Copolymers Of 2-hydroxyethyl Methacrylate Research Articles

The effect of Bilirubin on the phagocytic activity of mouse peripheral granulocytes and monocytesin vivo

Using an in vitro phagocytic assay with synthetic 2-hydroxyethylmethacrylate copolymer particles, the phagocytic activity of leukocytes of bilirubin-treated mice (85 and 170 mumol/L in 0.5 mL intraperitoneally) was studied. Bilirubin treatment significantly stimulated the phagocytosis of both peripheral blood granulocytes and monocytes; the increase of phagocytosis persisted for 6 h after bilirubin injection. The potential immunostimulating and/or immunotoxic effect of bilirubin is discussed.

Adsorption of bovine serum albumin onto styrene/2-hydroxyethyl methacrylate copolymer latex

The adsorption of bovine serum albumin (BSA) onto styrene (S)/2-hydroxyethyl methacrylate (HEMA) copolymer (PS/PHEMA) latex was studied. Polystyrene (PS) latex was used as a reference sample. All these latices were prepared without emulsifier and were highly monodisperse. The measurement results of surface charge density and ζ potential for these latices suggested that hydrous poly-HEMA layer existed on the surface of PS/PHEMA latex particles. The plateau values of the adsorption isotherms implied that BSA molecules adsorbed onto PS and PS/PHEMA latices in a side-on form at least near the isoelectric point (iep) of this protein. The adsorbability of BSA onto HEMA-copolymerized latex showed a similar tendency to that onto PS latex in the acidic pH region lower than the iep. However, in the alkaline pH region especially at a higher ionic strength, BSA adsorption onto HEMA-copolymerized latex was quite different from that onto PS latex. Namely, the amount adsorbed onto HEMA-copolymerized latex was hardly discernible at this pH region regardless of ionic strength.

Fibroblast cell proliferation on charged hydroxyethyl methacrylate copolymers

Two fibroblastic cell lines, 3T3 and 3T12, were grown on hydrophilic hydrogel substrates containing various amounts of positive or negative charge. The materials were copolymers of hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAA), N,N-dimethylaminoethyl methacrylate hydrochloride (DMAEMA-HCl), or trimethylaminoethyl methacrylate chloride (TMAEMA-Cl). The samples were prepared as spun cast films on ultraclean glass microscope slides. The cells were grown in 10% fetal bovine serum supplemented Dulbecco's modified medium (DMM). Both cell lines survived and proliferated on the positively charged DMAEMA-HCl or TMAEMA-Cl copolymers with HEMA. Cells did not survive on the negative MAA-HEMA copolymers nor on the neutral HEMA homopolymers. Proliferation did not correlate with water content of the gel materials. Attachment as well as proliferation did correlate well with zeta potential and mole percentage positive charge as determined by bulk titration data.

Hydrophilic polymeric microspheres : Their use in immunological methods

Hydrophilic polymeric microspheres were prepared by y-radiation initiated copolymerization of 2-hydroxyethyl methacrylate, ethylene dimethacrylate, methylenebisacrylamide and methacrylic acid in aqueous solution with possible addition of special monomers bearing fluorescent or other specific ligand groups. The microspheres were used in detection of different subtypes of immunoglobulin Fc-receptors and complement components receptors as well as in the studies of the process of receptor-mediated phagocytosis. A simple assay for testing the phagocytic activity of peripheral blood leukocytes is proposed for clinical applications.

Copolymers of 2-hydroxyethyl methacrylate and methyl methacrylate: an electron beam resist study

Abstract The electron beam development characteristics of copolymers of HEMA and MMA are reported. A copolymer with 4% of HEMA was found to have comparable sensitivity and enhanced contrast compared with conventional PMMA and this material would appear to be useful in lithographic applications.

Copolymerisation of 2-hydroxyethyl methacrylate with siloxanyl monomers

Acryloxymethylpentamethyldisiloxane (AMS) and methacryloxymethylpentamethyldisiloxane (MMS) have been prepared and purified chromatographically. Some physicochemical properties have been measured for these monomers as well as for highly purified 2-hydroxyethyl methacrylate (HEMA). Hydroxyl group analysis on copolymers of AMS with HEMA and of MMS with HEMA, obtained by free radical copolymerisation to low conversion, enabled monomer reactivity ratios to be determined by several procedures. The average values were r HEMA = 0.86, r AMS = 0.55 and r HEMA = 0.97, r MMS = 0.33. These values have been invoked in computing integral curves for the instantaneous copolymer composition throughout the whole range of conversion.

