Emulsion Polymerization Technique Research Articles

Development of a dual capsule self‐healing silicone composite using silicone chemistry and poly(melamine‐urea‐formaldehyde) shells

AbstractThis study aims to develop microcapsules that can be used as room‐temperature self‐healing agents in silicone‐based matrices. A telechelic reactive silanol‐terminated polydimethylsiloxane (PDMS) as the healing agent, was selected to ensure the homogeneity of the polymeric matrix and encapsulated in poly(melamine‐urea‐formaldehyde) shells through an in‐situ emulsion polymerization technique. To catalyze the polycondensation reaction of the healing agent, dibutyltin dilaurate (DBTL) was encapsulated within the same type of polymeric shell. The synthesized microcapsules were characterized using Fourier‐transform infrared spectrometry, optical microscopy, scanning electron microscopy (SEM), and differential scanning calorimetry. The analyses confirmed that the spherical microcapsules with an average size of 56 μm for PDMS‐MUF microcapsules and 42 μm for DBTL‐MUF microcapsules, with a shell wall thickness of 100–200 nm, and good thermal stability were formed. Therefore, the two‐component self‐healing silicone composite was successfully developed using 10:1.2 wt% PDMS: DBTL microcapsules within the silicone matrix. SEM showed the self‐healing ability of the silicone matrix by observing the successful healing of microcracks at room temperature. Tensile and trouser tear tests were adopted to assess the self‐healing performance of the elastomeric matrix, showing the self‐healing efficiencies of 67% and 55%, respectively.

Incorporating Hydrophobic Cellulose Nanocrystals inside Latex Particles via Mini‐Emulsion Polymerization

AbstractHydrophobic cellulose nanocrystals (CNCs) are encapsulated inside poly(butyl acrylate/vinyl acetate/acrylic acid) latex particles via mini‐emulsion polymerization (MEP). To achieve a genuine MEP, the effects of the concentration of surfactants (sodium dodecyl sulfate/Disponil A3065) and a hydrophobic agent (octadecyl acrylate (ODA)) are optimized in the presence of 0.5 wt% CNC. Using a combination of surfactant and ODA concentrations leading to a particle nucleation method restricted to the monomer droplets, the effects of CNC loading up to 1.5 wt% on the polymerization process and final nanocomposite properties are studied. Despite an increase in particle size and a lower rate of polymerization at higher CNC loadings, the droplet nucleation mechanism remains dominant up to 1.25 wt% CNC loading. Pressure‐sensitive adhesive (PSA) performance for nanocomposites produced using hydrophobic CNCs in MEP decreases whereas performance improves considerably when using hydrophilic and partially hydrophobic CNCs in conventional emulsion polymerization. These results shed light on emulsion polymerization technique selection and CNC surface properties for greener industrial production of water‐based PSAs.

Fucoidan-coated PIBCA nanoparticles containing oncocalyxone A: Activity against metastatic breast cancer cells

BackgroundOncocalyxone A (oncoA) is a natural benzoquinone isolated from Cordia oncocalyx, which exhibits many biological activities such as anti-tumor, anti-inflammatory, antioxidant, and hypoglycemic. However, it presents renal, cardiac, and pulmonary toxicity, which can be a limiting factor. The encapsulation of oncoA in polymeric nanoparticles can enhance its therapeutic effect, while reducing its toxicity. ObjectiveThus, this study aimed to develop nanoparticles of poly (isobutyl cyanoacrylate) containing oncoA, and to evaluate its activity against metastatic breast cancer cells. MethodsThe nanoparticles were obtained using the anionic emulsion polymerization technique and characterized by Fourier-transform Infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), Differential Scanning Calorimetry (DSC), and Thermogravimetry (TG), in addition to studies of long-term stability, including different pH, and blood compatibility. Antiproliferative activity was assessed by MTT and cell migration assays. ResultsThe nanoparticles were obtained with a particle size of 305 ± 6.49 nm and encapsulation rate of 101.5 ± 1.4%, and were stable at different pH over 7 months. The nanoparticles did not induce hemolysis. The encapsulation of oncoA in fucoidan-coated PIBCA nanoparticles increased its cytotoxicity on MDA-MB-231 cells, and inhibited cell migration. ConclusionIn conclusion, fucoidan-coated PIBCA nanoparticles containing oncoA may be a promising alternative for further anticancer in vivo studies.

