Conversion Of Methyl Methacrylate Research Articles

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.

Graft Copolymerization of Methyl Methacrylate and Vinyltriethoxysilane onto Natural Rubber

Preparation and characterization of natural rubber grafted with methyl methacrylate (MMA) and vinytriethoxysilane (VTES) were performed in the present work. Graft copolymerization of methyl methacryate was carried out in latex stage, and VTES was added during the graft copolymerization of MMA. FTIR and NMR spectroscopy were used to investigate the structure of graft copolymer and determination of conversion and grafting efficiency of MMA. It confirmed that the poly(methyl methacrylate) (PMMA) and silica particles (PVTES) were successfully formed in NR-graft-PMMA-PVTES graft copolymer. Conversions of MMA were about 90-100%; however, MMA grafting efficiency decreased as the MMA concentrations increased. Tensile property of NR-graft-PMMA-PVTES was found to improve compared with that of pure NR.

RAFT Dispersion Polymerization of Methyl Methacrylate in Mineral Oil: High Glass Transition Temperature of the Core-Forming Block Constrains the Evolution of Copolymer Morphology

RAFT dispersion polymerization of a prototypical methacrylic monomer, methyl methacrylate (MMA), is performed in mineral oil using various poly(lauryl methacrylate) (PLMA) precursors prepared with a trithiocarbonate-based RAFT agent. GPC analysis indicated reasonably narrow molecular weight distributions (Mw/Mn ≤ 1.39) for all diblock copolymers, with 1H NMR studies indicating high MMA conversions (≥95%) for all syntheses. An efficient one-pot synthesis protocol enabled high blocking efficiencies to be achieved when targeting higher PMMA DPs. However, the relatively high glass transition temperature (Tg) of the corresponding core-forming PMMA block unexpectedly constrains the evolution in copolymer morphology during polymerization-induced self-assembly (PISA). More specifically, well-defined PLMA22–PMMAx spheres (x = 19–39) and relatively short worms (x = 69–97) can be obtained at 90 °C when using a PLMA22 precursor but targeting higher x values (x ≥ 108) invariably leads to colloidally unstable aggregates of spheres, rather than long worms or vesicles. Interestingly, similar constraints were observed when targeting higher solids, when using n-dodecane instead of mineral oil, or when employing an alternative steric stabilizer block. Raising the PISA synthesis temperature from 90 to 115 °C (i.e., from below to above the Tg of the final PMMA block) does not alleviate this unexpected problem. Moreover, only spherical nanoparticles can be obtained at 115 °C when targeting PMMA DPs between 50 and 400 with the same PLMA22 precursor. This suggests that nanoparticle formation may occur by a chain expulsion/insertion mechanism at this relatively high reaction temperature. PLMA22–PMMAx nanoparticles were characterized in terms of their particle size and morphology using dynamic light scattering (DLS), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS). DLS and TEM studies of a 0.1% w/w dispersion of PLMA22–PMMA69 short worms indicated an irreversible worm-to-sphere transition on heating from 20 to 150 °C. Oscillatory rheology and TEM studies indicated that this thermal transition was only partially reversible for a 20% w/w dispersion of PLMA22–PMMA69 short worms.

Improving ZnO photoinitiation efficiency by surface reaction with 2-hydroxy-2-methylpropiophenone

ZnO was used as an inorganic photoinitiator in polymeric materials to reduce the pollutions of organic photoinitiators and their photolysis fragments. However, the ZnO photoinitiator suffered low monomer conversions and efficiencies. Therefore, a novel inorganic-organic hybrid ZnO photoinitiator (ZnO-TDI-1173) was prepared by the surface reaction of ZnO, on which OH groups reacted with one NCO group of toluene diisocyanate and then another NCO group reacted with 2-hydroxy-2-methylpropiophenone. The FTIR, scanning electron microscope, thermogravimetric analysis, and X-ray diffraction were characterized and proved the successful surface modification. The photoinitiated polymerization kinetics of ZnO-TDI-1173 in methyl methacrylate were studied. When the UV irradiation time was 220 s, the methyl methacrylate conversion with ZnO-TDI-1173 reached 32.14%, which was bigger than 18.26% of ZnO. This investigation demonstrated an improved photoinitiation efficiency of ZnO-TDI-1173 in comparison with that of ZnO, facilitating a new and easy method to upgrade the large ZnO powder to be an efficient photoinitiator.

