Emulsion Polymerization Technique Research Articles

Enzymatic Activity of Urokinase Immobilized onto Cu2+-Chelated Cibacron Blue F3GA-Derived Poly (HEMA) Magnetic Nanoparticles.

In this presented work, magnetic poly(2-hydroxyethyl methacrylate) (p (HEMA)) nanoparticles were synthesized by surfactant-free emulsion polymerization technique. Cibacron Blue F3GA was covalently attached to the magnetic p (HEMA) nanoparticles and Cu2+ ions were then chelated with dye molecules. Synthesized magnetic nanoparticles were spherical with the diameter of 80nm and exhibited magnetic character. Incorporation rate of Cibacron Blue for magnetic nanoparticles was found to be 28.125-μmol/g polymer. Loaded amount of Cu2+ ions was calculated as 10.229-μmol/g polymer. These Cu2+-Cibacron Blue F3GA-derived magnetic p (HEMA) nanoparticles were used for urokinase adsorption under different conditions (i.e., pH, enzyme initial concentration, ionic strength, temperature). Maximum adsorption capacity was found to be 630.43-mg/g polymer, and it was observed that Langmuir adsorption isotherm was applicable in this adsorption process. The adsorbed urokinase was desorbed from the Cu2+-Cibacron Blue F3GA-derived magnetic p (HEMA) nanoparticles by using 1.0M of NaCl with the desorption rate of 96%. It was also demonstrated that adsorption capacity did not change significantly after five adsorption/desorption cycles.

Microencapsulated oleic–capric acid/hexadecane mixture as phase change material for thermal energy storage

Thermal energy storage systems provide efficiency in order to have better utilization of energy sources while protecting the environment. Thermal energy storage can be classified as sensible and latent heat storage. The storage of latent heat allows a greater density of energy storage with a narrow temperature range during phase change. Phase change materials (PCMs) are important novel materials, which are used as the storage of thermal energy as latent heat, and can provide utilization of waste heat energy. In this study, the capric acid and oleic acid mixture containing hexadecane were encapsulated as the core with styrene–divinylbenzene copolymer shell by emulsion polymerization technique. Thermal properties of fatty acid microcapsules were characterized by differential scanning calorimetry and thermogravimetric analysis and also their morphology and structure were examined by scanning electron microscopy, polarized optical microscopy and Fourier transform infrared spectroscopy (FT-IR), respectively. The heat storage property of microencapsulated PCM was tested in a horizontal air flow channel system equipped with a flat heating plate, air fan and air flow sensors. The microencapsulated PCM was prepared successfully, and results of the analysis presented that this material is promising candidate for potential heating and cooling system applications.

Bacteria killer enzyme attached magnetic nanoparticles

The objective of the present work was to develop immobilized lysozyme systems through adsorption on magnetic nanoparticles for potential usage in bacteria killing studies. For this, magnetic poly(HEMA-GMA) nanoparticles were prepared by surfactant free emulsion polymerization technique and functionalized with dye ligand Reactive Green 5. Synthesized magnetic nanoparticles were then characterized by FTIR, SEM, EDX and ESR studies. Particle size range of the polymers was found to be as 90–120 nm. Magnetic behavior was also demonstrated by ESR with the g value of 2.48. Maximum lysozyme loading was found to be as 1045.1 mg/g nanopolymer. Repeated usability of the magnetic nanoparticles was also studied. Immobilized form of lysozyme protected 85.85% of its initial activity at the end of the immobilization process. Bacteria killing capacity of the lysozyme immobilized magnetic nanoparticles were investigated by using Micrococcus lysodeikticus bacteria and it was demonstrated that all bacteria were successfully destroyed by the lysozyme immobilized magnetic nanoparticles within 5 min.

