Glutamic acid containing supermacroporous poly(hydroxyethyl methacrylate) cryogel disks for UO22+ removal

Supermacroporous cryogel with an average pore size of 10–200 μm in diameter was prepared by cryopolymerization of N-methacryloyl-(l)-glutamic acid (MAGA) and 2-hydroxyethyl methacrylate (HEMA). The poly(HEMA–MAGA) cryogel was characterized by surface area measurements, FTIR, swelling studies, elemental analysis and SEM. The poly(HEMA–MAGA) cryogel had a specific surface area of 23.2 m²/g. The equilibrium swelling ratio of the cryogel is 9.68 g H₂O/g for poly(HEMA–MAGA) and 8.56 g H₂O/g cryogel for PHEMA. The poly(HEMA–MAGA) cryogel disks with a pore volume of 71.6% containing 878 μmol MAGA/g were used in the removal of UO₂²⁺ from aqueous solutions. Adsorption equilibrium of UO₂²⁺ was obtained in about 30 min. The adsorption of UO₂²⁺ ions onto the PHEMA cryogel disks was negligible (0.78 mg/g). The MAGA incorporation significantly increased the UO₂²⁺ adsorption capacity (92.5 mg/g). The adsorption process is found to be a function of pH of the UO₂²⁺ solution, with the optimum value being pH 6.0. Adsorption capacity of MAGA contained PHEMA based cryogel disks increased significantly with pH and then reached the maximum at pH 6.0. Consecutive adsorption and elution cycles showed the feasibility of repeated use for poly(HEMA–MAGA) cryogel disks.     

Polyurethane/poly(hydroxyethyl methacrylate) semi-interpenetrating polymer networks for biomedical applications

The thermodynamic miscibility, morphology, phase distribution, mechanical properties, surface properties, water sorption, bacterial adhesion and cytotoxicity of semi-interpenetrating polymer networks (semi-IPNs) based on crosslinked polyurethane (PU) and poly(hydroxyethylmethacrylate) (PHEMA) were studied to give an insight into their structure and properties. The free energies of mixing of the two polymers in semi-IPNs have been determined and it was shown that the values are positive and depend on the amount of PHEMA. This demonstrates that the components are immiscible, the extent of which is dependent upon variations in composition. The morphology of the semi-IPNs was analyzed with scanning electron microscopy and tapping mode atomic force microscopy (TMAFM). The micrographs of the semi-IPNs and TMAFM phase images indicated that distinct phase separation at the nanometer scale is observed. The mechanical properties reflect the changes in structure of semi-IPNs with composition. The stress at break increases from 3.4 MPa to 23.9 MPa, and the Young’s modulus from 12.7 MPa up to 658.5 MPa with increasing amounts of PHEMA, but strain at break has a maximum at 40.4% PHEMA. The bacterial adhesion and cytotoxicity data suggest that semi-IPNs with PHEMA content above 22% may be used for biomedical material applications.     

PHEMA cryogel for in-vitro removal of anti-dsDNA antibodies from SLE plasma

Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA) cryogel carrying DNA was used in the removal of anti-dsDNA antibodies from systemic lupus erythematosus (SLE) patient plasma. The PHEMA cryogel was prepared by bulk polymerization which proceeds in an aqueous solution of monomer frozen inside a plastic syringe. After thawing, the PHEMA cryogel contains a continuous matrix having interconnected macropores of 10–200 μm size. Pore volume in the PHEMA cryogel was 67.5%. Ester groups in the PHEMA structure were converted to imine groups by reacting with poly(ethyleneimine) (PEI) in the presence of NaHCO₃. Amino (? NH₂) content of PEI-modified PHEMA cryogel was determined as 82 mg PEI/g. Then, DNA was attached onto the PHEMA cryogel via amino groups (53.4 mg DNA/g cryogel). Anti-dsDNA-antibody concentration declined significantly from 780 IU/ml to 80 IU/ml with the time. The maximum anti-dsDNA-antibody adsorption amount was 70 × 10³ IU/g. Anti-dsDNA-antibodies could be repeatedly adsorbed and eluted without noticeable loss in the anti-dsDNA-antibody adsorption amount.     

