAN. Meanwhile for its better commercialization, the eco-friendly nature was studied via biodegradation.

Amphiphilic Triblock Copolymers Based on Acrylic Acid and Alkyl Acrylates Synthesized via RAFT Polymerization-Induced Self-Assembly and RAFT Miniemulsion Polymerization

The aim of this research is to reveal the advantages and limitations of different heterophase polymerization methods, such as dispersion, emulsifier-free emulsion and miniemulsion polymerization, for the obtaining of in situ self-assembled amphiphilic triblock copolymer core-shell particles. In the present research, we addressed the problems of the controlled synthesis of two- and three-component amphiphilic ABA triblock copolymers based on acrylic acid, fluoroalkyl acrylates and butyl acrylate via polymerizationinduced self-assembly and reversible addition fragmentation chain transfer polymerization (RAFT) miniemulsion polymerization using symmetrical trithiocarbonates.

Effect of nanosilver on the thermal stability and thermal decomposition kinetics of poly(acetoacetoxyethyl methacrylate–styrene)

Nanosilver/poly(acetoacetoxyethyl methacrylate–styrene) (nano-Ag/P(AAEM-St)) composites were synthesized via emulsifier-free emulsion with silver nitrate solution, AAEM, and St monomer copolymerization by ultrasonic. The morphology and structure of the composites were characterized by ultraviolet and visible spectroscopy, X-ray diffractometer, and transmission electron microscopy, respectively. The results show that Ag nanoparticles with face-centered cubic structure are homogeneously dispersed in the P(AAEM-St) matrix. The thermal stability and the thermal degradation kinetics of P(AAEM-St) were investigated using the thermogravimetric analysis and Kissinger and Flynn–Wall–Ozawa method, respectively. The results prove that the thermal stability of the pure P(AAEM-St) is better than that of the nano-Ag/P(AAEM-St) composites.

Development of biodegradable cellulose‐g‐poly(butyl acrylate)/kaolin nanocomposite with improved fire retardancy and mechanical properties

ABSTRACTThe main aim of the work is to convert a low cost renewable biopolymer to a high performance fire‐retardant biomaterial by modification via grafting. Cellulose, a linear and most abundant biomacromolecule, has gained increasing attention for its interesting properties and potential applications in the synthesis of polymer nanocomposites. Cellulose has been grafted with butyl acrylate via emulsifier free emulsion polymerization using in situ developed transition metal complex initiating system: CuSO4/glycine/ammonium persulfate with and without additive kaolin to prepare nanocomposites and copolymer, respectively. The morphology of so‐prepared grafted nanocomposites was characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, and field emission scanning electron microscopy. The enhancement in thermal behavior and mechanical properties of nanocomposites over copolymer were outstanding. The fire‐retardant properties were evaluated by limiting oxygen index and cone calorimetry test. The biodegradation and water absorbency of the fire‐retardant nanocomposites have been carried out for better commercialization and environmental concern. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45968.

Facile Fabrication of Composite Electrospun Nanofibrous Matrices of Poly(ε-caprolactone)-Silica Based Pickering Emulsion.

Functionalized matrices have been sought for their application in sensors, filtration, energy storage, catalysis, and tissue engineering. We report formation of an inorganic-organic composite matrix based on poly(ε-caprolactone) (PCL) functionalized with hydrophobically modified silica (m-silica) fabricated with reduced organic solvent usage. The matrix was obtained via electrospinning of a water-in-oil emulsion of PCL that was stabilized by judicious choice of m-silica as a Pickering agent resulting into an emulsifier free matrix. Inclusion of m-silica in PCL matrix resulted in enhancing tensile properties and cell proliferation efficiency. The electrospun composite matrix was free from any emulsifier or template polymer; thus any abrupt loss in mechanical properties was prevented when the matrix was subjected to aqueous conditions. The inorganic-organic biodegradable composite matrices thus produced using an emulsifier free emulsion find applications in tissue engineering and may further be evaluated for other areas including selective sorption and separation.