Synthesis and characterization of hydrophilic polymer nanoparticles using n-isopropylacrylamide (NIPAM) via emulsion polymerization technique

Poly(N-isopropylacrylamide) (PNIPAM) nanoparticles were successfully synthesized via emulsion polymerization techniques using different critical micelle concentrations (CMCs) of sodium dodecyl sulphate (SDS) surfactant, temperature and time of polymerization. The effects of surfactant concentrations on emulsion polymerization of PNIPAM nanoparticles have been discussed. Potassium persulfate (KPS) and N,N’-methylenebisacrylamide (MBAA) were used as initiator and cross-linker, respectively throughout the emulsion polymerization. The formation of PNIPAM nanoparticles was confirmed by Fourier transform infrared spectroscopy (FTIR) with absorption peaks observed at 2997 and 2930 cm-1 for C-H stretching of CH3 and CH2 groups, 1459 cm-1 for 2° amide C=O stretch, 3310 cm-1 and 3275 cm-1 for N-H stretching band. The particle size and morphology of PNIPAM nanoparticles were determined using scanning electron microscopy (SEM) where large aggregation of PNIPAM nanoparticles were observed with average diameters in the range of 20 – 50 μm and the appearance of pore structure on the hydrogel surface. Thermal stability of PNIPAM nanoparticles were obtained by thermogravimetric analysis (TGA) where it showed the percentage of mass loss at certain temperature.

Ternary composites of polyaniline with polyvinyl alcohol and Cu by inverse emulsion polymerization: A comparative study

AbstractAddition of inorganic particles and insulating polymeric materials to conducting polymers allows the alteration and modification of physical properties of the conducting polymer. An inverse emulsion polymerization technique was employed for the synthesis of polyaniline (PANI), composites of PANI with copper (PANI‐Cu), polyvinyl alcohol (PANI‐PVA), as well as composites of PANI with Cu and PVA (PANI‐Cu‐PVA) under comparable experimental conditions. The FTIR and UV/Vis, spectra were employed to determine the chemical structure. The morphology of the synthesized composites was studied by SEM technique. The XRD pattern illustrates good crystallinity of the composites with improved conductivity at room temperature. The TGA results show an increase in the thermal stability of the composites. The results show that co‐addition of PVA and Cu into PANI greatly affects the properties of PANI as well as the solubility as the composites were soluble in a number of commonly used organic solvents such as DMSO, NMP, chloroform, 2:1 mixture of chloroform and 2‐propanol, and 2:1 mixture of toluene and 2‐propanol.

Highly toxic Cr (VI) adsorption by (chitosan-g-PMMA)/silica bionanocomposite prepared via emulsifier-free emulsion polymerisation

This work focuses on developing some composites of desirable properties mainly for heavy metal ion adsorption from the water bodies leading to water remediation. Adsorption of Cr(VI) by a novel biopolymer-based hybrid nanocomposite material has been synthesized via emulsifier-free emulsion polymerisation technique and investigated its assess as proposed use. Chitosan is a biocompatible, biodegradable and non-toxic material, hence this biopolymer has been selected in this research work. The chemical modification of the biopolymer chitosan has been achieved via grafting of poly(methyl methacrylate) (PMMA) and crosslinker silica gel was added in order to improve the mechanical strength of the nanocomposite in nitrogen atmosphere taking ammonium persulphate as initiator. The resulting composite samples were characterized by using XRD, FTIR, SEM and TEM. Further, the biodegradability of the samples was studied at different time intervals from 15days to 6months and the so produced nanocomposite exhibited good biodegradability. Adsorption of Chromium (Cr) was investigated by varying the contact time between the adsorbate (Cr), the nanocomposite, pH of the solution and the doses of the composite. The optimum result for chromium removal was found at pH-4 and this result showed its use efficiently for the treatment of wastewater containing Cr (VI).

Effect of different surfactant monomers on alkali soluble emulsion polymer as a binder for water based printing inks

In this study hydrophobically alkali-soluble emulsion HASE was prepared by using semi batch emulsion polymerization technique and evaluated as a binder for water based printing inks. HASEwas prepared by using vinyl acetate and methyl methacrylate as hydrophobic monomers in addition to meth acrylic acid as a hydrophilic monomer. Besides, anionic and nonionic emulsifiers are used and sodium per sulfate as initiator. Three types of surfactant monomers are prepared by esterification of an acid or an anhydride with nonionic surfactant and then, the chemical structures were characterized using FT-IR spectroscopy. Each surfactant monomer was used in different ratios to prepare the emulsion polymer. However a sample without using of surfactant monomer was prepared for comparison. The prepared HASE was diluted and then neutralized by using mono ethanol amine till pH from 8 to 9. Neutralized polymer solution was mixed with pigment dispersion and then applied on paper sheet and color strength was measured. The best final polymer latex was characterized by FT-IR, DSC, and TEM. The prepared polymer showed advanced behavior compared with commercial binder in water based printing ink formulations. The results obtained revealed that uses of 5g of surfomer in polymerization of HASE enhance the color strength and gravimetric conversion and reduce the precipitate and viscosity.

