Search

Substrate-controlled divergent reactions of between salicylaldehydes and acrylates have been developed. By using methyl acrylate as the substrate with salicylaldehydes, a domino reaction was established, delivering coumarins with good yield (up to 81% yields) and high chemoselectivity under mild conditions. Whereas the methyl acrylate was changed to tert-butyl acrylate or iso-propyl acrylate, the classical Morita − Baylis − Hillman adducts were produced in good yields (up to 75% yields) under near exclusivity under the otherwise identical reaction conditions, without any other competitive products. Additionally, the synthetic utility of the present methodology was further demonstrated by synthetic transformation. The structure of the typical product was unambiguously established by single crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The adsorption of oligomeric peroxide of sebacic acid on aerosols was studied. The parameters of the adsorption process were found. The effect of aerosil on the polymerization of styrene (ST), methyl acrylate (MA), butyl acrylate (BA), methyl methacrylate (MMA) and butyl methacrylate (BMA) was studied. The initiators used were oligomeric sebacic acid peroxide (OPSA), benzoyl peroxide (BP), lauryl peroxide (PL) and didecanoyl diperoxy adipinate (DP). The mineral filler increases the polymerization rate of MMA, BMA, MA, BA initiated by OPSA. Under the same conditions, the polymerization rate of ST decreases with an increase in the aerosil content in the polymerization system. BP practically does not affect the polymerization rate of vinyl monomers in the presence of aerosil. The reaction of thermal decomposition of OPSA, DP, PL and BP in styrene in the presence of aerosol was studied. An increase in the content of aerosil leads to an increase in the effective decomposition constant of OPSA, DP, PL. in the case of BP, aerosil has practically no effect on the decomposition rate. [ABSTRACT FROM AUTHOR]

The novel PAMAM perylene tetracarboxydiimide 5 was synthesized via PAMAM divergent strategy, involves initial Michael addition of aminofunctional core 3 with methyl acrylate followed by exhaustive amidation of the resulting ester 4 with a large excess of ethylenediamine to afford the fluorescent dendrimer 5 with reactive amine groups of its periphery, The chosen fluorophore units are suitable donor–acceptor pair for light-harvesting materials which was in agreement with their good antibacterial activity. [ABSTRACT FROM AUTHOR]

In order to impart good application performance to locust bean gum (LBG) sizes for polyester yarns, methyl acrylate (MA) and acrylic acid (AA) monomers with a variation in feed molar ratio from 1/9 to 4/6 were grafted onto the molecular chains of native LBG to obtain LBG-g-P(MA-co-AA) products with similar grafting ratios through Fenton redox system. Effects of monomer compatibility of MA and AA on sizing performance of the LBG-g-P(MA-co-AA) were studied in terms of apparent viscosity, contact angle of sizing paste on polyester fibers, water-solubility, mechanical properties of sizing film, and adhesion to polyester fibers. It was found that grafting MA and AA with rational compatibility onto the molecular chains of LBG was an effective method to improve the application performance of the vegetable gelatin sizes, such as good toughness of sizing film and high adhesion to polyester fibers. In view of overall performance of the LBG-g-P(AA-co-MA) sizes, the appropriate feed molar ratio of MA/AA should be 3/7. [ABSTRACT FROM AUTHOR]

Acrylic resins are known for their multifarious characteristics. Diversified properties of acrylic resins have been utilised for the development of acrylic cationic electrodeposition multicolour mono-coat corrosion protective coatings by acrylic graft polymer of methyl acrylate, butyl acrylate, styrene, and methyl methacrylate in the presence of hydroxy propyl acrylate at 113–117°C in the presence of AIBN (Azo-bis iso-butyronitrile) as the initiator. The concept was to develop acrylic graft polymer wherein chemical bonds are protected against UV radiation 400 h or 18-month outdoor exposure. Developed acrylic resin has special characteristic e.g. excellent metal protection against corrosion 500 h salt spray test as per ASTM B117, excellent durability, economical primer, and finish coat in single application and meeting the International and National legislation. Resulting polymers were characterised by using FTIR spectroscopy, particle size analyser and other Morden instrumental techniques. Thus the obtained polymers have high solid content (72 ± 1%) and can be used in electrodeposition emulsion paint as a binder. The coatings are mono-coat prepared and their anticorrosion behaviour is discussed in this paper. The experimental results depict that the resin thus synthesised has high anticorrosive property, UV light stability, and excellent weather resistance. [ABSTRACT FROM AUTHOR]

In this study, the ethylene/methyl acrylate/glycidyl methacrylate (EGA) terpolymer was performed to improve the stereocomplexation and toughness of poly(L-lactic acid)/poly(D-lactic acid) (PLLA/PDLA). The effects of EGA presence on the competing formations and crystallization kinetics of homocrystallites (HCs) and stereocomplexes (SCs), phase morphology and mechanical properties of PLLA/PDLA blends were investigated. For non-isothermal melt crystallization, the degree of SC crystallinity of PLLA/PDLA blends increased after PLLA/PDLA blending with EGA. For both isothermal and non-isothermal cold crystallization, the crystallization rate of PLLA/PDLA blends increased as the mass fraction of EGA in the blends grew from 10% to 30%. The incorporation of EGA was observed to facilitate the HC-to-SC melt reorganization of PLLA/PDLA blends; moreover, a significant enhancement in the toughness of the PLLA/PDLA matrix was achieved by incorporating the EGA elastomer. When EGA was added to produce a blend containing 30 wt%, the blend's impact strength increased from 6.0 (for PLLA/PDLA) to 44.9 kJ/m2. Overall, this study provides effective guidance for achieving the melt-processability of PLLA/PDLA blends characterized by improved stereocomplexation ability and toughness. [ABSTRACT FROM AUTHOR]

