Polymerization Of Divinylbenzene Research Articles

High-Efficiency Synthesis of Cyclic Carbonates from Epoxides and CO2 over Hydroxyl Ionic Liquid Catalyst Grafted onto Cross-Linked Polymer

Hydroxyl ionic liquid grafted onto cross-linked divinylbenzene polymer (PDVB-HEIMBr) was fabricated and evaluated as a catalyst for the synthesis of cyclic carbonates from CO2 and epoxides without the use of any co-catalyst and organic solvent. The catalyst shows good performance across a wide range of epoxides, giving almost quantitative yield of carbonates (140 °C, 2.0 MPa of initial CO2, and ≤4 h). The effects of reaction temperature, time and initial CO2 pressure on product yield were investigated. It is suggested that the synergetic effect between the bromide ions and the hydroxyl groups facilitates the coupling reaction. Furthermore, the PDVB-HEIMBr catalyst shows excellent stability and reusability. From the viewpoint of industrial application, the catalyst is very attractive because of its simplicity, activity, stability, and reusability. Hydroxyl ionic liquid grafted onto divinylbenzene polymer was fabricated and evaluated for the solventless synthesis of cyclic carbonates from CO2 and epoxides. The catalyst shows good activity, selectivity, stability and reusability towards the coupling reaction.

Preparation of Silica/Poly(divinylbenzene) Composite Particles by Dispersion Polymerization in Supercritical Carbon Dioxide

Silica/poly(divinylbenzene) (PDVB) composite particles were synthesized by the dispersion polymerization of divinylbenzene (DVB) with ultrafine silica particles in supercritical carbon dioxide (scCO2). Silica particles of average diameter 130 nm were pretreated with 3-(trimethoxysilyl) propyl methacrylate in order to be well dispersed in CO2 and participated in the polymerization. Random copolymeric dispersant, poly(diisopropylaminoethyl methacrylate-co-heptafluorobutyl methacrylate) was used as a stabilizer to provide sufficient stabilization to latexes in scCO2 and the silica/PDVB composite powder was obtained in high yield from the polymerization. SEM analysis revealed that the composite particles prepared at 5% silica loading ratio and 6% stabilizer concentration with respect to monomer have the average diameter of 1.60 μm with uniform and spherical morphology. The composites were also characterized by FTIR spectroscopy and TGA.

Influence of the diameter of monolithic capillary columns on their gas chromatography characteristics

Divinylbenzene polymer monolithic capillary columns were prepared on the basis of capillaries 0.01 to 0.53 mm in diameter. Separation properties of the columns were investigated with the use of a test mixture of light hydrocarbons. The permeability and C parameter in the Van Deemter equation were determined for all the columns. For the most part, the columns had similar characteristics: permeability was in the range (2.2 ± 0.2) × 10−9 cm2, with parameter C in the range (0.7 ± 0.2) × 10−3 s (with n-butane as a sorbate). It was thus established that capillary diameter has only a slight effect on the efficiency of monolithic capillary columns (unlike packed capillary columns and microcolumns, whose properties, according to the literature data, depend strongly on the column diameter). The difference in properties between the narrowest monolithic column (capillary diameter 0.01 mm) and the others is explained by column overloading.

Investigation of sorption phenomena by solid phase extraction and liquid chromatography for the determination of some ether derivatives of tetrabromobisphenol A

