Anti-polyelectrolyte effect of zwitterions containing (meth)acrylic waterborne polymer chains as tool for colloidal stabilization and polymer reinforcement.

The anti-polyelectrolyte effect, a characteristic unique to polymer chains containing zwitterions, was investigated for its impact on colloidal stabilization during emulsion polymerization and on the resulting polymer characteristics. The zwitterionic monomer (ZM) 3-[(3-Acrylamidopropyl)dimethylammonio]propane-1-sulfonate (A3361) was selected for the synthesis of 30 wt% emulsifier-free methyl methacrylate/n-butyl acrylate (MMA/n-BA) polymer latex. Three pH conditions were examined: neutral, where the zwitterionic chains are in a collapsed state, and acidic and basic, where these chains adopt an extended conformation, leading to the anti-polyelectrolyte effect.

Overcoming Challenges of Incorporation of Biobased Dibutyl Itaconate in (Meth)acrylic Waterborne Polymers.

Polymeric derivatives of itaconic acid are gaining interest as biobased alternatives to petroleum-based monomers due to their versatility, renewable nature, commercial availability, and cost-effectiveness. Itaconate ester monomer's challenges incorporating in (meth)acrylic waterborne polymers are the low propagation rate, unfavorable reactivity ratios, and the depropagation process. To overcome these challenges, the seeded semibatch emulsion polymerization of 100% biobased dibutyl itaconate, methyl methacrylate, and butyl acrylate was investigated at different temperatures.

Resembling Graphene/Polymer Aerogel Morphology for Advancing the CO/N Selectivity of the Postcombustion CO Capture Process.

The separation of CO from N remains a highly challenging task in postcombustion CO capture processes, primarily due to the relatively low CO content (3-15%) compared to that of N (70%). This challenge is particularly prominent for carbon-based adsorbents that exhibit relatively low selectivity. In this study, we present a successfully implemented strategy to enhance the selectivity of composite aerogels made of reduced graphene oxide (rGO) and functionalized polymer particles.

Synthesis and Crystallization of Waterborne Thiol-ene Polymers: Toward Innovative Oxygen Barrier Coatings.

The synthesis of waterborne thiol-ene polymer dispersions is challenging due to the high reactivity of thiol monomers and the premature thiol-ene polymerization that leads to high irreproducibility. By turning this challenge into an advantage, a synthesis approach of high solid content film-forming waterborne poly(thioether) prepolymers is reported based on initiator-free step growth sonopolymerization. Copolymerization of bifunctional thiol and ene monomers diallyl terephthalate, glycol dimercaptoacetate, glycol dimercaptopropionate, and 2,2-(ethylenedioxy)diethanethiol gave rise to linear poly(thioether) functional chains with molar mass ranging between 7 and 23 kDa when synthesized at 30% solid content and between 1 and 9 kDa at increased solid content of 50%.

One Step Closer to Coatings Applications Utilizing Self-Stratification: Effect of Rheology Modifiers.

Self-stratification of model blends of colloidal spheres has recently been demonstrated as a method to form multifunctional coatings in a single pass. However, practical coating formulations are complex fluids with upward of 15 components. Here, we investigate the influence of three different rheology modifiers (RMs) on the stratification of a 10 wt % 7:3 w:w blend of 270 and 96 nm anionic latex particles that do not stratify without RM.

Unraveling the Complex Polymorphic Crystallization Behavior of the Alternating Copolymer DMDS--DVE.

A complex crystallization behavior was observed for the alternating copolymer DMDS--DVE synthesized via thiol-ene step-growth polymerization. Understanding the underlying complex crystallization processes of such innovative polythioethers is critical for their application, for example, in polymer coating technologies. These alternating copolymers have polymorphic traits, resulting in different phases that may display distinct crystalline structures.

Polymer Colloids: Current Challenges, Emerging Applications, and New Developments.

Polymer colloids are complex materials that have the potential to be used in a vast array of applications. One of the main reasons for their continued growth in commercial use is the water-based emulsion polymerization process through which they are generally synthesized. This technique is not only highly efficient from an industrial point of view but also extremely versatile and permits the large-scale production of colloidal particles with controllable properties.

Experimental and theoretical study of the effect of different functionalities of graphene oxide/polymer composites on selective CO capture.

There is a constant need for versatile technologies to reduce the continuously increasing concentration of CO in the atmosphere, able to provide effective solutions under different conditions (temperature, pressure) and composition of the flue gas. In this work, a combination of graphene oxide (GO) and functionalized waterborne polymer particles was investigated, as versatile and promising candidates for CO capture application, with the aim to develop an easily scalable, inexpensive, and environmentally friendly CO capture technology. There are huge possibilities of different functional monomers that can be selected to functionalize the polymer particles and to provide CO-philicity to the composite nanostructures.

Effect of Particle Interactions on the Assembly of Drying Colloidal Mixtures.