In order to solve such utilization problems as excessively high apparent viscosity of sizing paste and poor adhesion to polyester fibers, caused by macromolecular inherent defects of native sesbania gum (SG), various amounts of methyl acrylate (MA) monomers were grafted onto molecular chains of native SG through initiation of Fenton's reagent and a series of SG-g-PMA with different grafting ratios were prepared. Effects of the graft modification on sizing properties of SG-g-PMA were studied in terms of apparent viscosity, contact angle of sizing paste on polyester fibers, water-solubility, mechanical properties of sizing film, adhesion to polyester fibers, and tensile properties of sized polyester warp yarns. It was found that the graft modification for SG was a simple and effective method to improve its sizing properties for polyester yarns and to omit specific viscosity reduction procedure used commonly for SG at present. In view of overall performance of SG-g-PMA sizes, the appropriate grafting ratio should be 18.70%. [ABSTRACT FROM AUTHOR]

New insights for the effects of organic solvent polarities and solvent-monomer interactions on the radical copolymerization for an important copolymer, poly(acrylonitrile-co-methyl acrylate) (PAN-co-MA), were provided in this research. Solvents, dimethylformamide (DMF), dimethylacetamide (DMAc) and dimethyl sulfoxide (DMSO), were used as reaction media. The polarity of these solvents was in the sequence of DMAc < DMF < DMSO. By studying the reactivity ratios of AN and MA, the triad fractions of the resultant copolymers, the interactions between monomers and solvents, and the compositions of copolymers at various conversions, we concluded that the solvent polarity had minimal influence on the copolymerization of AN and MA, while the solvent-monomer interactions played important roles. The interactions between monomer-monomer, monomer-solvent, and solvent-solvent, were calculated based on quantum chemistry methods. Both theoretical calculations and experimental results suggested that AN and MA in DMSO tended to aggregate locally, while they could be homogeneously dissolved in DMAc and DMF. The interactions between solvent and monomers could cause local monomer concentration variations, or 'bootstrap' effect, which is one of the critical factors affecting the copolymerization process of AN and MA and the chemical structures of the resultant polymers. [ABSTRACT FROM AUTHOR]

A series of combinations of alkyl halide with tertiary amine such as ethyl α-bromophenylacetate/tris[2-(dimethylamino)ethyl)]amine (αEBP/Me6TREN), ethyl 2-bromoisobutyrate/triethylamine (EBiB/TEA), and ethyl 2-chloropropionate/N,N,N′,N′,N′′-pentamethyldiethylenetriamine (ECP/PMDETA) have been developed as novel free radical initiators and used for the polymerizations of methyl acrylate (MA), methyl methacrylate (MMA) and styrene (St). The effects of the structure of alkyl halide and tertiary amine on the polymerization of MA were investigated. Gel permeation chromatograph (GPC) and proton nuclear magnetic resonance (1H NMR) have been utilized to analyze the end group of the obtained poly(methyl acrylate). Electron spin resonance (ESR) spectroscopy was employed to identify the structure of the radicals produced by αEBP/Me6TREN, and the results indicated that αEBP reacted with Me6TREN via a single electron transfer (SET) nucleophilic mechanism to produce corresponding ethyl α-phenylacetate radicals which subsequently initiated the polymerization of MA. As both alkyl halide and tertiary amine are commercially available at low cost, non-explosive, and ease of use and storage in comparison with conventional azo, peroxide or persulfate initiators, the combination of alkyl halide and tertiary amine as a free radical initiator is promising for large-scale practical applications. [ABSTRACT FROM AUTHOR]

Morita-Baylis-Hillman adducts, prepared from 2-nitrobenzaldehyde precursors and either methyl acrylate or methyl vinyl ketone, have been used as critical synthons in the preparation of α-[(alkylamino)methyl]cinnamate esters and their but-3-en-2-one analogs, cinnamate ester-azidothymidine (AZT) conjugates, 2-quinolone and quinoline derivatives. Computer docking studies have been conducted to explore the potential of the cinnamate ester-AZT conjugates as potential dual-action HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. The results further demonstrate the applicability of Morita-Baylis-Hillman methodology in the construction of complex drug-like scaffolds. [ABSTRACT FROM AUTHOR]

An easy, solvent-free method for the synthesis of 1-(4-chlorophenyl)pyrazolidin-3-one has been achieved by grinding 4-chlorophenyl hydrazine and methyl acrylate in the presence of base in a ball mill. A systematic investigation of the reaction has been made in order to study the various factors affecting the reaction. [ABSTRACT FROM AUTHOR]

Four new diorganotin(IV) carboxylates, [n-Bu2SnL2] (1), [Et2SnL2] (2), [Me2SnL2] (3) and [n-Oct2SnL2] (4), where L = 3-(4-chlorophenyl)-2-methylacrylate, were synthesized and characterized by elemental analysis, FT-IR, multinuclear NMR (1H, 13C, and 119Sn) and X-ray single crystal analysis for 1. A chelating bidentate ligand and six-coordinate tin centers were confirmed in the solid state by IR for all complexes and for 1 by X-ray single crystal analysis. The NMR study has shown a decrease in the coordination number of tin in solution. The complexes were screened for their in vitro antibacterial and antifungal activities. A compromised lipo/hydrophilicity and a diffusion controlled antimicrobial activity was shown by the complexes in the order 1 > 2>3 > 4. Molecular docking studies have shown hydrogen bonding and hydrophobic interactions for 1 with the target proteins of the antimicrobial strains. [ABSTRACT FROM AUTHOR]