AbstractObserved sorption and chromatographic behaviour served as a starting point for the examination of four ether derivatives of the flame retardant tetrabromobisphenol A (TBBPA): dihydroxyethyl (DHEE), dimethyl (DMe), diallyl (DAE) and dibromopropyl (DBPE). To date, there is little or no information about these compounds in the scientific literature. The targets in the present study had calculated log Kow values of 6.0–10. A broad range of different types of solvents were used in order to elucidate the mechanisms of sorption onto silica (glass) and two solid phase extraction cartridges based on polystyrene divinylbenzene polymers, hydroxylated (Isolute ENV+) and vinylpyrrolidone (Oasis HLB) containing units. Also, three chromatographic columns (C18, C8 and dual C18‐based, i.e. a polar ligand together with C18 on a silica surface) were evaluated. The following were observed: desorption of the targets from silica surface by 1‐propanol showed the best results and the yields were further improved by silylation of the surface. Regardless of the experimental test conditions applied, the lowest recovery was seen for the DMe derivative, followed by TBBPA itself, which had calculated log Kow values in between the other targets. A washing solution containing up to 70% methanol could be used without elution of the targets from the solid phase extraction cartridge . The dihydroxethyl ether derivative of TBBPA is most probably not affected by environmental relevant pH due to a likely high pKa (ca 15). Also, this study shows that the polar character of the dual‐phase column was not as pronounced as asserted by the manufacturer. Copyright © 2009 John Wiley & Sons, Ltd.

Preparation of Divinylbenzene and Divinylbenzene-co-Glycidyl Methacrylate Particles by Photoinitiated Precipitation Polymerization in Different Solvent Mixtures

Polymerization of Divinylbenzene and Divinylbenzene-co-Glycidyl Methacrylate Particles by Photoinitiated Precipitation Polymerization in Different Solvent Mixtures

Synthesis of tri-layer hybrid microspheres with magnetic core and functional polymer shell

Tri-layer magnetite/silica/poly(divinylbenzene) (Fe 3O 4/SiO 2/PDVB) core-shell hybrid microspheres were prepared by distillation precipitation polymerization of divinylbenzene (DVB) in the presence of magnetite/3-(methacryloxyl)propyl trimethoxysilane (MPS) modified silica core-shell particles as seeds. The polymerization of DVB was performed in neat acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as initiator to coat magnetite/MPS-modified silica particles through the capture of DVB oligomers with the aid of vinyl groups on the surface of inorganic seeds in absence of any stabilizer or surfactant. Other magnetite/silica/polymer tri-layer hybrid particles, such as magnetite/silica/poly(ethyleneglycol dimethacrylate) (Fe 3O 4/SiO 2/PEGDMA) and magnetite/silica/poly(ethyleneglycol dimethacrylate- co-methacrylic acid) (Fe 3O 4/SiO 2/P(EGDMA- co-MAA)) with various polarity and functionality, were also prepared by this procedure. Magnetite/silica/poly( N,N′-methylenebisacrylamide- co-methacrylic acid) (Fe 3O 4/SiO 2/P(MBAAm- co-MAA)) were synthesized with unmodified magnetite/silica particles as seeds. The resultant tri-layer hybrid particles were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), dynamic light scattering, and vibrating sample magnetometer (VSM).

Hydrobromination of residual vinyl groups on divinylbenzene polymer particles followed by atom transfer radical surface graft polymerization

AbstractRigid and monodisperse spherical polymer particles with 2.36 ± 0.18 μm diameter containing residual surface vinyl groups were prepared by photoinitiated precipitation polymerization of divinylbenzene. Anti‐Markovnikov addition of HBr to the surface vinyl groups yielded a 2‐bromoethyl functionality that was used as macroinitiator for atom transfer radical polymerization (ATRP), providing the possibility for further functionalization by controlled “grafting from” processes. This was demonstrated by grafting of glycidyl methacrylate brushes from the particle surface, using an ATRP system based on CuBr and pentamethyl diethylenetriamine. Existence of a methacrylic overlayer was verified by FTIR and XPS measurements, and the grafted particles were easily dispersed in water, confirming conversion of the particle surface from hydrophobic to hydrophilic. Hydrobromination of residual vinyl groups yields a macroinitiator that can be used for grafting of glycidyl methacrylate by ATRP. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1259–1265, 2009

A simple and efficient method for the solid‐phase extraction of dissolved organic matter (SPE‐DOM) from seawater

