Showing papers on "Ethyl acrylate published in 2008"

Thermoreversible supramacromolecular ion gels via hydrogen bonding

Abstract: We report the thermoreversible viscoelastic properties of a supramolecular ion gel. Two building blocks were used to form “supramacromolecules”. An ABA triblock copolymer (Mn = 50 000, poly(2-vinylpyridine)-b-poly(ethyl acrylate)-b-poly(2-vinylpyridine)) (P2VP−PEA−P2VP), with a mole ratio of 0.1/0.8/0.1 as a telechelic polymer, and a poly(4-hydroxystyrene) (PHS) homopolymer, with Mn = 6600 as a connector, form a physical gel via hydrogen bonding between P2VP and PHS. The thermally stable, hydrophobic ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) provided a good solvent medium for PEA from room temperature up to at least 160 °C. A solution containing 10 wt % P2VP−PEA−P2VP and 4% PHS was a liquid at elevated temperatures but on cooling formed a network at 141.5 °C. Dynamic shear moduli obtained as a function of frequency at various temperatures from 30 to 160 °C could be superposed to form excellent master curves, with a distinct plateau modulus extending over more tha...

Synthesis of Block Copolymers of Ethylene with Styrene and n-Butyl Acrylate via a Tandem Strategy Combining Ethylene “Living” Polymerization Catalyzed by a Functionalized Pd−Diimine Catalyst with Atom Transfer Radical Polymerization

Abstract: We report a new two-step tandem strategy combining two versatile “living” polymerization techniques, Pd−diimine catalyzed ethylene “living” polymerization and atom transfer radical polymerization (ATRP), for the synthesis of functionalized polyethylene (PE) diblock copolymers containing an ethylene block and a functional monomer block, such as styrene and n-butyl acrylate. The key to the success of this tandem strategy is the development of a novel functionalized Pd−diimine catalyst, [(ArNC(Me)−(Me)CNAr)Pd(CH2)3C(O)O(CH2)2OC(O)C(CH3)2Br]+SbF6- (Ar = 2,6-(iPr)2C6H3) (3), which uniquely contains a 2-bromoisobutyryl substituting group on its chelate structure. This catalyst was synthesized by convenient equimolar reaction of the acetonitrile Pd−diimine adduct, [(ArNC(Me)−(Me)CNAr)Pd(CH3)(N⋮CMe)]+SbF6- (Ar = 2,6-(iPr)2C6H3) (1), with a functional acrylate monomer, 2-(2-bromoisobutyryloxy) ethyl acrylate (BIEA). The remarkable feature of 3 lies in its unprecedented ability to catalyze ethylene “living” polymer...

Patterning on nonplanar substrates: flexible honeycomb films from a range of self-assembling star copolymers.

Abstract: The effect of glass transition temperature, Tg, on the self-assembly of “honeycomb” microstructures on nonplanar substrates was probed by the synthesis of a library of core cross-linked star polymers with different arm compositions. Star polymers based on poly(dimethyl siloxane), poly(ethyl acrylate), poly(methyl acrylate), poly(tert-butyl acrylate), and poly(methyl methacrylate) were synthesized by the “arm first” strategy using atom-transfer radical polymerization. Reaction conditions were optimized, and a series of high molecular weight star polymers were prepared in high yield. The glass transition temperature of the star polymers ranged from −123 to 100 °C which allowed the suitability for the formation of porous honeycomb-like films via the “breath figure” technique on nonplanar surfaces to be investigated. All star compositions successfully formed ordered films on flat surfaces. However, only star polymer compositions with a Tg below 48 °C could form homogeneous honeycomb coatings on the surface of...

Study of pH-responsive microgels containing methacrylic acid: effects of particle composition and added calcium.

Abstract: pH-responsive microgel dispersions contain cross-linked polymer particles that swell when the pH approaches the pKa of the ionic monomer incorporated within the particles. In recent work from our group, it was demonstrated that the mechanical properties of degenerated intervertebral discs (IVDs) could be restored to normal values by injection of pH-responsive microgel dispersions (Saunders, J. M.; Tong, T.; LeMaitre, C.; Freemont, A. J.; Saunders, B. R. Soft Matter 2007, 3, 486). These dispersions change from a fluid to a gel with increasing pH. The present work investigates the pH-dependent properties of dispersions of microgel particles containing MAA (methacrylic acid) and also the effects of added Ca2+. Two microgels are discussed: microgel A is poly(EA/MAA/AM) (EA and AM are ethyl acrylate and allyl methacrylate), and microgel B is poly(EA/MAA/BDDA) (butanediol diacrylate). The pH-dependent particle properties investigated include hydrodynamic diameters and electrophoretic mobilities. The critical c...