Application of Some Polymer latexes in Preventing Paper Documents Forgery

The main objective of this research is to improve ink printability of papers via their modification with various types of water-based polymer latexes during paper manufacturing process. In order to achieve this target, various types of styrene-acrylate polymer latexes were used for modification of different types of papers. Styrene-acrylate latexes were prepared via emulsion polymerization of styrene with various acrylate monomers using emulsion polymerization technique. The effect of different emulsifying agents on the properties of the prepared emulsions was studied. The obtained results showed a significant improvement in degree of gloss and ink density on the polymer-coated papers which positively affect the ink ability, and ink holding properties of the modified paper. In addition, ink gloss and ink density of the coated papers improved with increasing the concentration of modifying latexes containing Texapon®P as emulsifier. These promising results open the way to use polymer latexes in treatment of documented value which can be used in stabilization of disappearing ink on paper leading to prevent forgery

Compatibilization of poly(vinylidene fluoride)/natural rubber blend by poly(methyl methacrylate) modified natural rubber

Natural rubber-grafted-poly(methyl methacrylate) (NR-g-PMMA) was successfully synthesized using emulsion polymerization technique. NR-g-PMMA with various PMMA levels was further blended with poly(vinylidene fluoride) (PVDF) at the fixed 50/50 wt% blend ratio, as simple blend or as dynamically cured blend. The compatibilization efficiency in the blend improved significantly with PMMA level. The morphological evaluation indicated that grafting PMMA onto NR reduced the domain size in the blend, resulting in improved mechanical and rheological properties. The enhanced properties were attributed to strong interactions between PVDF and NR-g-PMMA. Furthermore, the mechanical properties improved with PVDF content, consistent with the blend morphology. In addition, thermal analysis revealed low crystallinity in the blend, which corresponds to the molecular interactions of PVDF and grafted PMMA in NR-g-PMMA.

A facile approach to synthesize microencapsulated phase change materials embedded with silver nanoparicle for both thermal energy storage and antimicrobial purpose

In this study, a facile approach having the advantages of high efficiency and low-energy consumption for synthesis of microencapsulated phase change materials (MicroPCMs) with thermal energy storage and antimicrobial properties was demonstrated. Phase change materials (PCMs) was firstly encapsulated via the photocurable pickering emulsion polymerization technique, and then followed by silver reduction. The resulting microcapsules exhibited an excellent spherical morphology, narrow particle size distribution and a well-defined core-shell structure. The chemical composition and surface elemental distribution of Ag/SiO2-MicroPCMs were confirmed by the FTIR and EDS. The TEM observations indicated that Ag nanoparticles have been successfully attached on the surface of SiO2 nanoparticles. In addition, the results obtained from DSC and TGA indicated that the microcapsules achieved a good latent-heat storage capability, enhanced thermal reliability and stability. More importantly, Ag/SiO2-MicroPCMs was eventually combined with PVA hydrogel to prepare an antibacterial and thermoregulation composite material. As expected, the composite material obtained an excellent bactericidal properties, especially for Staphylococcus aureus. Furthermore, this composite material was also endowed with thermoregulation properties, due to the inherent latent heat storage characteristic of Ag/SiO2-MicroPCMs. It can be concluded that the microcapsules developed in this work show great potential in applications for thermal energy storage, food preservation, wound dressing, and etc.