A simple protocol is presented for the solid‐phase extraction of dissolved organic matter (SPE‐DOM) from seawater using commercially prepacked cartridges. The method does not require major instrumentation and can be performed in the field. Modified styrene divinyl benzene polymer type sorbents (Varian PPL and ENV) and sorbents of a silica structure bonded with different hydrocarbon chains (Varian C8, C18, C18OH, and C18EWP) were considered. Except for C18OH, which heavily contaminated the samples, none of the sorbents leached significant amounts of dissolved organic carbon (DOC) or nitrogen (DON). Samples from the North Brazil shelf with strong mixing gradients of terrigenous and marine DOM were used to compare the various sorbents. PPL was the most efficient—on average, 62% of DOC was recovered as salt‐free extracts. C18 was found to be most efficient among the silica‐based sorbents, but it showed only two‐thirds of the extraction efficiency of PPL. As indicated by [1H]NMR, C/N, and δ13C analyses, PPL extracted a more representative proportion of DOM than C18. Therefore, PPL was used for comparative studies in the Gulf of Mexico and Antarctica. From brackish marsh and river waters, 65% and 62% of total DOC, respectively, could be extracted. For purely marine DOM in Antarctica and the deep sea, the extraction efficiency was lower (43% on average). The efficiency of the new method to isolate marine DOM is better than or similar to highly laborious methods. A further advantage is the complete desalination of the sample. The isolation of a major DOM fraction, which is salt‐free, offers many possibilities to further characterize DOM by advanced analytical techniques.

Synthesis of Ellipsoidal Hematite/Silica/Polymer Hybrid Materials and the Corresponding Hollow Polymer Ellipsoids

Ellipsoidal trilayer hematite/silica/poly(divinylbenzene) hybrid particles were prepared by distillation precipitation polymerization of divinyl benzene (DVB) in the presence of hematite/3-(methacryloxy)propyl trimethoxysilane (MPS)-modified silica (SiO(2)) core-shell particles as the seeds. The polymerization of DVB was performed in neat acetonitrile with 2,2'-azobisisobtyronitrile (AIBN) as initiator to coat the hematite/MPS-modified SiO(2) seeds through the capture of DVB oligomer radicals with the aid of a vinyl group on the surface of the hematite/MPS-modified silica core-shell particles in the absence of any stabilizer or surfactant. The other hematite/silica/polymer trilayer hybrid particles with different polarity and various functionality, such as hematite/silica/poly(ethylene glycol dimethacrylate) and hematite/silica/poly(divinyl benzene- co-methacrylic acid) could also be prepared by this procedure. Hematite/silica/poly( N, N'-methylenebisacrylamide) composite particles could be prepared with unmodified hematite/silica particles as seeds. Hollow poly(divinyl benzene) (PDVB) and poly( N, N'-methylenebisacrylamide) (PMBAAm) ellipsoids with movable hematite cores were subsequently developed after the selective etching of the silica midlayer in diluted hydrofluoric acid from hematite/silica/PDVB and hematite/silica/PMBAAm trilayer hybrids. Hollow PDVB ellipsoids were obtained by removal of the silica midlayer and hematite core of the trilayer hybrids with concentrated HF solution. The resultant trilayer hybrid particles and hollow polymer ellipsoids were characterized by transmission electron microscopy and vibrating sample magnetometer.

PH‐Switchable Complexation between Double Hydrophilic Heteroarm Star Copolymers and a Cationic Block Polyelectrolyte

AbstractDouble hydrophilic heteroarm star copolymers of poly(methacrylic acid) (PMAA) and poly(ethylene oxide) (PEO) were synthesized via atom‐transfer radical polymerization (ATRP) using the “in‐out” method. The synthesis consisted of three steps. Namely, ATRP was applied to the preparation of a star macroinitiator with PEO arms and a cross‐linked core resulting from the polymerization of divinylbenzene (DVB) in the first step, chain extension with tert‐butyl methacrylate (tBMA) under ATRP conditions, and subsequent hydrolysis of the tert‐butyl groups afforded (PEO)n‐PDVB‐(PMAA)n heteroarm star copolymers with a cross‐linked microgel core. This novel type of double hydrophilic heteroarm star copolymer can be considered as unimolecular micelles with hybrid coronas. The star copolymers exhibited pH‐dependent solubility in water, being soluble at high pH and insoluble at low pH, due to the formation of hydrogen‐bonded complexes between the PEO and PMAA arms. A mixed solution of the heteroarm star copolymer and a PEO‐b‐PQDMA diblock copolymer, where PQDMA is poly(2‐(dimethylamino)ethyl methacrylate) fully quaternized with methyl iodide, remained stable in the whole pH range, and exhibited an intriguing pH‐switchable complexation behavior accompanied with structural rearrangement.magnified image