Kinetics of MMA Atom Transfer Radical Polymerization Initiated by Reducing Agent in Stirred Batch Emulsion Reactor

AbstractAb initio emulsion atom transfer radical polymerization (ATRP) differs from regular emulsion polymerization because the kinetic and thermodynamic aspects of each process are very unlikely alike. This paper presents a kinetic analysis of activator generated by electron transfer (AGET) ATRP of methyl methacrylate (MMA) in a stirred emulsion reactor. The focus of the study is to assess the variation of the monomer content in the organic phase and the rate polymerization for different reaction temperatures, as well as the impact of surfactant content and stirring speed on latex stability. Poly(methyl methacrylate) (PMMA) polymer samples are analyzed by means of gravimetry, dynamic light scattering, gel permeation chromatography, and HNMR techniques to determine monomer conversion, polymer particle diameter, molecular weight distribution, and polymer molecular structure, respectively. The results show the production of PMMA of narrow polydispersity index (Ð) and low molar mass (Mn) for MMA conversion around 60% and detect two‐regions instead of a three‐regions trend of rate of polymerization (Rp) as conventional emulsion polymerization. The reaction rate increases during the nucleation stage and then flattens over an invariant trend which confirms a living feature of the AGET ATRP polymerization. The average number of radicals per latex particle (ñ) is also debated.

Lignin-methyl methacrylate polymer as a hydrophobic multifunctional material

In this work, the modification of lignin (KL) with methyl methacrylate (MMA) is presented via free-radical polymerization in the presence of potassium persulfate as an initiator. One-step purification of the reaction products was also attested for generating KL-MMA with 95 wt% yield and 85 wt% MMA conversion. The characteristics of KL-MMA were studied comprehensively employing 1H NMR, 31P-NMR, 13C-NMR, SEM, FTIR, and GPC. KL-MMA demonstrated significantly higher thermal stability and UV absorption compared with unmodified KL and PMMA homopolymer. The hydrophobicity of lignin derivatives was substantially improved via reacting with acrylate monomer (a contact angle change from 25° for KL to 88° for KL-MMA). The performance of KL-MMA as an adsorbent for humic acid (HA) was also evaluated in detail by means of a Quartz crystal microbalance with dissipation (QCM-D). The results confirmed the superior adsorption performance of KL-MMA to that of KL and PMMA for HA. The modified lignin polymer possessed a multitude of excellent features including remarkable hydrophobic properties and adsorption capacity. The product offers a wide range of applications possibly in food packaging and water purification systems.

Experimental Design and Statistical Analysis of AGET ATRP of MMA in Emulsion Polymer Reactor

AbstractThis study investigates atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) using activators generated by electron transfer (AGET) as the initiation technique in an emulsion well‐mixed 2L stirred tank reactor. The performance of the AGET ATRP of MMA is analyzed for five key independent variables, namely temperature, catalyst complex (CuBr2/dNbpy), initiator (EBiB), reducing agent (ascorbic acid), and surfactant (Brij 98). The reaction is carried out based on a two‐step polymerization procedure. A resolution 5 fractional factorial design technique is employed to assess the influence of the five independent variables on the monomer conversion, polymer average molecular weights, and polydispersity index (PDI). An input–output model is constructed from the data of 21 designed experimental tests. A statistical analysis of the results shows that the temperature is the most influential variable for the three output process responses. The initiator strongly affects the poly(methyl methacrylate) (PMMA) molecular weights. It is the least important key variable affecting MMA conversion and PDI, and the surfactant is the least one affecting PMMA Mn. On assessing the independent interactions effect, the interactions of temperature‐surfactant on conversion, and temperature‐initiator for PMMA Mn are considered. Process simulation in 3D mapping has demonstrated that model predictions agree well with experimental data.

