Methyl Acrylate Research Articles

The effect of dynamically heterogeneous interphases on the particle dynamics of polymer nanocomposites.

The entanglements of dynamically asymmetric polymer layers influence relaxations of nanoparticles in polymer nanocomposites. In this work, the dynamics of polymer-adsorbed and polymer-grafted nanoparticles in a poly(methyl acrylate) matrix polymer was investigated using X-ray photon correlation spectroscopy (XPCS) to understand the role of chain rigidity and chemical heterogeneities in particle dynamics. Locations of dynamic heterogeneities close to nanoparticles and away from particle surfaces were examined with the comparison of adsorbed and grafted nanoparticles. Our results show that the chemical heterogeneities around dispersed nanoparticles transitioned the particle dynamics from Brownian diffusion into hyperdiffusion, and moreover, the high rigidity of chains in the chemically heterogeneous interfacial layers slowed down the particle dynamics. The hyperdiffusion measured both in grafted particles and adsorbed particles was attributed to the dense interfacial mixing of dynamically heterogeneous chains.

Conformational, crystalline and rheological properties of poly(octadecyl-co-methyl acrylate) statistically random copolymers

This work reports the conformational, crystalline and rheological properties of poly(octadecyl-stat-methyl acrylate) (P(ODAx-stat-MAy)Nb), where Nb is the degree of polymerization, and x and y are the molar fraction of ODA and MA, respectively.

Diastereoselective synthesis and structure-affinity relationships of σ1 receptor ligands with spirocyclic scaffold.

Spirocyclic scaffolds play an increasing role in drug discovery as they define a rigid three-dimensional space to increase specific interactions with protein binding sites. Herein, a spirocyclic center was introduced into the lead compound 1 to rigidify its flexible benzylaminoethyl side chain. The key step of the synthesis was the reaction of different α,β-unsaturated amides 6 and 13-16 with methyl acrylate in the presence of TBDMSOTf. DFT calculations explain the mechanism of this transformation as concerted Diels-Alder reaction (functionals B3LYP and TPSS) or double (aza)-Michael addition (functionals PBE and wB97X-D). After separation of the diastereomeric spirocyclic products 8 and 17-20, LiAlH4 reduction provided the spirocyclic hydroxymethyl piperidines 21a,b-25a,b showing low nanomolar σ1 affinity (Ki < 100 nM). trans-Configured ligands (a-series) showed higher or equal σ1 affinity and higher selectivity over σ2 receptors and GluN2B-NMDA receptors than their cis-configured analogs (b-series). The additional hydroxymethyl moiety brings the log D7.4 value in a promising range. The high σ1 affinity (Ki = 3.6 nM) and the low lipophilicity result in the highest lipophilic ligand efficiency for the dispiro compound 23a (LLE = 6.0). The spirocyclic compounds reported herein and in particular the dispiro compound 23a demonstrate that ligands containing a large number of sp3 C-atoms possess favorable pharmacological (σ1 receptor affinity, receptor selectivity) and physicochemical properties (log D7.4 value) resulting in promising LLE.

Topology-controlled self-assembly of amphiphilic block copolymers.

Contemporary synthetic chemistry approaches can be used to yield a range of distinct polymer topologies with precise control. The topology of a polymer strongly influences its self-assembly into complex nanostructures however a clear mechanistic understanding of the relationship between polymer topology and self-assembly has not yet been developed. In this work, we use atomistic molecular dynamics simulations to provide a nanoscale picture of the self-assembly of three poly(ethylene oxide)-poly(methyl acrylate) block copolymers with different topologies into micelles. We find that the topology affects the ability of the micelle to form a compact hydrophobic core, which directly affects its stability. Also, we apply unsupervised machine learning techniques to show that the topology of a polymer affects its ability to take a conformation in response to the local environment within the micelles. This work provides foundations for the rational design of polymer nanostructures based on their underlying topology.

Reductive photoredox transformations of carbonyl derivatives enabled by strongly reducing photosensitizers.

