Photopolymerization Of Acrylamide Research Articles

Hydrogel diffraction gratings functionalized with crown ether for heavy metal ion detection

Hydrogel diffraction gratings containing crown-ether functional groups were developed as a new sensing strategy for heavy metal ion detection. The gratings were fabricated by soft-lithographic duplication of photoinduced surface-relief-gratings (SRGs) on azo polymer masters to the hydrogel surfaces. In the fabrication, the elastomer stamps were obtained by replica-molding against the SRG-bearing masters. The hydrogel gratings were fabricated by micro-contact printing with the stamps and in situ photo-polymerization of acrylamide, crown ether monomer, crosslinker and photo-initiator in a mixed DMSO/H2O solution. The quantitative detection of Pb2+ ions was achieved by monitoring the variation of diffraction efficiency of the gratings when exposed to Pb(NO3)2 solutions with different ion concentrations. The diffraction efficiency (DE) variation was triggered by the binding of Pb2+ ions with crown-ether rings and increasing amount of mobile counter-ions in the hydrogel due to Donnan potential. The mobile ions in the hydrogel established an excess osmotic pressure, which caused the grating to swell and DE variation. The saturated diffraction efficiency (DE/DE0) was observed to be linearly correlated with the Pb(NO3)2 concentration in the testing range. The gratings developed in this study show excellent sensitivity to the Pb2+ ion with the fast response and high selectivity to the analytes.

Quantitative Contrasts in the Photopolymerization of Acrylamide and Methacrylamide‐Functionalized Gelatin Hydrogel Building Blocks

The synthesis and evaluation of gelatin acrylamide as an alternative to the well-established gelatin methacrylamide are reported. High-resolution magic angle spinning NMR is used for the quantitative determination of the chemical cross-linking density. The gelatin acrylamide precursors reveal enhanced cross-linking in terms of reactivity and double bond conversion, resulting in stronger networks. Remarkably, even at very low double bond conversions, ≈5%, gel fractions of ≈40% are obtained. The cross-linked networks are also reviewed in the framework of the rubber elasticity and thermodynamic swelling theories to estimate important nanostructural properties. Preliminary cell tests revealed that highly viable (>90%) cell-laden constructs are obtained.

Enhanced and selective adsorption of heavy metal ions on ion-imprinted simultaneous interpenetrating network hydrogels

Ion recognition-based separation techniques have received much attention because of the high selectivity for target ions. In this study, a novel Cu(II) ion-imprinted hydrogel [Cu(II)–IIH] with interpenetrating network structure has been prepared to remove Cu(II) ions with high selectivity. The Cu(II)–IIH was prepared by free radical/cationic hybrid photopolymerization of acrylamide (AAm) and triethylene glycol divinyl ether (DVE-3) using Cu(II) ions as template. The ability of the Cu(II)–IIH to adsorb and remove Cu(II) ions from aqueous solutions was assessed using a batch adsorption technique. The maximum adsorption capacity was observed at pH 5.0, and the adsorption process could be well described by the Freundlich isotherm. The adsorption equilibrium was achieved within 16 min, and the kinetics of adsorption followed a pseudo-second-order rate equation. Selective adsorption study indicated that ion imprinting resulted in stronger affinity of the Cu(II)–IIH toward Cu(II) ions than other competitor metal ions compared with the non-imprinted hydrogel. The prepared Cu(II)–IIH was repeatedly used and regenerated for five times without a significant decrease in metal binding affinity.

