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HEMA
Selected AbstractsElectroconductive Hydrogels: Electrical and Electrochemical Properties of Polypyrrole-Poly(HEMA) CompositesELECTROANALYSIS, Issue 7 2005Sean Brahim Abstract Composites of inherently conductive polypyrrole (PPy) within highly hydrophilic poly(2-hydroxyethyl methacrylate)-based hydrogels (p(HEMA)) have been fabricated and their electrochemical properties investigated. The electrochemical characteristics observed by cyclic voltammetry suggest less facile reduction of PPy within the composite hydrogel compared to electropolymerized PPy, as shown by the shift in the reduction peak potential from ,472,mV for electropolymerized polypyrrole to ,636,mV for the electroconductive composite gel. The network impedance magnitude for the electroconductive hydrogel remains quite low, ca. 100,,, even upon approach to DC, over all frequencies and at all offset potentials suggesting retained electronic (bipolaronic) conductivity within the composite. In contrast, sustained application of +0.7 V (vs. Ag/AgCl, 3,M Cl,) for typically 100,min. (conditioning) to reduce the background amperometric current to <1.0,,A, resulted in complete loss of electroactivity. Nyquist plots suggest that sustained application of such a modest potential to the composite hydrogel results in impedance characteristics that resembles p(HEMA) without evidence of the conducting polymer component. PPy composite gels supported a larger ferrocene monocarboxylate diffusivity (Dappt=7.97×10,5,cm2,s,1) compared to electropolymerized PPy (Dappt=5.56×10,5,cm2,s,1), however a marked reduction in diffusivity (Dappt=1.01×10,5,cm2,s,1) was observed with the conditioned hydrogel composite. Cyclic voltammograms in buffer containing H2O2 showed an absence of redox peaks for electrodes coated with PPy-containing membranes, suggesting possible chemical oxidation of polypyrrole by the oxidant [source] Macroporous monolithic chiral stationary phases for capillary electrochromatography: New chiral monomer derived from cinchona alkaloid with enhanced enantioselectivityELECTROPHORESIS, Issue 17 2003Michael Lämmerhofer Abstract A new chiral monomer derived from cinchona alkaloid, namely O -9-(tert -butylcarbamoyl)-11-[2-(methacryloyloxy)ethylthio]-10,11-dihydroquinine 1, was employed for the preparation of enantioselective monolithic capillary columns by an in situ copolymerization with 2-hydroxyethyl methacrylate 2 (HEMA), ethylene dimethacrylate 3 (EDMA) in the presence of cyclohexanol and 1-dodecanol as porogens (UV or thermal initiation of azobisisobutyronitrile (AIBN) as radical initiator). The porous properties and the electrochromatographic behavior of the new chiral monoliths were comparatively evaluated with previously described analogs obtained from O -9-[2-(methacryloyloxy)ethylcarbamoyl]-10,11-dihydroquinidine 4 as chiral monomer. Despite close structural and physicochemical similarities of the both chiral monomers, the pore distribution profiles of the resulting monoliths were shifted typically towards larger pore diameters with the new monomer 1. Once more, it was confirmed that a low cross-linking (10 wt% related to total monomers) and a pore diameter of about 1 ,m in the dry state provides the best electrochromatographic efficiency as a result of lower resistance to mass transfer (smaller C-term contribution to peak broadening) and more homogeneous flow profile (smaller A-term). Most importantly, as expected the new poly(1 - co -HEMA- co -EDMA) monoliths showed enhanced enantioselectivities and in addition faster separations as compared to poly(4 - co -HEMA- co -EDMA) analogs, which represents a significant improvement. Further, the elution order was reversed owing to the pseudoenantiomeric behavior of quinine- and quinidine-derived monomers. Fluorescence-labeled 9-fluorenylmethoxycarbonyl (FMOC), dansyl (DNS), 7-dimethylaminosulfonyl-1,3,2-benzoxadiazol-4-yl (DBD), carbazole-9-carbonyl (CC) amino acids could be separated with resolution values between 2 and 4 (with efficiencies typically between 100,000 and 200,000 plates/m) and fluorescence detection (variable wavelength fluorescence detector in-line with UV) yielding routinely a gain in detection sensitivities up to two orders of magnitude without specific optimization of the conditions with regards to fluorescence efficiency. [source] Spectroscopic investigation of the function of aqueous 2-hydroxyethylmethacrylate/glutaraldehyde solution as a dentin desensitizerEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2006Chuangye Qin Fourier-transform (FT)-Raman and -infrared (IR) spectroscopy were employed to investigate the function of the aqueous 2-hydroxyethylmethacrylate/glutaraldehyde solution (Gluma) as a desensitizer. 2-Hydroxyethylmethacrylate (HEMA), glutaraldehyde (GA), and the mixture of HEMA/GA (i.e. Gluma) were used to interact with dentin, collagen, hydroxyapatite (HAP), and bovine serum albumin (BSA) individually. All the interactions were monitored by an FT-Raman spectrometer. FT-IR spectroscopy was also used in this study. The results show that HEMA could be absorbed by dentin and collagen; GA could cross-link collagen and BSA; and when BSA was added to Gluma, polymerization of HEMA occurred. The results suggest that Gluma acts as a desensitizer whereby, first, GA reacts with part of the serum albumin in dentinal fluid, which induces a precipitation of serum albumin, then, second, a reaction of GA with serum albumin induces polymerization of HEMA. The function of Gluma as a desensitizer to block dentinal tubules occurs via these two reactions. [source] Identification of organic eluates from four polymer-based dental filling materialsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2003Vibeke Barman Michelsen Elution from polymer-based dental filling materials may have a potential impact on the biocompatibility