Emulsion Polymerization Of Methyl Methacrylate Research Articles

Cerium Oxide‐Armored Composite Latex Particles by Visible Light Emulsion Photopolymerization: From Synthesis to Film Properties

AbstractCerium dioxide (CeO2) has huge potential in many applications ranging from biochemical engineering to the coating industry. Here, the first example of visible light photo‐mediated Pickering emulsion polymerization of (meth)acrylate monomers is reported using CeO2 nanoparticles (NPs) as solid stabilizer. A ω,ω′−dicarboxylic acid diphenyl disulfide photoinitiator is anchored on the surface of the CeO2 NPs and used to initiate the emulsion polymerization of methyl methacrylate (MMA) and of MMA/n‐butyl acrylate (MMA/BA) under visible light leading to CeO2‐armored latexes. Radicals generated upon light irradiation trigger the formation of polymer chains chemically attached to the CeO2 NPs, promoting their subsequent adsorption on the latex surface. The composite films obtained from the CeO2‐armored P(MMA‐co‐BA) latexes exhibit a unique honeycomb nanostructure with the nanoceria located in the walls giving the materials excellent mechanical, anti‐UV, and photocatalytic properties.

Hyperbranched Organosilicon Surfactants as Emulsifiers for the Emulsion Polymerization of Methyl Methacrylate

This report is devoted to the investigation of the emulsion polymerization of methyl methacrylate in the presence of PEGylated hyperbranched polymethylethoxysiloxane as an emulsifier. It is shown that its use in the amount of 1–5 wt % affords stable 25–50% poly(methyl methacrylate) dispersions with the controlled particle sizes from 300 to 800 nm and a narrow particle size distribution.

ТЕХНОЛОГІЧНІ ВЛАСТИВОСТІ МЕТИЛМЕТАКРИЛАТНИХ КОМПОЗИЦІЙ З МОДИФІКОВАНИМИ НАПОВНЮВАЧАМИ

The influence of the nature of modified fillers (Ni- and Cu-containing polymer-silicate materials) on the kinetics of emulsion polymerization of methyl methacrylate in the presence of polyvinylpyrrolidone graft copolymers was investigated. The effect of modified metal-containing silicate fillers on the technological properties of the developed materials was determined. In particular, the introduction of fillers contributes to a significant reduction of technological shrinkage and moisture absorption of polymethyl methacrylate materials. An increase in the chemical resistance and maximum operating temperature of the developed materials is also noted.

Peculiar Behavior of Methyl Methacrylate Emulsion Polymerization-Induced Self-Assembly Mediated by RAFT Using Poly(Methacrylic Acid) Macromolecular Chain Transfer Agent.

Reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization of methyl methacrylate (MMA) is successfully performed in water in the presence of a poly(methacrylic acid) (PMAA) macromolecular chain transfer agent (macroCTA) leading to the formation of self-stabilized PMAA-b-PMMA amphiphilic block copolymer particles. At pH3.7, the reactions are well-controlled with narrow molar mass distributions. Increasing the initial pH, particularly above 5.6, results in a partial loss of reactivity of the PMAA macroCTA. The effect of the degree of polymerization (DPn) of the PMMA block, the solids content, the nature of the hydrophobic segment, and the pH on the morphology of the obtained diblock copolymer particles is then investigated. Worm-like micelles are formed for a DPn of PMMA of 20 (PMMA20), while "onion-like" particles and spherical vesicles are obtained for PMMA30 and PMMA50, respectively. In contrast, spherical particles are obtained for the DPns higher than 150. This unusual evolution of particle morphologies upon increasing the DPn of the PMMA block seems to be related to hydrogen bonds between hydrophilic MAA and hydrophobic MMA units.