Reduced graphene oxide/cellulose microfiber hybrid from the Vietnamese Nipa palm tree: Synthesis, properties, and applications for preparation of poly(methyl methacrylate) composite

Cellulose microfibers were successfully fabricated from Vietnamese Nipa palm by mechanical and chemical treatments. The Nipa palm petioles were simply rolled, pressed, and separated. They were then pretreated with an alkaline solution and submitted to acid hydrolysis to remove the impurities (tCell). The microfibers were reinforced with reduced graphene oxide to form a hybrid that was reduced with hydrazine hydrate in the last stage (tCell-rGO). The structure and properties of tCell and tCell-rGO were evaluated by FTIR, XRD, DSC, TGA, SEM, BET, and the sheet resistance. It was observed that the treated cellulose microfibers exhibited a diameter of 10–20 μm and had good crystallinity in the structure. Both tCell and tCell-rGO exhibited low-density values of 1.52 kg/m3 and 0.58 kg/m3, respectively, and had good specific surface area values of 11.2 m2/g and 13.0 m2/g, respectively. These results supported the decrease in the density and the increase in the specific surface area of the tCell-rGO samples in comparison with the tCell. The existence of rGO sheets in the cellulose microfiber matrix resulted in changes in the structure, arrangement, and crystallization of pristine microfibers. The thermal property and electrical conductivity of the reinforced GO cellulose microfibers were significantly improved. rGO not only showed its role as a surface modification agent that helps the cellulose microfibers disperse better in the non-polar substrate, but also contributed to the increase of the heat-stable and mechanical properties of polymer. The thermal stability of tCell-rGO/PMMA composite was notably improved more than 40°C in maximum decomposition temperature by an emulsion polymerization technique. The material based on cellulose microfibers from the Vietnamese Nipa palm tree and reduced graphene oxide overcame some disadvantages such as the poor heat resistance, poor dispersion of the original fibers in the non-polar polymer and displayed great potential for environmentally friendly future applications.

Polyaniline-fly ash nanocomposites synthesized via emulsion polymerization: Physicochemical, thermal and dielectric properties

The polyaniline (PANI)/nano-fly ash composites were synthesized by Inverted emulsion polymerization technique. The FTIR spectrum of PANI/nano-fly ash composite (50/50) shows the vibrational bands due to N–Hstretching (2165 cm−1), quinoid (1517 cm−1) and benzenoid ring stretching (1354 cm−1), etc. The UV–Visible absorption shows an absorption peak at 267 and 374 nm for PANI/nano-fly ash composite. Raman spectrum of composite shows peaks at 1635, 1339, 1179, 829, 569, 414 and 200 cm−1. The conductivity of pure polyaniline was decreased as a result of the addition of nano fly ash. X-ray diffraction of the composite shows two crystalline peaks at 20.9° and 26.2° (2Θ). The stability of pure PANI is enhanced by the incorporation of nano -fly ash. The coating of polyaniline on nano-fly ash has been confirmed by FESEM pictures. The AC conductivity was explained using the hopping model. The dielectric constant decreases as the frequency increases, it was explained by using Maxwell–Wagner polarization theory.

Synthesis and corrosion resistance properties of novel conjugated polymer-Cu2Cl4L3 composites

A novel conjugated polyaniline (PANI)-[Cu2Cl4(m-aminophenylbenzimidazole)3] hybrid nanocomposites were prepared by using novel benzoyl peroxide as an organic oxidant by Inverse emulsion polymerization technique. The FTIR spectra of nanocomposites revealed the vibrational bands due to N–H stretching (3437 cm−1), quinoid (1487 cm−1) and benzenoid ring stretching (1384 cm−1). The conductivity of nanocomposites increases with PANI content. TGA thermogram nanocomposites (50/50) undergoes two-step weight loss in the temperature range 38–279 °C and 279–791 °C for first and second with a mass loss of 18 and 42% respectively. Thermograms reveal that the thermal stability of pure polyaniline was slightly enhanced by the incorporation of [Cu2Cl4L3]·2H2O complex. The formation of PANI-[Cu2Cl4L3]·2H2O nanocomposite was confirmed by FESEM pictures. Potentiodynamic polarization results show that the prepared nanocomposite shows mixed type corrosion inhibitor in 0.1 M HCl on steel-316 surface.