High-performance one-pack ambient cross-linking latex binders containing low-generation PAMAM dendrimers and ZnO nanoparticles

This study focuses on ambient-temperature self-crosslinking acrylic latex coating compositions containing poly(amidoamine) (PAMAM) dendrimers and ZnO nanoparticles in the role of inter-particle cross-linking agents and flash rust inhibitors. Low-generation amine-terminated PAMAM dendrimers as aqueous solutions were added into latices containing diacetone acrylamide repeat units in their polymer structure. The incorporation of ZnO nanoparticles (without any surface treatment) was performed during the synthesis of a polymer dispersion carried out by the semi-continuous emulsion polymerization technique. The latex storage stability and coating performance with respect to zinc oxide and PAMAM presence were evaluated and compared with a conventional zinc oxide-free coating composition containing adipic acid dihydrazide as the cross-linking agent. It was found that the novel latices containing both PAMAM dendrimers and ZnO nanoparticles exhibited a long-term storage stability and provided crosslinked transparent coating films of high gloss, enhanced mechanical properties, solvent resistance and excellent water whitening resistance. Moreover, the latex compositions containing PAMAM dendrimers as the inter-particle cross-linkers were shown to provide flash rust resistance.

Emulsion‐polymerized polyindole nanoparticles and their electrorheology

ABSTRACTPolyindole (PIn) nanoparticles were synthesized through an emulsion polymerization technique in this study and then examined as an anhydrous semi‐conducting electro‐responsive material. Their surface morphology and chemical structure were observed with high‐resolution scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. When dispersed in silicone oil, the electrorheological (ER) properties of the PIn particles were examined using a rotational rheometer with both steady shear and oscillatory tests under various applied electric field strengths with direct observation using an optical microscope. Flow curves of shear stress as a function of shear rate were well fitted using the Cho‐Choi‐Jhon model. Dielectric analysis was also performed to examine the permittivity and loss factor in relation to the ER effect. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46384.

Experimental Investigation of Morphological and Electrical Characteristics of PS/MWCNT Nanocomposite Films

Electrical characteristics and morphology of nanocomposite films composed of two different polystyrene (PS) latexes impregnated with multi-walled carbon nanotubes (MWCNT) in the range between 0 wt% and 20 wt% were assessed by considering photon transmission (UV-Vis) technique and electrical conductivity measurements. Emulsion polymerization technique was employed both to synthesize very fine PS particles dispersed in water and to tailor the sizes of the PS particles as 382 nm and 560 nm, respectively. PS/MWCNT nanocomposite films were obtained from the liquid form on glass substrates via drop-casting method and all they dried at 40 QUOTE C. Each dried sample was then annealed at varying temperatures between 100 QUOTE C and 250 QUOTE C for 10 min. The surface conductivity QUOTE of each annealed film at 250 QUOTE C was measured and was found to increase dramatically above a certain mass fraction of MWCNT content, QUOTE . Each set of PS/MWCNT nanocomposite film had a similar electrical percolation threshold of QUOTE =1.5 wt% as the MWCNT content and critical exponents of QUOTE were found to be 2.64 and 1.19 for 382 nm and 560 nm PS latex systems, respectively.

Synthesis of Bioacrylic Polymers from Dihydro-5-hydroxyl furan-2-one (2H-HBO) by Free and Controlled Radical Polymerization.

In this work, dihydro-5-hydroxyl furan-2-one (2H-HBO), a renewable-sourced chemical containing the hydroxyl functionality, is converted into its acrylic counterpart for the first time through a green chemical procedure using methacrylic anhydride. This newly synthesized acrylic monomer is able to be polymerized using different techniques such as bulk, solution, and emulsion polymerization. The ability of this monomer to copolymerize with other commercially available acrylates is studied using emulsion polymerization techniques. The pendent lactone ring remains unopened during polymerization and the new monomer is able to copolymerize with other acrylates such as methyl methacrylate and styrene. Reversible addition-fragmentation chain transfer reaction emulsion polymerization is also studied with the same monomer, leading to a steady conversion (∼60%) with a low polydispersity of 1.06. The homopolymer produced from such an emulsion polymerization shows a higher molecular weight than that produced from other methods, with a glass transition temperature of around 105 °C. This demonstrates the potential of this monomer as an interesting, green replacement for methyl methacrylate in certain fields of application.