Poly(hydroxyethyl methacrylate) nanobeads containing imidazole groups for removal of Cu(II) ions

Poly(hydroxyethyl methacrylate) (PHEMA) nanobeads with an average size of 300 nm in diameter and with a polydispersity index of 1.156 were produced by a surfactant free emulsion polymerization. Specific surface area of the PHEMA nanobeads was found to be 996 m²/g. Imidazole containing 3-(2-imidazoline-1-yl)propyl(triethoxysilane) (IMEO) was used as a metal-chelating ligand. IMEO was covalently attached to the nanobeads. PHEMA-IMEO nanobeads were used for the removal of copper(II) ions from aqueous solutions. To evaluate the degree of IMEO loading, the PHEMA nanobeads were subjected to Si analysis by using flame atomizer atomic absorption spectrometer and it was estimated as 973 µmol IMEO/g of polymer. The PHEMA nanobeads were characterized by transmission electron microscopy and fourier transform infrared spectroscopy. Adsorption equilibrium was achieved in about 8 min. The adsorption of Cu²⁺ ions onto the PHEMA nanobeads was negligible (0.2 mg/g). The IMEO attachment into the PHEMA nanobeads significantly increased the Cu²⁺ adsorption capacity (58 mg/g). Adsorption capacity of the PHEMA-IMEO nanobeads increased significantly with increasing concentration. The adsorption of Cu²⁺ ions increased with increasing pH and reached a plateau value at around pH 5.0. Competitive heavy metal adsorption from aqueous solutions containing Cu⁺, Cd²⁺, Pb²⁺ and Hg²⁺ was also investigated. The adsorption capacities are 61.4 mg/g (966.9 µmol/g) for Cu²⁺; 180.5 mg/g (899.8 µmol/g) for Hg²⁺; 34.9 mg/g (310.5 µmol/g) for Cd²⁺ and 14.3 mg/g (69 µmol/g) for Pb²⁺. The affinity order in molar basis is observed as Cu²⁺ > Hg²⁺ > Cd²⁺ > Pb²⁺. These results may be considered as an indication of higher specificity of the PHEMA-IMEO nanobeads for the Cu²⁺ comparing to other ions. Consecutive adsorption and elution operations showed the feasibility of repeated use for PHEMA-IMEO nanobeads.     

Preparation and characterization of molecularly imprinted poly(hydroxyethyl methacrylate) microspheres for sustained release of gatifloxacin

Molecularly imprinted poly(hydroxyethyl methacrylate) microspheres (PHEMA MIPMs) were prepared via precipitation polymerization in this article, using gatifloxacin (GFLX), hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA) as template molecule, functional monomer and cross-linker, respectively. The effects of reaction medium, initial total monomers, cross-linker and molecular imprinting on the polymerization were investigated systematically. The interaction between GFLX and HEMA in pre-solution was studied by UV–Visible spectrophotometer, both size and morphology of products were characterized by a scanning electron microscope. When the total initial monomer concentration was 1 vol%, EGDMA content was 70 mol%, a group of uniform PHEMA MIPMs were prepared at different GFLX/MAA molar ratios, with diameter range from 2.06 ± 0.07 to 2.82 ± 0.20 μm. The results of drug loading and in vitro release experiments demonstrated that PHEMA MIPMs could achieve a higher GFLX loading content and a more acceptable sustained release than non-imprinted ones.     