High-concentration TiO2 suspension (>70 wt%) with low viscosity suitable for waterborne coatings

High-concentration TiO2 suspension is favored by industry since it would effectively simplify the processing of coatings, benefiting energy and cost savings. However, achieving a dense TiO2 suspension with low viscosity and good dispersion remains a challenge due to the large particle size and high density of pigment-grade TiO2 particles (200–400 nm). In this work, we proposed high-concentration TiO2 suspensions with low viscosity and excellent storage stability by grafting copolymer nanospheres to TiO2. The TiO2 particles are isolated through the steric hindrance and electrostatic repulsion of PMS (P(MMA-MPS)) nanospheres which are synthesized by emulsion polymerization of methyl methacrylate (MMA) and γ-methacryloxypropyltrimethoxysilane (MPS). The TiO2 suspension modified by PMS of 90 nm exhibits the highest concentration in water (74 wt%) while maintaining the lowest viscosity (95 mPa·s at the shear rate of 200 r/s). Through thermal storage at 50 °C in 28 d, the concentrated TiO2-PMS suspensions demonstrated excellent stability without any noticeable decline in coating properties compared to pure TiO2. The coating film of TiO2-PMS-90 suspension exhibited the optimal contrast ratio (92.4 %) and gloss value (78.5 GU) after thermal storage. The 50 L macro production results of TiO2-PMS-90 coincided with the lab results which will favor larger scale-up production. This work presents a strategy to enhance the dispersion stability of TiO2 particles to obtain a high-concentration slurry with low viscosity and superior flowability, particularly suitable for waterborne coatings.

A self-healing waterborne acrylic latex coating based on intrinsic hydrogen bonding

Acrylic coatings suffer damage in the form of cracking, which degrades both their protective and aesthetic performance over time. Self-healing technology offers the ability to solve this problem by allowing cracks to spontaneously heal without external diagnosis or intervention, offsetting the enormous costs associated with coating damage and repair. However, there is currently no efficient self-healing acrylic coating design, and research in the area remains noticeably sparse. In this research we sought to imbue a mechanically tough methyl methacrylate (MMA)/butyl acrylate (BA)/acrylic acid (AA) acrylic coating with self-healing functionality by incorporating self-healing monomers within the formulation. We synthesized a library of four acrylic monomers containing both a long amphiphilic spacer of variable length, and the 2-ureido-4[1H]-pyrimidinone (UPy) unit, which forms strong self-complementary quadruple hydrogen bonds. These UPy-monomers were able to participate in the emulsion polymerization of MMA, BA and AA, forming intrinsic hydrogen bonding networks within the subsequent acrylic coatings. These UPy functionalized coatings displayed optical self-healing and strain recovery over 24 h both at room temperature (∼28 %), and at elevated temperatures up to 50 °C (∼80 %). The coatings also displayed repeatable self-healing after four healing cycles, relative to an MMA/BA/AA coating.

Wavelength exponent based calibration for turbidity spectroscopy: Monitoring the particle size during emulsion polymerization reactions

Particle size and particle size distribution (PSD) are important properties of polymer latexes because they strongly affect the film formation and the rheological properties of the latexes. Thus, monitoring the particle size is of paramount importance during the production of waterborne polymeric dispersions, for which online/inline measurements of the particle size are required. Herein, turbidity spectroscopy (TUS) is used to measure the particle size of nanoparticles in dispersed media. Calibration curves based on a modified wavelength exponent method are introduced and assessed to monitor the evolution of a broad range of particle sizes in seeded semibatch emulsion polymerizations of methyl methacrylate, butyl acrylate, methacrylic acid (MMA/BA/MAA 51/47/2) terpolymers. It is shown that the wavelength exponent based calibration curves can be successfully used to retrieve the particle size during the polymerization process.

RAFT emulsion polymerization of methyl methacrylate mediated by protonated poly(2‐(dimethylamino)ethyl methacrylate) macromolecular chain transfer agent: A mechanism study

AbstractSurfactant‐free reversible addition‐fragmentation transfer (RAFT)‐mediated emulsion polymerization has been used in the synthesis of latex particles. Although this method has been developed for some time, some detailed mechanisms are not clear. Herein, RAFT emulsion polymerization of methyl methacrylate (MMA) mediated by protonated poly(2‐(dimethylamino)ethyl methacrylate) (H+‐PDMAEMA) macromolecular chain transfer agent (macro‐CTA) is studied. The effects of the molar ratios of MMA/macro‐CTA and initiator/macro‐CTA, and the macro‐CTA chain length on the emulsion polymerizations are investigated. At the nucleation stage, H+‐PDMAEMA‐CTA is chain extended with MMA dissolved in aqueous phase; and when the length of PMMA block is above a critical length, the formed amphiphilic block copolymer (BCP) chains self‐assemble into micellar particles. The nucleation time in the emulsion polymerization is strongly dependent on the chain length of H+‐PDMAEMA‐CTA, and the molar ratio of free radical initiator/macro‐CTA. The emulsion polymerization rate is in direct proportion to the molar ratio of free radical initiator/macro‐CTA. The size and the size distribution of the latex particles can be tuned through control of the macro‐CTA chain length and MMA/macro‐CTA molar ratio. Monodispersed latex particles can be synthesized under proper conditions. It is expected that well‐defined latex particles with a variety of hydrophilic polymers (or biomacromolecules) on the surfaces can be synthesized by this approach.