Copolymers of 2-Hydroxyethyl Methacrylate and Alkyl Methacrylates. Part III. Thermal Behavior

Abstract The relative thermal stability of copolymers of 2-hydroxyethyl methacrylate-ethyl methacrylate (HEMA-EMA) and HEMA-n-butyl methacrylate (HEMA-BMA) was investigated by thermogravimetry in an air/nitrogen atmosphere. The effect of molecular weight on thermal degradation was evaluated by taking five fractions of HEMA-EMA and four of HEMA-BMA copolymers. The enthalpic changes associated with the endothermic transition were evaluated by differential scanning calorimetry. The structural changes taking place in these copolymers during thermal degradation in air at 200°C were investigated by IR.

Copolymerization of 2-Hydroxyethyl Methacrylate with Alkyl Methacrylates. Part IV. Mechanical Properties and Biocompatibility

Abstract Mechanical properties of copolymers of 2-hydroxyethyl methacrylate with methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate have been investigated using an Instron tensile tester. It was observed that the overall mechanical properties decrease as the ester alkyl group of alkyl methacrylate becomes bulkier. Biocompatibility of the copolymers was also investigated by implanting them subcutaneously in rats.

Inverse Gas Chromatography on Graft and Random Copolymers of Styrene and 2-Hydroxyethyl Methacrylate

Inverse gas chromatography (IGC) was applied to amphiphilic graft copolymers of poly(2-hydroxyethyl methacrylate) (PHEMA) with polystyrene (PSt) branches using various probes at 160°C. Retention of tetradecane or amylbenzene, which selectively interacts only with PSt phase, suggested that a microphase inversion occurs around 20—30 wt% PSt, below which PSt segments constitute a discontinuous phase (islands). Rather nonselective probes such as dimethyl-formamide and 2-(2-methoxyethoxy)ethanol showed a retention which exceeds that expected from a simple additive relation, suggesting a considerable contribution of their interaction with the interface of the microphase-separated domains. In contrast, random copolymers showed a retention behavior as expected for a statistical distribution of the monomer units. General discussion is given on IGC as a means of characterizing binary polymer systems.

Synthesis and Interfacial Characterization of Graft and Random Copolymers of Styrene and 2-Hydroxyethyl Methacrylate

Polystyrene (PSt) macromonomers with methacrylate end-groups (M1) were copolymerized with 2-hydroxyethyl methacrylate (HEMA, M2) to give amphiphilic graft copolymers with PSt branches. The monomer reactivity ratio of HEMA was estimated as r2=1.7±0.4. The 1H NMR spectrum of a graft copolymer in methanol revealed a micelle formation with a PSt core, while chloroform caused the formation of a reversed micelle with a PHEMA core. The contact angle of water on polymer films suggested that the PSt segments generally dominate the surface properties of graft copolymers, independent of a composition above 15 wt% PSt. In contrast, the random copolymers of St and HEMA showed results as expected for a single-phase structure, both by 1H NMR and contact angle.

The effect of pH and temperature on the electrical conductivity of membranes made of methacrylic acid copolymers

The specific resistance was measured of swollen homogeneous and heterogeneous ion-exchange membranes made of methacrylic acid copolymers with N-(2-hydroxypropyl)methacrylamide and of its copolymers with 2-hydroxyethyl methacrylate. In the case of copolymers of 2-hydroxyethyl methacrylate and methacrylic acid, an increase in the methacrylic acid content raises the specific resistance of the membrane if the carboxylic groups are not ionized. At the degree of neutralization 0.5 the dependence becomes a reverse one. In copolymers of N-(2-hydroxypropyl)methacrylamide with 50 and more per cent of methacrylic acid the specific resistance of the membrane increases with increasing content of methacrylic acid in the case of the nonionized form while remaining virtually unchanged in the ionized form. All the investigated copolymers of N-(2-hydroxypropyl)methacrylamide have a maximum on the curve describing the dependence of the specific resistance on pH. This pH coincides with pH at which the diffusion mobility of the charge carrier of Na+ is highest. The dependence of the specific resistance on temperature can be described in terms of an empirical equation ρT = ρ0e-bT.

