Effect of the nature and degree of crosslinking on Rose Bengal binding by DVB‐, NNMBA‐, HDODA‐ and TTEGDA‐crosslinked poly(N‐vinylpyrrolidone)s

Poly(N‐vinylpyrrolidone)s with 2–20 mol% DVB, NNMBA, HDODA and TTEGDA crosslinkings were prepared by suspension polymerisation. The binding of Rose Bengal by these poly(N‐vinylpyrrolidone)s was followed by a batch equilibration method. In order to optimise the conditions of dye binding, the effect of the concentration of Rose Bengal solutions, temperature and pH were followed. Kinetic studies showed that the binding of Rose Bengal by poly(N‐vinylpyrrolidone)s is a phase boundary process followed by a three‐dimensional diffusion. Copyright © 2003 Society of Chemical Industry     

Effect of the nature and degree of crosslinking on the catalase‐like activity of polystyrene‐supported schiff base‐metal complexes

Catalase‐like activity of the metal complexes of various crosslinked polystyrene‐supported Schiff bases were carried out and correlated with the nature and degree of crosslinking in the polymer support. Polystyrenes with 2–20 mol % ethyleneglycol dimethacrylate (EGDMA), 1,4‐butanediol dimethacrylate (BDDMA) and 1,6‐hexanediol diacrylate (HDODA) were used as polymer supports. functions of diethylenetriamine and salicylaldehyde were incorporated to the chloromethylpolystyrene by polymer analogous reactions and complexed with Fe(II), Fe(III), Co(II), Ni(II), and Cu(II) ions. The metal uptake decreased in the order: Cu(II) > Co(II) > Ni(II) > Fe(III) > Fe(II), and extent of metal uptake by the various crosslinked system varied with the nature and degree of the crosslinking agent. The polymeric ligands and the metal complexes were characterized by various analytical techniques. The catalytic activities of these metal complexes were investigated towards the decomposition reaction of hydrogen peroxide. Generally among the various metal complexes, the catalytic activities decreased in the order: Co(II) > Cu(II) > Ni(II) > Fe(III) ? Fe(II). With increasing rigidity of the crosslinking agent their catalytic activity also decreased. Of the various crosslinked systems, the catalytic activity decreased in the order: HDODA‐ > BDDMA‐ > EGDMA‐crosslinked system. Also, the catalytic activity is higher for low crosslinked systems and decreased further with increasing degree of crosslinking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1271–1278, 2004     

Merrifield resin and 1,6‐hexanediol diacrylate‐crosslinked polystyrene resin for solid‐phase peptide synthesis: A comparative study

Three short peptides were synthesized on Merrifield resin (PS–DVB) and on polystyrene crosslinked with 1,6‐hexanediol diacrylate resin (PS–HDODA) to compare their efficiencies in solid‐phase peptide synthesis (SPPS). A 2% crosslinked polymeric system having almost equal capacity was used in both cases. The peptides were synthesized using standard solid‐phase methodology. In the case of the PS–HDODA resin, all the couplings were completed by the first coupling and the peptides were obtained in > 90% yield and > 95% purity. But in the case of the PS–DVB resin, most of the attachments require two to three couplings and the peptides were obtained in about a 65% yield. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1933–1939, 1999     

Effect of the nature of the crosslinking agent on the metal‐ion complexation characteristics of 4 mol % DVB‐ and NNMBA‐crosslinked polyacrylamide‐supported glycines

Metal‐ion complexation behavior of glycine functions supported on divinylbenzene (DVB)‐ and N,N′‐methylene bisacrylamide (NNMBA)‐crosslinked polyacrylamide was carried out toward Co(II), Ni(II), Cu(II), and Zn(II) ions. The polymeric ligands and the derived metal complexes were characterized by IR, UV, and EPR spectra and by SEM. The metal‐ion complexation of the rigid DVB‐crosslinked system is lower than that of the semirigid NNMBA‐crosslinked system. The glycine ligands renervated after the desorption of the metal ions showed an unusual specificity toward the desorbed metal ion. The low degree of crosslinking makes the desorption process simple and shows fast rebinding kinetics. The metal‐ion‐desorbed polymeric ligands would have pockets or holes characteristic of the desorbed metal ion, resulting in its specific rebinding. The rigidity of the crosslinking also determines the kinetics of metal‐ion rebinding. The specificity and selectivity characteristics of the crosslinked polymeric ligand was found to be increased as the crosslinking agent changes from semirigid NNMBA to rigid and hydrophobic DVB. Thus, copper‐desorbed resins showed an increased specificity toward copper ions and selectively binds copper ions from a mixture of copper and cobalt ions. The metal‐ion specificity and selectivity characteristics of the metal‐ion‐desorbed system is exploited for the concentration of desorbed metal ions from a mixture of metal ions. The resin is amenable for a continuous process and can be regenerated several times. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3432–3444, 1999     