Novel Gemini Surfactant for Binding Eu(III)-Polyoxometalate into Hydrogels and Polymer Latexes.

The incorporation of rare-earth ions into polymer matrices can lead to useful materials in various fields such as biomarkers, lasers, luminescent devices, optical storage materials, and so on. Methods of incorporation are either extremely simple, such as mixing the polymer and the ion of interest in adequate solvents, or more sophisticated such as synthesizing predesigned monomers that contain the rare-earth ion or binding the ion on an already formed polymer chain. Cationic gemini surfactants represent a class of surfactants that can be used to incorporate metal-oxygen cluster compounds by means of strong electrostatic interactions. In this study, first, a novel cationic gemini surfactant having double bonds on both side chains was designed and prepared. After characterization, the surfactant was used to synthesize hydrogels with different degrees of crosslinking and also as a surfmer in emulsion polymerization of methyl methacrylate. The resulted polymer matrices were able to bind europium-polyoxometalate Na9[EuW10O36].32H2O. In case of luminescent lanthanide ions, changing the microenvironment around the metal ion also changes the intensity of some emission peaks as well as other luminescent parameters. Investigation of emission spectra of Eu3+ indicates a decrease in the symmetry of the microenvironment, when the polyanions pass from water to latex, to surfactant solution, and to hydrogel.

Time-Resolved Small-Angle X-ray Scattering Studies during the Aqueous Emulsion Polymerization of Methyl Methacrylate.

Recently, we reported time-resolved synchrotron small-angle X-ray scattering (TR-SAXS) studies during aqueous emulsion polymerization using a bespoke stirrable reaction cell (J. Am. Chem. Soc. 2021, 143, 1474-1484). This proof-of-concept study utilized a semifluorinated specialty monomer (2,2,2-trifluoroethyl methacrylate) to ensure high X-ray contrast relative to water. Herein, we extend this approach to emulsion polymerization of methyl methacrylate (MMA) in the presence or absence of sodium dodecyl sulfate (SDS) at 70 °C. Solution conductivity measurements for this anionic surfactant indicated a critical micelle concentration (CMC) of 10.9 mM at this temperature. Thus, SDS was employed at either 1.0 or 20.0 mM, which corresponds to well below or well above its CMC. Postmortem analysis by 1H NMR spectroscopy indicated MMA conversions of 93-95% for these three formulations. We demonstrate that the X-ray contrast between water and PMMA is sufficiently large to produce high-quality scattering patterns during TR-SAXS experiments. Such patterns were fitted using a hard-sphere scattering model to monitor the evolution in particle diameter. This enabled (i) determination of the time point for the onset of nucleation and (ii) the evolution in particle size to be monitored during the MMA polymerization. The final particle diameters obtained from such TR-SAXS studies were consistent with postmortem DLS analyses, while TEM studies confirmed that near-monodisperse latex particles were formed. Micellar nucleation occurs within just 2 min when the SDS concentration is well above its CMC, resulting in a high particle number concentration and relatively small latex particles. In contrast, when SDS is either absent or present below its CMC, particle nuclei are formed by homogeneous nucleation over significantly longer time scales (14-15 min). In the latter case, adsorption of SDS onto nascent particles reduces their coagulation, giving rise to a larger number of smaller particles compared to the surfactant-free polymerization. However, the characteristic time required for the onset of nucleation is barely affected because this is mainly controlled by the kinetics of homogeneous polymerization of the relatively water-soluble MMA monomer within the aqueous phase. These results suggest that the aqueous emulsion polymerization of several other (meth)acrylic monomers, and perhaps also vinyl acetate, may be amenable to TR-SAXS studies.