Visible light photopolymerization in BHDC reverse micelles. Laser flash photolysis study of the photoinitiating mechanism

Abstract The photopolymerization of acrylamide (AA) in reverse micelles (RMs) of benzyl hexadecyl dimethylammonium chloride (BHDC) was investigated. The polymerization was performed by irradiation in the 500 nm region of the spectrum, employing as photoinitiating system the synthetic dye safranine-O and triethanolamine (TEOA) as co-initiator. The characterization of the nanoparticles of polyacrylamide was done by dynamic light scattering. Molecular weight determinations were carried out by viscosimetry. Small nanoparticles of polyacrylamide are formed with a low polydispersity and a molecular weight close to 10 6 . The results were compared with those in AOT (sodium bis(2-ethylhexyl) sulfosuccinate) RMs. Laser flash photolysis was used to investigate the photoinitiating mechanism. The maximum of the T – T absorption spectra in RMs confirms that, in spite of its positive charge, the dyes remain at the interface co-micellizing with BHDC. The triplet lifetime is much longer in the RMs than in homogeneous organic solvents. The triplet quenching by TEOA was very much more effective in the RMs than in a homogeneous solvent. The quantum yield of formation of active radicals was evaluated from the transient absorption spectra. It was concluded that they are generated by an intermicellar electron transfer process followed by an intramicellar proton transfer reaction. The quantum yield was found to be 0.2 ± 0.02. A similar radical yield in a homogeneous solvent requires an amine concentration near 50 times higher.

Photopolymerization of acrylamide induced by colloidal graphene oxide

Photochemical activity of colloidal graphene oxide in initiating of the acrylamide photopolymerization in aqueous solutions under the illumination with the visible light (λ > 420 nm) is reported for the first time. By photochemical activity graphene oxide occupies an intermediary place among typical visible-light-sensitive water-soluble photoinitiators of acrylamide polymerization. The photoinitiation involves photoexcited oxygen-containing functional groups of graphene oxide particles, the polymerization rate growing with an increase in the content of such functional groups and lowering drastically at their photoinduced elimination. The photopolymerization kinetics indicates the possibility of graphene oxide participation in the chain termination and shows that the aggregation of graphene oxide particles results in a decrease of their photochemical activity.

Preparation of an amperometric sensor for norfloxacin based on molecularly imprinted grafting photopolymerization

A sensitive amperometric sensor for norfloxacin (NF) was introduced. The receptor layer was prepared by molecularly imprinted photopolymerization of acrylamide and trimethylolpropane trimethacrylate on the surface of a gold electrode. The binding mechanism of the molecularly imprinted polymer was explored by ultraviolet (UV) and infrared (IR) spectroscopy. The chemosensor was characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance (EI), and scanning electron microscopy (SEM). The electrode prepared by photopolymerization has a better recognition ability to template molecules than that of electropolymerization and NIP. Some parameters affecting sensor response were optimized. Norfloxacin was detected by measurements of an amperometric i-t curve. The linear relationships between current and logarithmic concentration are obtained from 1.0 × 10(-9) to 1.0 × 10(-3) mol L(-1). The detection limit of the sensor was 1.0 × 10(-10) mol L(-1). The proposed method is sensitive, simple, and cheap, and is applied to detect NF in human urine successfully.

Fast preparation of monolithic immobilized pH gradient column by photopolymerization and photografting techniques for isoelectric focusing separation of proteins

A new method was developed to prepare monolithic immobilized pH gradient (M-IPG) columns in UV-transparent fused-silica capillaries by the 5-min photopolymerization of acrylamide and N,N'-methylenebisacrylamide, followed by the 20-min photografting of the focused ampholine-derived glycidylmethacrylate monomer on the monolithic matrix, by which the preparation time was reduced, and the stability of the formed pH gradient was improved, compared with our previous methods. Using the prepared M-IPG column, the baseline separation of proteins was achieved according to their pIs. Without carrier ampholytes added in the running buffer, the separated components could be detected with high sensitivity by UV at low wavelength.