Differentiation of postnatal neural stem cells into glia and functional neurons on laminin-coated polymeric substrates.

Abstract: A series of polymeric biomaterials, including poly(methyl acrylate), chitosan, poly(ethyl acrylate) (PEA), poly(hydroxyethyl acrylate) (PHEA), and a series of random copolymers containing ethyl acrylate, hydroxyethyl acrylate, and methyl acrylate were tested in vitro as culture substrates and compared for their effect on the differentiation of neural stem cells (NSCs) obtained from the subventricular zone of postnatal rats Immunocytochemical assay for specific markers and scanning electron microscopy techniques were employed to determine the adhesion of the cultured NSCs to the different biomaterials and the respective neuronal differentiation The functional properties and the membrane excitability of differentiated NSCs were investigated using a patch-clamp The results show that the substrate's surface chemistry influences cell attachment and neuronal differentiation, probably through its influence on adsorbed laminin, and that copolymers based on PEA and PHEA in a narrow composition window are suitable substrates to promote cell attachment and differentiation of adult NSCs into functional neurons and glia

Beneficial Effect of Nanoclay in Atom Transfer Radical Polymerization of Ethyl Acrylate: A One Pot Preparation of Tailor-Made Polymer Nanocomposite

Abstract: The atom transfer radical polymerization (ATRP) of ethyl acrylate (EA) was carried out in bulk at 90 °C in the presence of organically modified nanoclay as an additive. A remarkable enhancement in the rate of polymerization was observed and it was compared with the ATRP of EA without nanoclay. Time of dispersion of clay in monomer (td) prior to polymerization and the extent of clay loading were found to have a positive effect on polymerization rate. The polymerization proceeded through first-order kinetics and molecular weights increased linearly with conversion, close to the targeted molecular weights. The living nature of the end group was confirmed by MALDI-TOF-mass spectrometry and a chain extension experiment. Several factors may account for this unexpectedly rapid, yet controlled ATRP of EA in the presence of nanoclay additive. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectrometry (NMR), and dynamic mechanical thermal analysis (DMTA) studies showed that the added na...

Optical resolution of (+/-)-1,2-Bis(2-methylphenyl)ethylene-1,2-diamine as a chiral framework for 2-iminoimidazolidine with 2-methylphenyl pendant and the guanidine-catalyzed asymmetric michael reaction of tert-butyl diphenyliminoacetate and ethyl acrylate.

Abstract: (±)-1,2-Bis(2-methylphenyl)ethylene-1,2-diamine, prepared from benzil and ammonium acetate, was optically resolved as a chiral framework for 2-(1-benzyl-2-hydroxyethyl)imino-1,3-dimethylimidazolidine with 2-methylphenyl pendants at the 4,5-positions. Catalysis ability of the 1,3-dimethyl-4,5-bis(2-methylphenyl)imidazolidine and the related 1,3-dibenzyl-4,5-diphenylimidazolidine was examined in the asymmetric Michael reaction of t-butyl diphenyliminoacetate and ethyl acrylate.

Scrub and stain-resistant coating

Abstract: A waterborne coating composition is provided, comprising a vinyl copolymer with an optimized level of phosphorus-containing functional groups in conjunction with at least 20% by weight of the copolymer, of ethyl acrylate, methyl acrylate or combinations thereof and one or more opacifying colorants, preferably titanium dioxide.

Synthesis and characterization of PNIPAM‐b‐(PEA‐g‐PDEA) double hydrophilic graft copolymer

Abstract: A series of well-defined double hydrophilic graft copolymers, consisting of poly(N-isopropylacrylamide)-b-poly(ethyl acrylate) (PNIPAM-b-PEA) backbone and poly(2-(diethylamino)ethyl methacrylate) (PDEA) side chains, were synthesized by successive atom transfer radical polymerization (ATRP). The backbone was firstly prepared by sequential ATRP of N-isopropylacrylamide and 2-hydroxyethyl acrylate at 25 °C using CuCl/tris(2-(dimethylamino)ethyl)amine as catalytic system. The obtained diblock copolymer was transformed into macroinitiator by reacting with 2-chloropropionyl chloride. Next, grafting-from strategy was employed for the synthesis of poly(N-isopropylacrylamide )-b-[poly(ethyl acrylate)-g-poly(2-(diethylamino)ethyl methacrylate)] (PNIPAM-b-(PEA-g-PDEA)) double hydrophilic graft copolymer. ATRP of 2-(diethylamino)ethyl methacrylate was initiated by the macroinitiator at 40 °C using CuCl/hexamethyldiethylenetriamine as catalytic system. The molecular weight distributions of double hydrophilic graft copolymers kept narrow. Thermo- and pH-responsive micellization behaviors were investigated by fluorescence spectroscopy, 1 H NMR, dynamic light scattering, and transmission electron microscopy. Unimolecular micelles with PNIPAM-core formed in acidic environment (pH = 2) with elevated temperature (≥32 °C); whereas, the aggregates turned into vesicles in basic surroundings (pH >7.2) at room temperature.