聚甲基丙稀酸羟乙酯甘油凝胶仿软骨材料的制备与性能

为了使人体关节软骨损伤后得到修复,采用热聚合的方法制备了一种新型人工仿软骨材料。在水浴保温和引发剂条件下,采用甲基丙稀酸羟乙酯(CH2CCH3COOCH2CH2OH,HEMA)和医用甘油(C3H8O3)聚合成一种新型凝胶,并对其分别进行了表面形貌观察和猪软骨硬度的对比,以及抗压性、弹性等力学性能测试。使用FTIR红外光谱对其作分析表征,结果表明:凝胶主体仍然是聚甲基丙稀酸羟乙酯(PHEMA),甘油以凝胶态存在;凝胶硬度随甘油比例增加而下降,但凝胶表面粗糙度却增加;当HEMA与甘油质量比例为1∶1~1∶3时,凝胶的硬度较为接近猪软骨;在比例为1∶1和1∶2的条件下,表面光滑。4种比例下的凝胶都具有良好的抗压性和弹性,当质量比为1∶1时抗压性能和综合性能最好。实验结果表明PHEMA与甘油的凝胶聚合物如果作为人工仿软骨材料,具有力学性能良好的优点,将可能提供给临床实验作进一步考察。     

Quasi-solid-state dye-sensitized solar cells from hydrophobic poly(hydroxyethyl methacrylate/glycerin)/polyaniline gel electrolyte

Hydrophobic poly(hydroxyethyl methacrylate/glycerin) [poly(HEMA/GR)] gel with a three-dimensional (3D) framework was successfully fabricated and employed to integrate with polyaniline (PANi). The resultant poly(HEMA/GR)/PANi gel electrolyte exhibited interconnective porous structure for holding I⁻/I₃⁻, giving a similar conduction mechanism and ionic conductivity to that of liquid system but a much enhanced retention of I⁻/I₃⁻ redox couple. Fourier transform infrared spectroscopy, X-ray diffraction patterns, cyclic voltammograms as well as electrochemical impedance spectroscopy were employed to evaluate the molecular structure, crystallinity, and the electrochemical behaviors, showing that the combination of PANi with poly(HEMA/GR) caused a lower charge-transfer resistance and higher electrocatalytic activity for the I₃⁻/I⁻ redox reaction in the gel electrolyte. An efficiency of 6.63% was recorded from the quasi-solid-state DSSC assembled with the poly(HEMA/GR)/PANi gel electrolyte at 100 mW cm⁻².     

Nitrate removal by Thiobacillus denitrificans immobilized on poly(vinyl alcohol) carriers

Nitrate contamination is becoming a widespread environmental problem, and autotrophic denitrification with Thiobacillus denitrificans is a promising process considering efficiency, cost and maintenance. The denitrification efficiencies of T. denitrificans were compared in batch reactors between free cells and cells immobilized on polyvinyl alcohol (PVA) carriers made with thrice freezing/thawing and boric acid methods. The results indicated that the free cell reactor of T. denitrificans added with 10% (v/v) of PVA carrier made by thrice freezing/thawing (PVA-TFT) exhibited faster in S(2)O(3)(2-)-S consumption, SO(4)(2-) generation, and NO(3)(-)-N denitrification, with corresponding values being 165 mg (S(2)O(3)(2-)-S)/L.d, 491 mg (SO(4)(2-))/Ld, and 44 mg (NO(3)(-)-N)/Ld, which were increased by 50%, 61%, and 57% respectively compared to the control reactor with only free cells. Inhibition of denitrification by accumulated SO(4)(2-) in PVA-TFT reactor appeared at the concentration of approximately 6000 mg (SO(4)(2-))/L, and 75% of NO(3)(-)-N removal efficiency was achieved after 12d operation under the condition of initial 700 mg/L NO(3)(-)-N concentration.     