Frontal photopolymerization synthesis of multilayer hydrogels with high mechanical strength

Multilayer hydrogels were prepared by frontal photopolymerization of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid using hydrophilic reactive microgels (HRM) as crosslinkers instead of conventional crosslinkers. The hydrophilic microgels (HM) were prepared by inverse emulsion photopolymerization and then were chemical modified by N-methylolacrylamide (NMA) to obtain HRM with C C double bonds. The HM and HRM was characterized by dynamic light scattering measurements, SEM, TEM and FTIR, respectively. It was found that the resulting multilayer hydrogels showed high fracture strength and high tensile elongation along parallel direction. However their fracture strength and tensile elongation along perpendicular direction was very weak. The swollen multilayer hydrogels were about 1.0–2.0 mm in thickness, the maximal equilibrium swelling degree was only 30.45. The multilayer hydrogels were characterized by DSC, TEM and XRD, respectively. The swelling property and mechanical strength of some typical multilayer hydrogels were studied.

Photopolymerization of acrylamide with benzophenone/methylated-β-cyclodextrin inclusion complex in the presence of jeffamine based dendrimers as coinitiators in aqueous media

BP/Me-β-CD inclusion complex was synthesized and used in photoinduced free radical polymerization of acrylamide as a type II photoinitiator in the presence of a dendritic co-initiator. Characterization and photophysical studies of the inclusion complex were determined by 1H NMR, UV, laser flash photolysis and phosphorescence spectroscopy. According to acrylamide polymerization of the BP/Me-β-CD water soluble photoinitiator, BP/Me-β-CD initiates polymerization of acrylamide effectively with six and twelve armed dendritic co-initiators in aqueous media. The 24 armed dendritic co-initiator was not as efficient as the six and twelve armed dendritic co-initiators with the BP/Me-β-CD inclusion complex, due to the sterical hindrance of the amine groups in the co-initiator.

Bovine serum albumin as chain transfer agent in the acrylamide polymerization. Protein-polymer conjugates

Acrylamide photopolymerization at 25°C, using as chain transfer agent the single exposed cysteine residue of bovine serum albumin (BSA), resulted in a conjugate where a single poly(acrylamide) chain is bound to the cysteine residue of the protein. Studies of the intrinsic fluorescence of the protein and of the extrinsic probe, 1-anilino-8-naphthalene-sulfonic acid, indicate that the protein mostly maintains its native structure in the conjugate. Kinetic studies showed that the chain transfer efficiency of thiols depends on the microenvironment where the –SH group is located. The single exposed cysteine residue of BSA is a more efficient chain transfer agent of the acrylamide polymerization than the free cysteine or glutathione tripeptide. Other potentially reactive amino acids, such as tryptophan, tyrosine and histidine, are two orders of magnitude less efficient than the protein as chain transfer agents.

Thioxanthone based water-soluble photoinitiators for acrylamide photopolymerization

Abstract The two water-soluble thioxanthone-based 2-(carboxymethoxy) thioxanthone, 1A and 2-thioxanthone-thioacetic acid sodium salts, 2A were synthesized and characterized by spectroscopic methods. The quantum yield for fluorescence emission ( φ f ) in water was found to be 0.50 for 1A and 0.05 for 2A . The long phosphorescence lifetime, that is 201 and 114 ms in a matrix at 77 K for 1A and 2A , respectively, indicates a π–π∗ nature of the lowest triplet state. The triplet lifetimes were determined by laser flash photolysis as 12 and 12.6 μs for 1A and 2A . Polymerization of acrylamide (AAm) was initiated by both initiators in water. Decarboxylation of initiators was achieved during 20 min of irradiation. It was found that 2A initiated polymerization of AAm in water more efficiently than 1A .

Amphipathic hyperbranched polymeric thioxanthone photoinitiators (AHPTXs): Synthesis, characterization and photoinitiated polymerization

