Reaction Of Epoxy Groups Research Articles

Covalent immobilization of antibody fragments on well-defined polymer brushes via site-directed method

Well-defined polymer brushes and block copolymer brushes consisting of 2-methacryloyloxyethyl phosphorylcholine (MPC) and glycidyl methacrylate (GMA) were prepared by surface-initiated atom transfer radical polymerization (ATRP). The polymer brushes were used for the immobilization of antibody fragments in a defined orientation. Pyridyl disulfide moieties were introduced to the polymer brushes via a reaction of epoxy groups in GMA units. Fab’ fragments were then immobilized onto these surfaces via a thiol-disulfide interchange reaction and the reactivity of antibodies with antigens was investigated. Antigen/antibody binding on the polymer brushes was more preferable than that on epoxysilane films as a control surface. Furthermore, the activity of the antibodies immobilized on the block copolymer brushes having biocompatible PMPC was greater than that on other surfaces that did not have PMPC in their structures.

Synthesis of Functional Photopolymerized Macroporous PolyHIPEs by Atom Transfer Radical Polymerization Surface Grafting

A versatile platform to obtain highly functional macroporous materials was developed. A polymerizable initiator for atom transfer radical polymerization (ATRP) has been incorporated into a high internal phase emulsion (HIPE) without compromising the emulsion stability. Photopolymerization of this formulation led to polyHIPE with ATRP initiator groups on the surface available for polymer grafting reactions. The latter was first demonstrated by grafting of methylmethacrylate (MMA). Analysis by IR confirms the presence of PMMA in the polyHIPE. Moreover, scanning electron microscopy images show changes in the surface morphology of the polyHIPE after the grafting reaction. In accordance with the controlled character of ATRP, reinitiation from the PMMA-grafted polyHIPE with HEMA to afford block copolymers was possible. Moreover, functionalized polyHIPE was obtained by the grafting of glycidyl methacrylate. IR and SEM analysis confirm that this resulted in a smooth and homogeneous coverage of the polyHIPE surface with a high density of reactive epoxy groups. In a subsequent reaction these materials were rendered hydrophilic by ring opening of the epoxy rings and hydrophobic by subsequent reaction with pentafluorobenzoylchloride.

Heterogeneous surface modification of hollow fiber membranes for use in micro-reactor systems

The broad application of hollow fiber micro-bioreactors in various areas of biotechnology is still restricted due to a limited functionality of the membranes. With this paper a straight forward procedure for membrane functionalization is presented. Different commercially available polyethersulfone (PES) and polysulfone (PS) hollow fiber membranes were chemically modified by reacting terminal hydroxyl groups with ethylene glycol diglycidyl ether (EGDGE) to produce terminal epoxy groups. For increasing loading capacity hydroxyethyl cellulose polymers (HEC) were bound to the epoxy groups. Second epoxidation produced final polymers containing reactive epoxy groups on the hollow fiber surface. From this modified PES and PS, respectively, a wide variety of N-containing reagents (e.g. iminodiacetic acid (IDA)) can be bound to the epoxy groups. The different reactions were proved by acid orange II assay and phenol sulfuric assay. To assure intact hollow fiber surface after membrane modification scanning electron microscopic analyses were performed. The chelating IDA-membranes were complexed with different divalent metal ions (Cu 2+, Ni 2+, Co 2+, Zn 2+). Immobilized metal ion affinity PES hollow fiber membranes were used for purification of a recombinant protein (GFP-His) from Escherichia coli, which carried a polyhistidine sequence (His 6-tag). Determination of bound and unbound GFP-His 6 was performed by fluorescence spectroscopy, Bradford assay and SDS-PAGE.

Preparation and self‐assembly of poly(diglycidyl maleate‐co‐stearyl methacrylate)

AbstractPoly(diglycidyl maleate‐co‐stearyl methacrylate) (P(DGMA‐co‐SMA)) with reactive epoxy groups was synthesized by reaction of poly(maleic anhydride‐co‐stearyl methacrylate) (P(MA‐co‐SMA)) and epichlorohydrin. The effect of precipitant on self‐assembly behaviors of the resultant copolymer was investigated. It was found that vesicles and nanotubule liked aggregates can be obtained through self‐assembly of P(DGMA‐co‐SMA) in THF solution using CH3CH2OH (EtOH) as precipitant while spheral aggregates can be obtained using H2O as precipitant. The mechanism of the self‐assembly behavior was discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Characterization of polyether mixtures using thin‐layer chromatography and matrix‐assisted laser desorption/ionization mass spectrometry