Synthesis and characterization of poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-glutamic acid) copolymer beads for removal of lead ions

N-methacryloyl-(l)-glutamic acid (MAGA) was synthesized using methacryloyl chloride and l-glutamic acid methyl ester as a metal-complexing ligand and/or comonomer. MAGA was characterized by FTIR and NMR. Spherical beads with an average diameter of 150–200 μm were obtained by suspension polymerization of MAGA and 2-hydroxyethyl methacrylate (HEMA) performed in an aqueous dispersion medium. Poly(HEMA-MAGA) beads were characterized by swelling studies, surface area measurements and elemental analysis. Poly(HEMA-MAGA) beads have a specific surface area of 56.7 m²/g. Poly(HEMA-MAGA) beads were used in the removal studies of Pb²⁺ ions. Adsorption equilibrium was achieved in about 60 min. The adsorption of Pb²⁺ ions onto PHEMA beads was negligible (0.38 mg/g). The MAGA incorporation into the polymer structure significantly increased the lead adsorption capacity (348 mg/g). The adsorption of Pb²⁺ ions increased with increasing pH and reached a plateau value at around pH 5.0. Competitive adsorption of heavy metal ions from synthetic wastewater was also studied. The adsorption capacities are 42.5 mg/g for Pb²⁺, 26.8 mg/g for Hg²⁺ and 17.6 mg/g for Cd²⁺ at 0.5 mmol/l metal concentration. Consecutive adsorption and elution operations showed the feasibility of repeated use for poly(HEMA-MAGA) chelating beads.     

Poly(hydroxyethyl methacrylate) based magnetic nanoparticles for plasmid DNA purification from Escherichia coli lysate

The aim of this study is to prepare poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine) [PHEMAH] magnetic nanoparticles for plasmid DNA (pDNA) purification from Escherichia coli (E. coli) cell lysate. Magnetic nanoparticles were produced by surfactant free emulsion polymerization. mPHEMAH nanoparticles were characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), electron spin resonance (ESR), thermogravimetric analyses (TGA) and transmission electron microscopy (TEM). Surface area, average particle size and size distribution were also performed. Specific surface area of the mPHEMAH nanoparticles was found to be 1180 m²/g. Elemental analysis of MAH for nitrogen was estimated as 0.18 mmol/g polymer. The amount of pDNA adsorbed onto the mPHEMAH nanoparticles first increased and then reached a saturation value at around 1.0 mg/mL of pDNA concentration. Compared with the mPHEMA nanoparticles (50 μg/g polymer), the pDNA adsorption capacity of the mPHEMAH nanoparticles (154 mg/g polymer) was improved significantly due to the MAH incorporation into the polymeric matrix. The maximum pDNA adsorption was achieved at 25 °C. The overall recovery of pDNA was calculated as 92%. The mPHEMAH nanoparticles could be used six times without decreasing the pDNA adsorption capacity significantly. The results indicate that the PHEMAH nanoparticles promise high selectivity for pDNA.     

Macroporous interpenetrating cryogel network of poly(acrylonitrile) and gelatin for biomedical applications

Cryogels are supermacroporous gel network formed by cryogelation of appropriate monomers or polymeric precursors at subzero temperature. The beneficial feature of this system is a unique combination of high porosity with adequate mechanical strength and osmotic stability, due to which they are being envisaged as potential scaffold material for various biomedical applications. One of the important aspect of cryogel is simple approach by which they can be synthesized and use of aqueous solvent for their synthesis which make them suitable for different biological applications. Various modifications of the cryogels have been sought which involves coupling of various ligands to its surfaces, grafting of polymer chain to cryogel surface or interpenetrating networks of two or more polymers to form a cryogel which provides diversity of its applications. In the following work we have synthesized full interpenetrating network of polyacrylonitrile (PAN)-gelatin with varied gelatin concentration. The PAN-gelatin cryogel interpenetrating network is macroporous in nature and has high percentage swelling equlibirium in the range of 862–1,200 with a flow rate greater than 10 ml/min, which characterizes the interconnectivity of pores and convective flow within the network. PAN-gelatin interpenetrating cryogel network has good mechanical stability as determined by Young’s modulus which varies from 123 kPa to 819 kPa depending upon the polymer concentration. Moreover they are shown to be biocompatible and support cell growth within the scaffolds.     