Preparation of Hybrid Polyaniline/Nanoparticle Membranes for Water Treatment Using an Inverse Emulsion Polymerization Technique under Sonication

This manuscript describes a novel in situ interfacial dynamic inverse emulsion polymerization process under sonication of aniline in the presence of carbon nanotubes (CNT) and graphene nanoparticles in ethanol. This polymerization method is simple and very rapid (up to 10 min) compared to other techniques reported in the literature. During polymerization, the nanoparticles are coated with polyaniline (PANI), forming a core-shell structure, as confirmed by high-resolution scanning electron microscopy (HRSEM) and Fourier-Transform Infrared (FTIR) measurements. The membrane pore sizes range between 100–200 nm, with an average value of ~119 ± 28.3 nm. The film resistivity decreased when treated with alcohol, and this behavior was used for selection of the most efficient alcohol as a solvent for this polymerization technique. The membrane permeability of the PANI grafted CNT was lower than the CNT reference, thus demonstrating better membranal properties. As measured by water permeability, these are ultrafiltration membranes. An antimicrobial activity test showed that whereas the reference nanoparticle Bucky paper developed a large bacterial colony, the PANI grafted CNT sample had no bacterial activity. The thicker, 2.56 mm membranes exhibited high salt removal properties at a low pressure drop. Such active membranes comprise a novel approach for future water treatment applications.

Alkylacrylic-carboxyalkylacrylic random bipolymers as demulsifiers for heavy crude oils

This paper explains and analyses the process where two series of acrylic random bipolymers, based on alkyl acrylate/carboxyalkyl acrylate (KC) and alkyl acrylate/acrylic acid (KA), were prepared by means of emulsion polymerization technique. In both, the bipolymers’ monomers ratio was varied, while holding the more hydrophobic monomer in majority. The KC and KA bipolymers were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and size exclusion chromatography (SEC). Afterwards, demulsifying activity of the KC and KA bipolymers in two heavy crude oils was evaluated through bottle tests. According to the obtained results, the selection and determination of weight ratio of monomers have an important impact on the bipolymers efficiency to destabilize the water/crude oil emulsion. In both crude oils, KC bipolymer with a monomer ratio of K/C = 80/20 w/w showed the best demulsifying performance in comparison with KA bipolymer at the same weight ratio. Structure-activity parameters including partition coefficient (Log P), hydration energy (HE), molar refractivity (MR), and polarizability (α) were calculated for both bipolymers. The destabilization effectiveness of bipolymers of the water/crude oil interface was found to be related to the partition coefficient (Log P), which indicated a strong diffusion capacity of the bipolymer to traverse through the oil phase and destabilize the water/oil interface. Furthermore, higher values of molar refractivity and polarizability are preferable for higher water removal efficiency (WRE). Moreover, the structure–activity parameters, as well as the quantum parameters, specific characteristics of acrylic bipolymers and some physicochemical properties of the crude oil were deployed in the process to predict the water removal efficiency. E2 equation which accomplished the external validation acted as the resultant of the two equations, E1 and E2, that fulfilled the restriction for the internal validation of Q2 > 0.6. Predictive squared correlation coefficients (QF12,QF22, and QF32) and external validation metric parameter (rm2) were calculated based on E2. Consequently, the new alkylacrylic-carboxyalkylacrylic bipolymers, insusceptible to acid environment, showed significantly improved properties as emulsion breakers, drop coalescers, and clarifiers.