Correlation of reactivity ratios, transition-metal salts and ester hydrolysis to radical polymerization of electron-deficient comonomers with 2-(N,N-dimethylamino)ethyl methacrylate as the inimer

The radical copolymerization of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA, M1) as the inimer and electron-deficient monomers (M2, including methyl methacrylate (MMA), acrylamide (AAm) and N,N-dimethylacrylamide (DMAAm)) with transition-metal salts (such as copperII and ironIII) as the oxidizing agent was correlated to their reactivity ratios (r1 and r2), counterions to transition-metal salts and ester hydrolysis of DMAEMA with an objective to obtain high-molecular weight (MW) branched polymers. As r1 ≈ r2 ≈ 1.0, primary chain initiation occurred even at high MMA conversion during CuSO4-DMAEMA redox-initiated radical polymerization of MMA, and thus the polymerization failed to form high-MW branched PMMA free from linear analogues. As r1 > 1.0 > r2, DMAEMA was preferentially converted into -DMAEMA- units during Fe(NO3)3-DMAEMA redox-initiated aqueous radical polymerization of AAm/DMAAm, but N,N-dimethylaminoethanol formed via hydrolysis led to lower-MW chains. Under optimal conditions with minimum hydrolysis, FeCl3-DMAEMA redox-initiated aqueous radical polymerization of DMAAm proceeded via redox-initiated reverse atom transfer radical polymerization (ATRP) generating DMAEMA-terminated chains with a carbon-chloride terminal. FeII-catalyzed self-condensing ATRP led to high-MW branched PDMAAm even under aerobic conditions.

Aromatic biobased polymer latex from cardanol

We present for the first time the aqueous emulsion radical polymerization of cardanol derived methacrylic monomer (CAMA) in order to pave the way for the replacement of styrene. This monomer was synthesized in two-step routes by epoxidation of cardanol prior to methacrylation. Polymerization of CAMA was studied both in toluene solution and in aqueous emulsion. Radical aqueous emulsion homo- and co-polymerization of CAMA with methyl methacrylate (MMA) were performed with sodium dodecyl sulfate as surfactant. Stable latexes were obtained with particle size between 25 and 75nm. CAMA and MMA conversions were monitored versus time. Influence of radical initiator was studied on gel content, showing transfer to monomer in the case of persulfate as initiator. Glass transition temperature of homoPoly(CAMA) was determined and is suitable for coating application. Photo-crosslinking was performed by thiol-ene chemistry and allowed yielding cross-linked biobased aromatic coatings.

Catalytic and inhibiting effects of ferrocene on the bulk radical–coordination polymerization of methyl methacrylate from the standpoint of formal kinetics

The kinetic curves and rates of bulk radical–coordination polymerization of methyl methacrylate initiated by the benzoyl peroxide–ferrocene system at 293–373 K, initial benzoyl peroxide concentrations of 10–4–10–1 mol/L, and a constant initial ferrocene concentration of 10–3 mol/L have been calculated using a mathematical model in which the process is considered from the standpoint of formal kinetics. The calculations have demonstrated that, at low methyl methacrylate conversions, ferrocene catalyzes the process at any benzoyl peroxide concentration; at medium and high methyl methacrylate conversions, deficient amounts of ferrocene with respect to benzoyl catalyze the process as well, while excess ferrocene inhibits the process. The observed effect is explained by the specific ferrocene–benzoyl peroxide interaction, which, depending on the ferrocene: benzoyl peroxide ratio, either increases or decreases the concentration of radicals in the reaction mass.

Hydrogenation of methyl methacrylate under mild conditions using biosynthesis Ru catalyst

Hydrogenation of methyl methacrylate (MMA) was investigated over Ru-based catalyst supported on active carbons (AC), which was prepared by bio-reduction method, using C. Platycladi (CP) leaf extract as reductant. By varying reaction temperature, hydrogen pressure and reaction time, hydrogenation of MMA over the biosynthesis Ru-based catalyst was carried out, and resulted the optimum conditions, 30 °C (room temperature), 2.0 MPa, and 50 min. The as-prepared Ru/AC catalyst showed high catalytic activity towards the hydrogenation of MMA, affording 100% of MMA conversion even under mild conditions without solvent and methyl isobutyrate was the only product.