of the materials. Since information from the manufacturers about ingredients in the materials often is incomplete, analyses of eluates from the materials are necessary for a better knowledge about possible harmful compounds. The aim of this study was to identify organic eluates from polymerized samples of two composites, one compomer and one resin-reinforced glass ionomer cement. Samples were immersed in ethanol or Ringer's solution. Organic leachables were analyzed by gas chromatography,mass spectrometry. Identification was confirmed with reference substances, if available. Among components detected were monomers, co-monomers, initiators, stabilizers, decomposition products and contaminants. Thirty-two substances were identified and 17 were confirmed with reference substances. From elution in Ringer's we identified 13 eluates from Tetric Ceram, 10 from Z250, 21 from Dyract and six from Fuji II LC; HEMA, HC and CQ were found in all samples. From elution in ethanol 12 eluates from Tetric Ceram, 18 eluates from Z250, 19 from Dyract and 10 from Fuji II LC were identified. The diversity of eluates from the four materials under study is demonstrated. Owing to variation between the materials, the biocompatibility including the allergenic potential may be different. [source] Structural Evolution and Copper-Ion Release Behavior of Cu-pHEMA Hybrids Synthesized In Situ,ADVANCED ENGINEERING MATERIALS, Issue 11 2009Yen-Yu Liu Abstract A novel Cu-pHEMA hybrid was successfully prepared by in situ photopolymerization of 2-hydroxyethyl methacrylate (HEMA) monomer in the presence of Cu(II) copper ions, following an in situ chemical reduction. Experimental observations indicate that intermolecular interactions such as the coupling force and hydrogen bonding between the Cu and the hydroxyl groups further stabilize the hybrid structure to a considerable extent. Localization of the metallic copper particles within the pHEMA network structure as a result of those intermolecular interactions gives rise to the formation of discretely distributed nanocrystallites with particle sizes ranging from 5 to 25,nm in diameter. A crystallographic change of the Cu nanophase from an amorphous-like to a crystalline structure is observed as the H2O:HEMA molar ratio increases, upon synthesis, accompanied with an increase in the particle size. A relatively slow and sustained release of the Cu (in the form of cupric ions) from the hybrids was measured for a time period of about 10 days, which also illustrates a Cu(II)-induced proliferation of the endothelial cells over a relatively small range of release rate of the Cu from the hybrids. Such a new type of Cu-loaded hybrid hydrogel is expected to be compatible and may be considered as a candidate biomaterial for biomedical/therapeutic uses. [source] Clean and Flexible Modification Strategy for Carboxyl/Aldehyde-Functionalized Upconversion Nanoparticles and Their Optical ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Huan-Ping Zhou Abstract Rare-earth upconversion nanoparticles (UCNPs) exhibit great potential in luminescent biolabels and other multifunctional probes; however, their applications are limited by their low water solubility and the lack of binding groups. To address these problems, a clean and flexible strategy to modify hydrophobic monodisperse UCNPs into hydrophilic ones that are capped with functional groups is developed. The modification process is implemented by direct oxidation of oleic acid ligands with ozone under specific conditions, where the oleic acid (OA) ligands on the surface of the UCNPs can be converted into azelaic acid ligands (HOOC(CH2)7COOH) or azelaic aldehyde HOOC(CH2)7CHO, as is revealed by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) measurements. This oxidation process has no significant side-effects on the morphology, phase, composition, or luminescent properties of the UCNPs. Free carboxylic acid groups on the surface endow the UCNPs with good water solubility, while aldehyde groups at the surface provide binding sites for amino-containing molecules via Schiff-base condensation, such as 2-(4-aminophenylethylyl)-5-methoxy-2-(2-pyridyl)thiazole (MPTEA) and 2-aminoethanethiol hydrochloride (NH2CH2CH2SH·HCl, HEMA). A Ce4+ sensor is constructed based on the dual-emission arising from the different spectral responses of MPTEA and the UCNPs. Facilitated by the covalent linkage between the terminal aldehyde group on the UCNPs and the amino group in HEMA, a hybrid structure of UCNPs and Au NPs is fabricated. The effective coupling between the aldehyde group and the amino group suggests that these functionalized UCNPs have potential in combining other functional units for simultaneous biolabeling, or other optical applications. [source] Functionalized, Swellable Hydrogel Layers as a Platform for Cell StudiesADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Núria Marí-Buyé Abstract This paper reports the design, synthesis and characterization of thin films as a platform for studying the separate influences of physical and chemical cues of a matrix on the adhesion, growth and final phenotype of cells. Independent control of the physical and chemical properties of functionalized, swellable hydrogel thin films is achieved using initiated chemical vapor deposition (iCVD). The systematic variation in crosslink density is demonstrated to control the swelling ability of the iCVD hydrogel films based on 2-hydroxyethyl methacrylate (HEMA). At the same time, the incorporation of controllable concentrations of the active ester pentafluorophenyl methacrylate (PFM) allows easy immobilization of aminated bioactive motifs, such as bioactive peptides. Initial cell culture results with human umbilical vein endothelial cells (HUVEC) indicate that the strategy of using PFM to immobilize a cell-adhesion peptide motif onto the hydrogel layers promotes proper