Visible-light photoredox catalysis is well-established as a powerful and versatile organic synthesis strategy. However, some substrate classes, despite being attractive precursors, are recalcitrant to single-electron redox chemistry and thus not very amenable to photoredox approaches. Among these are carbonyl derivatives, e.g. ketones, aldehydes, and imines, which in most cases require Lewis or Brønsted acidic additives to activate via photoinduced electron transfer. In this work, we unveil a range of photoredox transformations on ketones and imines, enabled by strongly reducing photosensitizers and operating under simple, general conditions with a single sacrificial reductant and no additives. Specific reactions described here are umpolung C-C bond forming reactions between aromatic ketones or imines and electron-poor alkenes, imino-pinacol homocoupling reactions of challenging alkyl-aryl imine substrates, and γ-lactonization reactions of aromatic ketones with methyl acrylate. The reactions are all initiated by photoinduced electron transfer to form a ketyl or iminyl that is subsequently trapped.

Design, synthesis and antiproliferative screening of newly synthesized acrylate derivatives as potential anticancer agents.

A new series of acrylic acid and acrylate ester derivatives as modified analogs of tubulin polymerization inhibitors were designed and synthesized. The antiproliferative activity of the constructed molecules was investigated against MCF-7 breast carcinoma cells using CA-4 as positive molecule. Methyl acrylate ester 6e emerged as the most potent cytotoxic agent against MCF-7 cells, with an IC50 value of 2.57 ± 0.16 μM. Also, methyl acrylate ester molecule 6e showed good β-tubulin polymerization inhibition activity. Cellular cycle analysis showed that compound 6e can arrest MCF-7 cells at the G2/M phase. In addition, this compound produced a significant increase in apoptotic power as compared to control untreated MCF-7 cells. Furthermore, the effect of acrylate ester 6e on the gene expression levels of p53, Bax and Bcl-2 was investigated. This molecule increased the expression levels of both p53 and Bax, and decreased the gene expression level of Bcl-2 as compared to control untreated MCF-7 carcinoma cells.

Molecular hydrogen and water activation by transition metal frustrated Lewis pairs containing ruthenium or osmium components: catalytic hydrogenation assays.

The transition metal frustrated Lewis pair compounds [(Cym)M(κ3S,P,N-HL1)][SbF6] (Cym = η6-p-MeC6H4iPr; H2L1 = N-(p-tolyl)-N'-(2-diphenylphosphanoethyl)thiourea; M = Ru (5), Os (6)) have been prepared from the corresponding dimer [{(Cym)MCl}2(μ-Cl)2] and H2L1 by successive chloride abstraction with NaSbF6 and AgSbF6 and NH deprotonation with NaHCO3. Complexes 5 and 6 and the previously reported phosphano-guanidino compounds [(Cym)M(κ3P,N,N'-HL2)][SbF6] [H2L2 = N,N'-bis(p-tolyl)-N''-(2-diphenylphosphanoethyl) guanidine; M = Ru (7), Os (8)] and pyridinyl-guanidino compounds [(Cym)M(κ3N,N',N''-HL3)][SbF6] [H2L3 = N,N'-bis(p-tolyl)-N''-(2-pyridinylmethyl) guanidine; M = Ru (9), Os (10)] heterolytically activate H2 in a reversible manner affording the hydrido complexes [(Cym)MH(H2L)][SbF6] (H2L = H2L1; M = Ru (11), Os (12); H2L = H2L2; M = Ru (13), Os (14); H2L = H2L3; M = Ru (15), Os (16)). DFT calculations carried out on the hydrogenation of complex 7 support an FLP mechanism for the process. Heating 9 and 10 in methanol yields the orthometalated complexes [(Cym)M(κ3N,N',C-H2L3-H)][SbF6] (M = Ru (17), Os (18)). The phosphano-guanidino complex 7 activates deuterated water in a reversible fashion, resulting in the gradual deuteration of the three cymene methyl protons through sequential C(sp3)-H bond activation. From DFT calculations, a metal-ligand cooperative reversible mechanism that involves the O-H bond activation and the formation of an intermediate methylene cyclohexenyl complex has been proposed. Complexes 5-10 catalyse the hydrogenation of the CC double bond of styrene and a range of acrylates, the CO bond of acetophenone and the CN bond of N-benzylideneaniline and quinoline. The CC double bond of methyl acrylate adds to catalyst 9, affording complex 19 in which a new ligand exhibiting a fac κ3N,N',C coordination mode has been incorporated.