Ru-dimethyl sulfoxide complexes as catalysts precursors for ROMP of norbornene and ATRP of methyl methacrylate

The catalytic activity of the five-coordinated [RuCl2(PPh3)(S-dmso)2] complex was investigated for ring-opening metathesis polymerization (ROMP) of norbornene (NBE) and for atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Syntheses via ROMP of polyNBE were dependent on the ethyl diazoacetate (EDA) amount, used as starting carbene source, monomer concentration, temperature, and reaction time. The best polyNBE yields were obtained at 50°C for 120min with [NBE]/[Ru]=5000 in presence of 5μL of EDA. MMA polymerization via ATRP was conducted as a function of time with different ethyl 2-bromoisobutyrate initiator and monomer concentrations. The kinetic data for ATRP show linear increase between MMA conversion and molecular weight. Kinetic studies with the six-coordinated [RuCl2(S-dmso)3(O-dmso)] complex also showed an increase in the molecular weight with conversion, but with a marked deviation from theoretical molecular weights. This is consistent with the better control in the polymerization supported by electronic and steric properties of the PPh3 ligand in the title complex

Using a Novel CFD Model to Assess the Effect of Mixing Parameters on Emulsion Polymerization

AbstractA novel computational fluid dynamics (CFD) model was developed and validated with the experimental data to explore the effect of the agitator type, rotational speed, and the installation of baffles on the methyl methacrylate conversion, particle size and number of particles of poly methyl methacrylate (PMMA) produced in an emulsion polymerization reactor. The originality of this study was to include the reaction kinetics to the population balance through nucleation and growth rates while taking into account the velocity gradients generated by the impeller rotation inside the reactor. The number density achieved by the Rushton impeller was higher than that for the pitched blade impeller. The distribution of polymer volume fraction was more uniform with the pitched blade impeller than that for the Rushton impeller.

Synthesis, characterization and application of a novel carbon bridged half-metallocene chromium catalyst for methyl methacrylate polymerization

A new carbon bridged cyclopentadienyl chromium complex of the type [(C5H4)C(CH3)2 CH2(C5H4N)]CrCl2 was prepared by treatment of CrCl3·(THF)3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups. The chromium complex was characterized by 1H NMR and elemental analysis(EA), and the crystal structure was determined by X-ray diffraction analysis. Activated by Al(i-Bu)3, the chromium complex displayed a very high activity for methyl methacrylate (MMA) polymerization. After 24 hours,more than 95.5% MMA was converted to polymethyl methacrylate (PMMA) with a viscosity average molecular weight (Wη) of 416000 g·mol−1 at 60 °C for MMA/Al(i-Bu)3/chromium catalyst molar ratio of up to 2000:20:1. Effects of temperature, molar ratios of MMA/catalyst and catalyst/cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.

Achieving High‐Conversion Bulk ATRP with Good Livingness and Well Controlled by Design and Optimization of Polymerization Temperature Profile

AbstractControlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP) is often conducted in solution processes and stopped at medium monomer conversions to yield well controlled polymer samples. A great challenge lies in running bulk CRP up to high conversions but still retaining system livingness and molecular weight control. In this work, we demonstrate the achievement of good living and well controlled high‐conversion bulk ATRP by means of design and optimizing polymerization thermal histories. The initiator‐for‐continues‐activator‐regeneration (ICAR) ATRP of methyl methacrylate (MMA) is used as a model system. Employing step functions in temperature, MMA conversions are pushed up to 98% and the PMMA samples possess polydispersities <1.3. Chain extension experiments confirm good livingness of synthesized polymers collected at high conversions.

Synteza kopolimerow poli(uretanowo-metakrylowych) z zastosowaniem makroinicjatora tetrafenyloetanouretanowego metoda polimeryzacji kontrolowanej ARGET ATRP

Poly(methyl methacrylate)-b-polyurethane-b-poly(methyl methacrylate) tri-block copolymers were synthesized for the first time using ARGET ATRP method. A specially prepared for this purpose tetraphenylethane-urethane macroinitiator (TPE-PUR-TPE) was used as a transitional product reacting with methyl methacrylate (MMA) in the presence of CuBr2 or CuCl2 catalyst and N,N,N',N”,N”-pentamethyldiethylenetriamine (PMDETA) or 2,2'-bipyridine (Bpy) as a complexing agent. It was found that both the molecular weight of the resulting copolymer versus MMA conversion and the value of ln([M]0/[M]) as a function of polymerization time increase linearly. High coefficients of linear correlation for the studied relationships indicate that the formation of tri-block copolymers takes place according to the mechanism of atom transfer radical polymerization. The results of FT-IR, 1H and 13C NMR spectral analyses as well as DSC and TGA thermal studies confirm the expected chemical structure of the synthesized macroinitiator and poly(urethane-methacrylate) copolymers produced with its involvement. Additionaly, the studies of surface properties (roughness, contact angle and SFE) of polymer films prepared from these copolymers indicate, based on the observed increase of hydrophobicity, the presence of block segments derived from PMMA.

