Copolymers Of 2-hydroxyethyl Methacrylate Research Articles

HPMA and HEMA copolymer bead interactions with eukaryotic cells

Two different hydrophilic acrylate beads were prepared via aqueous suspension polymerization. Beads produced of a hydroxypropyl methacrylate (HPMA) and ethyleneglycol methacrylate (EDMA) copolymer were obtained using a polyvinyl alcohol suspending medium. Copolymers of 2hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA) and ethyleneglycol methacrylate (EDMA) beads were obtained using magnesium hydroxide as the suspending agent. Following characterization by scanning electron microscopy (SEM), nitrogen sorption analysis (NSA) and mercury intrusion porosimetry (MIP), the beads were cultured with monkey fibroblasts (COS7) to evaluate their ability to support cell growth, attachment and adhesion. Cell growth behavior onto small HPMA/EDMA copolymer beads and large HEMA/MMA/EDMA copolymer beads is evaluated regarding their hidrophilicity/hidrophobicity and surface roughness.

Dynamic studies of molecular imprinting polymerizations

Mechanisms of interaction of a three-dimensional polymer with solutes are of interest in the development and function of synthetic biomimetic polymers. We have investigated the effects of template/monomer interactions and template concentration on conversion and polymerization rates of a molecularly imprinted polymer. Copolymers of 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) dimethacrylate (PEG600DMA) were prepared in the presence of glucose. The polymerization reaction kinetics of non-imprinted networks as well as those imprinted with glucose at concentration ratios of [HEMA]/[Glucose] between 11 and 1 were monitored in situ by ATR–FTIR spectroscopy and differential photocalorimetry (DPC). The rates of polymerization for imprinted polymers showed an early lag period followed by a late autoacceleration, indicative of the complexation between monomer and template. Hydrogen-bonding was also observed using FTIR through the C O (carbonyl) bond of the monomers by FTIR. A significant effect of the template on conversion and polymerization rate of imprinted polymers was observed compared to non-imprinted ones. These values provide guidelines for kinetic models of interacting systems.

Investigation into the diffusion of water into HEMA-co-MOEP hydrogels.

Cross-linked homopolymers and copolymers of 2-hydroxyethyl methacrylate, HEMA, and ethylene glycol methacrylate phosphate, MOEP, have been synthesized, and the diffusion of water into these systems has been investigated. Only polymers with 0-20 mol % MOEP exhibited ideal swelling behavior as extensive fracturing occurred in the systems with greater than 20 mol % MOEP as the polymers began to swell during water sorption. Gravimetric studies were used in conjunction with magnetic resonance imaging of the diffusion front to elucidate the diffusion mechanism for these systems. In the case of the cross-linked HEMA homopolymer gels, the water transport mechanism was determined to be concentration-independent Fickian diffusion. However, as the fraction of MOEP in the network increased, the transport mechanism became increasingly exponentially concentration-dependent but remained Fickian until the polymer consisted of 30 mol % MOEP where the water transport could no longer been described by Fickian diffusion.

NMR imaging of the diffusion of water at 310 K into semi-IPNs of PEM and poly(HEMA-co-THFMA) with and without chlorhexidine diacetate.

Magnetic resonance imaging has been used to monitor the diffusion of water at 310 K into a series of semi-IPNs of poly(ethyl methacrylate), PEM, and copolymers of 2-hydroxyethyl methacrylate, HEMA, and tetrahydrofurfuryl methacrylate, THFMA. The diffusion was found to be well described by a Fickian kinetic model in the early stages of the water sorption process, and the diffusion coefficients were found to be slightly smaller than those for the copolymers of HEMA and THFMA, P(HEMA-co-THFMA), containing the same mole fraction of HEMA in the matrix. A second stage sorption process was identified in the later stage of water sorption by the PEM/PTHFMA semi-IPN and for the systems containing a P(HEMA-co-THFMA) component with a mole fraction HEMA of 0.6 or less. This was characterized by the presence of water near the surface of the cylinders with a longer NMR T(2) relaxation time, which would be characteristic of mobile water, such as water present in large pores or surface fissures. The presence of the drug chlorhexidine in the polymer matrixes at a concentration of 5.625 wt % was found not to modify the properties significantly, but the diffusion coefficients for the water sorption were systematically smaller when the drug was present.