Macroporous interpenetrating cryogel network of poly(acrylonitrile) and gelatin for biomedical applications

Cryogels are supermacroporous gel network formed by cryogelation of appropriate monomers or polymeric precursors at subzero temperature. The beneficial feature of this system is a unique combination of high porosity with adequate mechanical strength and osmotic stability, due to which they are being envisaged as potential scaffold material for various biomedical applications. One of the important aspect of cryogel is simple approach by which they can be synthesized and use of aqueous solvent for their synthesis which make them suitable for different biological applications. Various modifications of the cryogels have been sought which involves coupling of various ligands to its surfaces, grafting of polymer chain to cryogel surface or interpenetrating networks of two or more polymers to form a cryogel which provides diversity of its applications. In the following work we have synthesized full interpenetrating network of polyacrylonitrile (PAN)-gelatin with varied gelatin concentration. The PAN-gelatin cryogel interpenetrating network is macroporous in nature and has high percentage swelling equilibrium in the range of 862-1,200 with a flow rate greater than 10 ml/min, which characterizes the interconnectivity of pores and convective flow within the network. PAN-gelatin interpenetrating cryogel network has good mechanical stability as determined by Young's modulus which varies from 123 kPa to 819 kPa depending upon the polymer concentration. Moreover they are shown to be biocompatible and support cell growth within the scaffolds.     

Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for heavy metal removal

The effective removal of toxic heavy metals from environmental samples still remains a major topic of present research. Metal-chelating membranes are very promising materials as adsorbents when compared with conventional beads because they are not compressible, and they eliminate internal diffusion limitations. The purpose of this study was to evaluate the performance of a novel adsorbent, Procion Green H-4G immobilized poly(hydroxyethylmethacrylate (HEMA)/chitosan) composite membranes, for the removal of three toxic heavy metal ions, namely, Cd(II), Pb(II) and Hg(II) from aquatic systems. The Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes were characterized by elemental analysis, scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The immobilized amount of the Procion Green H-4G was calculated as 0.018+/-0.003 micromol/cm(2) from the nitrogen and sulphur stoichiometry. The adsorption capacity of Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for selected heavy metal ions from aqueous media containing different amounts of these ions (30-400mg/l) and at different pH values (2.0-6.0) was investigated. The amount of Cd(II), Pb(II) and Hg(II) adsorbed onto the membranes measured at equilibrium, increased with time during the first 45 min and then remained unchanged toward the equilibrium adsorption. The maximum amounts of heavy metal ions adsorbed were 43.60+/-1.74, 68.81+/-2.75 and 48.22+/-1.92 mg/g for Cd(II), Pb(II) and Hg(II), respectively. The heavy metal ion adsorption on the pHEMA/chitosan membranes (carrying no dye) were relatively low, 6.31+/-0.13 mg/g for Cd(II), 18.73+/-0.37 mg/g for Pb(II) and 18.82+/-0.38 mg/g for Hg(II). Competitive adsorption of the metal ions was also studied. When the metal ions competed with each other, the adsorbed amounts were 12.74+/-0.38 mg Cd(II)/g, 28.80+/-0.86 mg Pb(II)/g and 18.41+/-0.54 mg Hg(II)/g. Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes can be regenerated by washing with a solution of nitric acid (0.01 M). The percent desorption achieved was as high as 95%. These novel membranes are suitable for repeated use for more than five adsorption/desorption cycles without any considerable loss in adsorption capacity. Adsorption equilibria were well described by Langmuir equation. It can be concluded that Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes may effectively be used for the removal of Cd(II), Pb(II) and Hg(II) ions from aqueous solutions.     