Emulsion Polymerization Using an Amphiphilic Oligoether Ionic Liquid as a Surfactant.

We investigate the use of an ionic liquid (IL) as a surfactant in emulsion polymerization (EP) reactions. ILs have been proposed as surfactants for micellar dispersions, emulsions, micro-emulsions and suspensions. Thus, it is important to acquire knowledge of the application of ILs in heterogeneous polymerizations. We selected the amphiphile cationic oligoether IoLiLyte C1EG™ as an IL for this purpose and compared its performance to that of the conventional surfactant dodecyl trimethyl ammonium bromide (DTAB) in the EP of methyl methacrylate and styrene. After we found the proper concentration range of the IL, this amphiphile showed similar polymerization rates to those observed with DTAB for both monomers. The evolution of monomer conversion and the final average diameter of formed polymeric particles were similar for both evaluated surfactants, demonstrating their capability to stabilize the EPs of the investigated monomers. We simulated the evolution of monomer conversion and particle size using a conventional model for emulsion polymerization, which showed good agreement with the experimental data, suggesting that the EP with this IL follows Smith-Ewart kinetics.

Functional core/shell PMMA/P(MMA‐co‐PDSECAE)‐SH particles with thiol groups in the shell and their adsorption of heavy metal ions

AbstractThe relationships between morphology and properties are important for functional polymer particles. In this work, stable core/shell PMMA/P(MMA‐co‐PDSECAE) (C/S) latexes with uniform particle size are first prepared through semi‐continuous soap‐free seeded emulsion polymerization of methyl methacrylate (MMA) and 2‐(((2‐[pyridin‐2‐yldisulfanyl]ethoxy)carbonyl)amino) ethyl acrylate (PDSECAE), and thiol‐functionalized core/shell PMMA/P(MMA‐co‐PDSECAE)‐SH (C/S‐SH) submicron particles (SPs) are then obtained by reduction of disulfide bonds with dithiothreitol (DTT). Adsorption behaviors of heavy metal ions on the SPs are investigated. Results show that, the C/S‐SH SPs, with more thiol groups distributed closer to the surface, have nearly twice the Pb2+ adsorption capacity of the homogeneous SPs prepared via batch emulsion polymerization. The C/S‐SH SPs show strong selective adsorption capacities toward Hg2+ and Pb2+, and maximum adsorption capacities reach 0.477 and 0.303 mmol g−1, respectively. Due to their high selectivity, adsorption capacity, specific surface area and simple preparation process, these core/shell SPs have promising applications in water treatment.

Cationic and Biocompatible Polymer/Lipid Nanoparticles as Immunoadjuvants.

Nanostructures have been of paramount importance for developing immunoadjuvants. They must be cationic and non-cytotoxic, easily assembling with usually oppositely charged antigens such as proteins, haptens or nucleic acids for use in vaccines. We obtained optimal hybrid nanoparticles (NPs) from the biocompatible polymer poly(methyl methacrylate) (PMMA) and the cationic lipid dioctadecyl dimethyl ammonium bromide (DODAB) by emulsion polymerization of methyl methacrylate (MMA) in the presence of DODAB. NPs adsorbed ovalbumin (OVA) as a model antigen and we determined their adjuvant properties. Interestingly, they elicited high double immune responses of the cellular and humoral types overcoming the poor biocompatibility of DODAB-based adjuvants of the bilayer type. The results suggested that the novel adjuvant would be possibly of use in a variety of vaccines.

Preparation of Monodisperse Poly(Methyl Methacrylate)/Polystyrene Composite Particles by Seeded Emulsion Polymerization Using a Sequential Flow Process