An advantageous method for detection of Fc-receptors and for studying Fc-receptor-mediated phagocytosis

A method employing fluorescent 2-hydroxyethyl methacrylate copolymer particles with dinitrophenyl haptenic group and anti-haptenic murine monoclonal antibodies of different isotypes is described for tracing Fc-receptors and for studies of phagocytosis via these cell surface structures. The possibility of quenching the fluorescence of non-phagocytosed particles enables us to distinguish clearly and reliably between internalized and cell surface-bound particles.

Gradient‐IPN‐modified hydrogel beads: Their synthesis by diffusion–polycondensation and function as controlled drug delivery agents

AbstractInterpenetrating polymer network (IPN) membranes and gradient–IPN polymers were synthesized by immersing crosslinked, 2‐hydroxyethylmethacrylate copolymer beads which were swollen in polyol in solutions of diisocyanates. Diffusion of reactants and polycondensation take place simultaneously, and the polymer beads are modified by a polyurethane–IPN layer whose thickness and compositional gradient are a function of reaction rate and diffusion rate. When the reaction is fast relative to diffusion, the reaction zone is narrow and the IPN boundary layer is sharp, whereas when diffusion dominates, the reaction zone and the IPN‐modified region becomes broader and more diffuse. A water‐soluble drug imbibed into such gradient‐IPN‐modified hydrogel beads is released over a prolonged time period due to the less permeable IPN barrier and because of a drug‐distribution gradient in the polymer, which follows the polyurethane gradient. Diffusion polycondensation can be considered a special case of interfacial polycondensation, one in which the interface area is expanded into and stabilized by a preformed polymer matrix, which serves as reaction medium.

Thermal degradation of copolymers of 2-hydroxyethyl methacrylate and alkyl methacrylates

Thermal degradation of homopolymers of ethyl methacrylate ( I), n-butyl methacrylate ( II), 2-hydroxyethyl methacrylate ( III), and copolymers of III with I and II were carried out by thermal volatilization analysis (TVA) up to 440°C with subsequent subambient thermal volatilization analysis (SATVA). An on-line mass spectrometry coupled with TVA and SATVA was employed to identify the products of thermal degradations. Isothermal pyrolyses of the polymers were carried out separately at 400°C in vacuum for 30 min and the liquid products of decomposition were collected and analysed by gas chromatography. The relationship between the amounts of I and II obtained from pyrolysis and the amounts of these components actually present in the copolymer samples was determined. Also the amount of III and ethyleneglycol dimethacrylate obtained from pyrolysis increases with the amount of III in the copolymer. The polymers were also characterized by differential thermal analysis.

Adsorption of proteins from plasma to a series of hydrophilic-hydrophobic copolymers. I. Analysis with the in situ radioiodination technique.

The adsorption of proteins affects cellular interactions with foreign surfaces and thus plays an important role in determining the biocompatibility of implants. Previous studies have indicated differences in the affinity of various proteins for a given polymer, and differences in the affinity of fibrinogen for a series of polymers varying in hydrophilicity. These studies suggest that differences in the composition of the protein layer adsorbed to polymers from plasma might exist. To examine this hypothesis, the proteins adsorbed from plasma to a series of polymers varying in hydrophilicity were analyzed with the iodogram technique. Copolymers of hydroxyethyl methacrylate and ethyl methacrylate made by the radiation grafting technique were exposed to plasma for 0.5 or 150 min. The adsorbed proteins were iodinated, eluted with SDS, and separated with polyacrylamide gel electrophoresis. Fibrinogen, immunoglobulin G, hemoglobin, and a peak tentatively ascribed to prothrombin were the major proteins detected. Very little iodine was incorporated into adsorbed albumin, even though it was shown to be present by a separate experiment using dye binding. The fraction of total radioactivity associated with each of nine proteins was found to vary markedly and systematically among the surfaces. The distribution of radioactivity into the proteins was very different on 0.5 and 150-min plasma exposed polymers. The results reflect both compositional differences in the adsorbed protein layer on the polymers and differences in the accessibility of proteins to the labeling reagent in the adsorbed state. Differences in the organization of the adsorbed protein layer may play a key role in determining whether cell surface receptors can come in contact with the specific plasma protein able to further stimulate the cell.