Continuous production of methyl acrylate and acrylic acid via co-activation reaction of aldehyde condensation and esterification catalyzed by siloxane-functionalized vanadium phosphorus oxide-TiO2 catalyst

Continuous production of methyl acrylate and acrylic acid via the co-activation reaction of aldehyde condensation and esterification.

Measurement and Modeling of Semi-Batch Solution Radical Copolymerization of N-tert-Butyl Acrylamide with Methyl Acrylate in Ethanol/Water.

The synthetic polymer industry is transitioning from the use of organic solvents to aqueous media in order to reduce environmental impact. However, with radical polymerization kinetics affected by hydrogen-bonding solvents, there is limited information regarding the use of water as a solvent for sparingly soluble monomers. Thus, in this paper, the radical polymerization of methyl acrylate (MA) and N-tert-butylacrylamide (t-BuAAm) is studied in water and ethanol (EtOH), as the copolymer product is of commercial interest. A series of semi-batch reactions are conducted under a range of operating conditions (i.e., reaction temperature, solvent-to-monomer ratio, and comonomer composition) to demonstrate that the copolymer can be successfully synthesized without significant drifts in product molar masses or composition. The experiments provide additional data to probe the influence of the solvent on the polymerization rate and copolymer properties, as the low monomer concentration maintained under starved-feed operation leads to a solvent-to-monomer ratio different from that in a batch system. A model that captures the influence of backbiting and solvent effects on rate, previously developed and tested against batch polymerizations, also provides an excellent description of semi-batch operation, validating the set of mechanisms and kinetic coefficients developed to represent the system.

Citronella-based polyesters by organocatalyzed ring-opening polymerization and their recyclable crosslinked films

Independence of food supply chain is a grand challenge encountered by the development of bio-based polymers. Here, we demonstrate the synthesis of amorphous aliphatic polyesters via organocatalyzed ring-opening polymerization of 9-membered lactone monomer, a novel downstream product of non-edible citronella oil. In particular, chemical transformation of trisubstituted alkene moiety owned by this renewable biomass was achieved by cross-metathesis of this bulky group with methyl acrylate. Three-armed star polymers were converted to free-standing films by UV-induced crosslinking. In particular, these crosslinked thin films could be efficiently recycled as ω-hydroxy ester upon methanolysis. This work opens a new avenue for the synthesis and application of terpene- and terpenoid-based polymers.

Influence of modification of aged spruce wood by in situ polymerization with ethyl methacrylate and methyl acrylate and paraloid B72 on color and water absorption

Influence of modification of aged spruce wood by in situ polymerization with ethyl methacrylate and methyl acrylate and paraloid B72 on color and water absorption. Wood is hydrophilic in nature, which creates problems such as dimensional instability and susceptibility to biological degradation. By using chemical modification, wood can be refined into new products with improved properties. Such a combination of wood and polymer is called a wood-polymer composite (WPC). The presented work compares the modification of aged wood by two methods. In situ polymerization with ethyl methacrylate and methyl acrylate with modification with Paraloid B72 solution. The determinants of the modifications carried out are percentage weight gain (WPG), color change and water absorption. Unmodified wood aged and unaged were the control samples. Also unaged and modified wood samples were prepared to compare results. The greatest change in color intensity and total color difference after the aging process was recorded for samples modified with Paraloid B72, and after UV light treatment - modified by the in situ polymerization. The in situ-modified samples had the lowest water absorption among aged samples, and Paraloid B72-modified samples had the lowest water absorption among unaged samples. The highest WPG was obtained from the aged samples modified by the in situ polymerization.