On interaction between nano-Cu-Ga and P(AAEM-St) matrix prepared via ultrasonic initiation

In this article, the copper–gallium (Cu-Ga)/poly(acetoacetoxyethylmethacrylate-styrene) (P(AAEM-St)) nanocomposites were prepared and characterized according to the following steps. Firstly, Cu-Ga/P(AAEM-St) nanocomposites were prepared via emulsifier-free emulsion with metal Ga in copper acetate solution and copolymerization of St and AAEM monomers by ultrasonic under nitrogen protection. Secondly, the constituent, i.e., the interaction between metal nanoparticles and polymeric matrix of the composites, was tested by various techniques including X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Cu, Ga, and CuGa2 phase in polymeric matrix were identified by above techniques. It was revealed that the interaction is a chemical force between Cu atoms belonging to metal nanoparticles and C=O associated with acetoacetoxy from polymeric matrix.

Synthesis of novel quaternary silica hybrid bioactive microspheres.

To survey the preparation of novel hybrid microspheres of quaternary silicate glassy composition (SiO2 P2 O5 CaONa2 O) and the prospect of using them as an osteogenic system with enhanced bioactive properties for the development of hydroxyapatite. In line with our previous synthetic procedure a two-step process was followed, wherein polystyrene (PS) microspheres were prepared by the emulsifier free-emulsion polymerization method and constituted the core for the sol-gel coating of the silicate inorganic shell. The development of the hybrid microspheres was based on silane and phosphate precursors and was assesses at different ratio of ethanol/water (of 9/1, 4/1, and 2/1, in mL) and at varied ammonia concentration of 4.8-1.0mL. The hybrid microspheres had an average size ranged between 350 and 550nm according to SEM, depending on the ethanol/water solution rate and ammonia content. The final microspheres probably exhibited a porous-like structure through the formation of diffused voids along with the low carbon content of the EDX analysis, which could be regulated by the catalyst content. The hybrid microspheres exhibited effective in vitro bioactivity assessed in simulated body fluids (SBF). Quaternary hybrid silica microspheres were effectively synthesized. The bioassay evaluation of the final microspheres revealed the rapid in vitro formation of a bone-like apatite layer. The results verify the bioactivity of the microspheres and promote further research of their suitability on regenerative treatment of bone abnormalities. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 112-120, 2018.

Silica-polymer hybrid materials as methylene blue adsorbents

Nanohybrid materials have emerged as effective adsorbents for the removal of contaminants from the polluted water bodies. In this study we report two new hybrid materials as adsorbents for methylene blue from its aqueous solutions. Nanohybrid materials were prepared from methacrylic acid and methyl methacrylate or 2-hydroxyproypl methacrylate by emulsifier–free emulsion polymerization using 3–aminopropyltriethoxysilane (APTES) as silane coupling agent, and tetraethoxysilane (TEOS) and polyvinyl alcohol (PVA) as silica component precursor and polymeric colloid stabilizer, respectively. Adsorption was studied as a function of various factors, including contact time using two cationic dyes methylene blue (MB) and malachite green and one anionic dye Congo red. Since the results obtained suggest more affinity of the adsorbents for MB than other two dyes, hence the former was selected to assess the effect of variation of temperature, pH and concentration, which control the dye adsorption process. The hybrid materials exhibited high adsorption capacity both in the cumulative as well as in the reusability studies. Experimental data was subjected to different kinetic models and adsorption isotherms to understand the adsorption mechanism.

Emulsifier free emulsion: Comparative study between a new high frequency ultrasound process and standard emulsification processes

Emulsifier-free-emulsions were prepared with high frequency ultrasounds (HFU) generated by a piezoelectric ceramic transducer vibrating at 1.7 MHz. HFU emulsions were compared with emulsions made with standard emulsification processes: low frequency ultrasounds (LFU) and high pressure homogenization (HPH). Emulsions were prepared by combining sunflower oil with an aqueous phase either in the presence or absence of essential oil emulsifier. Oil droplets size distribution was determined by static light diffraction and nanoparticles tracking analysis (NTA) for the characterization of micrometric and nanometric droplets fraction respectively. More than 90% (v/v) of emulsion droplets were nanometric for HFU emulsions and were stable against coalescence during 30 days at 37 °C unlike other processed emulsions (LFU or HPH). Oily phases of emulsions analyzed by FTIR showed that oil composition was not affected during processing and that orange essential oil decreased edible oil oxidation during storage time.