HUVEC growth and enhances their phenotype. [source] Synthetic Strategies for Hybrid Materials to Improve Properties for Optoelectronic Applications,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2008Olga García Abstract We report, for the first time to the best of our knowledge, a systematic study to relate the laser action from BODIPY dyes, doped into monolithic hybrid matrices, with the synthetic protocols of the final materials prepared via sol-gel. To this aim, the influence of both the hydrolysis time, increased in a controlled way, and the nature of the neutralization agent (pyridine, 3-amino-propyltriethoxy-silane (APS), N -[3-(trimethoxysilyl)propyl]-ethylene diamine (TSPDA), and N1 -[3-(trimethoxysilyl)propyl]- diethylene triamine (TSPTA) on the laser action of PM567, incorporated into hybrid matrices based on copolymers of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA), with methyltriethoxysilane (TRIEOS) as inorganic precursor, was analyzed. The presence of the amine-modified silane TSPDA as neutralization agent, which is able at the same time to be anchored to the inorganic network enhancing the inorganic-organic compatibility through the matrix interphase, and utilization of hydrolysis times lower than 10 minutes, increased significantly the lasing efficiency and photostability of dye. The extension of this study to the laser behavior of BODIPY dyes embedded in other different hybrid materials based on hydrolyzed-condensed copolymers of MMA with 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) in a 1/1 volumetric proportion, validates the generalization of the above conclusions, which provide guides for the optimization of the synthesis of organic-inorganic hybrid materials with optoelectronic innovative applications independently of their composition. [source] Temperature- and pH-Sensitive Multicolored Micellar ComplexesADVANCED MATERIALS, Issue 23 2009Yong-Yong Li Novel multicolored micellar complexes self-assembled from P(NIPAAm- co -EIPPMMA,·,Eu(DMB)3)- b -PVPhol and P(NIPAAm- co -HEMA,·,FITC)- b -PVP polymers are prepared. These complexes exhibit temperature- and pH-dependent fluorescence, suggesting promising applications for in vivo sensing of the pH and temperature in complicated microenvironments. [source] Copper(II) Triflate as a Source of Triflic Acid: Effective, Green Catalysis of Hydroalkoxylation ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Mathieu J.-L. Abstract The hydroalkoxylation of dicyclopentadiene (DCPD) and norbornene (NB) with 2-hydroxyethyl methacrylate (HEMA) for the synthesis of industrially relevant monomers has been investigated with various metal-based Lewis acids and strong Brønsted acids. In the absence of other additives, copper(II) triflate is the most efficient catalyst system. Kinetics, electron spin resonance (ESR), catalyst poisoning and cross experiments indicate that triflic acid (TfOH) is the true active catalyst in these reactions. This in situ generation of TfOH occurs via reduction of Cu(OTf)2 by the olefin reagent (DCPD, NB). The copper ions present in the reaction mixture act as radical polymerization retardants, preventing polymerization of HEMA (which is observed with most other metal salts and strong Brønsted acids investigated), thus improving the selectivity and yield (up to 95%) for the desired products. These observations have led to the development of a highly effective green process, using bulk reagents (no solvent) and a cheap, metal-free catalyst system, based on TfOH and a phenolic radical inhibitor (2,5-di- tert -butylhydroxytoluene, BHT). [source] An investigation into the morphology and electro-optical properties of 2-hydroxy ethyl methacrylate polymer dispersed liquid crystalsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Huey-Ling Chang Abstract Polymer dispersed liquid crystal (PDLC) films are fabricated using E7 liquid crystals, tetraethylene glycol diacrylate (TeGDA) crosslinking agent, and 0,66.49 mol % 2-hydroxy ethyl methacrylate (HEMA). The effects of different levels of HEMA addition on the microstructure and electro-optical properties of the PDLC samples are examined using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and UV-Vis spectroscopy, respectively. The results show that the refractive index of the PDLC films is insensitive to the level of HEMA addition. However, an increasing HEMA content improves the degree of phase separation during the polymerization process and increases the size and uniformity of the liquid crystal domain. As a result, the electro-optical properties of the PDLC films are significantly improved as the level of HEMA addition is increased. Overall, the results show that a PDLC comprising 40 wt % E7 liquid crystals, 33.51 mol % TeGDA and 66.49 mol % HEMA has a high contrast ratio (13 : 1) and a low driving voltage (10 V) and is therefore an ideal candidate for a wide variety of intelligent photoelectric applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Lower critical solution temperature determination of smart, thermosensitive N -isopropylacrylamide- alt -2-hydroxyethyl methacrylate copolymers: Kinetics and physical propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Mohammad M. Fares Abstract The lower critical solution temperatures (LCSTs) were verified and determined for different molar feed ratios of N -isopropylacrylamide (NIPAAm) and 2-hydroxyethyl methacrylate (HEMA) monomers with ultraviolet spectroscopy and differential scanning calorimetry techniques. Increases in the NIPAAm monomer content played a crucial role in the LCST, which increased up to 36.7°C at 50 mol %. However, a further increase in the NIPAAm monomer content steadily reduced the LCST, which decreased to 33°C at 100 mol % NIPAAm [i.e., pure poly(N -isopropylacrylamide)]. The rate of copolymerization, assessed by the conventional conversion (%),time method, and the apparent activation energies were determined. The reactivity ratios of the monomers, determined by the Kelen,Tudos and Fineman,Ross techniques, together with the results of an equation, showed that the copolymer which formed was an alternating copolymer. The Q,e values for the NIPAAm monomer were determined. The equation showed the linear Arrhenius behavior of ln(r1r2) versus the reciprocal of the temperature (where r1 and r2 are the reactivity ratios of NIPAAm and HEMA, respectively): the activation energy difference [i.e., (E12 + E21) , (E11 + E22), where E12, E21, E11, and E22 are various activation energies] was found to be ,109 kJ/mol. The copolymers were characterized with 1H-NMR, 13C-NMR, Fourier transform infrared, ultraviolet,visible, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy techniques. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis of a new photoreactive gelatin with BTDA and HEMA derivativesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Fan-Chun Ding Abstract A novel bio-affinitive, photocuring, and membrane-forming gelatin derivative was synthesized in this study. This process was based on the amide formation between carboxylic acid and the amine in methanol,water media using dicyclohexyl-carbodiimide (DCC) as a condenser. Gelatin and glycine were the sources of amine in the model reaction. Since there were two anhydride groups in each 3,3,,4,4,-benzophenone tetra-carboxylic dianhydride (BTDA) molecule, two 2-hydroxyethyl methacrylate (HEMA) molecules were used to induce the ring-opening reaction of BTDA and release two carboxylic acid groups. The resulting photoreactive gelatin was called GE-BTHE, of which the photoreactive component was the ketone groups of BTDA and HEMA that played the role of double bond supplier. This photoreactive gelatin could be converted from the transparent liquid phase into swollen membrane by a 6-min irradiation of high pressure mercury lamp. The most efficient irradiation was at 267 nm and the highest degree of swelling of the cured GE-BTHE membrane could reach 5.9. The elongation from the dried gel remained 5,10%, i.e., relatively elastic. The properties of this gelatin derivative were investigated using amide formation analysis, calculation of the gel content and the swelling ratio, and monitoring of the photocuring process. The GE-BTHE synthesized in this study should be very potential in applications such as protective wound dressings and hemostatic absorbents for minimally invasive surgery. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Spectral characterization of lysozyme adsorption on dye-affinity beadsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Nilgün Basar Abstract Cibacron Blue F3GA-attached magnetic poly(2-hydroxyethyl methacrylate) [mPHEMA] beads were prepared by suspension polymerization of HEMA in the presence of magnetite (Fe3O4) nanopowder. Average diameter size of the mPHEMA beads was 150,200 ,m. The characteristic functional groups of Cibacron Blue F3GA-attached mPHEMA beads were analyzed by Fourier transform infrared spectrometer (FTIR) and Raman scattering spectrometer. The lysozyme adsorption and desorption characteristics of Cibacron Blue F3GA-attached mPHEMA beads were also investigated using FTIR and Raman spectroscopic techniques. When the Raman spectrum of lysozyme adsorbed mPHEMA is evaluated characteristic Amide-I band appears at 1657 cm,1. The intensity of this band decreases in the spectrum of lysozyme desorbed mPHEMA sample. When the characteristic bands of lysozyme adsorbed and desorbed mPHEMA samples are compared, the band intensities of desorbed sample are lower than those of lysozyme adsorbed sample except for the band appearing at 656 cm,1 (Tyr vCS). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis, characterization, and antimicrobial properties of novel quaternary amine methacrylate copolymersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Supriya Punyani Abstract A novel amine methacrylate monomer trimethylolpropane trimethacrylate,piperazine,ethyleneglycol dimethacrylate (TMPTMA-PPZ-EGDMA) was synthesized by amination of trimethylolpropane trimethacrylate (TMPTMA) with excess of piperazine (PPZ) followed by reaction with ethyleneglycol dimethacrylate (EGDMA). Copolymerization of TMPTMA-PPZ-EGDMA with 2-hydroxyethyl methacrylate (HEMA) was carried out by free radical polymerization using ammonium persulfate (APS) and N,N,N,,N,-tetramethyl ethylenediamine (TEMED) as a redox initiator. The copolymers obtained were then quaternized with 1-iodooctane. The monomers were characterized by FTIR and 1H NMR spectral studies. The molecular weights and polydispersity values of the monomers were determined with gel permeation chromatography. Quaternized copolymers containing more than 20% amine methacrylate monomer showed microporosity in the range of 9.9,10.4 ,m. The antibacterial activity of the quaternized copolymers against Escherichia coli and Staphylococcus aureus was studied using UV,vis spectrophotometer and scanning electron microscopy. Quaternized copolymers showed broad-spectrum contact-killing antibacterial properties without releasing any active agent as checked by iodide selective ion meter. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] FTIR, 1H-NMR spectra, and thermal characterization of water-based polyurethane/acrylic hybridsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008O. R. Pardini Abstract Polyurethane (PU) polymer was synthesized following a prepolymer mixing process, by polyaddition of isophorone diisocyanate (IPDI), poly(propylene glycol) (PPG), 2-hydroxyethyl methacrylate (HEMA), and 2,2-bis(hydroxymethyl)propionic acid (DMPA). The PU anionomer having 2-ethoxymethacrylate terminal groups was dispersed in water by prior neutralization of carboxylic acid groups of DMPA with triethylamine (TEA), chain extended with hydrazine (HZM) in water and a dispersion polymerization with methyl methacrylate/n -butyl acrylate/acrylic acid mixture was performed. The above polymerization reactions lead to the formation of PU/acrylic hybrids having a chemical bond between PU and acrylic moieties. Acrylic content was varied from 0 to 50 wt % and samples were purified to eliminate oligomers and impurities before characterization. The FTIR and 1H-NMR spectra of these purified hybrid samples were obtained and bands and peaks assignments were discussed. Thermal properties (DSC and TGA) were also discussed. Breaking hydrogen bonds is the main reason for changes in properties with increasing acrylic content. Particle size data of dispersions is also presented and discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Water sorption kinetics in light-cured poly-HEMA and poly(HEMA- co -TEGDMA); determination of the self-diffusion coefficient by new iterative methodsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Irini D. Sideridou Abstract The present investigation is concerned with the determination of self-diffusion coefficient (D) of water in methacrylate-based biomaterials following Fickian sorption by two new methods: the Iterative and the Graphical methods. The D value is traditionally determined by means of the initial slope of the corresponding sorption curve and the so-called Stefan's approximation. The proposed methods using equations without approximations and data resulting from the whole sorption range reach to accurate values of D, even when the sorption curve does not present an initial linear portion. In addition to D, the Graphical method allows the extrapolation of the mass of the sorbed water at equilibrium (M,), even when the equilibrium specimen's mass fluctuates around its limited value (m,). The test of the proposed procedures by means of ideal and Monte Carlo simulated data revealed that these methods are fairly applicable. The obtained D values compared with those determined by means of the Stephan's method revealed that the proposed methods provide more accurate results. Finally, the proposed methods were successfully applied to the experimental determination of the diffusion coefficient of water (50°C) in the homopolymer of 2-hydroxyethyl methacrylate (HEMA) and in the copolymer of HEMA with triethylene glycol dimethacrylate (98/2 mol/mol). These polymers were prepared by light curing (, = 470 nm) at room temperature in presence of camphorquinone and N,N -dimethylaminoethyl methacrylate as initiator. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Synthesis, characterization, and cure reaction of methacrylate-based multifunctional monomers for dental compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Mousa Ghaemy Abstract The synthesis of 2,2-bis[(4-(2-hydroxy-3-methacryloxyethoxy)phenyl]propane (BHEP) and (1-methacryloxy-3-ethoxymethacryloxy-2-hydroxy)propane (MEHP) for use as the monomer phase in dental composites are reported. The monomers were prepared by the reaction of 2-hydroxyethyl methacrylate (HEMA) with diglycidyl-ether of bisphenol A (DGEBA) and with glycidyl methacrylate (GMA), respectively. The progress of the reaction was followed by measuring the disappearance of the epoxide group peak using FTIR and the structure of the monomers was characterized by 1H-NMR. BHEP and MEHP have lower viscosity because of the presence of long aliphatic spacer on both sides of the aromatic ring in BHEP and the absence of aromatic rings and the presence of only one hydroxyl group in each molecule of MEHP. Thermal curing of the monomers was conducted in a DSC using benzoyl peroxide as an initiator. Photopolymerization of the monomers was also conducted with the visible light using camphorquinone and N,N -dimethylaminoethyl methacrylate as the photoinitiating system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Surface modification of nylon-6 fibers for medical applicationsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007S. E. Shalaby Abstract Hydroxyethylmethacrylate (HEMA) is considered to be one of the important vinyl monomers. The ability of polyhydroxyethyl-methacylate (PHEMA) graft sites to consecutive chemical modification makes the use of nylon-6 fibers grafted with PHEMA a feasible bed for immobilization of a wide range of biologically active reagents, specially enzymes, drugs, cells, and immunadsorbents. Stemming from the above discussions, in this article, the graft copolymerization of HEMA onto modified nylon-6 fibers containing Polydiallyldimethylammonium chloride (PDADMAC) in the presence of Cu2+,K2S2O8 as a redox initiating system was carried out, with very high rate and almost without homopolymer formation. The factors affecting the grafting reaction (monomer, K2S2O8 and cupric ion concentrations, the amount of PDADMAC as well as the reaction temperature) were studied. Kinetic investigation revealed that the rate of grafting (Rp) of HEMA onto modified nylon-6 fibers is proportional to [HEMA]1, [CuSO4.5H2O] 0.7, [PDADMAC]0.4, and [K2S2O8]1.4. The overall activation energy was calculated (71 KJ/mol). The fine structure, surface topography, thermal and electrical properties of parent and grafted nylon-6 fibers were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3788,3796, 2007 [source] Preparation and adsorption characteristic of polymeric microsphere with strong adsorbability for creatinineJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 3 2008Baojiao Gao Abstract Cross-linking terpolymer microspheres (HEMA/NVP/MBA; it can also be designated as HEMA/NVP because HEMA and NVP are main components) with an average diameter of 180 µm, were prepared via inverse suspension copolymerization by using 2-hydroxyethyl methacrylate (HEMA) and N -vinylpyrrolidone (NVP) as monomers and N,N,-methylene bisacrylamide (MBA) as cross-linked agent. The microsphere HEMA/NVP was chemically modified with 3,5-dinitrobenzoyl