Experimental and Theoretical Study on Mechanical Properties of Porous PDMS

Polydimethylsiloxane (PDMS) is extensively used in clinical flexible electronics, due to its biocompatibility and stability. When it is employed in a stretchable epidermal sensor for long-term monitoring, PDMS must have open pores within it to assure the sweat penetration. In the present paper, we focus on the mechanical properties of porous PDMS with different volume porosities at different temperatures. The emulsion polymerization technique is applied to fabricate porous PDMS. By controlling the ratio of water to PDMS prepolymer, different porosities of PDMS were obtained, and elastic moduli of such porous PDMS were measured in experiment. Results indicate that the elastic modulus increases nonlinearly as its temperature rises from 0 °C to 40 °C (a temperature range frequently encountered in clinical applications). Meanwhile, an asymptotic homogenization method (AHM) is employed to theoretically predict the elastic modulus and Poisson's ratio of porous PDMS, whose reliability is testified by comparing the results with experimentally measured data. Further theoretical discussions on mechanical properties are carried out, and results show that the pore size of porous PDMS has almost no effect on the elastic modulus and Poisson's ratio for certain porosities. Porosity of porous PDMS, however, has significant effect on both of these two mechanical parameters. Two fitted nonlinear formulas are then proposed to estimate the elastic modulus and Poisson's ratio of porous PDMS for any volume porosity less than 50%. All the results in the present paper are essential for mechanical design and optimization of clinical flexible electronics based on porous PDMS.

Overcoming Surfactant-Induced Morphology Instability of Noncrosslinked Diblock Copolymer Nano-Objects Obtained by RAFT Emulsion Polymerization.

RAFT emulsion polymerization techniques including polymerization-induced self-assembly (PISA) and temperature-induced morphological transformation (TIMT) are widely used to produce noncrosslinked nano-objects with various morphologies. However, the worm, vesicle and lamellar morphologies produced by these techniques typically cannot tolerate the presence of added surfactants, thus limiting their potential applications. Herein we report the surfactant tolerance of noncrosslinked worms, vesicles, and lamellae prepared by RAFT emulsion polymerizations using poly(di(ethylene glycol) ethyl ether methacrylate-co-N-(2-hydroxypropyl) methacrylamide) (P(DEGMA-co-HPMA)) as a macromolecular chain transfer agent (macro-CTA). Significantly, these P(DEGMA-co-HPMA) nanoparticles are highly stable in concentrated solutions of surfactants (e.g., sodium dodecyl sulfate (SDS)). We also demonstrate that the surfactant tolerance is related to the limited binding of SDS to the main-chain of the P(DEGMA-co-HPMA) macro-CTA constituting the particle shell. This work provides new insight into the interactions between surfactants and thermoresponsive copolymers and expands the scope of RAFT emulsion polymerization techniques for the preparation of noncrosslinked and surfactant-tolerant nanomaterials.

Augmentation of power conversion efficiency of amorphous silicon solar cell employing poly(methyl methacrylate-co-acrylic acid) nanospheres encapsulated with gold nanoparticles

An array of poly(methyl methacrylate-co-acrylic acid) nanospheres of various sizes (i.e., average size of 101 nm) with excellent thermal stability has been successfully synthesized via emulsion polymerization technique. The thermal properties of such materials in addition to the optical property of the metal nanoparticles have been carefully characterized. The integration of the nanospheres onto a photovoltaic cell has effectuated an increment of the power conversion efficiency from 2 to 3.14% (i.e., a relative enhancement of 57%). A further enhancement of the electrical characteristics has been observed if gold nanoparticles have been encapsulated by the polymeric nanospheres. The power conversion efficiency of the PV cell incorporated with gold nanoparticles of 3.75 × 10−3 wt% has attained 5.32% (i.e., a relative enhancement of 166%). This may be attributed to the localized surface plasmon effect as a strong absorption peak of the gold nanoparticles has been detected at the wavelength of 525 nm. A comparison of electrical characteristics conducted between nanospheres which have been encapsulated with silver and gold nanoparticles indicates the fact that both noble metals have yielded a momentous enhancement of the power conversion efficiency. Consequently, this novel technique utilizing nanospheres which have been encapsulated with noble metals (i.e., Ag and Au) is assuredly paving a way toward high-efficiency photovoltaic cell.