In order to endow feather keratin with good sizing properties for all-polyester or high-polyester yarns, methyl acrylate (MA) and acrylic acid (AA) monomers with a variation in feed molar ratio from 10/90 to 30/70 were grafted onto the molecular chains of native feather keratin under equal monomer concentration. Effects of monomer compatibility of MA/AA on sizing properties of the feather keratin-g-P(AA-co-MA) were studied in terms of apparent viscosity, contact angle of sizing paste on polyester fibers, mechanical properties of sizing film, and adhesion to polyester fibers. It was found that grafting MA & AA monomers with rational compatibility onto the molecular chains of feather keratin was an effective method to improve sizing properties of grafted feather keratin, such as adhesion to polyester fibers and toughness of sizing film. In view of overall performance of the grafted feather keratin sizes, the appropriate feed molar ratio of MA/AA should be 20/80. [ABSTRACT FROM AUTHOR]

Composites of poly(lactic acid) with wood flour which was grafted by melt extruding with methyl acrylate in the presence of benzoyl peroxide (BPO) were investigated. The modification of filler (WF-g-PMA) was carried out to enhance the filler-matrix interactions, while the treated component was characterized by infrared spectrum. Properties of binary (PLA/WF, PLA/WF-g-MA) composites were analyzed as a function of the grafting monomer amount by scanning electron microscopy, differential scanning calorimeter, thermogravimetric analysis, water absorption and mechanical tests. Compared with the untreated system (PLA/WF), all treated composites showed higher interfacial compatibility as a result of chemical bonding between WF and grated monomer. All composites showed higher tensile modulus and lower strength and elongation at break as compared to pure PLA; grafting modification with methyl acrylate led to an increased stiffness and decreased water absorption of the composites because of an enhanced filler-matrix interfacial compatibility. [ABSTRACT FROM PUBLISHER]

A novel copolymer was synthesized by vinylidene chloride (VDC)/methyl acrylate (MA)/glycidyl methacrylate (GMA). The Fourier transform infrared (FTIR) and1H-nuclear magnetic resonance analyses indicated that the copolymer of VDC/MA/GMA (PVMG) was synthesized successfully. The influences of GMA on the molecular weight, melting point, and thermal stability of copolymer were investigated by gel permeation chromatograph, differential scanning calorimeter, thermogravimetric analysis–FTIR, respectively. The copolymerization eliminated the phenomenon of “double melting peaks” for poly(vinylidene chloride), and the melting point was reduced to 165°C. The GMA also enhanced the thermal stability of copolymer, which was proved by the increased decomposition temperature of copolymer. The existence of GMA caused the cross-linking of the copolymer, which contributed to the improvement of barrier performance of PVMG. [ABSTRACT FROM AUTHOR]

There is currently strong motivation due to ecological concerns to develop effective anti-biofouling coatings that are environmentally benign, durable, and stable for use by the maritime industry. The antifouling (AF) and fouling-release (FR) efficacy of amphiphilic, charged copolymers composed of ~52% acrylamide, ~34% acrylic acid, and ~14% methyl acrylate grafted to poly(dimethyl siloxane) (PDMSe) surfaces were tested against zoospores of the green algaUlva linzaand the diatomNavicula incerta. The biofouling response to molecular weight variation was analyzed for grafts ranging from ~100 to 1,400 kg mol−1, The amphiphilic coatings showed a marked improvement in the FR response, with a 55% increase in the percentage removal of diatoms and increased AF efficacy, with 92% reduction in initial attachment density of zoospores, compared to PDMSe controls. However, graft molecular weight, in the range tested, was statistically insignificant. Grafting copolymers to PDMSe embossed with the Sharklet™ microtopography did not produce enhanced AF efficacy. [ABSTRACT FROM AUTHOR]

Objectives of this study were the delivery of gamma aminobutyric acid (GABA) into the brain by means of developing brain targeted, nanosized, non-toxic and biocompatible polymeric nanoparticles, and investigating their effectiveness in epilepsy. For this purpose, GABA conjugatedN,N-dimethylacrylamide-based pegylated nanoparticles were designed and characterised for particle size, zeta potential, pH, morphology, DSC, XRD, FTIR, GABA quantification andin vitrorelease. Formulations showed smaller particle size, cationic zeta potential characteristic, possible GABA polymeric matrix interaction and prolonged release pattern. Brain responses were examined using epileptic rats. Both formulations prepared were found to increase latency of seizure, decrease ending time of convulsion, duration of severe convulsion and mortality rate significantly compared with GABA solution. When GABA concentration was measured inStratum corsatum, there was no statistical difference between GABA solution and formulations. All findings suggested enhancement in all phases of seizures indicating efficient delivery of GABA into the brain via formulations. [ABSTRACT FROM PUBLISHER]