The Role of Sodium Lauryl Sulfate on the Film Properties of Styrene-Butyl Acrylate-Acrylic Acid Copolymer Latex

In this study, the concentration effect of sodium lauryl sulfate (SLS) as a surfactant in the synthesis of styrene/acrylic acid/butyl acrylate copolymer (SAC) latex particles via seeded emulsion polymerization technique was investigated. Scanning electron microscopy (SEM), minimum film-forming temperature (MFFT), differential scanning calorimetry (DSC), dynamic light scattering (DLS), and thermal gravimetric analysis (TGA) techniques were used to explain the change on physicochemical properties and morphology. The main goal is to determine an optimal surfactant concentration to obtain latexes with low MFFT. DLS studies showed that the particle size decreases 118.30 to 75.18 nm with the increase of SLS concentration. MFFT of latexes decreased with increasing SLS concentration. From the TGA curves, it was found that all the SAC latex particles exhibit a three-step decomposition process. The observed single Tg values for SAC particles showed that the latexes were prepared successfully.

Properties of Porous PDMS and Stretchability of Flexible Electronics in Moist Environment

Abstract Polydimethylsiloxane (PDMS) is a good choice for the substrate and encapsulation of clinical flexible electronics, since it possesses some distinguished characteristics such as high elasticity, excellent optical characteristic, good biocompatibility, and stability. In the present study, the emulsion polymerization technique was used once more to fabricate porous PDMS, which is expected to assure the sweat penetration through the flexible electronics, and therefore to reduce the irritation to the skin due to the flexible electronics. To assess the mechanical performance of flexible electronics with moisture, the saturated moisture concentration, coefficient of moisture expansion, and elastic modulus of porous PDMS for different relative wetness fraction were measured in experiment. Meanwhile, an asymptotic homogenization method (AHM) was adopted to predict these parameters theoretically. Results indicate that the saturated moisture concentration is linear to the porosity, while the coefficient of moisture expansion is independent of the porosity, both of which are well verified by the experimental data. The fitted formula on the elastic modulus for different porosities suggested in our previous study was developed to take account of the relative wetness fraction based on the experimental data. These three parameters were finally applied in calculating the stretchability of a flexible electronic with serpentine interconnects in moist environment. Numerical stimulation reveals that the stretchability increases with the porosity and relative wetness fraction of the substrate and encapsulation. The present work is hoped to pave the way for flexible electronics in clinical applications.

Waterborne hygienic coatings based on self-crosslinking acrylic latex with embedded inorganic nanoparticles: a comparison of nanostructured ZnO and MgO as antibacterial additives

This paper deals with a facile fabrication of environmentally friendly hygienic coatings based on acrylic latex comprising embedded inorganic nanoparticles originating from nanostructured ZnO and MgO, respectively, in the role of antibacterial agents. The incorporation of surface-untreated powdered nanostructured oxides into the latex was performed during the latex synthesis carried out by a two-step emulsion polymerization technique. With this technological approach, latexes comprising dispersed inorganic nanoparticles in the content of ca 0.5 – 1.1 wt. % (based on solids) were successfully prepared. For obtaining high-performance coating films, keto-hydrazide self-crosslinking chemistry was introduced into latexes. The antibacterial efficiency of the coatings was evaluated with respect to the type and concentration of incorporated nanoparticles. It was determined that all the latex coating compositions containing inorganic nanoparticles exhibited a long-term storage stability and provided smooth transparent coating films of enhanced solvent and water resistance due to the combination of covalent and ionic interfacial crosslinking. The latex films displayed significant antibacterial activity, which was more pronounced with the increased content of nanoparticles. It was also found that the addition of nanostructured MgO enabled significant savings of a commercial biocidal additive while maintaining a high antibacterial efficiency.

Microcapsules Prepared via Pickering Emulsion Polymerization for Multifunctional Coatings

Micro/nanocontainer-based self-healing coatings have achieved enormous interest in scientific community during the last decade. However, the search for multifunctional micro/nanocontainers still has research challenge, especially for the micro/nanocontainers with dual functionality (both anticorrosion and antimicrobial). Here, a novel type of microcapsules with antimicrobial shell and anticorrosion core was prepared by the Pickering emulsion polymerization technique. Dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (QC18) and linseed oil were encapsulated as the antimicrobial and the anticorrosion agents, respectively. The results of local electrochemical impedance spectroscopy (LEIS) at 10 Hz demonstrated corrosion suppression in the scratched area of coatings doped with multifunctional microcapsules. Additionally, the QC18-modified microcapsules exhibited high antibacterial performance, showing over 90 % antimicrobial efficacy against gram-positive bacteria. This type of dual-functional coating might guide future design of micro/nanocontainer-based self-healing paint formulations.