Controlled Release of Biomolecules from pH-Sensitive Hydrogels Prepared by Radiation Polymerization

Copolymers of 2-hydroxyethyl methacrylate and methacrylic acid based hydrogels were studied as hydrogel drug delivery systems. Radiation copolymerization of 2-hydroxyethyl methacrylate and methacrylic acid (mixed with 3,3'-azobis(6-hydroxy benzoic acid)(ABHB) as an azo derivative of 5-aminosalicylic acid were carried out with various amounts of methacryloyloxyethyl esters of terephthalic acid for crosslinking. The polymer structures were characterized by FTIR, 1H NMR, 13C NMR spectroscopy and glass transition temperature (Tg). The hydrolysis of the drug–polymer conjugates were carried out in dialysis bags containing aqueous buffer solutions (pH 1 and 7.4) at 37°C. The drug-release profiles indicate that the amount of drug release depended on the degree of swelling and crosslinking.

Controlled Release of Biomolecules from pH-sensitive Network Polymers Prepared by Radiation Polymerization

Copolymers of 2-hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAA) based hydrogels containing 5 and 10% of a cross-linking agent were studied as drug delivery systems. Terephthalic acid was covalently linked with HEMA, abbreviated as CA. Radiation copolymerization of HEMA and MAA, mixed with a particulate glibenclamide with the various ratios CA as crosslinking agent were carried out at the room temperature. The structure of the CA was confirmed by FTIR, 1H NMR and 13C NMR spectroscopy. The compositions of the cross-linked three-dimensional polymers were determined by FTIR spectroscopy. Glass transition temperature (Tg) of the network polymers was determined calorimetrically. The hydrolysis of drug-polymer conjugates was carried out in cellophane membrane dialysis bags containing an aqueous buffer solution (pH 7.4 and pH 1) at 37°C. The drug-release profiles indicate that amount drug release depends on their degree of swelling and cross-linking.

Local Segmental Dynamics of Poly(2-hydroxyethyl Methacrylate) in Methanolic Solution by Spin Label X-Band ESR

A copolymer of 2-hydroxyethyl methacrylate (HEMA) with spin-labeled methacrylic acid units distributed randomly along the main chain (∼3 mol %) was synthesized. ESR spectra of methanolic solutions of the copolymer at concentrations ranging from 2 to 50 wt % were measured at X-band (9 GHz) over a broad temperature range. Temperature dependence of the parameter RS, characterizing the local segmental dynamics in PHEMA chain, and of the other parameters characterizing local dynamics and conformation of the copolymer were determined by fitting experimental ESR spectra to the theoretical spectra calculated using the MOMD model. Arrhenius plots of the rotational parameters exhibit atypical nonlinear behavior characterized by two breaks at particular temperatures in the RS plot. It is concluded that, similarly to PMMA in a number of solvents, PHEMA in methanol undergoes a conformational transition from a less compact to more compact conformation of the polymer chain when the temperature increases in a particular ...

Influence of the Coil Block on the Properties of Rod−Coil Diblock Copolymers with Oligofluorene as the Rigid Segment

Rod−coil diblock copolymers of 2-hydroxyethyl methacrylate (HEMA) with well-defined oligofluorene initiator were synthesized using the atom transfer radical polymerization (ATRP) technique. The resulting copolymers were characterized using spectroscopic (1H NMR, GPC), optical (UV, photoluminesence), and thermal (DSC) techniques. The incorporation of the initiator into the polymeric chain was confirmed by spectroscopic methods, while strong evidence for microphase separation was obtained both from DSC and AFM. A detailed AFM study of the surface morphology in thin films was performed using rod−coil diblock copolymers having different flexible blocks, namely HEMA and polystyrene. Common solvents for both rod and coil blocks were used as a function of the solutions concentration of the diblock copolymers. By increasing the concentration of a selective solvent, formation of either islands, a stringlike morphology, and honeycomblike structures was observed. The optical properties of the HEMA copolymers from TH...