Banana fiber (BF)-reinforced low-density polyethylene (LDPE) unidirectional composites were fabricated by the compression molding process with 40 wt% fiber loading. The fibers were modified with methylacrylate (MA) mixed with methanol (MeOH) along with 2% benzyl peroxide under thermal curing method at different temperatures (50–90 °C) for different curing times (10–50 min) in order to have better compatibility with the matrix. The effect of fiber surface modification on the mechanical properties (tensile and impact properties) of the composites were evaluated. Monomer concentration, curing temperature, and curing time were optimized in terms of polymer loading and mechanical properties. The mechanical properties were found to be improved based on the improved interaction between the reinforcement and the matrix. Optimized BFs were again treated with 2–5 wt% starch solutions and composites made of 4% starch treated BF showed the highest mechanical properties than that of MA treated composites. Scanning electron microscopy (SEM) was performed to get an insight into the morphology of the composites. Water uptake and soil degradation test of the composites were also investigated. [ABSTRACT FROM AUTHOR]

We synthesized new bi-sensitive statistical copolymers and A-B-A triblock copolymers from 2-cyclopropyl-2-oxazoline (CPOxa) and 2-methoxycarbonylethyl-2-oxazoline (MEtOxa) using 1,4-dibromobutene as a bi-functional initiating moiety. These new bi-sensitive polymers were obtained via quasi-living polymerization of the oxazoline monomers and subsequent hydrolysis of the methyl ester of MEtOxa. Their thermal conformational transitions in aqueous solution were between 30 and 60 °C and these values were dependent of the copolymer composition, polymer structure (statistical or block copolymer), and of the pH of the solution, where the polymers were dissolved. The achieved polymers could find application in biomaterial science, in microsystems and sensors, and as smart nanocarriers. [ABSTRACT FROM AUTHOR]

The viscoelastic behavior of poly(methyl methacrylate) (PMMA) homopolymer and poly(methyl methacrylate-co-methyl acrylate) random copolymers was characterized by dynamic mechanical analysis and nanoindentation. Differential scanning calorimetric results showed only one glass transition, indicating the random distribution of comonomers in the copolymers. The α relaxation temperature (Tα) and activation energy (Hα) decreased with increasing content of methyl acrylate monomers (CMA%). The β relaxation temperature (Tβ) also decreased whereas the activation energy (Hβ) showed only small variations compared with Hα. Moreover, the indention displacement and creep compliance strongly depended on CMA%. Two creep stages were found in the creep compliance curves. [ABSTRACT FROM AUTHOR]

In this study, the author has investigated the polymerization of styrene (St), methyl methacrylate, and methyl acrylate initiated with guanidinium-based ionic liquids such as guanidinium tris(pentafluoroethyl)trifluorophosphate ([gua]e3fap), guanidinium trifluoromethanesulfonate, N,N,N′N′-tetramethyl-N′′-ethylguanidinium tris(pentafluoroethyl)trifluorophosphate, and N,N,N′N′-tetramethyl-N′′-ethylguanidinium trifluoromethanesulfonate to elucidate the new possibility of ionic liquids as an initiator of radical polymerization. For example, the polymerization of St initiated with [gua]e3fap proceeded at 70°C under air and under argon. It was strongly suggested that the St-polymerization initiated with [gua]e3fap proceeds via a radical pathway, because the inhibitory effects of 2,6-di-tert-butyl-p-cresol and hydroquinone as a radical inhibitor and 1-dodecanethiol as a radical chain transfer agent were observed. [ABSTRACT FROM AUTHOR]

Catalytic dimerization of methyl acrylate by homogenous ruthenium catalysts was investigated. The effect of the addition of acidic additives, supporting ligands, polymerization inhibitor, and reaction conditions on the selectivity of dimerization was studied, and possible reaction mechanism was discussed. Conversion and selectivity were significantly affected by using triphenylarsine as supporting ligand. Under mild conditions, conversion up to 98% with good selectivity to tail-to-tail product was achieved. Dimerization of methyl acrylate by ruthenium-based homogenous catalysts. The effect of the addition of supporting ligands on selectivity was studied. Conversion and selectivity were significantly affected by using triphenyl arsine. Possible reaction mechanism to achieve the tail to tail product was discussed. [ABSTRACT FROM AUTHOR]

Electrophilic trisubstituted ethylenes, ring-disubstituted methyl 2-cyano-3-phenyl-2-propenoates, RPhCH&dbnd;C(CN)CO2CH3(where R is 2,4-(CH3)2, 3,5-(CH3)2, 4-CH3O-2-CH3, 4-C2H5O-3-CH3O, 3,4-(C6H5CH2O)2, 3-C6H5CH2O-4-CH3O, 4-C6H5CH2O-3-CH3O, 2,3-(CH2)2O, 4-CH3-3-NO2) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and methyl cyanoacetate, and characterized by CHN analysis, IR,1H and13C-NMR. All the ethylenes were copolymerized with styrene (M1) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR,1H and13C-NMR. The order of relative reactivity (1/r1) for the monomers is 4-CH3-3-NO2(0.31) > 2,3-(CH2)2O (0.26) > 3-C6H5CH2O-4-CH3O (0.20) > 2,4-(CH3)2(0.18) > 4-C6H5CH2O-3-CH3O (0.16) > 3,4-(C6H5CH2O)2(0.14) > 4-C2H5O-3-CH3O (0.13) > 4-CH3O-2-CH3(0.11) > 3,5-(CH3)2(0.08). Relatively highTgof the copolymers in comparison with that of polystyrene indicates decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (2–33% wt), which then decomposed in the 500–800°C range. [ABSTRACT FROM PUBLISHER]