Rheological properties of polyacrylates used as synthetic road binders

Abstract: Most adhesives and binders, including bitumen for asphalt mixture production, are presently produced from petrochemicals after the refining of crude oil. The fact that crude oil reserves are a finite resource means that in the future, it may become necessary to produce these materials from alternative and probably renewable sources. Suitable resources of this kind may include polysaccharides, plant oils and proteins. This paper deals with the synthesis of polymer binders from monomers that could, in future, be derived from renewable resources. These binders consist of polyethyl acrylate (PEA) of different molecular weight, polymethyl acrylate (PMA) and polybutyl acrylate (PBA), which were synthesised from ethyl acrylate, methyl acrylate and butyl acrylate, respectively, by atom transfer radical polymerisation. The rheological properties of these binders were determined by means of oscillatory testing using a dynamic shear rheometer and combinations of stress/strain, temperature and frequency sweeps. The results indicate that PEA can be produced to have rheological properties similar to that of ‘soft’ 100/150 penetration grade bitumen, PMA with similar rheological properties to that of ‘hard’ 10/20 penetration grade bitumen, while PBA, due to its highly viscous nature and low dynamic moduli, cannot be used on its own as a binder. The synthetic polymers were found to be thermo-rheologically simple, and the shift factors, used to produce the dynamic moduli master curves, were found to fit an Arrhenius function.

Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

Abstract: Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results.

Preparation of divinylbenzene copolymer particles with encapsulated hexadecane for heat storage application

Abstract: From the viewpoint of heat storage application, encapsulation of n-hexadecane (HD) was carried out by microsuspension copolymerizations of divinylbenzene (DVB) and acrylic monomers (butyl acrylate, BA; ethyl acrylate, EA) utilizing the self-assembling of phase-separated polymer (SaPSeP) method proposed by the authors. The heat of solidification (H s) of encapsulated HD in the micron-sized, cross-linked particles was determined by the differential scanning calorimeter (DSC). H s of the encapsulated HD in poly(DVB) particles was much lower than that of pure HD, but it was increased with BA or EA content copolymerized up to that of pure HD. Such an influence of encapsulation on the H s was discussed.

Tailor‐made hybrid nanostructure of poly(ethyl acrylate)/clay by surface‐initiated atom transfer radical polymerization

Abstract: Hybrid nanoarchitecture of tailor-made Poly(ethyl acrylate)/clay was prepared by surface-initiated atom transfer radical polymerization (SI-ATRP), by tethering ATRP initiator on active hydroxyl group, present in surface as well as in the organic modifier of the clay used. Extensive exfoliation was facilitated by using these initiator modified clay platelets. Poly(ethyl acrylate) chains with controlled polymerization and narrow polydispersities were forced to be grown from within the clay gallery (intergallery) as well as from the outer surface (extragallery) of the clay platelets. The polymer chains attached onto clay surfaces might have the potential to provide the composites with enhanced compatibility in blends with common polymers. Attachment of the initiator on clay platelets was confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), elemental analysis, Wide-angle X-ray diffraction (WAXD), and microscopic analysis. Finally, end group analysis (by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry, and chain extension experiment) of the cleaved polymer and morphological study (by WAXD, Transmission Electron Microscopy), performed on the polymer grafted clays examined the effect of grafting on the efficiency of polymerization and the degree of dispersion of clay tactoids in polymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5014–5027, 2008

Fast‐swelling Superabsorbent Hydrogels from Poly(2‐hydroxy ethyl acrylate‐co‐sodium acrylate) Grafted on Starch

Abstract: Fast-swelling highly porous superabsorbent hydrogels were synthesized through a rapid radical polymerization under normal atmospheric conditions. To synthesize a biopolymer-based superabsorbent hydrogel, 2-hydroxyethyl acrylate (HEA) and sodium acrylate (AANa) were grafted on the starch backbone in an aqueous solution. The graft copolymerization reaction was carried out in the presence of ammonium persulfate (APS) as an initiator and N,N'-methylenebisacrylamide (MBA) as a crosslinker in a homogeneous medium. The chemical structure of the hydrogels was confirmed by FT-IR spectroscopy and thermogravimetric analysis (TGA). The morphology of the samples was examined by scanning electron microscopy (SEM). The results indicated that with increasing the amount of sodium acrylate both swelling capacity and swelling under load (AUL) were increased. Preliminary swelling and deswelling behaviors of the hydrogels were also studied. The effects of pH and inorganic salt on the swelling behavior of the hydrogels were investigated as well.