We develop a sequential flow process for the production of monodisperse poly (methyl methacrylate) (PMMA)/polystyrene (PS) composite particles through a soap-free emulsion polymerization of methyl methacrylate (MMA) using the first water-in-oil (W/O) slug flow and a subsequent seeded emulsion polymerization of styrene (St) using the second W/O slug flow. In this process, monodisperse PMMA seed particles are first formed in the dispersed aqueous phase of the first W/O slug flow. Subsequently, removal of the oil phase from the slug flow is achieved through a porous hydrophobic tubing, resulting in a single flow of the aqueous phase containing the seed particles. The aqueous phase is then mixed with an oil phase containing St monomer to form the second W/O slug flow. Finally, monodisperse PMMA/PS composite particles are obtained by a seeded emulsion polymerization of St using the second W/O slug flow. We compared the reaction performance between the slug flow and the batch processes in terms of particle diameter, monomer conversion, particle size distribution, and the number of particles in the system. We found that internal circulation flow within the slugs can enhance mass transfer efficiency between them during polymerization, which results in monodisperse PMMA/PS composite particles with a large particle diameter and a high monomer conversion in a short reaction time, compared to those prepared using the batch process. We believe that this sequential microflow process can be a versatile strategy to continuously produce monodisperse composite particles or core-shell particles in a short reaction time.

Amphiphilic Statistical Copolymers from Catalytic Chain Transfer as Reactive Surfactants in Emulsion Polymerization

Statistical copolymers of methacrylic acid (MAA) and methyl methacrylate (MMA), butyl methacrylate (BMA), or lauryl methacrylate (LMA) were synthesized via cobalt(II)-mediated catalytic chain transfer polymerization (CCTP) and used as macromonomeric stabilizers in the emulsion polymerization of MMA. By varying the composition, length, and concentration of the macromonomers, we were able to tune the particle size, molar mass, and rheological behavior of the latexes. Most latexes stabilized with macromonomers containing BMA and LMA showed rheological properties such as small yield stress and shear thinning behavior similar to those of binders for coating applications.

Block Copolymer Nanoparticles are Effective Dispersants for Micrometer-Sized Organic Crystalline Particles.

Well-defined sterically stabilized diblock copolymer nanoparticles of 29 nm diameter are prepared by RAFT aqueous emulsion polymerization of methyl methacrylate using a dithiobenzoate-capped poly(glycerol monomethacrylate) precursor. These nanoparticles are evaluated as a dispersant for the preparation of organic crystalline microparticles via ball milling. This is exemplified for azoxystrobin, which is a broad-spectrum fungicide that is widely used to protect various food crops. Laser diffraction and optical microscopy studies indicate the formation of azoxystrobin microparticles of approximately 2 μm diameter after ball milling for 10 min at 400 rpm. Nanoparticle adsorption at the surface of these azoxystrobin microparticles is confirmed by electron microscopy studies. The extent of nanoparticle adsorption on the azoxystrobin microparticles can be quantified using a supernatant assay based on solution densitometry. This technique indicates an adsorbed amount of approximately 5.5 mg m–2, which is sufficient to significantly reduce the negative zeta potential exhibited by azoxystrobin. Moreover, this adsorbed amount appears to be essentially independent of the nature of the core-forming block, with similar data being obtained for both poly(methyl methacrylate)- and poly(2,2,2-trifluoroethyl methacrylate)-based nanoparticles. Finally, X-ray photoelectron spectroscopy studies confirm attenuation of the underlying N1s signal arising from the azoxystrobin microparticles by the former adsorbed nanoparticles, suggesting a fractional surface coverage of approximately 0.24. This value is consistent with a theoretical surface coverage of 0.25 calculated from the adsorption isotherm data. Overall, this study suggests that sterically stabilized diblock copolymer nanoparticles may offer a useful alternative approach to traditional soluble copolymer dispersants for the preparation of suspension concentrates affecting the context of agrochemical applications.

Effects of dispersion techniques on the emulsion polymerization of methyl methacrylate

Poly(methyl methacrylate) (PMMA) latices for organic coating systems were prepared via emulsion polymerization using various emulsifying techniques. The dispersion modes have an important effect on the particle size and particle size distribution (PSD) of polymeric latices during the emulsion polymerization process. The different dispersion modes, such as magnetic stirring, ultrasound, and the combination of magnetic stirring and ultrasound, were examined to prepare particle size small and narrow PSD polymer latex. PMMA latex of size less than 20 nm in diameter and narrow PSD was successfully produced using the probe ultrasound method. By modifying the amplitude, temperature, and duration of the ultrasound probe and surfactant/water ratio, the optimal ultrasound conditions for the microemulsion polymerization were determined. This research provides new insights into the relationship between the dispersion modes and the colloidal properties of latex, which may offer more effective and simpler routes to prepare latices with fast polymerization rate and high conversion.