Multilayers of poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) microspheres with core-shell morphology: Characterization by AFM, SIMS and XPS

The methods of preparation and characterization of core-shell poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) particles arranged in colloidal crystals are described. The particles were prepared via emulsifier free emulsion copolymerization of styrene and α-tert-butoxy-ω-vinylbenzyl-polyglycidol macromonomer in aqueous medium, initiated by potassium persulfate. The individual polymerizations differed in a way of addition of macromonomer to the polymerization mixture. The particles assemblies were characterized by atomic force microscopy, Secondary Ion Mass Spectrometry (SIMS) and X-ray Photoelectron Spectroscopy (XPS). In-depth distribution of chemical states was determined by XPS combined with argon gas cluster ion sputtering (Ar-GCIB). The morphology of microspheres assemblies reflected the composition of the entire particles. It was found that the method of macromonomer addition to the polymerization mixture affects the particles size, surface and overall morphology. The XPS profiles revealed the chemical composition of the particles arranged in multilayers. It was found that distribution of polyglycidol segments at the particles interfacial layer depends on the time and way of addition of macromonomer. The thickest outer layer composed from polystyrene-polyglycidol segments was obtained for particles when macromonomer was added at the beginning of polymerization.

Electrospun composite matrices of poly(ε-caprolactone)-montmorillonite made using tenside free Pickering emulsions

The production of composite electrospun matrices of poly(ε-caprolactone) (PCL) using an emulsifier-free emulsion, made with minimal organic solvent, as precursor is reported. Pickering emulsions of PCL were prepared using modified montmorillonite (MMT) clay as the stabilizer. Hydrophobic tallow group of the modified MMT clay resulted in analogous interaction of clay with oil and aqueous phase and its adsorption at the interface to provide stability to the resultant emulsion. Composite fibrous matrices of PCL and MMT were produced using electrospinning under controlled conditions. The fiber fineness was found to alter with PCL concentration and volume fraction of the aqueous and oil phases. A higher tensile strength and modulus was obtained with inclusion of MMT in PCL electrospun matrix in comparison to a matrix made using neat PCL. The presence of clay in the fibrous matrix did not change the cell proliferation efficiency in comparison to neat PCL matrix. Composite fibrous matrices of PCL/MMT bearing enhanced tensile properties may find applications in areas other than tissue engineering for example food packaging and filtration.

Cationic styrene-butyl acrylate-quaternary ammonium copolymer nanospheres for surface modification of cotton fibers

Cationic copolymer nanospheres are important functional materials, for example, for fiber modification. Here, emulsifier-free ternary emulsion copolymerizations of styrene (St) and butyl acrylate (BA) with two different quaternary ammonium cationic monomers (QACMs), methacryloxyethyl trimethyl ammonium chloride (DMC) and trimethyl (vinylbenzyl) ammonium chloride (VBT), and 2,2’-azobis[2-methylpropionamidine] dihydrochloride (AIBA) as an initiator were conducted at 80 ×C, under agitation at 300 rpm. The differences between the two cationic comonomers strongly influenced the monomer conversion, diameter, morphology, and surface charge density of the nanospheres. In particular, a higher cationic comonomer content is found to produce more oligomer radicals and thus more primary particles in the polymerization process, which leads to higher monomer conversion, smaller particle diameter, and increased surface charge density. The cationic nanospheres could be adsorbed in either a monolayer or in multiple layers on the oppositely charged cotton fiber because of their fierce electrostatic attraction. Compared with poly(St-BA-VBT) nanospheres, the distribution of poly(St-BA-DMC) nanospheres was more nonuniform on fiber surfaces accompanied by agglomerates.

A new approach to fabricate bioactive silica binary and ternary hybrid microspheres.

Bioactive microspheres represent an extremely developing field in biomedical applications, such as bone tissue engineering and bone pathologies (metabolic bone disease, trauma or bone cancer). Their innate osteogenic properties have turned them to biomaterials with improved added value. The aim of this study was to prepare binary and ternary hybrid silica microspheres with enhanced bioactive properties according to our previous synthetic procedure. In brief, the synthetic approach based on the emulsifier free-emulsion polymerization method, by which polystyrene (PS) microspheres were produced and used as core template for the sol-gel coating method. During the coating reaction an inorganic shell was fabricated by silane and phosphate precursors (tetraethoxysilane, trimethylphosphate). The final microspheres were treated by different catalyst concentrations, during the coating process, which resulted in the formation of diffused voids (a porous-like structure). The in vitro bioactivity of the resultant microspheres was studied by treatment in simulated body fluids (SBF). The bioassay evaluation indicates the deposition of a bone-like apatite layer on microspheres' surface with enhanced bioresorbability, which verifies their bioactivity and permits their application in the treatment of bone pathologies.