Thin-layer chromatography (TLC) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were combined to achieve characterization of polyether mixtures. Three polyethers, polyethylene glycol (PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG), or mixtures of these compounds, were studied. One shortcoming of mixture analysis of synthetic polymers using MALDI-MS is that individual polymers in the mixture may display different detection sensitivities. For example, the MALDI mass spectrum of an equimolar mixture of PEG, PPG and PTMG displayed a high intensity of PPG ions, while no PTMG ions were detectable; however, PTMG ions were detected after the mixture had been separated by TLC. This combined TLC and MALDI-MS analysis of a PPG polymer bearing reactive epoxy groups showed that the polymer contained byproducts with different end-groups. These byproducts were identified as chloro-substituted polymers formed during polymer synthesis. Our study shows TLC to be a rapid and low-cost separation technique, and that it can be combined with MALDI-MS to achieve effective analysis of synthetic polymers.

Structure and swelling behaviour of epoxy networks based on α,ω-diamino terminated poly(oxypropylene)- block-poly(oxyethylene)- block-poly(oxypropylene)

Structure and swelling behaviour of hydrophilic epoxy networks prepared from α,ω-diamino terminated poly(oxypropylene)- block-poly(oxyethylene)- block-poly(oxypropylene) and diglycidyl ether of brominated Bisphenol A in dependence on the initial molar ratio of reactive amino and epoxy groups has been investigated by small- and wide-angle X-ray scattering (SAXS and WAXS), differential scanning calorimetry (DSC) and dynamic mechanic analysis (DMA). Anomalous swelling behaviour of the networks in water has been found. The anomaly is attributed to the changing microphase separation in the networks controlled by their composition and crosslinking density, and inhomogeneous swelling on nanometer space scale.

Repeatedly usable immobilized pH gradient in a monolithic capillary column

Glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) were used to synthesize a monolithic capillary column containing reactive epoxy groups. Glutaraldehyde was introduced and linked to the monolith after a process of amination. An aqueous solution of commercial carrier ampholytes (CAs, Ampholine) was focused in such a polymer column. The primary amino groups of CAs reacted with glutaraldehyde along the capillary. CAs were immobilized at different positions in the column according to their isoelectric points (pI), resulting in a monolithic immobilized pH gradient (M-IPG). Isoelectric focusing (IEF) was performed without CAs in such an M-IPG column. Due to the covalent attachment of the CAs this M-IPG can be repeatedly used after its preparation. Good stability, linearity, and reproducibility were obtained.

A thermosensitive amphoteric microsphere and its potential application as a biological carrier

Thermosensitive poly(N-isopropylacrylamide) moieties were introduced onto amphoteric styrene/glycidyl methacrylate copolymer seed microspheres prepared by use of amphoteric initiators. The resulting microspheres exhibited thermosensitive and amphoteric behavior, so dual sensitivity to both pH and temperature was observed. The colloidal properties of the microspheres before and after seeded polymerization were characterized by varying the temperature and the pH. The results indicated that the specific surface structure emerged when the environmental conditions were changed. In addition, the reactive epoxy groups on the microsphere surface could be utilized to immobilize the protein molecules. The behavior of protein adsorption and immobilization onto the microspheres was examined in order to understand their potential applications in biological areas.

Synthesis and photochemical properties of novel multifunctional photopolymers with both pendant epoxy groups and phenacyl ester groups

Novel multifunctional photopolymers with both pendant epoxy groups and phenacyl ester groups were synthesized by the one-pot method for the reaction of poly(methacrylic acid) with epibromohydrin; this was followed by a reaction with phenacylbromide with 1,8-diazabicyclo-[5.4.0]undecene-7 as a condensation reagent. These esterification reactions proceeded smoothly and quantitatively under mild conditions. Moreover, the photochemical reactions of the resulting polymers were evaluated by UV and IR spectroscopy. The pendant phenacyl ester groups were photocleaved to give corresponding carboxyl groups, and then the produced carboxyl groups reacted with pendant epoxy groups. Furthermore, the baking process promoted a crosslinking reaction because of the addition reaction of epoxy groups with carboxyl groups after irradiation. It was also proven that the photochemical reactivity of the resulting polymers was affected by the structure of the phenacyl ester group. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 530–538, 2001

Chemical modification and adhesion in carbon fiber/epoxy micro-composites; coupling and surface coverage

Four compounds were used to improve adhesion between carbon fibers and an epoxy matrix. Triglycidyl isocyanurate (TGIC) and 3-glycidoxy-propyl-triethoxysilane (EPS) contained reactive epoxy groups, while N-(3-trimethoxysilane-propyl)ethylene diamine (AMS) a primary and a secondary amino group. The fourth coupling agent was 4,4' diphenylmethane-diisocianate (MDI). The interaction of the fiber and the coupling agents was studied by dissolution experiments. Chemical reactions taking place on the surface of the fiber were followed by FTIR spectroscopy. Interfacial shear stress determined by fragmentation was used for the characterization of matrix/fiber adhesion. Beside coupling to the surface, EPS, AMS and MDI formed a polymer layer on the surface, but TGIC also entered into secondary reactions during the treatment. Both the type and the amount of the coupling agent affects strongly interfacial adhesion, which is determined by the thickness and properties of the formed coupling agent layer. The combination of dissolution experiments with the fragmentation test yields valuable information about the processes taking place on the surface of the fiber, facilitate the selection of the best coupling agent, as well as the development of surface treatment technology.