Reversible color-changing and thermal-energy storing nanocapsules of three-component thermochromic dyes

Three component thermochromic dyes including fluoran type leuco dye, n-tetradecanol, and phenolphthaleinwere prepared and encapsulated in polymethylmethacrylate in this study. Nanoencapsulated system was prepared via oil in water emulsion polymerization technique. According to the morphological investigation by SEM, nanocapsules having spherical shape, compact morphology and lower average diameter around 200 nm were prepared successfully. UV–Visible Spectroscopy analysis and the photographs taken by a digital camera indicated that thermochromic systems and their nanocapsules exhibited reversible color change with thermal stimuli. They were green color at room temperature and lost their color at temperatures upon melting point of the thermochromic systems. In the study, 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone were added to the thermochromic systems to investigate UV resistance of the colorants in the systems. The effect of the UV absorbers on UV resistance of the thermochromic systems was investigated by color measurements based on CIELab system after UV aging of the nanoencapsulated systems. The results proved that especially 2,4-dihydroxybenzophenone was an effective material for increasing UV resistance of the systems and had color developer property. Besides, both thermochromic systems and their nanoencapsulated derivatives exhibited thermal energy storage/releasing property. While thermochromic systems had a heat storage capacity of over 200 J/g, the heat storage capacity of their nanocapsulated derivatives had reached up to 180 J/g. Melting temperature of the solvent n-tetradecanol decreased slightly in the thermochromic systems and further in nanoencapsulated form due to the cryoscopic effect of the non-volatile solutes in the system.

New water-based flexographic ink based on new ter-polymer nano-particles as eco-friendly binders – Part II

PurposeThe purpose of this study is to prepare, characterise and evaluate nano-emulsions of ter-polymers of various compositions as eco-friendly binders for flexographic ink industry.Design/methodology/approachVarious nano-emulsions of ter-polymers were prepared based on Vinyl acetate, Vinyl Versatate, butyl acrylate, acrylic acid and acrylamide monomers by means of a conventional seeded emulsion polymerisation technique, using K2S2O8 as the initiator. The characterisation of the prepared emulsions was performed using Fourier transform infrared, thermo-gravimetric analysis, gel permeation chromatography and transmission electron microscopy. A selection of co-polymers and ter-polymers were formulated with pigments and additional ingredients, as water-based flexographic inks. The inks were characterised for their rheological properties, pH, degree of dispersion, water-resistance and colour density.FindingsIt was found that the low viscosity of the prepared polymers may reduce the film thickness of the flexographic inks and may also increase the spreading of the ink on the surface. As a result, stable modified poly acrylate-based latex with improved physico-mechanical properties was obtained. The prepared latexes showed improved properties such as enhanced thermal stability and better water resistance. The effect of the emulsifier type on the properties of the resulting emulsion latexes and their corresponding films were investigated. Also, as the hydrophobic monomer increases, so does the colour density and increasing the binder ratio enhances the gloss values. The improving in gloss values were obtained and provide excellent adhesion properties for both the pigment particles and the base paper.Research limitations/implicationsThe study focusses on the preparation of new water-based ter-polymer nano-particles and their use as eco-friendly binders for flexographic ink industry. Ink formulations based on other different type emulsion polymers could also be studied to assess the applicability of the ink formulation system found for other binders.Practical implicationsThe ink formulations developed could find use in industrial-scale printing.Originality/valueEco-friendly environment and low-cost ink formulations for printing on paper substrates are novel.