Synthesis of poly(ethyl acrylate) by single electron transfer-degenerative chain transfer living radical polymerization in water catalyzed by Na2S2O4

Abstract: Living radical polymerization of ethyl acrylate was achieved by single-electron-transfer/degenerative-chain transfer mediated living radical polymerization in water catalyzed by sodium dithionite. The plots of number-average molecular weight versus conversion and In[M]/[M] versus time are linear, indicating a controlled polymerization. This method leads to the preparation of α,α-di(iodo)poly(ethyl acrylate) (α,ω-di(iodo)PEtA) macroinitiator that can be further functionalized. The molecular weight distributions were determined using a combination of three detectors (TriSEC): right-angle light scattering, a differential viscometer and refractive index. The method studied in this work represents a possible route to prepare well-tailored macromolecules made of ethyl acrylate in environmental friendly reaction medium. To the best of our knowledge there is no previous report dealing with the synthesis of PEtA by any LRP approach in aqueous medium. Furthermore, the method described in this article was successfully applied in pilot scale reactions under industrial production conditions.

Chemoselective synthesis of β-amino acid derivatives by hydroamination of activated olefins using AlSBA-15 catalyst prepared by post-synthetic treatment

Abstract: β-Amino acid derivatives have a wide variety of applications viz in the synthesis of peptide analogues, precursor for amino alcohols, optically active amino acids, lactums and diamines Chemoselective anti-Markovnikov hydroamination reaction of activated olefins was effectively used to synthesize β-amino acid derivatives using AlSBA-15 and AlMCM-41 catalysts These catalysts with different Si/Al ratios were synthesized by isomorphous substitution of aluminium into the framework of SBA-15, which induces the Bronsted and Lewis acid sites The structural integrity of the catalysts was established by characterizing with XRD, N2-sorption, TEM, NH3-TPD, 27Al MAS NMR and 29Si MAS NMR techniques Hydroamination of ethyl acrylate with aniline was used as a test reaction, which gave N-[2-(ethoxycarbonyl)ethyl]aniline with high selectivity The performance of AlSBA-15 catalyst was also determined with different acrylates and amines to know the general applicability of the catalyst in hydroamination reactions

Structure and properties of tailor‐made poly(ethyl acrylate)/clay nanocomposites prepared by in situ atom transfer radical polymerization

Abstract: An in-depth study was carried out on the structure and properties of a series of poly(ethyl acrylate)/clay nanocomposites prepared by in situ atom transfer radical polymerization (PNCIs) with well-defined molecular weights and narrow molecular weight distributions. Wide-angle X-ray diffraction and transmission electron microscopy studies revealed an exfoliated clay morphology, whereas conventional solution blending generated an intercalated structure. The storage moduli of the PNCIs showed a moderate increase over that of the neat polymer [poly(ethyl acrylate)]. The sample containing 4 wt % clay (PNCI4, where the number following PNCI indicates the weight percentage of clay) exhibited the highest improvement (31.9% at 25°C). In PNCIs, the β-transition temperature showed a remarkable decrease (by 175% in PNCI4) along with a shift toward higher temperatures. This indicated the probability of the anchoring of the OH group of the clay layers to the >CO group of the pendant acrylate moiety, which was also confirmed by Fourier transform infrared analysis. Rheological measurements indicated a significant increase in the shear viscosity [by 9% in PNCI2, 15% in PNCI4, and 6% in the poly(ethyl acrylate)/clay nanocomposite with 2 wt % clay prepared by solution blending]. The PNCIs registered enhanced thermal stability, as indicated by the shift in the peak maximum temperature (388 and 392°C for the neat polymer and PNCI4, respectively) and a decrease in the rate of degradation (by 3.5% in PNCI2, 10.2% in PNCI4, and 49.3% in PNCI6). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Design and Characterization of an Adhesive Matrix Based on a Poly(ethyl Acrylate, Methyl Methacrylate)