Neutral Styrene Divinylbenzene Copolymers for Adsorption of Toxins in Liver Failure

In artificial extracorporeal liver support systems, albumin-bound toxins such as bilirubin, bile acids, or aromatic amino acids are removed by adsorption to polymer beads. To overcome the potential weaknesses of anion exchange polymers currently used in liver support, namely, binding of heparin and activation of coagulation, we prepared two series of neutral polystyrene divinylbenzene resins with average pore sizes of 5-6 and 8-9 nm, respectively. In in vitro experiments using human plasma spiked with bilirubin, cholic acid, tryptophan, and phenol, we found that only pores larger than 5-6 nm were accessible to strongly albumin-bound substances, such as bilirubin. On the other hand, less strongly albumin-bound substances, such as bile acids, were efficiently bound by polymers of the small pore size range due to a higher accessible surface area. None of the neutral resins bound significant amounts of heparin. To assess the influence of the polymers on activation of coagulation, generation of thrombin-antithrombin complexes (TAT) was measured at different citrate concentrations. While none of the neutral polymers induced TAT generation, TAT levels were significantly elevated after incubation of plasma with an anion exchange polymer that is in clinical use for extracorporeal liver support. Binding characteristics of the neutral resins for the natural anticoagulants protein C and antithrombin showed remarkable differences, with weak binding of antithrombin but strong removal of protein C, not only for the anion exchanger, but also for neutral polymers of the large pore size range. In conclusion, neutral polystyrene divinylbenzene polymers with a pore size larger than 5-6 nm are efficient adsorbents for albumin-bound toxins that do not induce generation of thrombin-antithrombin complexes.

Phosphoric acid activation—Functionalization and porosity modification

4,4′-Bis(maleimidodiphenyl) methane (BM) and divinylbenzene (DVB) copolymers with different compositions were used for production of carbons by carbonization and phosphoric acid activation. It has been shown that both BM and DVB polymers are good carbon precursors which show the same potential to produce carbonaceous material. However, despite cross-linked nature of all polymers, BM softens before formation of coke giving non-porous material. Phosphoric acid activation of polymer precursor increased the yield, surface area and pore volume as compared to acid-free heat treatment. Phosphoric acid activation of polymer precursor resulted in carbon material containing 6–8% of phosphorus and considerable amount of surface acidic groups of four types (total 2.6–3.2 mmol/g) which are responsible for metal ion adsorption from aqueous solutions.

Synthesis and characterization of poly (4vp- co-dvb)/montmorillonite nanocomposites by in situ intercalative polymerization

“4-Vinylpyridine” (4vp) crosslinked with 2% divinylbenzene (dvb) polymer [poly (4vp- co-dvb)]/OMMT (organically modified montmorillonite) nanocomposites were synthesized by in situ intercalative suspension polymerization. Sodium montmorillonite (SMMT) with a cation exchange capacity (CEC) of 90 meq/100 g was organically modified (OMMT) by the intercalation of cetyl “trimethylammonium” bromide (CTAB). The intercalation of CTAB into montmorillonite was confirmed from the expansion in basal space of the layered silicate from 1.5 to 2.0 nm as detected in the XRD (X-ray diffraction) pattern. OMMT was subsequently used as host along with the monomers for the preparation of polymer nanocomposites. It was found that OMMT was easily intercalated by 4vp and dvb to form a stable crosslinked polymer/clay intercalated hybrid. The nanocomposites were examined by means of XRD, transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Thermal stability of the nanocomposites increased as compared to the pure polymer. It was observed that the spherical shape of the pure polymer beads disappeared on composite formation as evidenced by SEM.