Effect of fillers and plasticizers on the performance of novel heat and oil-resistant thermoplastic elastomers from nylon-6 and acrylate rubber blends

The effects of various fillers (SRF black, silica, and clay) and plasticizers (dibutyl phthalate and dioctyl phthalate) on the mechanical, dynamic mechanical, and rheological properties and on the heat and oil resistance of the thermoplastic elastomeric reactive blends of nylon-6 and acrylate rubber (ACM) were investigated. The mixing torque behavior of the blends in Brabender Plasticorder shows reduced extent of interaction between the two component polymers in the presence of both fillers and plasticizers. Silica-filled blends show the highest viscosity increment due to the possibility of reaction between its surface silanol groups and the reactive epoxy groups present in the ACM chain during melt-blending operation. Though the addition of fillers reduces the processability of the blends, it improves the extensibility as well as the tension set properties of the blends. The mechanical integrity and the damping characteristics of the blends are also improved with the addition of fillers; the latter is evidenced from the dynamic mechanical thermal analysis of the blends. The tensile strength and hardness of the filled blends remain practically unchanged after ageing at 175°C for 72 h and, also, the oil swell does not change appreciably with the addition of fillers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1490–1501, 1999

Dendritic hyperbranched polymers as tougheners for epoxy resins

Dendritic hyperbranched polymers (HBPs) show outstanding performance as tougheners in epoxy resins. The critical strain energy release rate, G Ic, of a DGEBF resin is increased by a factor of 6 from 120 J/m 2 to 720 J/m 2 using only a 5% modifier weight content. This does not lead to a decrease in resin stiffness or glass transition temperature and the favourable processability of epoxy resins is fully maintained without requiring the use of solvents. Toughness properties are induced by a finely-dispersed particulate structure which is obtained by a controlled phase separation process during resin curing. A strong mechanical phase interaction is ensured by chemical bonding through reactive epoxy groups grafted onto the HBP. By tailoring the HBP's epoxy functionality and polarity to control reactivity, phase separation, final morphology and phase interactions, this toughening system is potentially applicable to a variety of thermoset resins. With this in view, the influence of the chemical architecture of the HBP modifiers on phase separation, processability, properties and toughening mechanisms is investigated.

Epoxy reactive dyes for wool and wool/polyester blends

Disperse azo dyes with two reactive epoxy groups were synthesised using N,N-diglycidylaniline as the coupling component. Dyeing conditions, wet-fastness and light-fastness on wool and wool/polyester blends were studied.

Preparation and investigation of chemically modified porous polyamide ultrafiltration membranes

The asymmetric ultrafiltration membranes for these investigations were made from a fully aliphatic (PA 66), a fully aromatic (polyaramid referred to as PA-L48_ and an aliphatic-aromatic polyamide (Trogamid T). The latter were heterogeneously reacted with glycidyl methacrylate yielding an epoxidized polyamide membrane. The reactive epoxy group opened up a spectrum of further modifications. Both positively and negatively charged substituents were introduced. Heterogeneous chemical modification of the cast membrane is needed as homogeneous polymer modification eliminates the polymers film forming properties. The reaction steps reduce the transport cross section as grafting is performed also on the inner pore walls and some reactions needed higher temperatures with shrinking of the membrane as a consequence. The fouling behavior was determined using dilute human serum albumin solutions at different pH values. The original polyamide membranes display the expected performance: the polyaramid membrane is least sensitive to protein adsorption followed by the mixed aliphatic-aromatic and the aliphatic ones. Applying negatively charged membranes at higher pH of the solution the protein is repulsed due to its isoelectric point of 4.8. On the contrary, the positively charged membranes adsorb the oppositely charged protein causing a strong volume flow reduction. The change in surface properties by protein adsorption is demonstrated by means of electrokinetic measurements.