Stimulus-Responsive Water-Soluble Polymers Based on 2-Hydroxyethyl Methacrylate

The homopolymerization and block/statistical copolymerization of 2-hydroxyethyl methacrylate (HEMA) using atom transfer radical polymerization (ATRP) in methanol at 20 °C has been investigated. For the homopolymerizations, both high conversions and low polydispersities (Mw/Mn < 1.25) were obtained over a wide range of target degrees of polymerization. According to the literature, HEMA homopolymer is usually described as only water-swellable, but in this work low molecular weight HEMA oligomers (target degrees of polymerization, DPn, less than 20) exhibited water solubility over a wide temperature range (no cloud point behavior). Furthermore, for actual DPn's between 20 and 45, HEMA homopolymers exhibited inverse temperature solubility in dilute aqueous solution at pH 6.5, and their cloud points increased systematically as the DPn was reduced. Gravimetric studies indicated that “water-insoluble” HEMA homopolymers with DPn's higher than 50 were actually partially soluble: GPC studies confirmed that fractionation occurred due to preferential dissolution of the shorter chains. Furthermore, HEMA homopolymers with DPn's up to 50 are water-soluble at pH 2.2 and do not exhibit cloud points. This is attributed to protonation of the terminal morpholine groups derived from the ATRP initiator. Thus, depending on the mean DPn and the solution pH, water can be a good solvent, a marginal solvent or a nonsolvent for HEMA homopolymer. Chain extension (self-blocking) experiments conducted for the ATRP of HEMA in methanol at 20 °C using a Cu(I)Cl catalyst and bpy ligand indicated reasonable living character. Statistical copolymerizations of HEMA with other comonomers such as glycerol monomethacrylate (GMA) and 2-hydroxypropyl methacrylate (HPMA) allowed the cloud point behavior to be manipulated. Finally, a range of novel HEMA-based block copolymers were synthesized in which the HEMA block was either thermoresponsive or permanently hydrophilic, depending on its DPn and the nature of the second block. Thus, diblock copolymer micelles with either hydroxylated cores or coronas could be prepared.

NMR imaging of the diffusion of water at 310 K into poly[(2-hydroxyethyl methacrylate)-co-(tetrahydrofurfuryl methacrylate)] containing vitamin B12 or aspirin

The ingress of water into copolymers of 2-hydroxyethyl methacrylate (HEMA) and tetrahydrofurfuryl methacrylate (THFMA) loaded with either one of two model drugs, ie vitamin B-12 or aspirin, was studied at 310 K using three-dimensional nuclear magnetic resonance (3D NMR) imaging. The poly(HEMA) was loaded with 5 wt% of the drugs. From the imaging profiles it was observed that incorporation of vitamin B-12 into the polymers rich in HEMA resulted in crack formation at the interface between the rubbery region and the glassy core on sorption of water, although these cracks were 'healed' behind the diffusion front. However, for the copolymers with low HEMA contents and for those containing aspirin, no evidence for similar crack formation was found. For the copolymers loaded with 5 wt% of aspirin or vitamin B-12 the values of the water diffusion coefficients, determined by curve-fitting the relative water concentration profiles from magnetic resonance imaging (MRI) measurements, were found to be smaller than those obtained from a mass uptake study. (C) 2004 Society of Chemical Industry.

Binding of methyl orange or ethyl orange dyes by some dioxolane copolymers: Synthesis of the copolymers and thermodynamics of the dye-copolymer interactions

The extent of binding of methyl orange or ethyl orange by (2-phenyl-1,3-dioxolane-4-yl) methyl methacrylate (PDMMA), 2-hydroxyethyl methacrylate (HEMA), and vinyl-pyrrolidone (VPy) copolymers has been investigated by the equilibrium dialysis method. The dialysis experiments have been carried out in a Tris (hydroxy methyl) aminomethane buffer (pH = 7) and at the temperatures of 15, 25, and 35°C. The PDMMA-co-HEMA and PDMMA-co-VPy copolymers have been prepared in the laboratory by using the related monomers in different ratios. The synthesized products were analyzed by Fourier Transform-infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) spectroscopy, differential thermal analysis (DTA), and differential scanning calorimetry (DSC) techniques. The binding extent of the dyes by the copolymers was determined by ultraviolet (UV) absorbance measurements. The results indicate that the extent of binding is relatively higher for ethyl orange than that for methyl orange under identical conditions. The binding slightly decrease with increasing temperature, and it is accompanied with favorable free energy, and exothermic enthalpy change within the temperature range studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3355–3361, 2004

Contribution of the comonomers to the bulk and surface properties of methacrylate copolymers