The relative merits of two different Baylis–Hillman approaches toward the preparation of coumarin derivatives, containing peptide-like side chains, have been explored. In one approach, use of methyl acrylate as the activated alkene requires a protecting group strategy, an approach that is not necessary when usingtert-butyl acrylate. [Supplementary materials are available for this article. Go to the publisher's online edition ofSynthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] [ABSTRACT FROM AUTHOR]

Poly (hydroxy ethyl methyl acrylate-co-acrylic acid) pH sensitive microspheres crosslinked with N,N′-Methylenebisacrylamide were prepared by free radical emulsion polymerization. Different formulations was prepared by varying amounts of 2-hydroxy ethyl methacrylate (HEMA) acrylic acid (AA) and N,N′-Methylenebisacrylamide (NNMBA), Triprolidine hydrochloride (TPH), and hypertensive drug was loaded during in situ polymerization and in vitro release studies was performed at 37°C. DSC analysis reveals that the drug is molecularly dispersed in the microspheres. SEM studies indicate the formation of microspheres with smooth surface and spherical shape. The in vitro release studies of the microspheres were carried out in pH 1.2 and 7.4 media. [ABSTRACT FROM AUTHOR]

A series of novel hindered amine light stabilizers (HALSs) containing four hindered amine groups were designed and synthesized from diamines, methyl acrylate, and 2,2,6,6-pentamethyl-piperidine-4-ol through Michael addition and transesterification. The structures of target compounds were confirmed by 1H NMR and 13C NMR. Two of them were chosen to be evaluated for their antioxidation and anti-aging properties, compared with HALS tinuvin 770, chimassorb 944, tinuvin 622, antioxidant irganox B215, and irganox B225 in polypropylene (PP) and polyethylene (PE), and the results indicated that their oxidation resistance and photostabilization efficiency were better than HALS tinuvin 770, chimassorb 944, rinuvin 622, and antioxidant irganox B215. [ABSTRACT FROM AUTHOR]

Poly(carboxyalkyl methacrylates) were studied as a cationic-drug delivery system, at pH 6.8 and 8.0. Different polymer/drug complexes were used to prepare compressed tablets. By kinetics experiments, we have found that drug release is dependent on both the hydrophobicity of the whole complex and the pH of the environment. Furthermore, a mechanism of dissociation/erosion clearly describes the drug release from a complex formed by a polymer soluble at target pH; otherwise, a mechanism of dissolution/diffusion is depicted. Additionally, we have observed that hydrophilic fillers increase the drug release rate. Since our results using different polymer/drug complexes exhibit pH-sensitive drug release, we propose that the poly(carboxyalkyl methacrylates) have potential as a colon-specific drug-delivery system. [ABSTRACT FROM AUTHOR]

Viscosities and densities of three binary liquid mixtures, benzene + methyl acetate, benzene + methyl propanoate and benzene + methyl butanoate, have been measured at 283.15, 298.15 and 313.15 K, and atmospheric pressure. From experimental data, viscosity deviation, excess energy of activation for viscous flow, and excess molar volume were calculated and satisfactorily correlated with Redlich and Kister equation. Empirical and semiempirical equations and the predicted group-contribution method, universal automatic computer, were applied. [ABSTRACT FROM AUTHOR]

Benzocyclobutene (BCB) moieties were incorporated into a typical polyolefin, poly(methyl acrylate), by free radical copolymerization of benzocyclobutene-4-yl acrylate and methyl acrylate. The subsequent cross-linking of the generated copolymers by ring-opening reaction of BCB gave rise to shape-memory polymers. This new cross-linking process did not require cross-linker and yielded small molecules. Most importantly, submicron-sized particles within the cross-linked polymers, which were observed using atomic force microscope, were induced by this cross-linking strategy. The results of the shape-memory tests suggested that the cross-linked polymers displayed good shape-memory performance. [ABSTRACT FROM PUBLISHER]

In this paper, the thermal and chemical changes in Hibiscus sabdariffa stem fiber on graft copolymerization with methyl acrylate (MA) and acrylonitrile (AN) monomer, using a ceric ammonium nitrate – nitric acid initiator system, has been reported. Different reaction parameters such as temperature, time, initiator concentration, monomer concentration, and pH were optimized to get the maximum graft yield. The graft copolymer thus formed was characterized by FTIR, SEM, TGA, DTA, and XRD techniques. The swelling behavior of graft copolymers in methanol, n-butanol, water and di methyl formamide was studied and screened for dye uptake behavior in 0.1% gentian violet dye for seven hours. With increase in percentage grafting the percentage crystallinity, crystallinity index, and moisture absorbance were found to decrease whereas chemical resistance (against 1 N HCl and 1 N NaOH) and thermal resistance were found to increase for its various advanced applications. [ABSTRACT FROM AUTHOR]

Jute fabrics were modified with methyl acrylate (MA), ethyl acrylate (EA), and 2-hydroxyethyl acrylate (2-HEA) using UV radiation at different periods of time. It was found that 30% MA at 60 min, 15% EA at 40 min, and 15% 2-HEA at 15 min irradiation time in methanol along with photoinitiator showed the best results. Some additives, such as urea, acrylamide (AM), ethylhexyl acrylate (EHA), tripropelene glycol diacrylate (TPGDA), and trimethylol propane triacrylate (TMPTA), were incorporated into the optimized monomer solutions and monitored its effect on the properties. Various physico-mechanical properties of both treated and untreated jute fabrics were also performed. [ABSTRACT FROM AUTHOR]