Preparation and characterization of porous polysulfone membranes with spacer‐bonded N‐containing groups

AbstractUltrafiltration membranes were prepared from epoxidized polysulfone by the conventional phase separation procedure. For epoxidizing, the polymer was first lithiated and a reaction followed with glycidyl‐4‐oxohexylether providing an eight atomic spacer. The reaction of the epoxy group with N‐containing substituents was performed heterogeneously using the ready membranes. The stability of the substituted membranes is visible by the fact that they are reacted under reflux conditions for 24 h. The reagents were trimethyl amine, diethylamine, n‐butyl amine, and tauric acid. Thus, positively charged, negatively charged, and neutral membranes were obtained. The membranes were characterized via ultrafiltation using dextran solution as well as human albumin solutions. In addition, the streaming potential was measured in the presence and absence of the protein. By these measurements the obviously neutral membranes were surprisingly identified to be positively charged. This is related to subsequent reactions of the spacer‐bonded epoxy groups with the amino groups. © 1995 John Wiley & Sons, Inc.

Functional membranes for flow buffering

Synthesis of functional membranes applicable to the buffering of pH in flow systems is described. The membranes are interpenetrating polymer networks of 2,3-epoxypropyl methacrylate and ethylene dimethacrylate in a preformed porous polymeric polypropene substrate. The pendant reactive epoxy groups in the membranes are converted into several functional groups with different p K a values. The functionalized membranes are able to continuously adjust the pH of both acidic and alkaline flowing streams to a value close to the pH of the regenerant buffer.

Synthesis and characterization of affinity membranes made from polysulfone

Polysulfone was chemically modified by a metalation reaction which could be further reacted with glycidyl-4-oxohexylether. Thus, the final polymer contained a reactive epoxy group with a 7-atom distance from the polymeric backbone. From this modified polysulfone, asymmetric ultrafiltration membranes were cast conventionally and iminodiacetic acid was bonded to the epoxy group. The reaction was proved by electrokinetic measurements. The membranes, now with chelating properties, were complexed with copper ions. By this method a high-performance affinity matrix was obtained which was used for the adsorption of various amino acids. Using histidine the complexation constant was determined to log K=4.34 (phosphate buffer, pH 7, c NaCl 1 M). The affinity membranes were used for concentrating a dilute histidine solution ( c=4 μmol/l) as well as for the separation of a solution consiting of four amino acids.

Curing kinetics of liquid-crystalline epoxy resins

Abstract By endcapping mesogenic rigid rod molecules with reactive epoxy groups a novel class of liquid-crystalline thermoset has been obtained. In fact is has been shown that the nematic molecular arrangement is sustained over the crosslinking reaction of liquid-crystalline epoxy resins when the curing reaction is carried out in the thermal stability range of the liquid-crystalline phase. Calorimetric analysis was used in characterizing the isothermal cure. An unsophisticated model is proposed for evaluating the activation energies of the crosslinking reaction. For liquid-crystalline epoxy resins lower activation energies result with respect to the cure reactions for non liquid-crystalline epoxy resins.

Compatibilized and dynamically vulcanized thermoplastic elastomer blends of poly(butylene terephthalate) and ethylene propylene diene rubber

AbstractCompatibilized and dynamically vulcanized thermoplastic elastomer blends of poly(butylene terephthalate) (PBT) and ethylene propylene diene terpolymer (EPDM) can be prepared by using an EPDM rubber that contains reactive epoxy groups. During melt mixing the epoxy groups react with PBT endgroups to form graft copolymer. The compatibilized blends can be dynamically vulcanized by conventional vulcanization agents for EPDM such as peroxides or by vulcanization agents that react with residual epoxy groups on the EPDM such as diamines. This paper describes the effects of compatibilization and dynamic vulcanization on microstructure and mechanical properties.

New epoxy compounds derived from substituted maleamic acids

AbstractEight new epoxy compounds bearing maleamic acid moieties were prepared starting from 4‐(2,3‐epoxypropoxy)benzaldehyde (EPB) or 2,3‐epoxypropylglyoxylate monohydrate (EPG). The monomaleamic acid derived from an aromatic diamine (1,4‐phenylenediamine, 4‐aminophenyl ether, 4,4′‐diaminodiphenylmethane or 4,4′‐diaminodiphenylsulfone) reacted with EPB or EPG to afford the epoxy compounds. They were characterized by IR and 1H‐NMR spectroscopy. Their DTA traces showed that thermal polymerization started at 187–211°C. Network systems were obtained by crosslinking from the reaction of epoxy group with the maleamic carboxyl and through the olefinic bond. The TGA thermograms of crosslinked polymers showed that they were stable up to 275–295°C in N2 or air and afforded anaerobic char yield of 47–65% at 800°C. In addition, isothermal gravimetric analysis (IGA) was used to evaluate the thermo‐oxidative stability of a typical cured resin.