Thermal properties optimization of microencapsulated a renewable and non-toxic phase change material with a polystyrene shell for thermal energy storage systems

Thermal energy storage (TES) plays an important role in the development of an efficient solar energy system by storing the solar energy when available during the daytime and use it at night when required. The main component of a TES system is encapsulated phase change materials in macro, micro and nano sacles. Microencapsulated lauric acid (LA) as a renewable (obtained from vegetable oils) and non-toxic Phase Change Material (PCM) with a polystyrene shell was prepared using an emulsion polymerization technique. The individual and interactive effects of operating variables including lauric acid to styrene mass ratio, sodium dodecyl sulfate (SDS) to styrene (St) mass ratio, stirring rate and temperature on the microencapsulation ratio (ME.R) were investigated. Response surface method was applied to the statistical design, analysis of experiments and process optimization. Analysis of Variance (ANOVA) showed that the interaction between the stirring rate and temperature had non-significant effects on ME.R (%). The maximum achieved value of ME.R was 92.3% in the process optimization. It was enhanced compared with microencapsulation ratio of lauric acid in previous studies. By using the optimal values, LA/St mass ratio of 0.42, emulsifier (SDS) to styrene mass ratio of 0.01, stirring rate of 1076 rpm and the temperature of 55 °C, ME.R of 91.64% was obtained. Thermal properties, morphology and thermal stability of the optimal microcapsules were studied using DSC thermograms, Scanning Electron Microscopy (SEM) and thermogravimetry analysis (TGA), respectively. The results showed that microencapsulated renewable PCM with a melting point of 43.77 °C and latent heat of 167.26 kJ/kg has a good potential for utilizing renewable solar energy.

Magnetic-Responsive Microparticles that Switch Shape at 37 °C

Shape-memory polymers have seen tremendous research efforts driven by the need for better drug carries and biomedical devices. In contrast to these advancements, fabrication of shape-memory particles which actuate at body temperature remains scarce. We developed a shape-memory microparticle system with dynamically tunable shapes under physiological temperature. Temperature-responsive poly(ε-caprolactone) (PCL) microparticles were successfully prepared by an in situ oil-in-water (o/w) emulsion polymerization technique using linear telechelic and tetra-branched PCL macromonomers. By optimizing the mixing ratios of branched PCL macromonomers, the crystal-amorphous transition temperature was adjusted to the biological relevant temperature. The particles with a disk-like temporal shape were achieved by compression. The shape recovery from the disk to spherical shape was also realized at 37 °C. We also incorporated magnetic nanoparticles within the PCL microparticles, which can be remote-controllable by a magnet, in such a way that they can be actuated and manipulated in a controlled way.

Grafting of Poly(2–hydroxyethyl methacrylate) on Natural Rubber (NR–g–PHEMA): Characterizations and Water Sorption Selectivity of NR–g–PHEMA Membranes

Poly(2–hydroxyethyl methacrylate) (PHEMA) was grafted onto NR latex particles employing emulsion polymerization technique. Grafting efficiency (%GE) of PHEMA on NR particles was found to increase with increasing 2–hydroxyethyl methacrylate monomer (HEMA). Differently, %GE increased rapidly at low initiator concentrations before leveling off at higher concentrations. The NR–g–PHEMA latex was cast into a thin membranes. The membranes were subjected to the tensile testing. The Young’s modulus of NR–g–PHEMA membrane was found to improved as %GE increased in contrast to the elongation at break. Revealing by DSC, the states of water in the NR–g–PHEMA membranes appeared as the free water and non–freezing bound water and both increased with %GE. Swelling behavior of NR–g–PHEMA membranes in water–acetone mixtures was investigated. The membrane swelling showed a non–ideal behavior where a maximum swelling degree was found at certain concentrations of water–acetone mixtures. The water sorption selectivity of the membranes was enhanced when increasing %GE for low water content in the water–acetone mixtures. However, as increasing water content, the water sorption selectivity was declined.