Properties of magnetic poly(glycidyl methacrylate) and poly(N-isopropylacrylamide) microspheres

Iron oxide colloids were prepared by coprecipitation of Fe(II) and Fe(III) salts in alkaline media and stabilized by perchloric acid, oleic acid, or poly(acrylic acid). In an attempt to obtain magnetic polymer microspheres differing in size, dispersion polymerization of glycidyl methacrylate (GMA) in ethanol containing HClO₄-stabilized magnetite, dispersion copolymerization of GMA and 2-hydroxyethyl methacrylate (HEMA) in toluene/2-methylpropan-1-ol mixture in the presence of oleic acid-coated magnetite, and inverse suspension copolymerization of N-isopropylacrylamide (NIPAAm) and N,N′-methylenebisacrylamide (MBAAm) in cyclohexane in the presence of poly(acrylic acid)-coated maghemite were compared. The microspheres were characterized by morphology, size, polydispersity, and some magnetic properties.     

Properties of biocomposites from waste seashells and poly(methyl methacrylate)

The paper presents the preparation of biocomposites from waste seashells as reinforcement and poly(methyl methacrylate), abbreviated as PMMA as the matrix. The used seashells belong to the snow‐white Bahamian species of tiger lucine (Codakia orbicularis) from the Island of Coco Cay. Seashells were grinded and homogenized with poly(methyl methacrylate) powder, with the seashell powder content ranging between 2 and 14 wt%, and finally hot pressed. Morphology of prepared composites was analyzed by scanning electron microscopy, and it was determined that the particle distribution was homogenous with no agglomeration. Mechanical properties (microhardness, compressive strength, Young's modulus) of biocomposite materials produced from different amount of waste seashells in poly (methyl methacrylate) were determined and analyzed. The best overall combination of mechanical properties was achieved when 6 wt% of seashell particles below 50 μm size were added to poly (methyl methacrylate).     

Thick dye-doped poly(methyl methacrylate) films for real-time holography

Molding and direct-polymerization techniques are used for the fabrication of holographic materials based on dye-doped poly(methyl methacrylate). The thickness of the samples obtained ranges from several micrometers to several millimeters. Pump-signal cross modulation is studied experimentally, and photophysical mechanisms responsible for refractive-index and absorption changes are discussed. Self-developing intensity and polarization holographic recording capability, strong anisotropy of diffraction, and high angular selectivity are demonstrated in thick samples.     

Activation energy of poly(methyl methacrylate) from rheometry and polymer welding

In this article, activation energies for a poly(methyl methacrylate) material were determined by shear rheometry and by bond strength in welding. Functions for temperature dependency of viscosity and for bond strength, depending on time and temperature, were found. These functions were fitted to measurements from shear rheometry between 230 and 270 °C and from strength of lap-shear joints welded from 105 to 130 °C, where by values of activation energies were found. It was found that bonding pressure was less than significant. Despite experimental differences, there was good correlation with data from literature for each method as well as for temperature dependency.     

Comparison of porous poly (vinyl alcohol)/hydroxyapatite composite cryogels and cryogels immobilized on poly (vinyl alcohol) and polyurethane foams for removal of cadmium

Three novel adsorbents of hydroxyapatite/poly (vinyl alcohol) (HAp/PVA) cryogel, HAp/PVA cryogel immobilized on PVA foam and HAp/PVA cryogel immobilized on polyurethane (PU) foam have been investigated to compare the morphology and sorption performances for removal of cadmium. The adsorption kinetics was interpreted by double-exponential model, pseudo-first-order model and pseudo-second-order models. The equilibrium time was found to be 36, 24, and 12 h for cryogel, cryogel immobilized on PVA foam and PU foam, respectively. The adsorption was found to follow Langmuir isotherm model and the maximum sorption capacity was estimated to be 53.3, 53.1 and 47.7 mg g(-1) for cryogel, cryogel immobilized on PVA foam and PU foam. The effects of HAp/PVA ratio and drying method on cadmium sorption were also studied. The difference of adsorption kinetics model and equilibrium time among the three adsorbents was suggested to be ascribed to different pore size. Oven-dried HAp/PVA cryogel immobilized on PU foam was preferable due to short equilibrium time and good sorption ability.