Abstract Amphipathic hyperbranched polymeric thioxanthone (TX) photoinitiators (AHPTXs) were synthesized by introducing TX, and polyethylene glycol monoethylether glycidyl ether (E-PEO), which contained short poly (ethylene oxide) (PEO) chain, into periphery of hyperbranched poly(ethylene imine) (HPEI), as well as low-molecular weight analogue 2-(2-hydroxy-3-(methyl(2,3,4,5,6-pentahydroxyhexyl)amino)propoxy) thioxanthone (MGA-TX). AHPTXs possess UV–vis absorption spectra similar to TX derivatives, and weaker fluorescence emission in comparison to low-molecular weight analogues. AHPTXs can be not only dispersed easily in many solvents and acrylate monomers, but also are soluble in water. AHPTXs are very efficient in photopolymerization of acrylamide (AM), poly(ethylene glycol) diacrylate (PEGDA) and 2,2-bis[4-(acryloxypolyethoxy)phenyl] propane (A-BPE-10). In comparison to low-molecular weight analogues photoinitiator systems 2-(2,3-epoxypropyloxy) thioxanthone/triethylamine (ETX/TEA) and MGA-TX/TEA, AHPTX1 is very efficient for photoinitiation of A-BPE-10 and AM in aqueous solution

Macromol. Rapid Commun. 7/2009

Back Cover: A general approach to enhance the mechanical performance and solvent resistance of photonic crystals (PCs) is demonstrated by the photo‐crosslinking of latex spheres by photopolymerization of acrylamide (AAm), which is of great importance for the practical application of PCs. Further details can be found in the article by E. Tian, L. Cui, J. Wang,* Y. Song,* and L. Jiang on page 509.

Tough Photonic Crystals Fabricated by Photo‐Crosslinkage of Latex Spheres

A general method to enhance the mechanical properties and solvent resistance of photonic crystals (PCs) has been demonstrated. This is carried out by the crosslinkage of latex spheres via photopolymerization of acrylamide (AAm) infiltrated among them. The crosslinked PAAm enhances the interaction among latex spheres of the PCs film, and contributes to the improvement of mechanical strength and solvent resistance. The result provides a simple approach to make tough PCs films by photo-crosslinkage, and can be extended to a wide variety of materials, will be of great importance for the practical application of PCs.

Effect of Modification of SeO2/Acrylamide Ratios on Diffraction Efficiencies in PVA/AA Photopolymer Films

The highest diffraction efficiency(DE) value after illumination and post-curing of photopolymer films were obtained at the <TEX>$SeO_2$</TEX>/Acrylamide(AA) Ratios of AA 3.0 g, <TEX>$SeO_2$</TEX> 1.0g and the DE's were stable values of over 90%. By the addition of <TEX>$SeO_2$</TEX>, the maximum DE at the initial stage of illumination was reached at 300 seconds, which suggests <TEX>$SeO_2$</TEX> slows down the photopolymerization of AA, which enhances the maximum DE value by giving more migration time. DE variation curve for the optimum composition during extended-time illumination of 9,000 seconds resembles a sine curve due to the combination of the monomer diffusion and the photopolymerization, and the photopolymer film expanded by about 8% after photopolymerization due to monomer migration.

A water‐soluble supramolecular‐structured photoinitiator between methylated β‐cyclodextrin and 2,2‐dimethoxy‐2‐phenylacetophenone

AbstractA water‐soluble supramolecular‐structured photoinitiator (SSPI) was synthesized by supramolecular self‐assembling between methylated β‐cyclodextrin (MβCD) and hydrophobic 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA). The structure of SSPI was characterized by X‐ray diffraction, FTIR, 1H NMR, UV–vis, and fluorescence spectra. The results indicated that MβCD and DMPA had formed 1 : 1 inclusion complex in methanol solution. The binding constant (K) for the complex was 7.51 × 102M−1. SSPI could be dissolved in water easily and its water‐solubility was 15.3 g/100 mL. SSPI was the more efficient photoinitiator than DMPA for the photopolymerization of acrylamide (AM) in homogeneous aqueous system. The conversion for photopolymerization of trimethylolpropane triacrylate system initiated by SSPI was similar to that initiated by DMPA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Photoinitiation of acrylamide polymerization by Fe 2O 3 nanoparticles