Relationships between formulation, bulk properties, and surface properties are investigated on series of copolymers prepared with hydroxyethylmethacrylate (HEMA), methylmethacrylate (MMA), and ethylmethacrylate (EMA) monomers, and on the homopolymers PMMA and PHEMA. The bulk water content, swelling ratio, and static (sessile drop and captive bubble) and dynamic (Wilhelmy plate technique) contact angles and the electrokinetic potential (streaming potential) are measured. The bulk water content and swelling ratio of HEMA copolymers are proportional to the amount of HEMA and are linearly correlated to the contact angle hysteresis. Periodic instabilities in the wetting cycles, similar to Haines jumps, are observed with HEMA copolymers and support a bidirectional relaxation of the hydrophilic groups respectively towards external water and capillary water. The origin of the electrokinetic potential of these nonionizable polymers is attributed to specific adsorption of OH − ions. Its dependence on surface hydrophobicity and statistical length of the side-chains is interpreted in terms of the properties of water molecules near the interface.

Chromatographic behaviour and purification of linear lambda phage and plasmid DNA molecules on 2-hydroxyethyl methacrylate–ethylene dimethacrylate-based supports

The HEMA-BIO 1000 support, which is based on a copolymer of 2-hydroxyethyl methacrylate and ethylene dimethacrylate, was used for separation of lambda DNA and its fragments and plasmid pBR322 DNA. The separation of fragments greater than 6.6 kbp was demonstrated according to the slalom chromatography mechanism on column for size-exclusion chromatography in the case of linear lambda DNA fragments. The influence of particle size of column packing, mobile phase rate, and KCl concentration in mobile phase is discussed. The purification of plasmid DNA pBR322 using size-exclusion chromatography was more rapid compared to gel electrophoresis. The presence of salts in the eluate is not disadvantageous. DNA can be recovered from the eluate by ethanol precipitation. Plasmid DNA pBR322 isolated in this way was suitable for different biological applications (cleavage with restrictases, electrotransformation into bacterial cells).

Evolution of Surface Morphology in 2-Hydroxyethyl Methacrylate Copolymer Exposed to γ Radiation

Buckling patterns were observed on the outer surface of HEMA copolymers irradiated in air and subsequently immersed in solvents. The structure parameters of these buckling patterns on the irradiate...

10 kHz repetition rate solid-state dye laser pumped by diode-pumped solid-state laser

We describe the operation of an all solid-state pulsed dye laser of high repetition rate (10 kHz) pumped by a diode-pumped laser. Three different active media in the form of coin-sized disks were investigated: the dye rhodamine 6G doped in a copolymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) [Rh6G/P(MMA:HEMA)], and the dye pyrromethene 567 (PM567) doped in copolymers of MMA with pentaerythritol triacrylate (PETA) and with pentaerythritol tetraacrylate (PETRA) [PM567/P(MMA:PETA) and PM567/P(MMA:PETRA)]. Pump radiation at 527nm was provided by a frequency-doubled diode-pumped Nd:YLF laser Q-switched at 10 kHz. Laser output was observed with an initial average power of 560 mW for Rh6G in P(MMA:HEMA), and with an initial average power of 430 mW for PM567 in P(MMA:PETRA) and 220 mW for PM567 in P(MMA:PETA). In the case of Rh6G/P(MMA:HEMA), the output decreased to about half the initial value after about 6.6 min (or about 4.0 million shots) due to dye degradation. The device constitutes a tunable, all solid-state, high repetition rate laser system possibly suitable for biomedical and dermatological applications.

Photothermal analysis of polymeric dye laser materials excited at different pump rates.

The photothermal properties and heat diffusion of polymeric lasers, made up from solutions of Rhodamine 6G in solid matrices of poly(2-hydroxyethyl methacrylate) with different amounts of the cross-linking monomer ethylene glycol dimethacrylate and copolymers of 2-hydroxyethyl methacrylate and methyl methacrylate have been studied through photothermal deflection spectroscopy. The heat load that is due to the pumping process was quantified as a function of the pump excitation repetition frequency (0.25-10 Hz), determining the time-dependent temperature changes at different locations within the laser matrix. A theoretical model, which reproduces these changes with high accuracy, was developed on the basis of the heat-diffusion equation of optically dense fluids. The observed thermal effects became important for impairing the laser stability at pump repetition frequencies higher than 1 Hz. In addition, the irreversible optical changes produced in the laser matrices at high pump fluence values (>1 J/cm2) were also analyzed. These effects originate, most likely, from a two-step photothermal mechanism.