RGD-Tagged Microbubbles Generated by Versatile Fabrication Protocols for In Vitro Cell Targeting and In Vivo Mouse Imaging of Tumor Vascularization

By using an organic framework to fabricate functional biomaterials, novel design and advanced biomedical applications of polymeric microbubbles for in vivo targeting and disease-oriented imaging of tumor vascularization can be developed. The present study describes novel synthetic protocols to fabricate RGD (Arginine-Glycine-Aspartic)-tagged αvβ3-targeted ultrasound microbubbles. The microbubbles were synthesized by emulsion polymerization techniques. Two types of microbubbles (MBs-1 and MBs-2) were obtained via biotin-streptavidin conjugation to poly(butyl cyanoacrylate) microbubbles (MBs-0) obtained by one-step synthesis in reverse order. The size distributions and surface zeta potentials were characterized. The results showed that the sizes of the MBs-2 were larger than that those of the MBs-1, and the MBs-2 showed decreased charge compared to MBs-1. In cell targeting studies, MBs-2 exhibited relatively stronger targeting affinity for αvβ3 integrins, while MBs-1 showed weaker targeting capability. Furthermore, in vivo mice imaging using MBs-2 for intravenous injection exhibited an obvious and sustained signal increase, which revealed the accumulative of MBs-2 anchoring in tumor. Hence, MBs-2 have been proven to be a promising candidate for using as ultrasound contrast agents for the early diagnosis of αvβ3-overexpressing malignant tumors, including breast cancer.

Development of Multifunctional Biopolymeric Auto-Fluorescent Micro- and Nanogels as a Platform for Biomedical Applications.

The emerging field of theranostics for advanced healthcare has raised the demand for effective and safe delivery systems consisting of therapeutics and diagnostics agents in a single monarchy. This requires the development of multi-functional bio-polymeric systems for efficient image-guided therapeutics. This study reports the development of size-controlled (micro-to-nano) auto-fluorescent biopolymeric hydrogel particles of chitosan and hydroxyethyl cellulose (HEC) synthesized using water-in-oil emulsion polymerization technique. Sustainable resource linseed oil-based polyol is introduced as an element of hydrophobicity with an aim to facilitate their ability to traverse the blood-brain barrier (BBB). These nanogels are demonstrated to have salient features such as biocompatibility, stability, high cellular uptake by a variety of host cells, and ability to transmigrate across an in vitro BBB model. Interestingly, these unique nanogel particles exhibited auto-fluorescence at a wide range of wavelengths 450–780 nm on excitation at 405 nm whereas excitation at 710 nm gives emission at 810 nm. In conclusion, this study proposes the developed bio-polymeric fluorescent micro- and nano- gels as a potential theranostic tool for central nervous system (CNS) drug delivery and image-guided therapy.

Synthesis, kinetics and characterization of environment friendly waterborne acrylate copolymers

The copolymers consisting of acrylic and methacrylic esters have achieved prime importance due to their versatile environment friendly applications. Copolymerization of Methyl methacrylate (MMA) with suitable vinyl monomers such as alkyl acrylate and methacrylate has been carried out for modifying the properties of the polymer. In current research synthesis of waterborne copolymer of MMA and 2- Ethyl hexyl acrylate (2-EHA) carried out by ecofriendly emulsion polymerization technique and the kinetics of polymerization, characterizations of the copolymers have been studied. Synthesized copolymers were characterized by FTIR, NMR, DSC, and TGA. The kinetics results of the MMA-co-EHA copolymer was compared with the previously synthesized copolymer MMA with Butyl acrylate (BA). On comparing these results, it was found that EHA gives higher conversion with respect to BA under the same reaction conditions. Out of all the prepared latexes some are suitable for binder purposes in environment friendly water borne coating applications.

Preparation and migration study of graphene oxide-grafted polymeric microspheres: EOR implications

Through an inverse emulsion polymerization technique, graphene oxide-grafted polymeric microspheres (RGO-PMSs) with superior suspension properties, thermostability, hydration swelling, elasticity and strength were developed for in-depth profile control and displacement. RGO-PMSs undergo migration and adsorption in large pores; capture by means of single plugging, coincidence plugging and bridging plugging; and elastic deformation-recovery in small pores to increase seepage resistance. When matching coefficient was 2.11, RGO-PMSs particles could not enter the porous media. However, RGO-PMSs particles entered core samples smoothly and perform plugging when the matching coefficient ranged from 0.78–1.44, while RGO-PMSs particles could not effectively block the pores when the matching coefficient was 0.67. An increase in the injection rate improved RGO-PMSs injectivity while weakening plugging efficiency. Additionally, the increase in the RGO-PMSs concentration and strength enhanced the plugging efficiency. Moreover, RGO-PMSs had a favorable anti-outwash property with a retention ratio of 88.7%, maximum additional flow resistance of 7.12 kPa and additional flow resistance of 4.53 kPa during migration. All the results indicated that RGO-PMSs could be an applicable candidate for in-depth profile control and displacement.