Risk factors for the development of bronchopulmonary pathology in workers producing synthetic polyacrylonitrile fiber

Aim of the study was to assess the risk of bronchopulmonary pathology in workers of the production of synthetic polyacrylonitrile fiber as a result of exposure to harmful chemicals and smoking tobacco products . Material and methods . During the periodic medical examination , the function of external respiration and adherence to smoking in 137 employees were studied , medical records were analyzed (025/u accounting form ). Hygienic assessment of working conditions was carried out on the basis of the results of in-situ sanitary and hygienic studies . Results and discussions . As a result of a hygienic assessment of working conditions , it was found that workers engaged in the production of polyacrylonitrile fiber are subject to the combined intermittent effects of harmful chemicals of hazard classes 1–3 ( acrylonitrile , methyl acrylate , hydrocyanide , ammonia , sodium rhodanide , sulfuric acid , methanol , isopropyl alcohol , ethylene glycol ), the content of which in the working area exceeded the maximum permissible concentrations in 1.6% of samples . The occupational risk of developing bronchopulmonary diseases in groups of workers who smoke is assessed as unacceptably high , while in people exposed to harmful chemicals , its level is 28.46 times higher than in people who are not exposed to these effects . The risk of the formation of ventilation disorders in groups of smoking workers is unacceptably high , while its level is 2.46 times higher in workers exposed to harmful chemicals than in non-workers in such conditions . In groups of workers exposed to harmful chemicals , the occupational risk of obstructive disorders is unacceptably high , in the group of smokers the risk is 2.32 times higher . Conclusions . Among the employees of the enterprise producing synthetic polyacrylonitrile fiber , the influence of tobacco smoking on the development of bronchopulmonary pathology is higher than the influence of harmful working conditions , and the use of smoking tobacco products significantly increases the negative effect of chemical pollutants .

Direct Synthesis of Partially Chain-Straightened Propylene Oligomers and P-MA Co-Oligomers Using Axially Flexible Shielded Iminopyridyl Palladium Complexes.

In this study, a series of partially chain-straightened propylene oligomers and functional propylene−methyl acrylate (P-MA) co-oligomers were synthesized with 8-alkyl-iminopyridyl Pd(II) catalysts. The molecular weight and polar monomer incorporation ratio could be tuned by using Pd(II) catalysts with various 8-alkyl-naphthyl substituents (8-alkyl: H, Me, and n-Bu). In propylene oligomerization, all the 8-alkyl-iminopyridyl Pd(II) catalysts convert propylene to partially chain-straightened (119−136/1000 C) oligomers with low molecular weights (0.3−1.5 kg/mol). Among the catalysts, Pd1 with non-substituent (H) on the ligand showed the highest activity of 5.4 × 104 g/((mol of Pd) h), generating oligomers with the lowest molecular weight (Mn: 0.3 kg/mol). Moreover, polar-functionalized propylene-MA co-oligomers with very high incorporation ratios (22.8−36.5 mol %) could be obtained in the copolymerization using these 8-alkyl-iminopyridyl Pd(II) catalysts. Additionally, Pd1 exhibited the best performance in propylene-MA copolymerization as it displayed the highest MA incorporation ratio of up to 36.5 mol%. All the three catalysts are capable of generating partially chain-straightened P-MA co-oligomers and the activities decrease gradually while the molecular weight increases with the increasing steric hindrance of the alkyl substituent (H < Me < n-Bu). Compared to Pd4 with the rigid 8-aryl substituent, the flexible 8-alkyl-iminopyridyl Pd(II) catalysts (Pd1-3) not only showed much higher activities in the propylene oligomerization, but also yielded P-MA co-oligomers with significantly higher incorporation ratios in the propylene co-oligomerization.