New Macroporous Crosslinked Polymer Gels Prepared via Living Radical Polymerization

ABSTRACTMacroporous crosslinked polymer gels have been prepared via TEMPO-mediated living radical polymerization of divinylbenzene (DVB) in a solvent with a counter polymer. Incorporating a counter polymer, poly(dimethylsiloxane) (PDMS), induced macroscopic spinodal-type phase separation during the course of polymerization of DVB while suppressing the segregation of DVB-derived particles from the solution by living polymerization. Well-defined macroporous morphologies comprising continuous DVB-derived skeletons have thus obtained. Macropore volume and diameter were independently controlled by altering the concentrations of PDMS and the solvent. Since the present polymer gels are prepared using only the multifunctional “crosslinker”, mechanical durability against bending and compression was found to be as high as inorganic ceramics with similar morphologies and porosities.

Preparation of Narrow or Monodisperse Polymer Microspheres with Cyano Group by Distillation-Precipitation Polymerization

Narrow- or monodisperse poly(divinylbenzene-co-acrylonitrile) (poly(DVB-co-AN)) microspheres with reactive cyano group were prepared by distillation-precipitation polymerization of divinylbenzene (DVB) and acrylonitrile (AN) in neat acetonitrile with 2,2′-azobis(isobutyronitrile) (AIBN) as initiator in the absence of any stabilizer or additive without stirring. The effects of the comonomer feed on the morphology and the size of poly(DVB-co-AN) microspheres were investigated. All the polymer microspheres were characterized with scanning electron microscopy and FT-IR spectra.

Determination of omeprazole, hydroxyomeprazole and omeprazole sulfone using automated solid phase extraction and micellar electrokinetic capillary chromatography

A sensitive method for the determination of omeprazole and its metabolites has been developed. It involves an automated solid phase extraction (SPE) procedure and capillary electrophoresis with UV detection. Omeprazole, hydroxyomeprazole and omeprazole sulfone could be separated by micellar electrokinetic capillary chromatography using a background electrolyte composed of 20 mM borate buffer and 30 mM sodium dodecyl sulfate, pH 9.5. The isolation of omeprazole and its metabolites from plasma was automatically accomplished with an original SPE procedure using surface-modified styrene–divinylbenzene polymer cartridges. Good recovery data and satisfactory precision values were obtained. Responses were linear for the three analytes, from 0.08 to 2.0 μg/mL of plasma. Intra- and inter-day precision values of about 1.6% R.S.D. ( n = 10) and 2.5% R.S.D. ( n = 36), respectively, were obtained. The method is highly robust and no breakdown of the current or capillary blockages were observed during several weeks of operation. The validated method was applied to the determination of omeprazole in pharmaceutical preparations and for the analysis of plasma samples obtained from three volunteers who received oral doses of omeprazole.

Use of a Self-Assembling Organogel as a Reverse Template in the Preparation of Imprinted Porous Polymer Films

The concept of reverse templating of an organogel to form imprinted porous divinylbenzene polymer films with submicrometer channels is demonstrated. The organogel comprising a 1:1 molar ratio of two organogelators, that is, bis(2-ethylhexyl) sodium sulfosuccinate and 4-chlorophenol, was formed in divinylbenzene. The gel was cast as a thin film before UV polymerization of the solvent, and the organogelators were later removed by simple washing with water and isooctane. The integrity of the fiber bundles of the organogel was preserved during polymerization, and an exact hollow replica was obtained after the organogelators were leached away. It is easily possible to imprint gel fiber bundle structures into polymeric films through this technique. The gel can also be formed on macroporous substrates to yield supported thin porous polymeric films. With the incorporation of functional nanoparticles in AOT inverse micelles and hence the organogel, nanoparticle-containing porous polymer films exhibiting luminescence or magnetic properties are envisioned.