Polyacrylamide hybrid nanocomposites hydrogels for efficient water treatment

Spherical polyacrylamide nanoparticles (PAM-NPs) were prepared by inverse emulsion polymerization technique. Polyacrylamide/functionalized-multiwalled carbon nanotubes (PAM/f-MWCNTs) and polyacrylamide/TiO2 (PAM/TiO2) nanocomposites were successfully prepared by in situ emulsion polymerization and solution mixing methods to investigate their efficiencies in removal of organic dyes. The super-hydrogel behavior of the prepared nanocomposites proved water absorbance of 3664% and 2996% for PAM/1% f-MWCNT and PAM/10% TiO2 nanocomposites; respectively. A maximum photodegradation efficiency of 35% was achieved upon using PAM/10% TiO2 nanocomposite for CR dye removal, while in case of MG dye it reached 76% after 240 min irradiation time. Dye removal efficiency increased as f-MWCNT loading increased and reached maximum values of 49% and 80% for CR and MG dyes, respectively, using PAM/1% f-MWCNT nanocomposite after 240 min irradiation time. Pseudo-second-order kinetic model best fitted the adsorption kinetics behavior which reached maximum rates of 0.0615 and 0.463 for CR and MG dyes, respectively, using PAM/1% f-MWCNT nanocomposite. However, in the case of PAM/10% TiO2 nanocomposite it was found that adsorption reached maximum rates of 0.552 and 0.571 for CR and MG dyes, respectively. On the other hand, pseudo-first-order kinetic model best described the photodegradation behavior of the prepared nanocomposites with higher degradation rate of 0.0018 and 0.0075 for CR and MG dyes, respectively, using PAM/10% TiO2 nanocomposite. In this work, the combination of PAM-NPs, prepared by inverse emulsion polymerization, TiO2 NPs with photocatalytic activity and CNTs with high adsorption activity combined the photocatalytic and absorption activities of these nanoparticles in conjunction with reducing their amounts and diminishing the risk of fine catalyst dispersion in the treated water.

New water-based copolymer nanoparticles and their use as eco-friendly binders for industry of flexographic ink, part I

Purpose The purpose of this paper is to prepare, characterise and evaluate nano-emulsions of copolymers of various compositions as eco-friendly binders for flexographic ink industry. Design/methodology/approach Various nano-emulsions of copolymers were prepared using styrene (St), butyl acrylate (BuAc), acrylic acid (AA) and acrylamide (AAm) monomers by means of a conventional seeded emulsion polymerisation technique, using K2S2O8 as the initiator. The characterisation of the prepared emulsions was performed using Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), gel permeation chromatography (GPC) and transmission electron microscopy (TEM). A selection of copolymers was formulated with pigments and additional ingredients, as water-based flexographic inks. The inks were characterised for their viscosity, pH, degree of dispersion, water resistance and colour density. Findings It was found that the low viscosity of the prepared copolymers may reduce the film thickness of the flexographic inks and may also increase the spreading of the ink on the surface. As a result, stable modified polyacrylate-based latex with improved physico-mechanical properties were obtained. The prepared latexes were showed improving and enhancing in water resistance; gloss values, and the print density that ranged from 2.06 to 2.51 and the maximum gloss values (39 and 48) were also obtained. Also, these binders provide excellent adhesion properties for both the pigment particles and the base paper. Practical implications This study focuses on the preparation of new water-based copolymer nanoparticles and their use as eco-friendly binders for flexographic ink industry. Social implications The ink formulations developed could find use in industrial-scale printing. Originality/value Eco-friendly environment ink formulations for printing on paper substrates are novel.