A new approach for the one-step synthesis of bioactive PS vs. PMMA silica hybrid microspheres as potential drug delivery systems

In this work, hybrid microspheres were prepared in a two-step process combining the emulsifier free-emulsion polymerization and the sol–gel coating method. In the first step, polystyrene (St) and poly(methyl methacrylate) (PMMA) microspheres were prepared as sacrificial template and in the second step a silanol shell was fabricated. The functionalized surface of the hybrid microspheres by silane analogs (APTES, TEOS) resulted in enhanced effects. The hollow microspheres were resulted either in an additional step by template dissolution and/or during the coating process. The microspheres’ surface interactions and the size distribution were optimized by treatment in simulated body fluids, which resulted in the in vitro prediction of bioactivity. The bioassay test indicated that the induced hydroxyapatite resembled in structure to naturally occurring bone apatite. The drug doxorubicin (DOX) was used as a model entity for the evaluation of drug loading and release. The drug release study was performed in two different pH conditions, at acidic (pH=4.5) close to cancer cell environment and at slightly basic pH (pH=7.4) resembling the orthopedic environment. The results of the present study indicated promising hybrid microspheres for the potential application as drug delivery vehicles, for dual orthopedic functionalities in bone defects, bone inflammation, bone cancer and bone repair.

Nanosized palladium supported on diethylenetriamine modified superparamagnetic polymer composite microspheres: Synthesis, characterization and application as catalysts for the Suzuki reactions

Superparamagnetic polymer composite microspheres Fe3O4/P(GMA-AA-MMA) prepared by an emulsifier free emulsion polymerization using DPE as free radical control agent were used to support palladium nanoparticles. The magnetic catalyst can provide excellent reactivity in the Suzuki coupling reactions of aryl halides with phenylboronic acids under mild condition (at 80°C) in EtOH/H2O (1:1) mixture. Furthermore, the novel catalyst can be conveniently recovered by an external magnet field and reused at least five times without significant loss of its catalytic activity.

Synthesis and Characterization of Poly (Vinyl Acetate)/MMT Nanocomposite Flame Retardant

Current environmental benign and flame retardant poly (vinyl acetate) (PVAc)/montmorillonite (MMT) clay nanocomposites were prepared by emulsifier free emulsion technique in microwave (MW) oven. MMT clay was incorporated as additional filler in PVAc/MMT nanocomposites to improve the homogeneity of the ‘physical’ barrier, since clay produces silicon-oxy-carbide (Si-O-C) char on heating. The fine dispersion of the MMT and the interactions between PVAc and clay created significant improvement of the flame retardancy which has been evaluated using cone calorimeter. The presence of clay in PVAc/MMT nanocomposites was characterized with infrared (IR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The fire retardancy of PVAc/MMT nanocomposites caused by the formation of Si-O-C char was characterized by scanning electron microscopy (SEM). The biodegradation property was tested by activated sludge water via water absorbency and was further confirmed from SEM for its better commercialization and ecofriendly nature.

Emulsification by high frequency ultrasound using piezoelectric transducer: Formation and stability of emulsifier free emulsion

Emulsifier free emulsion was developed with a new patented technique for food and cosmetic applications. This emulsification process dispersed oil droplets in water without any emulsifier. Emulsions were prepared with different vegetable oil ratios 5%, 10% and 15% (v/v) using high frequency ultrasounds generated by piezoelectric ceramic transducer vibrating at 1.7MHz. The emulsion was prepared with various emulsification times between 0 and 10h. Oil droplets size was measured by laser granulometry. The pH variation was monitored; electrophoretic mobility and conductivity variation were measured using Zêtasizer equipment during emulsification process. The results revealed that oil droplets average size decreased significantly (p<0.05) during the first 6h of emulsification process and that from 160 to 1μm for emulsions with 5%, 10% and from 400 to 29μm for emulsion with 15% of initial oil ratio.For all tested oil ratios, pH measurement showed significant decrease and negative electrophoretic mobility showed the accumulation of OH− at oil/water interface leading to droplets stability in the emulsion. The conductivity of emulsions showed a decrease of the ions quantity in solution, which indicated formation of positive charge layer around OH− structure. They constitute a double ionic layer around oil particles providing emulsion stability. This study showed a strong correlation between turbidity measurement and proportion of emulsified oil.