Immobilization of Enzymes by Radiation-Induced Copolymerization of 2-Hydroxyethyl Methacrylate and Other Hydrophilic or Hydrophobic Comonomers

Abstract Immobilization of enzymes by radiation-induced copolymerization was studied at low temperatures by use of various comonomer systems consisting of 2-hydroxyethyl methacrylate and other more hydrophilic or hydrophobic comonomers. The matrices obtained by copolymerization with more hydrophilic and more hydrophobic comonomers decreased the porosity in the matrix equally. However, the activity yield of the immobilized enzyme showed different changes with repeated use in the more hydrophilic and more hydrophobic matrices. That is, the initial activity decreased rapidly with repeated use owing to the enzyme leakage from the matrix, in the increased hydrophilic matrices. On the other hand, in the more hydrophobic matrices enzyme leakage was completely retarded and activity did not change with repeated use. Moreover, the activity yield showed a maximum at a certain monomer composition in the copolymerization with hydrophobic comonomer. Finally, it was found that the maximum activity yield of the hydrophob...

Strong-acid membranes with enhanced hydrophilicity

A number of membranes have been synthesized on the basis of a cross-linked gel with a hydrophilic neutral matrix, containing polymerized hydrophilic monomers with strongly dissociable groups. p]The membrane is a copolymer of 2-hydroxyethyl methacrylate (matrix) and sulfooxyethyl methacrylate with the crosslinking agent (ethylenedimethacrylate). Presented in this paper are the effects of cross-linking, concentration of the dissociable groups, and pH on the membrane concentration potentials, electrical conductivity, and swelling of the merebranes. The hydrophilic character of the membrane matrix causes departures from the theoretical behavior derived for membranes with a hydrophobic character, and influences its behavior more than would be anticipated from the presence of the strong-acid groups. Cross-linking is more effective in attaining a high permsetectivity than is the density of fixed dissociable groups and/or their dissociation, so that by combining the content of the ionogenic component with cross-linking it was possible to find highly hydrophilic merebrane gels with a virtually theoretical electrochemical behavior and with a small dependence on pH.

Alkaline hydrolysis of pivalic esters of ethylene glycol in water-acetone solutions

The paper reports alkaline hydrolysis of ethylene dipivalate and 2-hydroxyethyl pivalates as compounds modelling the structural unit and crosslinking site of hydrophilic gels, i.e. copolymers of 2-hydroxyethyl methacrylate and ethylene dimethacrylate. The kinetics of hydrolysis was investigated in water-acetone solutions containing respectively 50, 75, 80, 85 and 90% by vol. (related to 20°C) of acetone at 20, 30, 40, and 50°C. It was demonstrated that, owing to steric hindrance, the preferential hydrolysis of monoester was more pronounced in the case of pivalic esters of ethylene glycol compared with acetic esters of ethylene glycol. The results are discussed in connection with the selectivity of the alkaline hydrolysis of ester bonds in "pendant" parts of structural units in hydrophylic methacrylate gels.

The photoelastic behaviour and small-angle x-ray scattering of ionized gels of copolymers of 2-hydroxyethyl methacrylate with methacrylic acid

The photoelastic behaviour and small-angle X-ray scattering of ionized, loosely crosslinked gels of copolymers of 2-hydroxyethyl methacrylate (HEMA) with methacrylic acid (MA) swollen in 0.5 M NaCl are characterized by the following specific features. Increasing neutralization of gels causes a steep decrease in the volume fraction of the polymer in the gel, v 2, and in the modulus G. The time dependences of photoelastic functions, which are the most pronounced for PMA, become weaker with swelling. The slopes of the dependence of the extrapolated equilibrium modulus log G c on log v 2 is large (φ 0.6) 1.5 for PMA. The stress-optical coefficiént C passes at about v 2 φ 0.25 through a pronounced maximum, probably due to a decisive effect of the shape contribution, caused by possible correlation structures in the copolymers. Increasing ionization leads to a rise in swelling, first increasing the contrast of the correlation structures but then obviously causing their dissociation. The small-angle X-ray data indicate a considerable heterogeneity of the order 10 nm in size of gels in the ionized state: the structural characteristics calculated using a two-phase model are in agreement with the assumed shape contribution to birefringence.

Studies of 2-hydroxyethyl methacrylate and ethyl acrylate copolymers as negative photoresists

The potential of 2-hydroxyethyl methacrylate and ethyl acrylate copolymers as negative photoresists was studied. Negative photoresist solution was prepared by esterfication of copolymers with cinnamoyl chloride. The effects of photosensitizer concentration, copolymer composition, and exposure time were investigated. A resolution of 30 μm was attained from these photoresists.