Effect of nitrobenzene on initiator-fragment incorporation radical polymerization of divinylbenzene with dimethyl 2,2′-azobisisobutyrate

The polymerization of divinylbenzene (DVB) with dimethyl 2,2′-azobisisobutyrate (MAIB) was conducted at 70 and 80°C in benzene in the presence of nitrobenzene (NB) as a retarder. When the concentrations of DVB, MAIB, and NB were 0.45, 0.50, and 0.50mol/l, respectively, the polymerization proceeded without any gelation to yield soluble polymers. The polymer yield (up to 65%) and the molecular weight (Mn=1.5–4.2×l04 at 70°C and 1.3–3.9×l04 at 80°C) increased with time. The polymer formed in the polymerization at 80°C for 4h consisted of the DVB units with (4mol%) and without double bond (41mol%), methoxycarbonylpropyl group as MAIB-fragment (48mol%), and NB unit (7mol%). Incorporation of such a large number of the initiator-fragments as terminal groups in a polymer molecule indicates that the polymer is of a hyperbranched structure. The polymer showed an upper critical solution temperature (40°C on cooling) in an acetone-water [14:1 (v/v)] mixture. The results of MALLS and viscometric measurements and TEM observation supported that the polymers formed in the present polymerization have a hyperbranched structure. The polymerization system at 70°C involved an ESR-observable nitroxide radical formed by the addition of polymer radical to the nitro group of NB. The polymerization was kinetically investigated in dioxane. The initial polymerization rate (Rp) at 70°C was expressed by Rp=k[MAIB]0.5[DVB]0.9[NB]−0.4. The kinetic results were explained on the basis of the reversible addition of polymer radical to NB and the termination between the polymer radical and the nitroxide radical. The overall activation energy of the polymerization was 27.8kcal/mol.

Multiresidue determination of fluoroquinolones in milk by column liquid chromatography with fluorescence and ultraviolet absorbance detection

Column liquid chromatography with fluorescence (FLD) and UV-diode array detection (UV-DAD) was used for the simultaneous determination of ciprofloxacin (CIPRO), enrofloxacin (ENRO), marbofloxacin (MARBO), danofloxacin (DANO) and sarafloxacin (SARA) residues in milk, using norfloxacin (NOR) as internal standard. Two solid-phase extraction (SPE) cartridges, were evaluated for sample clean-up and preconcentration, Strata X, based on a modified styrene–divinylbenzene polymer, and Strata Screen A, a mixed anion exchanger/C 8 reversed-phase sorbent. The fluoroquinolones (FQs) were separated on a polar endcapped column (AQUA™ C 18). The recoveries for raw milk spiked with the antibiotics at three concentrations close to the maximum residue limit (MRL), were 80–103% for ENRO, CIPRO and DANO, with relative standard deviations (R.S.D.) lower than 6.6%. SARA recoveries were 70% (R.S.D.=7%) and values in the order of 95% (R.S.D.=1.5%) were obtained for MARBO at the MRL level. The quantification limits ranged from 2.4 to 10 ng ml −1 and are below the MRL established for these drugs by the European Union. The method was successfully applied to the analysis of ENRO and its metabolite CIPRO in an incurred milk sample.

Analysis of Mepivacaine in Human Serum by Gas Chromatography After Solid-Phase Extraction

A method using solid-phase extraction (SPE) has been developed for analysis of mepivacaine in human serum. A procedure for isolation of mepivacaine and lidocaine (internal standard) from human serum by use of Chromosorb 104 (acrylonitrile–divinylbenzene polymer) as extraction adsorbent is described in detail. Analysis was performed by gas chromatography on an HP-INNOWax (cross-linked PEG) capillary column, with flame ionization detection, after splitless injection. Relative standard deviations ranged between 3.6 and 4.4 for a serum mepivacaine concentration of 0.5 μg mL−1 and between 4.7 and 5.9 for a concentration of 1 μg mL−1. Recoveries were approximately 95%. The method was applied in a stomatological clinic to healthy volunteers to whom anesthesia with mepivacaine was administered.