Preparation of Composite Materials of Waste Clay and Polymethyl Methacrylate Using Mechanochemial Polymerization in an Organic Solvent

In order to use a waste clay effectively and to investigate mechanochemical polymerization as preparation method of the inorganic-organic composite materials, the mechanochemical polymerization of methyl methacrylate (MMA) was carried out by grinding the waste clay in n-heptane solvent. The waste clay was a halloysite with 16.2m2/g in specific surface area. The grinding operation was performed using a vibrating ball mill with a laboratory scale. The effect of monomer concentration in n-heptane solvent on the polymerization rate and the molecular mass of polymer were examined. As a result, the mechanochemical polymerization of MMA also proceeded by the grinding of the clay in n-heptane solvent. It was found that the polymerization rate increased with the increase of MMA concentration and that the conversion of MMA reached than 90%. Although the number average molecular mass of resulting polymer was in the order of 104 to 105, the molecular mass was decreased with the grinding time due to the scissions of polymer chains by the mechanical action. This polymerization mechanism was found to be radical reaction from the investigation of polymer tacticity. As for the composite of clay and PMMA obtained by the mechanochemical polymerization, a die molding was possible directly without kneading process.

A Novel Embed Fluorescence Method for Monitoring the Change from Emulsion Polymeriztion to Microemulsion Polymerization

In this paper, we present a novel embed fluorescence method that allows one to monitor the change from emulsion polymerization to microemulsion polymerization with low monomer contents. The microemulsion polymerization of methyl methacrylate (MMA) was investigated using N-(2-anthracene) methacrylamide (AnMA) as the probe whose fluorescence emission intensity was proportional to the conversion of MMA into the polymer.In this research, the trace amount of AnMA unit looked like embed in the MMA chain. In a solution containing 3wt% of MMA with respect to water, with the anionic surfactant of sodium dodecyl sulphate (SDS) and water-soluble initiator of potassium persulfate (KPS), the process of changing from emulsion to microemulsion has been monitored. By contrast, with the non-ionic surfactant of polyoxyethylene (20) oleyl ether (Brij98) or water-insoluble initiator of 2,2′-azobis(isobutyronitrile) (AIBN), the process of changing from emulsion to microemulsion also have been monitored.

Mechanochemical polymerization of methyl methacrylate initiated by the grinding of quartz in an n-heptane solvent

Abstract The information on mechanoradicals produced by grinding quartz in an n-heptane solvent was examined by means of electron spin resonance spectroscopy (ESR). The wet grinding of quartz was carried out by using a vibrating ball mill with a laboratory scale. The data of the ESR measurement revealed that E′ center radicals ( Si ) primarily produced from ground quartz in an n-heptane solvent and that the concentration of the mechanoradicals was approximately proportional to the specific surface area of ground quartz. The polymerization of methyl methacrylate (MMA) mechanochemically initiated by the grinding of quartz in the mixture solvent of n-heptane and MMA was also attempted by using the vibrating ball mill. The effect of the concentration of MMA monomer on the polymerization was investigated. As a result, the existence of the induction period to be observed well in radical polymerization was confirmed in all of the concentrations of MMA. It was found that the conversion of MMA increased with the decrease of MMA monomer and that the largest polymer yield was obtained at the concentration where the amount of monomer and solvent was the same in volume.

The characterization of latex particles prepared by pulsed electron beam induced emulsion polymerization

The emulsion polymerization of styrene (St) and methyl methacrylate (MMA) induced by 10MeV pulsed electron beams (PEB) was investigated. The monomer conversion of MMA and St was found to be very low so that the final prepared poly(methyl methacrylate) (P(MMA)) and polystyrene (PS) latex particles exhibit porous structures, as verified by TEM and SEM observations. The results of dynamic light scattering (DLS) and gel permeation chromatography (GPC) showed that both the particle size and the molecular weight of PS and PMMA latexes decrease with the increase of the absorbed dose. However, the molecular weights and the particle sizes of the PS and PMMA latexes change differently with the irradiation time. This work indicated that emulsion polymerization induced by high energy electron beam has an advantage over that induced by γ-ray or chemical initiators in the preparation of latex with a low molecular weight and porous structure.