Abstract: The main issue in the development of transdermal patches made of poly(ethyl acrylate, methyl methacrylate) (Eudragit® NE 40D, PMM) is the shrinkage phenomenon during the spreading of the latex onto the release liner. To solve this problem, the latex is usually freeze-dried and then re-dissolved in an organic solvent (method 1). To simplify the production process, we prepared an adhesive matrix by adding to the commercial PMM latex a plasticizer and an additive (anti-shrinkage agent) that avoids the shrinkage of the water dispersion spread onto the release liner (method 2). In some cases the active ingredient itself, such as potassium diclofenac (DK) and nicotine (NT), works as anti-shrinkage agent. In this work, the effects of the preparation method, types and concentrations of the plasticizer (triacetin and tributyl citrate) on the adhesive properties of the transdermal patches were investigated. The adhesive properties of the prepared patch were determined by texture analysis, peel adhesion test and shear adhesion. The PMM/plasticizer interactions were evaluated by ATR-FTIR spectroscopy. Furthermore, the in vitro skin permeation profiles of DK and NT released from the patch were determined by Franz cell method. Generally speaking, the variables that mainly modify the adhesive properties are the concentration and type of the plasticizer. The skin permeation profiles of DK and NT from the patch prepared by method 2 overlapped with those obtained with the commercial products. The results underline that the PMM latex can be used conveniently in the development of transdermal patches.

Efficient Enzymatic Acrylation Through Transesterification at Controlled Water Activity

Abstract: Enzymatic acrylation is a process of potentially strong interest to the chemical industry. Direct esterification involving acrylic acid is unfortunately rather slow, with inhibition phenomena appearing at high acid concentrations. In the present study the acrylation of 1-octanol catalyzed by immobilized Candida antarctica lipase B (Novozym 435) was shown to be as much as an order of magnitude faster when ethyl acrylate served as the donor of the acrylic group. Water activity is a key parameter for optimizing the rate of ester synthesis. The optimum water activity for the esterification of octanol by acrylic acid was found to be 0.75, that for its esterification by propionic acid to be 0.45 and the transesterification involving ethyl acrylate to be fastest at a water activity of 0.3. The reasons for these differences in optimum water activity are discussed in terms of enzyme specificity, substrate solvation, and mass transfer effects.

Self-assembled, fluorescent polymeric micelles of a graft copolymer containing carbazole for thermo-controlled drug delivery in vitro.

Abstract: A novel thermosensitive amphiphilic graft copolymer PNIPAAm-g-PCbzEA appending carbazole group was successfully designed and synthesized by the free radical copolymerization of N-isopropylacrylamide with hydrophobic precursor polymers of vinyl-functionalized poly(2-(N-carbazolyl)ethyl acrylate) (PCbzEA) in DMF. The PNIPAAm-g-PCbzEA copolymer was characterized by FTIR, 1H NMR, GPC analysis, UV–vis spectroscopy and fluorescence spectroscopy. The TEM observation shows that the graft copolymer may self-assemble into polymeric micelles exhibiting a nanospheric morphology within a narrow size range of 30–60 nm in aqueous solution. From the 1H NMR and FTIR analysis, the polymer micelles are composed of hydrophobic PCbzEA segments as the cores and the hydrophilic PNIPAAm segements as outer shells. The resulting micelles exhibited the temperature sensitivity with a lower critical solution temperature (LCST) of 31.5°C and a critical micelle concentration (CMC) of 12.9 mg/L in water. In the study of drug release, an “on–off” drug release profile was found in response to stepwise temperature changes between 20 and 40°C. The cytotoxicity assays for vero cells shows good biocompatibility of the graft copolymer in vitro. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008

Photocatalytic Oxidative Degradation of Poly(alkyl acrylates) with NanoTiO2

Abstract: The degradation of poly(alkyl acrylates) was investigated in the presence of two catalysts: commercial Degussa P-25 and $TiO_2$ synthesized by combustion synthesis $(CS-TiO_2)$. The molecular weight distributions of the polymers were measured by gel permeation chromatography. The effect of alkyl group substituents on the photodegradation of poly(alkyl acrylates) was investigated. The degradation rate of poly(alkyl acrylates) decreased with increase in the number of carbon atoms of the alkyl substituents, and the degradation of the polymers in the presence of $CS-TiO_2$ was significantly higher than that obtained with Degussa P-25. The effect of oxidizer on the UV-assisted oxidative degradation kinetics of poly(ethyl acrylate) was studied. The degradation was also investigated at various temperatures without UV, and enhancement in the oxidative degradation rate under UV exposure was observed compared to that under thermal conditions. Theoretical models for the degradation in the presence and absence of oxidizers using continuous distribution kinetics were developed to determine the kinetic parameters. The hydrogen abstraction and oxidative random chain scission rate coefficients were found to be independent of the oxidizer and were dependent only on the polymer. The overall polymer degradation rate in the presence of different oxidizers was predicted without any adjustable parameters.