chloride (DNBC), and the functional microsphere DNBZ-HEMA/NVP, on which a great number of 3,5-dinitrobenzoate group (DNBZ) were bound, was obtained. The functional microsphere DNBZ-HEMA/NVP were characterized with FTIR and the chemical analysis method. The adsorption characteristics and mechanism of the absorption of DNBZ-HEMA/NVP for creatine was mainly studied. The results of static adsorption experiments show that the functional microsphere DNBZ-HEMA/NVP has very strong adsorption ability for creatinine, and the saturated adsorption amount is 25 mg/g. The adsorption capacity of the functional microsphere DNBZ-HEMA/NVP for creatinine is enhanced 20 times as against unmodified microsphere HEMA/NVP. The adsorption capacity is smaller, at lower and higher pH, and has a maximum as pH 8.5. The higher the salinity of the medium, the smaller the adsorption capacity. The adsorption capacity decreases with increasing temperature. The study results show that the adsorption of the microsphere DNBZ-HEMA/NVP for creatinine is ascribed to a chemical adsorption by driving of electrostatic interaction. © 2008 Wiley Periodicals, Inc. J Biochem Mol Toxicol 22:166,174, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20221 [source] Preparation and characterization of infection-resistant antibiotics-releasing hydrogels rods of poly[hydroxyethyl methacrylate- co -(poly(ethylene glycol)-methacrylate]: Biomedical application in a novel rabbit penile prosthesis modelJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008M. Yakup Ar Abstract In this work, preparation and characterization of novel three different antibiotic loaded penile prosthesis in the rod form were investigated by copolymerization of 2-hydroxyethylmethacrylate (HEMA) with poly(ethylene glycol)-methacrylate, (PEG-MA). To achieve this goal, a series of novel copolymer hydrogels were prepared in rod form using HEMA and PEG-MA monomers via UV initiated photopolymerization. The thermal stability of the copolymer was found to be lowered by increase in the ratio of PEG-MA in the rod structure. Contact angle measurements on the surface of copolymer hydrogel demonstrated that the copolymer gave rise to a significant hydrophilic surface compared with pure poly(HEMA). The blood protein adsorption and platelet adhesion were significantly reduced on the surface of the copolymer hydrogels compared with control pure poly(HEMA). Poly(HEMA:PEG-MA;1:1)-1 formulation containing different antibiotics (20 mg antibiotic/g polymer) released about 90, 91, and 55% of the total loaded cephtriaxon, vancomycin, and gentamicin in 48 h at pH 7.4, respectively. Finally, antibiotics loaded biocompatible poly(HEMA:PEG-MA;1:1)-1 hydrogel compositions was used as a penile prosthesis in preventing cavernous tissue infections in a rabbit prosthesis model. The efficacy of the three different antibiotics loaded hydrogel system was evaluated in four different groups of rabbits, in which various infectious agents were inoculated. The animals were sacrificed after predetermined time periods, and clinical, histological and microbiological assessment on the implant side were carried out to detect infections. Eventually, we concluded that three different antibiotic loaded penile prostheses (i.e. poly(HEMA:PEG-MA;1:1)-1 hydrogel systems) were as effective as parenteral antibiotics applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Onium salt reduces the inhibitory polymerization effect from an organic solvent in a model dental adhesive resinJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008Fabrício A. Ogliari Abstract This study evaluated the effect of organic solvent concentration on the polymerization kinetics for a model dental adhesive resin containing a ternary photoinitiator system. A monomer blend based on the bis-GMA, TEGDMA, and HEMA was used as a model dental adhesive resin, which was polymerized using a binary system [camphorquinone (CQ) and ethyl 4-dimethylamine benzoate (EDAB)] and a ternary system [CQ, EDAB, and diphenyliodonium hexafluorphosphate (DPIHFP)]. Additionally, these blends had 0, 10, 20, 30, and 40 wt % ethanol added. Real-time Fourier transform infrared spectroscopy was used to investigate the polymerization reaction over photoactivation time. Data were plotted, and Hill's three-parameter nonlinear regression was performed for curve fitting. The addition of a solvent to the monomer blends decreased the polymerization kinetics, directly affecting the rate of polymerization, delaying vitrification, and attenuating the Trommsdorf effect. The introduction of DPIHFP displayed a strong increase in reaction kinetics, reducing the solvent inhibition effect. After 10 s of photoactivation, the binary system obtained in 0, 10, 20, 30, and 40% of ethanol, a degree of conversion of 44.6, 26.3, 13.4, 1.15, and 0.0%, respectively, whereas when a ternary system was used, the values were 54.6, 40.5, 27.4, 14.5, and 3.4%. An improvement was observed in the polymerization kinetics of a model dental adhesive resin when using a ternary photoinitiation system, making the material less sensitive to the residual presence of a solvent before photoactivation. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Characterization of the physicochemical, antimicrobial, and drug release properties of thermoresponsive hydrogel copolymers designed for medical device applicationsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2008David S. Jones Abstract In this study, a series of hydrogels was synthesized by free radical polymerization, namely poly(2-(hydroxyethyl)methacrylate) (pHEMA), poly(4-(hydroxybutyl)methacrylate) (pHBMA), poly(6-(hydroxyhexyl)methacrylate) (pHHMA), and copolymers composed of N -isopropylacrylamide (NIPAA), methacrylic acid (MA), NIPAA, and the above monomers. The surface, mechanical, and swelling properties (at 20 and 37°C, pH 6) of the polymers were determined using dynamic contact angle analysis, tensile analysis, and thermogravimetry, respectively. The Tg and lower critical solution temperatures (LCST) were determined using modulated DSC and oscillatory rheometry, respectively. Drug loading of the hydrogels with chlorhexidine diacetate was performed by immersion in a drug solution at 20°C ( Equivalences between refractive index and equilibrium water content of conventional and silicone hydrogel soft contact lenses from automated and manual refractometry,JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007José M. González-Méijome Abstract Purpose The purpose of the present study was to develop mathematical relationships that allow obtaining equilibrium water content and refractive index of conventional and silicone hydrogel soft contact lenses from refractive index measures obtained with automated refractometry or equilibrium water content measures derived from manual refractometry, respectively. Methods Twelve HEMA-based hydrogels of different hydration and four siloxane-based polymers were assayed. A manual refractometer and a digital refractometer were used. Polynomial models obtained from the sucrose curves of equilibrium water content against refractive index and vice-versa were used either considering the whole range of sucrose concentrations (16,100% equilibrium water content) or a range confined to the equilibrium water content of current soft contact lenses (,20,80% equilibrium water content). Results Values of equilibrium water content measured with the Atago N-2E and those derived from the refractive index measurement with CLR 12,70 by the applications of sucrose-based models displayed a strong linear correlation (r2 = 0.978). The same correlations were obtained when the models are applied to obtain refractive index values from the Atago N-2E and compared with those (values) given by the CLR 12,70 (r2 = 0.978). No significantly different results are obtained between models derived from the whole range of the sucrose solution or the model limited to the normal range of soft contact lens hydration. Conclusions Present results will have implications for future experimental and clinical research regarding normal hydration and dehydration experiments with hydrogel polymers, and particularly in the field of contact lenses. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] COVALENT IMMOBILIZATION OF INVERTASE ON CHEMICALLY ACTIVATED POLY (STYRENE-2-HYDROXYETHYL METHACRYLATE) MICROBEADSJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2008HAYDAR ALTINOK ABSTRACT A carrier for invertase enzyme was synthesized from styrene (S) and 2- hydroxyethyl methacrylate (HEMA) in the form of microbeads. These poly (styrene-2-hydroxyethyl methacrylate), P(S-HEMA) microbeads were activated by epichlorohydrin (ECH) treatment for covalent immobilization. The free and immobilized invertase were assayed in the hydrolysis of sucrose to glucose, and the obtained results were compared. The optimum pH was 4.5 for free and 5.5 for immobilized invertase. The optimum temperature of invertase shifted from 45C to 55C upon immobilization. For free and immobilized enzymes, kinetic parameters were calculated as 4.1 × 10,3 mol L,1and 9.2 × 10,3 mol L,1for Km, and 6.6 × 10,2 mol L,1 min,1and 4.1 × 10,1 mol L,1 min,1for Vmax, respectively. After 1 month of storage at 4C, free enzyme retained 36% of its initial activity, while for the ECH-activated P(S-HEMA) immobilized enzyme, P(S-HEMA)-E, this value was observed as 67%. In repeated batch use, i.e., 20 times in 3 days, 78% retention of the initial activity was observed for P(S-HEMA)-E system. PRACTICAL APPLICATIONS Immobilization of enzymes are very important for many industrial applications, e.g., food, medicine, pharmacology, etc. Invertase converts sucrose to glucose and fructose, which have wide applications in food industry especially as sweeteners. Glucose,fructose mixture has much lower crystallinity compared to sucrose and therefore used in the production of noncrystallizing jams and creams. They are also used as liquid sweeteners. Immobilization enables repeated use, provides significant reduction in the operation costs, facilitates easy separation and speeds up recovery of enzyme and extends the stability of enzyme by protecting the active material from deactivation. Industrial application of immobilized invertase may decrease the production cost of glucose,fructose mixture because it could be used repeatedly for long periods. Although invertase is not a very expensive enzyme, the technique can also be applied to expensive ones for biotechnological productions. [source] Enhancing therapeutic loading and delaying transport via molecular imprinting and living/controlled polymerizationAICHE JOURNAL, Issue 1 2010Asa D. Vaughan Abstract This work demonstrates for the first time molecular imprinting using a "living/controlled" polymerization (LCP) strategy to enhance template loading/affinity and delay release in weakly crosslinked gels. Two gel systems were studied: poly(DEAEM- co -HEMA- co -PEG200DMA) gels imprinted for diclofenac sodium and poly(MAA- co -EGDMA) gels imprinted for ethyl adenine-9-acetate. Experimental evidence confirms that template diffusion coefficients within imprinted gels can be heavily influenced by template binding affinity. Recognition studies revealed significant increases in template loading/affinity with large increases in loading for LCP, and dynamic template release studies showed that imprinting via LCP extends the template release profile by twofold over that of imprinting via conventional free-radical polymerization techniques and fourfold over the control network (less Fickian and toward zero-order release with a profile coefficient of 0.70). Analysis of reaction kinetics indicated that LCP with reversible termination events increases the chemically controlled chain propagation mechanism, and that binding sites are formed during this phase of the polymerization. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Effect of disinfectants containing glutaraldehyde on bonding of a tri- n -butylborane initiated resin to dentineJOURNAL OF ORAL REHABILITATION, Issue 5 2002N. Baba The purpose of this study was to evaluate the effects of disinfectants on the bond strength of resin to dentine. The surface of bovine dentine was exposed to formaldehyde (FA) aqueous solutions, glutaraldehyde (GA) aqueous solutions, 2-hydroxyethyl methacrylate aqueous solutions (HEMA), a commercially available dentine primer (Gluma CPS desensitizer, GLUMA), isotonic sodium chloride solution (IS), and distilled water (DW), and placed in a humidor (HU) at 37 °C, or non-stored (baseline). All dentine surfaces were conditioned with a 10% citric acid and 3% ferric chloride solution (10-3 liquid), and then bonded to an acrylic rod with a self-curing adhesive resin (Super-Bond C&B). The mean tensile bond strengths determined 24 h after bonding were compared by analysis of variance (ANOVA) and Fisher's protected LSD test (n=5, P , 0·05). The exposure of dentine to IS, DW and HU for both 48 and 168 h resulted in a decrease in bond strength when compared with the baseline. The highest bond strengths after 168 h of exposure were obtained with 5% GA, 10% HEMA, and GLUMA, the values of which were equivalent to baseline and were significantly higher than that of FA. It is concluded that disinfectant pre-treatment with 5% GA or GLUMA stabilizes the bonding of tri- n -butylborane (TBB) initiated luting agent to bovine dentine conditioned with 10-3 liquid. [source] Titanium-mediated [CpTiCl2(OEt)] ring-opening polymerization of lactides: A novel route to well-defined polylactide-based complex macromolecular architecturesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2010Nikolaos Petzetakis Abstract Among three cyclopentadienyl titanium complexes studied, CpTiCl2(OEt), containing a 5% excess CpTiCl3, has proven to be a very efficient catalyst for the ring-opening polymerization (ROP) of L -lactide (LLA) in toluene at 130 °C. Kinetic studies revealed that the polymerization yield (up to 100%) and the molecular weight increase linearly with time, leading to well-defined PLLA with narrow molecular weight distributions (Mw/Mn , 1.1). Based on the above results, PS- b -PLLA, PI- b -PLLA, PEO- b -PLLA block copolymers, and a PS- b -PI- b -PLLA triblock terpolymer were synthesized. The synthetic strategy involved: (a) the preparation of OH-end-functionalized homopolymers or diblock copolymers by anionic polymerization, (b) the reaction of the OH-functionalized polymers with CpTiCl3 to give the corresponding Ti-macrocatalyst, and (c) the ROP of LLA to afford the final block copolymers. PMMA- g -PLLA [PMMA: poly(methyl methacrylate)] was also synthesized by: (a) the reaction of CpTiCl3 with 2-hydroxy ethyl methacrylate, HEMA, to give the Ti-HEMA-catalyst, (b) the ROP of LLA to afford a PLLA methacrylic-macromonomer, and (c) the copolymerization (conventional and ATRP) of the macromonomer with MMA to afford the final graft copolymer. Intermediate and final products were characterized by NMR spectroscopy and size exclusion chromatography, equipped with refractive index and two-angle laser light scattering detectors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1092,1103, 2010 [source] Simultaneous reversible addition fragmentation chain transfer and ring-opening polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2008Maude Le Hellaye Abstract The simultaneous ring-opening polymerization (ROP) of ,-caprolactone (,-CL) and 2-hydroxyethyl methacrylate (HEMA) polymerization via reversible addition fragmentation chain transfer (RAFT) chemistry and the possible access to graft copolymers with degradable and nondegradable segments is investigated. HEMA and ,-CL are reacted in the presence of cyanoisopropyl dithiobenzoate (CPDB) and tin(II) 2-ethylhexanoate (Sn(Oct)2) under typical ROP conditions (T > 100 °C) using toluene as the solvent in order to lead to the graft copolymer PHEMA- g -PCL. Graft copolymer formation is evidenced by a combination of size-exclusion chromatography (SEC) and NMR analyses as well as confirmed by the hydrolysis of the PCL segments of the copolymer. With targeted copolymers containing at least 10% weight of PHEMA and relatively small PHEMA backbones (ca. 5,000,10,000 g mol,1) the copolymer grafting density is higher than 90%. The ratio of free HEMA-PCL homopolymer produced during the "one-step" process was found to depend on the HEMA concentration, as well as the half-life time of the radical initiator used. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3058,3067, 2008 [source] Preparation of amphiphilic statistical copolymers of 2-hydroxyethyl methacrylate with 2-diethylaminoethyl methacrylate, precursors of water-soluble copolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2002Gerardo Martinez Abstract Statistical copolymers of 2-hydroxyethyl methacrylate (HEMA) and 2-diethylaminoethyl methacrylate (DEA) were synthesized at 50 °C by free-radical copolymerization in bulk and in a 3 mol L,1N,N,-dimethylformamide solution with 2,2,-azobisisobutyronitrile as an initiator. The solvent effect on the apparent monomer reactivity ratios was attributed to the different aggregation states of HEMA monomer in the different solvents. The copolymers obtained were water-insoluble at a neutral pH but soluble in an acidic medium when the molar fraction of the DEA content was higher than 0.5. The quaternization of DEA residues increased the hydrophilic character of the copolymers, and they became water-soluble at a neutral pH when the HEMA content was lower than 0.25. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2427,2434, 2002 [source]
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