Synthesis of block copolymer of vinyl acetate and methyl acrylate by cobalt-mediated radical polymerization in a packed column system: simultaneous control of molecular weight, separation, and purification

Synthesis of block copolymer of vinyl acetate and methyl acrylate by cobalt-mediated radical polymerization in a packed column system: simultaneous control of molecular weight, separation, and purification

Electronic effects of amine-imine nickel and palladium catalysts on ethylene (co)polymerization

A series of bis-(aryl)-amine-imine nickel and palladium complexes with electron-donating (OMe), H, and -withdrawing (F and Br) groups at the para-aryl position were synthesized and characterized to probe the ligand electronic effects on homo- and copolymerization of ethylene. The influences of electronic perturbations on complex synthesis, polymerization property, and polymer microstructure were investigated systematically. The electronic effects of para-substituents were verified by Hammett constants and topographic steric maps of nickel and palladium complexes. Electron-rich ligands had stronger complexation ability to the nickel and palladium metal, thereby facilitating the synthesis of nickel and palladium complexes. Ethylene polymerizations at different temperatures showed that electron-deficient amine-imine nickel and palladium catalysts were more active than electron-rich analogues at low temperatures while the reverse trend was observed at high temperatures. The electronic effects of para-substituents affected polyethylene molecular weight, but had little influence on the branching density of highly branched polyethylenes. Copolymerization of ethylene and methyl acrylate (MA) using palladium catalysts demonstrated that the electron-donating group promoted copolymerization performance, and was favorable for direct insertion of MA to produce main-chain MA unit. Electronic effects of amine-imine nickel and palladium catalysts on ethylene polymerization were comprehensively summarized to electronic perturbations on the metal electrophilicity and the thermal tolerance of catalyst.

Photons and photocatalysts as limiting reagents for PET-RAFT photopolymerization

The kinetics of photoinduced electron/energy transfer - reversible addition fragmentation chain transfer (PET-RAFT) polymerization were investigated using a model system of methyl acrylate (MA) in the presence of trithiocarbonate chain transfer agents and tris(2-phenylpyridine)iridium(III) (Ir(ppy)3) as the photocatalyst. A powerful polymerization through oxygen approach was developed. Efficient PET-RAFT occurred under blue, violet, and green light with catalyst loadings of 10 ppm. Minimal polymerization was observed under orange or red light. Kinetic scaling analysis was developed to evaluate the impact of light intensity, catalyst loading and geometry of both the light source and the reaction vessel. A universal scaling law was developed for Ir(ppy)3 and other energy transfer catalyzed PET-RAFT, allowing both polymerization through oxygen and deoxygenated systems from the literature to be described across a range of light intensities, reaction conditions and geometries. Finally, the scaling analysis indicates that PET-RAFT systems should be subject to less retardation than conventional RAFT systems, due to the chain transfer agent being involved in radical generation steps.

Volatile Compound Emissions from Stereolithography Three-Dimensional Printed Cured Resin Models for Biomedical Applications.

Stereolithography three-dimensional printing is used increasingly in biomedical applications to create components for use in healthcare and therapy. The exposure of patients to volatile organic compounds (VOCs) emitted from cured resins represents an element of concern in such applications. Here, we investigate the biocompatibility in relation to inhalation exposure of volatile emissions of three different cured commercial resins for use in printing a mouthpiece adapter for sampling exhaled breath. VOC emission rates were estimated based on direct analysis using a microchamber/thermal extractor coupled to a proton transfer reaction-mass spectrometer. Complementary analyses using comprehensive gas chromatography-mass spectrometry aided compound identification. Major VOCs emitted from the cured resins were associated with polymerization agents, additives, and postprocessing procedures and included alcohols, aldehydes, ketones, hydrocarbons, esters, and terpenes. Total VOC emissions from cubes printed using the general-purpose resin were approximately an order of magnitude higher than those of the cubes printed using resins dedicated to biomedical applications at the respective test temperatures (40 and 25 °C). Daily inhalation exposures were estimated and compared with daily tolerable intake levels or standard thresholds of toxicological concerns. The two resins intended for biomedical applications were deemed suitable for fabricating an adapter mouthpiece for use in breath research. The general-purpose resin was unsuitable, with daily inhalation exposures for breath sampling applications at 40 °C estimated at 310 μg day-1 for propylene glycol (tolerable intake (TI) limit of 190 μg day-1) and 1254 μg day-1 for methyl acrylate (TI of 43 μg day-1).