A variety of techniques have been employed in order to reduce problems caused by the crystallization of paraffin during the production and/or transportation of paraffin oils and derivatives. Ethylene acrylic acid copolymer, PEAA, was esterified with 1-docosanol, DcA, in the presence of p-toluene sulfonic acid, PTSA, as a catalyst and xylene as a solvent. The produced ester was characterized by FTIR and 1H NMR. The polymeric additive was added at different doses ranged from 1000 to 5000 ppm to crude oil to reduce its pour point and viscosity. The copolymer achieved a large reduction in the pour point and the viscosity of samples of Egyptian wax crude oils. The polymer was show good reduction of pour point temperature and viscosity of the crude oil tested depending on the composition of crude oil. [ABSTRACT FROM AUTHOR]

Polystyrene, poly(methylacrylate) and poly(methyl methacrylate) four and three-arm stars were synthesized by Reversible Addition Fragmentation chain-Transfer (RAFT) polymerization by using two new dithioester-derived chain transfer agents [CTA or R-S-(C = S)Z]), CTA-1 and CTA-2. CTA-1 is a four arm CTA while CTA-2 is a three-arm CTA. These were easily synthesized from commercially available reagents and were characterized by spectroscopic techniques such as 1H-NMR, 13C-NMR, IR and mass spectrometry. It is demonstrated that the two new CTAs enable the growth of arms away from the core (i.e., core first approach). An attempt has been made to study the effect of the structure of the R-group, which is present as the core in the CTA, on the polymerization, by analyzing the detailed kinetics. This study suggests that CTA-2, with a benzylic R group, enables the controlled star polymerization of styrene while CTA-1, with a R group similar in structure to the propagating radical derived from the polymerization of methyl acrylate (MA), enables the controlled polymerization of MA although to a lesser extent. This study also reveals that the temperature of free radical initiated RAFT (star) polymerization should be chosen in such a way that it is a compromise between reasonable rate of homolysis of the initiator and the CTA (R-group). [ABSTRACT FROM AUTHOR]

The effect of fullerene (C60) on the radical polymerization of methyl acrylate (MA), in dioxane, was studied kinetically, where triphenyl bismuthonium 1,2,3,4 tetra phenyl cyclopentadiene ylide and ylide-mercuric chloride {ylide-HgCl2} complex were used as initiators. Rp, at low fullerene concentration, may be expressed as Rp ∝ [Ylide]0.5 [MA]1.0 [Full]-0.5 on the basis of the results at 60°C. The {ylide-HgCl2} complex has been found to be more efficient initiator than ylide for the polymerization. The polymer has been characterized by FTIR, 1H-NMR and 13C-NMR spectroscopic analysis. A mechanism for polymerization, involving the reactions of free radical produced by decomposition of ylide or ylide-complex (initiator) with MA and C60 in initiation steps, has been proposed. Fullerene competes with MA for free radicals and acts as a free radical inhibitor that can also be incorporated into the final polymer to produce fullerene terminated polymeric structures. [ABSTRACT FROM AUTHOR]

Various reaction parameters for the graft copolymerization of Hibiscus sabdariffa fiber with methyl acrylate, ethyl acrylate, butyl acrylate, and acrylonitrile monomer were optimized using ceric ammonium nitrate-nitric acid as initiator system. The graft copolymers thus obtained were characterized by SEM, FT-IR, and XRD. Their evaluation and X-ray diffraction studies revealed change in morphology of the grafted fiber. The percentage crystallinity and crystallinity index were found to decrease with increase in percentage grafting, however, the cellulose I form remains unchanged in the fiber after graft copolymerization, under the optimized reaction conditions. [ABSTRACT FROM AUTHOR]

The kinetics of the addition of arenesulfinic acids to methacrylic derivatives were studied. The reactions were found to be second order over a range of concentrations from 0.01 to 0.10 M. For pH values ranging from 4 to 8, the following rate constants were obtained pH the methylacrylate, chloromethylacrylate, and bromomethylacrylate with benzenesulfinic acids (278 K) were investigated: 2.37 (± 0.2).10-4 M-1s-1, 2.60 (± 0.1).10-4 M-1s-1, 3.15 (± 0.3).10-4 M-1s-1. GRAPHICAL ABSTRACT[image omitted] [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) granules were grafted with methyl acrylate (MA) from the solution containing 10% MA in methanol (86%) solvent and photo initiator (4%) for 10 min and then cured under UV radiation. MA-grafted PET films were prepared at 260°C and 5 ton pressure using heat press. Jute fabric-reinforced, MA-grafted, PET-based composites (25% fiber by weight) were fabricated by compression molding. Mechanical, thermal and soil degradation tests of the composites were performed. It was found that the MA grafted PET composites showed higher mechanical properties over the ungrafted PET/jute composite. [ABSTRACT FROM AUTHOR]

Acrylonitrile/methyl acrylate copolymers were synthesized by suspended emulsion polymerization with water as dispersed phase and monomers as continuous phase, potassium peroxydisulphate (KPS) as initiator, Span-80 as emulsifier, and poly(vinyl alcohol) (PVA) as suspending agent. Effects of reaction parameters such as water/monomer mass ratio, concentration of initiator, polymerization temperature and agitation rate on polymerization conversion and the particle size distribution of acrylonitrile/methyl acrylate copolymers were studied. It was found that polymerization conversion increased with an increase of water/monomer mass ratio, concentration of initiator and polymerization temperature, while the agitation rate had no significant effect on the polymerization conversion. Particle size distribution became narrower with an increase of water/monomer mass ratio and agitation rate. Under the same initiator concentration and polymerization temperature, particle size distribution became wider along with polymerization time. The differential scanning calorimetry (DSC) results indicated that the peak temperature of the copolymers decreased with increasing MA content. [ABSTRACT FROM AUTHOR]