Equilibrium swelling and solvation studies on crosslinked polyacrylamides

Polyacrylamide (PA) crosslinked with four different crosslinking agents, triethyleneglycol dimethacrylate (TEGDMA), N,N′‐methylene bisacrylamide (NNMBA), hexanediol dimethacrylate (HDDMA) and divinylbenzene (DVB), with mole percents ranging from 5 to 20, was prepared by solution polymerization and subjected to swelling and solvation studies. Solubility parameters and cohesive energy density were determined from swelling studies. Molecular weight between crosslinks for these systems were determined by Flory–Rehner analysis. There is a discontinuous volume change for 10% NNMBA and HDDMA crosslinked PA, 15% TEGDMA crosslinked PA and 10 and 15% DVB crosslinked PA in solvent mixtures of acetic acid and water due to phase change occurring at this stage. The hydrogels exhibit inhomogeneous crosslink distribution due to multiple crosslinking, cyclization and network irregularity owing from arising from entanglements. As the percentage of crosslinking increases, crosslinks become more homogeneous due to a decrease in entanglements. Copyright © 2004 Society of Chemical Industry     

Effect of the nature of crosslinking agent on the unusual metal ion specificity and selectivity of N,N‐bis(2‐aminoethyl)polyacrylamide

Metal ion desorbed crosslinked N,N‐bis(2‐aminoethyl)polyacrylamides showed enhanced specificity for the desorbed metal ion, and these polymers selectively rebind the desorbed metal ion from a mixture of metal ions. For this, polyacrylamide with 8 mol % divinylbenzene (DVB) and N,N′‐methylene‐bisacrylamide (NNMBA) crosslinking were prepared by solution polymerization. Diethylenetriamino functions were incorporated into the polymers by polymer analogous reactions. The complexing ability of the amino polymers were investigated toward various transition metal ions like Co(II), Ni(II), Cu(II), and Zn(II). Polymeric ligand and metal complexes were characterized by various spectral methods. The removal of the metal ion from the polymer matrix resulted in a memory for the desorbed metal ion. On rebinding, these polymers specifically rebind the desorbed metal ion and from a mixture of metal ions, it showed selectivity to the desorbed metal ion. Thus, the Cu(II) desorbed polymer specifically and selectively rebind Cu(II) ion from a mixture of Cu(II) and other metal ion. This selectivity is higher in the rigid DVB‐crosslinked system, resulting from the high rigidity of the crosslinked matrix compared to the semirigid NNMBA‐crosslinked system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Host–guest phenomena in polystyrene networks

A correlation between the extent of crosslinking and the amount of organic substrates encapsulated within organized macromolecular assemblies was established. The encapsulation of benzoic acid in the cavities of styrene‐based copolymers and their controlled release in the presence of different solvents were studied. Polystyrene networks with encapsulated benzoic acid were prepared with divinyl benzene (DVB) and hexane diol dimethacrylate (HDDMA) as the crosslinking agents. The amount of benzoic acid released followed the order of 5% > 10% > 20% > 15% in chloroform and toluene for both DVB‐ and HDDMA‐crosslinked polystyrene. However, in methanol and water, the release was in the order of 5% > 10% > 15% > 20% for both systems. As the percentage of the crosslinking agent was increased, the pore size decreased (mesopores), and hence the amount of benzoic acid encapsulated also decreased up to 15%. Beyond 15%, the number, rigidity, and stability of the micropores increased, and more benzoic acid was encapsulated with 20% than 15%. The quantitative interpretation of the experimental results was made in terms of a Flory–Rehner analysis of the swelling measurements of the free polymer and the host–guest system. The theoretical results were in excellent agreement with the experimental results of release studies. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of crosslinkers on the preparation and properties of ETFE‐based radiation‐grafted polymer electrolyte membranes

This study concerns a comparative study of three crosslinkers, divinylbenzene (DVB), 1,2‐bis(p,p‐vinylphenyl)ethane (BVPE), and triallyl cyanurate (TAC) crosslinked poly(ethylene‐co‐tetrafluoroethylene) (ETFE)‐based radiation‐grafted membranes, which were prepared by radiation grafting of p‐methylstyrene onto ETFE films and subsequent sulfonation. The effect of the different types and contents of the crosslinkers on the grafting and sulfonation, and the properties such as water uptake, proton conductivity, and thermal/chemical stability of the resulting polymer electrolyte membranes were investigated in detail. Introducing crosslink structure into the radiation‐grafted membranes leads to a decrease in proton conductivity due to the decrease in water uptake. The thermal stability of the crosslinked radiation‐grafted membranes is also somewhat lower than that of the noncrosslinked one. However, the crosslinked radiation‐grafted membranes show significantly higher chemical stability characterized in the 3% H₂O₂ at 50°C. Among the three crosslinkers, the DVB shows a most pronounced efficiency on the crosslinking of the radiation‐grafted membranes, while the TAC has no significant influence; the BVPE is a mild and effective crosslinker, showing the moderate influence between the DVB and TAC crosslinkers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4565–4574, 2006     