Photocatalytic activity of α-Fe 2O 3 nanoparticles in the acrylamide photopolymerization in aqueous solutions has been investigated. The photoreaction proceeds efficiently both in degassed and air-exposed solutions, at low photoinitiator concentrations ([Fe 2O 3] < 1 × 10 −3 M), under the near UV and the visible light ( λ < 600 nm), and results in the formation of polyacrylamide with relatively high molecular mass (1.2 × 10 6 g/mole in degassed solutions and 0.7 × 10 6 g/mole in air-exposed solutions). Kinetics of the photoinduced acrylamide polymerization has been studied and optimal reaction conditions determined. It has been shown that the quantum yields of the photopolymerization and the photoinitiation in the systems under investigation do not exceed, respectively, 10 2 and 10 −2. The mechanism of the photopolymerization has been proposed, which includes the photoinitiation stage with the participation of acrylamide radicals, the latters originating from the monomer oxidation by the photogenerated Fe 2O 3 valence band holes, the free-radical chain growth and subsequent recombination of the growing macroradicals.

Holographic characteristics of two different films using methyl violet dyes in polyvinyl alcohol matrices

The holographic characteristics of two different photopolymer films containing methyl violet dyes in polyvinyl alcohol matrices were examined. One of the films contains only dye in the matrix. A holographic grating in the film is created by bleaching the dye. The other film contains acrylamide as a monomer and triethanolamine as a promoter as well as dye in the matrix, and a holographic grating is formed by the photopolymerization of acrylamide. In this study, the temporal evolution of diffraction efficiency was measured during holographic recording, by changing the dye concentration, exposure power, etc. For the film exposed to bleaching, the diffraction efficiency had a peak at a specific exposure time, and then decreased with overexposure. For the film exposed to photopolymerization, the diffraction efficiency was saturated at high exposure, and the maximum efficiency was approximately 40%, much higher than that of the other film.

Photopolymerization of acrylamide initiated by the three‐component system safranine/triethanolamine/diphenyliodonium chloride: The effect of the aggregation of the salt

AbstractThe effects of diphenyliodonium chloride (DPI) on the polymerization of acrylamide photoinitiated by the dye safranine with triethanolamine as a coinitiator were investigated in aqueous solutions. The salt notably increased the polymerization rate. This accelerating effects increased appreciably at concentrations of DPI at which the light scattering of the solutions became important. The effects of DPI on the photophysical properties of the dye were also investigated. Although the absorption and fluorescence were scarcely affected, the triplet yield increased by 60%. However, the polymerization rate increased by a factor much higher than that of the triplet yield. The results obtained at high concentrations of the salt could be ascribed to the presence of aggregates of the hydrophobic cations. The lower limit established for the formation of the aggregates was a DPI concentration of approximately 1 × 10−3 M. Possible mechanisms for the action of the salt were examined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4916–4920, 2004

Novel water soluble copolymers based on thioxanthone: photochemistry and photoinitiation activity

The absorption, luminescence and photoreduction properties of five novel water soluble thioxanthone copolymers are reported. The new polymers have been prepared by copolymerization of 1-methyl-4-(3-acryloxypropoxy) thioxanthone (TX3), 1-chloro-4-acryloxy thioxanthone (TX4), 1-chloro-4-oxyethylacrylate thioxanthone (TX5), and 1-chloro-4-allyloxy thioxanthone (TX6), with two water soluble comonomers, acrylamide (AAm) and 2-acryloxyethyl trimethylammonium iodide (MI). The photoinitiation effectiveness of these new copolymers was studied by photocalorimetry and photodilatometry for acrylamide photopolymerization in aqueous solution and in the presence of a tertiary amine. The results compared to those of the corresponding low molecular weight model compounds, (TX1), 1-methyl-4-(2-hydroxy-3- N, N, N-trimethylammoniumpropoxy) thioxanthone chloride salt, and TX2, 1-chloro-4-(2-hydroxy-3- N, N, N-trimethylammoniumpropoxy) thioxanthone chloride salt. The new copolymers show high polymerisation rates under the experimental conditions used, and confirm that these compounds operate as effective photoinitiators of polymerization. The data are discussed in relation to their photophysical and photochemical properties.