Mild and efficient Triton B-catalyzed Michael addition of oximes to electron-deficient alkenes is described. This convenient methodology allows for the preparation of a variety of functionalized oxime ethers in high yield. [ABSTRACT FROM AUTHOR]

Various reaction parameters of the graft copolymerization of Hibiscus sabdariffa fiber with methyl acrylate as principal monomer and its binary mixture with acrylonitrile, acrylic acid, and acrylamide were optimized. The graft copolymers obtained were characterized by XRD, TGA-DTA, SEM, and FT-IR techniques and were evaluated for different physicochemical changes like moisture absorption and chemical resistance against 1 N NaOH and 1 N HCl. The percentage crystallinity and crystallinity index were found to decrease with increase in grafting, while there was reduction in moisture absorption and increase in chemical and thermal resistance of the graft copolymers. [ABSTRACT FROM AUTHOR]

Graft copolymerization of methyl acrylate (MA) onto OPEFB fiber has been successfully carried out using hydrogen peroxide and ferrous ammonium sulfate as initiators in an aqueous medium. The effects of reaction temperature, reaction period, and amount of monomer and initiators on the percentage of grafting were investigated. The results show that the percentage of grafting depends on reaction period and temperature as well as concentration of monomers and initiators. With 33.36 mmol of MA, the optimum percentage of grafting was obtained when the reaction was carried out using 6.00 mmol of H2O2 and 0.191 mmol of Fe2+ for 210 min at 75°C. The presence of the functional group in the grafted polymers was characterized by FTIR spectroscopy. Scanning electron microscopy was used to study the surface morphology. Thermogravimetric analysis indicated that the grafted OPEFB is thermally stable than the OPEFB [ABSTRACT FROM AUTHOR]

Atom transfer radical bulk copolymerization of MA and MMA was performed in the presence of CuCl/PMDETA as catalyst system and trichloromethyl-terminated poly(vinyl acetate) macroinitiator at 80°C. The overall monomer conversion was followed gravimetrically and chemical composition of the copolymer was determined by 1H-NMR spectrometry. The results have been used to calculate monomer reactivity ratios by linear and nonlinear methods. Reactivity ratios calculated were in the range of 0.3766-0.4988 and 1.8832-2.0963 for MA and MMA, respectively. These values were in good agreement with the values reported for a similar system in the free radical copolymerization. It was observed that the copolymerization system tends to produce a random copolymer with longer sequences of MMA than MA in the initial stage of polymerization before any significant decrease of the concentration of MMA in the monomer mixture. Copolymer microstructures in this study indicated that radical stabilization capability of MMA compared to MA is higher. The accuracy of the reactivity ratios were confirmed by 95% joint confidence limits. It was found that considering the effect of conversion in these methods makes the calculation result more accurate. The theoretical composition drifts in the comonomer mixture and copolymer as a function of the overall monomer conversion are also reported. [ABSTRACT FROM AUTHOR]

Radical copolymerization reaction of vinyl acetate (VA) and methyl acrylate (MA) was performed in a solution of benzene-d6 using benzoyl peroxide (BPO) as the initiator at 60°C. Kinetic studies of this copolymerization reaction were investigated by on-line 1H-NMR spectroscopy. Individual monomer conversions vs. reaction time, which was followed by this technique, were used to calculate the overall monomer conversion, as well as the monomer mixture and the copolymer compositions as a function of time. Monomer reactivity ratios were calculated by various linear and nonlinear terminal models and also by simplified penultimate model with r2(VA)=0 at low and medium/high conversions. Overall rate coefficient of copolymerization was calculated from the overall monomer conversion vs. time data and kp . kt-0.5 was then estimated. It was observed that kp . kt-0.5 increases with increasing the mole fraction of MA in the initial feed, indicating the increase in the polymerization rate with increasing MA concentration in the initial monomer mixture. The effect of mole fraction of MA in the initial monomer mixture on the drifts in the monomer mixture and copolymer compositions with reaction progress was also evaluated experimentally and theoretically. [ABSTRACT FROM AUTHOR]

Terpolymerization of styrene, methyl acrylate and acrylonitrile in 1,4-dioxane flushed with nitrogen, initiated by the ylide 1,2,3,4-tetraphenylcyclopentadiene-triphenylstibonium, was carried out for 1 h at 60 ± 0.2°C. The kinetic expression is Rp α [I]0.27 [Sty]0.86 [MA]0.91 [AN]0.88. It indicates non-ideal radical kinetics due to primary radical termination, as well as degradative chain-transfer reactions. The overall activation energy, calculated from the slope of the Arrhenius plot, is 47 kJ/mol. The values of reactivity ratios, calculated using the Kelen–Tüdos method, are 0.25 ± 0.05 and 0.22 ± 0.05 for r1 (Sty) and r2 (MA + AN) respectively. The NMR spectrum shows a singlet at 7.1δ for the phenyl group in styrene and three distinct peaks at 2.1δ, 2.5δ and (3.4–3.8)δ for the methoxy group in methyl acrylate. The reaction was retarded by hydroquinone, which confirms the radical mode of terpolymerization. The possible mechanism for the synthesis of terpolymer has been elucidated. [ABSTRACT FROM AUTHOR]