Bilirubin adsorption column Medisorba BL-300.

Bilirubin adsorption column Medisorba BL-300 (Kuraray Medical Inc.) for the treatment of hyperbilirubinemia is introduced. The adsorbent packed in this column is the porous anion exchange resin coated with hydrophilic 2-hydroxyethyl methacrylate copolymer in order to improve blood compatibility. The adsorbent showed a high adsorption rate for direct bilirubin and indirect bilirubin in patient plasma in vitro. This column is used in plasmaperfusion therapy in clinical use. BL-300 showed high removal rate for direct bilirubin, indirect bilirubin and bile acid in clinical evaluation. BL-300 is approved in Japan and it has been used for the treatment of hyperbilirubinemia caused by many diseases such as liver failure and hepatitis.

Testing the Durability of Polymyxin B Immobilization on a Polymer Showing Antimicrobial Activity: A Novel Approach with the Ion-Step Method

A polymyxin B (PMB) modified copolymer of ethyl acrylate and 2-hydroxyethyl methacrylate is reported that shows antibacterial activity towards E. coli. The polymer is designed for biosensor interfaces to provide protection against microbial contamination. However, leaching of a biomolecule from its solid support is a well-known problem in immobilization chemistry. It has been proposed that antimicrobial activity results from release of the antibiotic from the polymer matrix, but in the work reported here, bactericidal action was seen for tresyl activated polymers even when no polymyxin B could be detected in the supernatant and where covalent attachment of PMB was indicated. Further evidence for the in situ action of PMB on the polymer was provided using a novel method of investigation, subjecting the polymer, deposited on an Ion-Sensitive Field-Effect Transistor (ISFET) to a step change in ion-concentration (Ion-step). With the ion-step method activation of the polymer and the grafting of Polymyxin-B were followed. A comparison of absorbed PMB on a nonactivated polymer and PMB on the tresyl activated polymer suggested that if leaching of PMB from the latter occurred, it was below the detection limit and well below the minimum inhibitory concentration (MIC) for antimicrobial action. Bactericidal action was thus attributed to PMB attached to the polymer.

Graft Copolymerization of 2-Hydroxy Ethyl Methacrylate onto Chitosan with Cerium (IV) Ion. I. Synthesis and Characterization

Graft copolymerization of 2-Hydroxy ethyl methacrylate (HEMA) on to chitosan was studied using cerium (IV) as the initiator. Optimization of the grafting was worked out by varying the reaction time and monomer concentration. Under controlled conditions, up to 685% grafting with a grafting yield of 92.4% was achieved. FTIR, thermal and XRD techniques were used to confirm the formation of the grafted copolymer. Grafting caused a marginal decrease in the mechanical strength in the dry conditions and a significant decrease under wet conditions for the resultant polymer. The products showed significantly improved swelling at pH 7.4 and pH 1.98 compared to the original chitosan. Grafted polymer showed enhanced Tg and decomposition temperature. The grafting also resulted in improved hydrophilicity as is evident from the contact angle studies of the films.

Cytotoxicity study of homopolymers and copolymers of 2-hydroxyethyl methacrylate and some alkyl acrylates for potential use as temporary skin substitutes.

The cytotoxicities of both homopolymers and copolymers of 2-hydroxyethyl methacrylate (HEMA) and various alkyl acrylates (AA) were investigated using cell culture techniques. The particular alkyl acrylates used were methyl acrylate (MA), ethyl acrylate (EA) and butyl acrylate (BA). The AA contents of the polymers studied were in the range of 0-25% by weight. They were synthesized via bulk polymerization in the form of thin sheets of 0.5+/-0.1 mm thickness. After sterilization using ethylene oxide gas, cytotoxicity tests, including both direct and indirect contact tests, were performed using cell lines of L929 and normal human dermal fibroblasts. The results showed that P(HEMA-co-EA) with EA contents of 15-25% and P(HEMA-co-BA) with BA contents of 10-25% appeared to be non-cytotoxic and attractive for more specific cytocompatibility tests and in vivo studies with a view to their use as temporary skin substitutes.