The effects of particle interactions on the size segregation and assembly of colloidal mixtures during drying were investigated. A cationic surfactant was added to a binary latex/silica colloidal dispersion that has been shown to self-stratify upon drying at room temperature. Atomic force microscopy was used to show that the change in particle interactions due to the presence of surfactants reduced the degree of stratification and, in some cases, suppressed the effect altogether.

Semi-Crystalline Poly(thioether) Prepared by Visible-Light-Induced Organocatalyzed Thiol-ene Polymerization in Emulsion.

A photocatalytic thiol-ene aqueous emulsion polymerization under visible-light is described to prepare linear semicrystalline latexes using 2,2'-dimercaptodiethyl sulfide as dithiol and various dienes. The procedure involves low irradiance (3 mW cm ), LED irradiation source, eosin-Y disodium as organocatalyst, low catalyst loading (<0.05% mol), and short reaction time scales (<1 h).

Ionic Inter-Particle Complexation Effect on the Performance of Waterborne Coatings.

The performance of waterborne (meth)acrylic coatings is critically affected by the film formation process, in which the individual polymer particles must join to form a continuous film. Consequently, the waterborne polymers present lower performance than their solvent-borne counter-polymers. To decrease this effect, in this work, ionic complexation between oppositely charged polymer particles was introduced and its effect on the performance of waterborne polymer films was studied.

Toward enhanced catalytic activity of magnetic nanoparticles integrated into 3D reduced graphene oxide for heterogeneous Fenton organic dye degradation.

Composite Fenton nanocatalyst was prepared by water-based in situ creation of FeO nanoparticles integrated within the self-assembly 3D reduced graphene oxide (rGO) aerogel. The hybrid applied for the degradation of Acid Green 25 (AG-25) organic dye in an aqueous solution, in the presence of HO. By investigating the conditions that maximize the dye adsorption by the 3D composite, it was found that the pH of the solution should be adjusted between the pKa of the functional groups present on the rGO surface (carboxylic acid) and that of the dye (sulfonic acid) to promote electrostatic interactions dye-3D structure.

Effect of Graphene Characteristics on Morphology and Performance of Composite Noble Metal-Reduced Graphene Oxide SERS Substrate.

Graphene/noble metal substrates for surface enhanced RAMAN scattering (SERS) possess synergistically improved performance, due to the strong chemical enhancement mechanism accounted to graphene and the electromagnetic mechanism raised from the metal nanoparticles. However, only the effect of noble metal nanoparticles characteristics on the SERS performance was studied so far. In attempts to bring a light to the effect of quality of graphene, in this work, two different graphene oxides were selected, slightly oxidized GOS (20%) with low aspect ratio (1000) and highly oxidized (50%) GOG with high aspect ratio (14,000).

Uptake and effects of graphene oxide nanomaterials alone and in combination with polycyclic aromatic hydrocarbons in zebrafish.

Because of its surface characteristics, once in the aquatic environment, graphene could act as a carrier of pollutants, such as polycyclic aromatic hydrocarbons (PAHs), to aquatic organisms. In this study we aimed to (1) assess the capacity of graphene oxide (GO) to sorb PAHs and (2) to evaluate the toxicity of GO alone and in combination with PAHs on zebrafish embryos and adults. GO showed a high sorption capacity for benzo(a)pyrene (B(a)P) (98% of B(a)P sorbed from a nominal concentration of 100 μg/L) and for other PAHs of the water accommodated fraction (WAF) of a naphthenic North Sea crude oil, depending on their log K (95.

Dry sonication process for preparation of hybrid structures based on graphene and carbon nanotubes usable for chemical sensors.

The combination of graphene (G) and multi-walled carbon nanotubes (MWCNTs) creates three-dimensional hybrid structures particularly suitable as next-generation electrical interface materials. Nevertheless, efficient mixing of the nanopowders is challenging, unless previous disaggregation and eventual surface modification of both is reached. To avoid use of solvents and multistep purification process for synthesis of stable G/MWCNTs hybrids, herein, a novel dry method based on an air sonication process was used.

A green synthesis of nanocatalysts based on reduced graphene oxide/magnetic nanoparticles for the degradation of Acid Red 1.

The increasing amount of organic dye-polluted wastewater from the textile industry makes the development of techniques for the efficient purification and reuse of wastewater an urgent issue. Accordingly, solid adsorbents based on three-dimensional (3D) reduced graphene oxide (rGO) aerogels combined with magnetic nanoparticles (rGO@FeO) appear to be potential materials, which offer fast and efficient discoloration of dye solutions by dye adsorption, simultaneously acting as Fenton reaction nanocatalysts, and thus may eliminate organic dyes. In this work, 3D rGO@FeO aerogel nanocatalysts were synthesized a low-energy, simple, one-step method, in which GO and FeSO·7HO were simultaneously reduced.

Reduced Graphene Oxide/Polymer Monolithic Materials for Selective CO Capture.

Polymer composite materials with hierarchical porous structure have been advancing in many different application fields due to excellent physico-chemical properties. However, their synthesis continues to be a highly energy-demanding and environmentally unfriendly process. This work reports a unique water based synthesis of monolithic 3D reduced graphene oxide (rGO) composite structures reinforced with poly(methyl methacrylate) polymer nanoparticles functionalized with epoxy functional groups.