A series of methyl acrylate-ethyl acrylate copolymers were prepared via emulsion polymerization using a batch reactor. Some reaction parameters, such as composition and temperature, were varied in order to determine their influence on the polymerization rate. A high exothermic behavior (Trommsdorf effect) was observed when the temperature was increased. Very stable lattices were obtained and characterized by gravimetry, infrared spectroscopy, quasi-elastic light scattering (QELS), differential scanning calorimetry, and transmission electron microscopy methods. In all cases, monodispersed, small sized particles were obtained. The position annihilation parameters t 3 and I 3 of all the copolymers were also measured and related with their glass transition temperatures. [ABSTRACT FROM AUTHOR]

The optimum reaction conditions for affording maximum percentage of grafting have been established in the case of grafting of acrylonitrile (AN), methyl acrylate (MA), methyl methacrylate (MMA), and ethyl methacrylate (EMA) onto sodium salt of partially carboxymethylated guar gum (Na-PCMGG, DS = 0.497) using ceric ammonium nitrate (CAN) as a redox initiator in an aqueous medium by using different reaction parameters. Under the optimized reaction conditions, the following reactivity order of monomers was observed: AN > MA > MMA > EMA. The plausible explanation for this observed order of reactivity has been furnished. The thermal behavior of different graft copolymers of Na-PCMGG (DS = 0.497) has been studied at four different heating rates by thermogravimetric analysis (TGA) and the results obtained have been analyzed by employing Osawa as well as Freeman-Carroll (multiple heating rate) methods for the evaluation of activation energy (E). The values of E calculated at various constant conversions as well as the average activation energy values (for both the steps of thermal degradation) calculated according to Osawa as well as Freeman-Carroll methods, for all the four different graft copolymers of Na-PCMGG (DS), have been found to be in good agreement with each other. The evidence of grafting has been ascertained by spectral (IR/¹H-NMR) and scanning electron microscopic (SEM) methods. [ABSTRACT FROM AUTHOR]

An experimental investigation of comb-like polymers (CP) was conducted in three synthesis steps by using two monomers: ethyl acrylate and methyl acrylate. The synthesis of comb-like homo and copolymers was achieved by using macroinitiators. These compounds imply the formation of hydroxyl terminates polyacrylates (HTP) by a chain transfer reaction. The HTP possessed a broad molecular weight distribution (Mw/Mn&ThickSpace;=&ThickSpace;1.61). The CP was freed of its precursors and its molecular weight distribution was rather narrow (1.31–1.44). In addition, the length and number of the “comb” can be controlled. The products were characterized by UV-VIS, FTIR, Gel Permeation Chromatography (GPC), microRaman Spectroscopy (RS), Differential Scanning Calorimetry (DSC), and hydroxyl number titration. The results show that there are situations where it is possible to produce comb-like polymers of interest with high efficiency. [ABSTRACT FROM AUTHOR]

A bulky type of phosphine oxide-carboxylic acid bearing 9,10-dihydro-9,10-ethanoanthracene moiety was synthesized by the Diels-Alder reaction of 2-anthryldiphenylphosphine oxide and methyl acrylate, for which the structure was confirmed on the basis of 1 H NMR spectral data to be dimethyl 2-diphenylphosphinoyl-9,10-dihydro-9,10-ethanoanthracene-11,11- and 12,12-dicarboxylates. [ABSTRACT FROM AUTHOR]

A novel redox system, potassium diperiodatocuprate(III) [Cu (III)]-poly(vinyl alcohol) (PVA) redox system, was employed to initiate the graft copolymerization of methyl acrylate (MA) onto PVA in alkaline medium. The grafting parameters varied with concentrations of monomer, initiator, macromolecular backbone (DP=1750, M=80 000) and temperature. The formation of the graft copolymer was confirmed by Fourier transfer infrared spectroscopy (IR), scanning electron microscope (SEM), X-ray diffraction and thermogravimetric analysis (TGA). It was found that [Cu (III)]-PVA system is an efficient redox initiator for this graft copolymerization. A mechanism is introduced to explain the formation of radicals and the initiation. At the same time, the other acrylate monomers, such as methyl methacrylate, ethyl acrylate and n-butyl acrylate, were used as reductant to produce graft copolymerization. It was definitely observed that these reactions could occur in some degree. Thermal stabilities were checked by TGA and this indicated that graft copolymer was resistant to moisture absorption. [ABSTRACT FROM AUTHOR]

A novel redox system, potassium diperiodatonickelate [Ni (IV)]-chitosan, was employed to initiate the graft copolymerization of methyl acrylate (MA) onto chitosan in alkali aqueous solution. The effects of reaction variables such as monomer concentration, initiator concentration, reaction time, pH and temperature were determined. By means of a series of copolymerization, the grafting conditions were optimized. The maximum grafting percentage obtained was 404.1% when 0.3 g chitosan was copolymerized with 1.8 mL monomer at 35°C for 5 hours with [Ni (IV)]=9.4×10-4 M and the total volume was 20 mL. Ni (IV)-chitosan system is found to be an efficient redox initiator for this graft copolymerization. A single electron transfer mechanism is proposed to explain the formation of radicals and the initiation. The grafted copolymers were characterized by IR and X-ray diffraction diagrams. The thermal stability of chitosan and chitosan-g-PMA was studied by thermogravimetric analysis (TGA). [ABSTRACT FROM AUTHOR]