Water-Resistant Latex Coatings: Tuning of Properties by Polymerizable Surfactant, Covalent Crosslinking and Nanostructured ZnO Additive

This paper deals with the development of acrylic latexes providing high-performance water-resistant coatings. For this purpose, mutual effects of anionic surfactant type (ordinary and polymerizable), covalent intra- and/or interparticle crosslinking (introduced by allyl methacrylate copolymerization and keto-hydrazide reaction, respectively) and ionic crosslinking (provided by nanostructured ZnO additive) were investigated. The latexes were prepared by the standard emulsion polymerization of methyl methacrylate, butyl acrylate and methacrylic acid as the main monomers. The addition of surface-untreated powdered nanostructured ZnO was performed during latex synthesis, resulting in stable latexes comprising dispersed nanosized additive in the content of ca 0.9−1.0 wt.% (based on solids). The coating performance with emphasis on water resistance was evaluated. It was determined that the application of the polymerizable surfactant improved coating adhesion and water-resistance, but it wasn′t able to ensure high water-resistance of coatings. Highly water-resistant coatings were obtained provided that covalent intra- and interparticle crosslinking together with ionic crosslinking were employed in the coating composition, forming densely crosslinked latex films. Moreover, coatings comprising nanostructured ZnO additive displayed a significant antibacterial activity and improved solvent resistance.

Effectiveness of Copolymer of Polymethylmethacrylate and Styrene as a Plugging Agent in Water-Based Drilling Fluids

In the development of shale gas, it is important to ensure the stability of the borehole wall. The stability of the borehole wall depends on the plugging ability of the drilling fluid, while the stabilizing ability of the drilling fluid is provided by adding the plugging agent to the fluid. Conventional plugging agents are characterized by a relatively high volume and do not allow one to effectively plug micropores and microcracks in shale rock. In this work, the PMMA-St copolymer was synthesized by emulsion polymerization of methyl methacrylate and styrene. The characteristics of the PMMA-St copolymer were studied by FT-IR, TGA, and phase analysis optical scanning methods. The results show that the size of PMMA-St nanoparticles ranges from 34 to 58 nm, and the average diameter is about 40.6 nm. The decomposition temperature of PMMA-St nanoparticles is 374.8°C, which indicates the good thermal stability of the copolymer. The PMMA-St nanoparticles have little affect on the rheological properties of water-based drilling fluids. The mud cake simulation method was used to evaluate the plugging performance of PMMA-St nanoparticles. The permeability of mud cake is 2.24 × 10-5 m2, which is close to the permeability of shale formation. When 0.5 wt % of the PMMA-St copolymer is added to the solution, the blocking rate is 70.27%. With increase in PMMA-St concentration, the blocking rate of the mud cake increases. The best stabilizing effect is achieved when the PMMA-St copolymer concentration is 1.0%. The results of the core experiments are consistent with the mud cake simulation, which indicates the excellent sealing ability of the PMMA-St copolymer. Therefore, PMMA-St nanoparticles can be effectively used as a plugging agent to ensure borehole stability in the shale formation.

Synthesis of chitosan grafted polymethyl methacrylate nanopolymers and its effect on polyvinyl chloride membrane for acetone recovery by pervaporation

In comparison to conventional nanoparticles biopolymer like chitosan based nanoparticles will be of much lower cost, non-toxic and more compatible with polymer membranes. As a cationic polymer surfactant chitosan is able to generate polymer nanoparticles during emulsion polymerization of methyl methacrylate. Accordingly, the organophilicity of polyvinyl chloride (PVC) membrane was significantly improved by incorporating chitosan grafted polymethyl methacrylate (PMMA) nanopolymers(NPs) prepared by emulsion polymerization. The NPs and the PVC-NP blend membranes were characterized. The chitosan: MMA wt. ratio and the wt.% of NP in PVC were optimized by a 5-level factorial design. The membranes prepared from i) PVC, PVC blended with 6.5 wt.% each of ii) chitosan, iii) PMMA and iv) NP showed a pervaporative flux (kg/m2h)/acetone selectivity of 0.439/24.31, 0.477/21.56, 0.461/23.41 and 0.502/27.96, respectively for 5.6 wt.% acetone in feed. The sorption and pervaporation data showed close fitting to ENSIC and six-parameter solution-diffusion model, respectively.