Low-Energy Encapsulation of α-Tocopherol Using Fully Food Grade Oil-in-Water Microemulsions.

Encapsulation of active agents, such as vitamins and antioxidants, is one of the possibilities that allow their incorporation in beverages, food, or in pharmaceutical products. Simultaneously, encapsulation protects these active agents from oxidation, producing more stable active compounds. Formation of nanodroplets by spontaneously formed microemulsion (ME) offers, on one hand, a low-energy technology of encapsulation and, on the other hand, because of a small size of the droplets, it assures long-term stability even in harsher environments.

Toward a Green Synthesis of Polyurethane/(Meth)acrylic Dispersions through Control of Colloidal Characteristics.

Polyurethane (PU)/acrylic waterborne hybrids are an attractive class of materials with wide application possibilities, but their synthesis typically requires significant quantities of solvent which has negative economic and environmental consequences. In this work, solvent-free and surfactant-free polyurethane (PU)/acrylic waterborne hybrids were obtained by synthesizing the PU prepolymer containing carboxylic groups directly in (meth)acrylic monomers that act as solvent. Then, the mixture is dispersed in water; the PU is chain-extended with diamines, and the (meth)acrylic monomers are polymerized.

Covalent-Bonded Reduced Graphene Oxide-Fluorescein Complex as a Substrate for Extrinsic SERS Measurements.

When graphene is used as SERS substrates, it contributes to the chemical mechanism (CM) of enhancement of Raman signal, owing to which the detection limit is very low (lower than mM content of probe molecules). The CM of enhancement depends largely on the interactions between the substrate and the probe molecules. Therefore, in this work, we have investigated the possibility of increasing the SERS activity of graphene by improving the interaction between the probe molecule and the graphene substrate by establishing exclusively strong covalent bonding between them.

Miniemulsion copolymerization of (meth)acrylates in the presence of functionalized multiwalled carbon nanotubes for reinforced coating applications.

Film forming, stable hybrid latexes made of methyl metacrylate (MMA), butyl acrylate (BA) and 2-hydroxyethyl methacrylate (HEMA) copolymer reinforced with modified multiwalled carbon nanotubes (MWCNTs) were synthesized by in situ miniemulsion polymerization. The MWCNTs were pretreated by an air sonication process and stabilized by polyvinylpyrrolidone. The presence of the MWCNTs had no significant effect on the polymerization kinetics, but strongly affected the polymer characteristics ( and insoluble polymer fraction).

Intracellular localization and toxicity of graphene oxide and reduced graphene oxide nanoplatelets to mussel hemocytes in vitro.

Recently, graphene materials have attracted tremendous research interest due to their unique physicochemical properties that hold great promise in electronics, energy, materials and biomedical areas. Graphene oxide (GO) is one of the most extensively studied graphene derivatives. In order to improve GO electrical properties, nanoplatelets are chemically reduced, thus increasing nanoplatelet conductivity.

Design of Stable and Powerful Nanobiocatalysts, Based on Enzyme Laccase Immobilized on Self-Assembled 3D Graphene/Polymer Composite Hydrogels.

Graphene-based materials appear as a suitable answer to the demand for novel nanostructured materials for effective nanobiocatalytic systems design. In this work, a design of stable and efficient nanobiocatalysts made of enzyme laccase immobilized on composite hydrogels [reduced graphene oxide (rGO)/polymer] is presented. The composite hydrogel supports were synthesized by self-assembly of graphene oxide nanoplatelets in the frame of a polymer latex matrix, where the polymer nanoparticles were adsorbed onto the GO surface, creating hybrid nanoplatelets.

MoS₂ nanoplatelet fillers for enhancement of the properties of waterborne pressure-sensitive adhesives.

Nanocomposite pressure-sensitive adhesives (PSAs) composed of polyurethane (PU)/(meth)acrylates reinforced with MoS2 nanoplatelets were prepared by blending aqueous dispersions. MoS2 crystals were exfoliated by sonication in water in the presence of poly(vinylpyrrolidone) (PVP, molecular weight of 10,000 g mol(-1)) to prepare an aqueous dispersion. Waterborne colloidal polymer particles (latex) were synthesized by miniemulsion photopolymerization in a continuous tubular reactor.

High-performance adhesives resulting from spontaneous formation of nanogels within miniemulsion particles.

Molecular structure plays a crucial role in determining the final properties of pressure-sensitive adhesives. Here, we demonstrate that the molecular structure of polyurethane/(meth)acrylic hybrids synthesized by miniemulsion photopolymerization changes during storage of the dispersion at room temperature because of the spontaneous formation of nanogels by the assembly of polymer chains within the polymer particles. Analysis of the nanogel structure by asymmetric-flow field-flow fractionation allows identification of the molecular structure that provides the unusual combination of high tack adhesion and excellent shear resistance at high temperature [maximum value of the shear-adhesion failure temperature (SAFT) test, >210 °C].