Unsymmetrical Strategy on α-Diimine Nickel and Palladium Mediated Ethylene (Co)Polymerizations.

Among various catalyst design strategies used in the α-diimine nickel(II) and palladium(II) catalyst systems, the unsymmetrical strategy is an effective and widely utilized method. In this contribution, unsymmetrical nickel and palladium α-diimine catalysts (Ipty/iPr-Ni and Ipty/iPr-Pd) derived from the dibenzobarrelene backbone were constructed via the combination of pentiptycenyl and diisopropylphenyl substituents, and investigated toward ethylene (co)polymerization. Both of these catalysts were capable of polymerizing ethylene in a broad temperature range of 0-120 °C, in which Ipty/iPr-Ni could maintain activity in the level of 106 g mol-1 h-1 even at 120 °C. The branching densities of polyethylenes generated by both nickel and palladium catalysts could be modulated by the reaction temperature. Compared with symmetrical Ipty-Ni and iPr-Ni, Ipty/iPr-Ni exhibited the highest activity, the highest polymer molecular weight, and the lowest branching density. In addition, Ipty/iPr-Pd could produce copolymers of ethylene and methyl acrylate, with the polar monomer incorporating both on the main chain and the terminal of branches. Remarkably, the ratio of the in-chain and end-chain polar monomer incorporations could be modulated by varying the temperature.

Continuous Plug Flow Process for the Transesterification of Methyl Acrylate and 1,4-Butanediol by a Zn-Immobilized Catalyst for Producing 4-Hydroxybutyl Acrylate

Continuous environmentally benign and sustainable procedures for synthesizing fine chemicals are in high demand. Based on our previous report, this paper describes the developments of anchoring homogeneous Zn or Zr complexes useful for the catalytic transesterification of acrylates with diols that preferentially generate monoesters upon coordinating with the ligands of several solid supports. A flow reaction system was arranged to continuously supply a monoesterified product derived from methyl acrylate and 1,4-butanediol with the immobilized catalysts without weakening the catalytic activities under optimized conditions.

Photoinduced Clusteroluminescence Redshift of Poly(methyl acrylate) via Radicals.

One-step photopolymerization and photochromism of clusteroluminescence (CL) polymers mean that the polymer materials can be prepared on a large scale and applied widely. Herein, we reported unique photochromic CL polymers prepared by one-step radical photopolymerization. Seven copolymerized films (PMAxBA) with methyl acrylate and butyl acrylate as monomers, a cross-linked PMA (PMA-CL) film, a double-network PMAPBA film based on the first network PMA-CL, and four PMA films with increasing content of photoinitiator ethoxy benzoin (BEE) were prepared to study CL formation and transition. Experimental results prove that increasing the ratio of the PMA chains in PMAxBA enhances the photochromic effect, which verifies the main role of PMA chains with the shorter branched alkanes. Surprisingly, cross-linking in PMA-CL strengthens interchain packing and interchain through-space interactions (TSIs), leading to the formation of larger clusters and further CL redshift from 410 to 491 nm, whereas the PBA chains filled in the cross-linked network weakens interchain TSIs among PMA chains and makes CL red shift from 410 to 472 nm. In addition, as the BEE content increases in the PMA films, a higher radical concentration also promotes the formation of TSIs and clusters, which benefits the photochromism. For applications, colorless, dissolvable, and thermoplastic PMA featuring photochromism in this case can be widely used in information loading, rewriting, and multifunctional coating. This work provides a new strategy to enrich the properties of CL polymers toward diverse applications.