Encapsulation and controlled release in polyacrylamide hydrogels

A novel host–guest system was developed by the encapsulation of simple organic guest molecules in the hydrophilic molecular architecture of crosslinked polyacrylamide hydrogels. The crosslinking agents used for the preparation of the host systems were hexanediol dimethacrylate (HDDMA) and divinyl benzene (DVB). This enabled us to construct hydrogels with different hydrophobic–hydrophilic equilibria. The model guest system used for the studies was benzoic acid. The selections gave simple but excellent host–guest systems with fine polar–apolar balancing. Polyacrylamide hydrogels with encapsulated benzoic acid were prepared with varying crosslink densities (5, 10, 15, and 20 mol %) by the solution polymerization technique. The rate of release of the host from the host–guest assembly was studied in different swelling conditions. The rate of release depended on the interaction forces between the polymer and the solvents. Polar forces, dispersion forces, and hydrogen bonding all played a vital role. The swelling behavior of the host‐polymer system and the host–guest assembly was analyzed and compared by the Flory–Rehner method. The amount of benzoic acid encapsulated in the DVB‐crosslinked polymer was higher than in the HDDMA‐crosslinked polymer, and the rate of release was in the order 5 > 15 > 10 > 20% for the DVB‐crosslinked polymer. The rate of release for the HDDMA‐crosslinked host–guest assembly was in the order 10 > 5 > 15 > 20%. These results were in excellent agreement with those of the Flory–Rehner analysis of the swelling properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1816–1824, 2004     

Structural features of the polymer matrix affecting the efficiency of acyl transfer reactions

Polystyrene and polyacrolein were prepared using divinylbenzene (DVB) and tetraethylene glycol diacrylate (TEGDA) as crosslinking agents with varying extents of crosslinking. These polymeric supports were used to prepare acyl transfer reagents like oximino esters and oximino dithiocarbonic anhydrides. The reactivity of the acylating function was determined as a function of the varying macromolecular characters. Investigations revealed a significant influence of the nature of macromolecular support, nature and extent of crosslinking, and the chemical environment of the reagent functions in deciding the extent of the acyl transfer reaction. In the case of DVB crosslinked reagents, the reactivity decreased with increase in the extent of crosslinking, whereas in the case of TEGDA crosslinked reagents, the reactivity increased up to 4% crosslinking and then decreased as the degree of crosslinking was increased. © 1996 John Wiley & Sons, Inc.     

Pore and crosslinking structures of cotton cellulose crosslinked with DMDHEU‐maleic acid

Two dicarboxylic acids (maleic acid and tartaric acid) were used in conjunction with DMDHEU as the crosslinking agents to treat cotton fabric samples. The treated fabrics then were dyed with direct red 81. The results show that the values of the dye absorption, equilibrium absorption, rate constants, and the pore index of structural diffusion resistance constant for the various crosslinking agents are ranked as DMDHEU‐tartaric acid > DMDHEU‐maleic acid > DMDHEU alone at the same dyeing temperature. The activation energies for the three crosslinked fabrics are in the rank of DMDHEU > DMDHEU‐maleic acid > DMDHEU‐tartaric acid. The CL length values for the various crosslinking agent systems are in the series of DMDHEU‐tartaric acid > DMDHEU‐maleic acid > DMDHEU alone for a given number of CL/AGU. The values of the pore index of structural diffusion resistance constant and dyeing rate constant are increased with the increase of CL length. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 143–148, 2005     

1,6‐hexanediol diacrylate‐crosslinked polystyrene: Preparation,characterization, and application in peptide synthesis

A copolymer of 1,6‐hexanediol diacrylate (HDODA) and styrene was prepared by a suspension polymerization method. The resin was characterized by infrared and carbon‐13 cross‐polarization magic‐angle spin (¹³C CP‐MAS) spectroscopy. The topology of the resin was examined by scanning electron microscopy (SEM). The polymer swells extensively in common solvents used for peptide synthesis. The resin exhibited chemical stability even in neat trifluoroacetic acid. The applicability of the new resin was demonstrated by synthesis of Val‐Ala‐Val‐Ala‐Ala‐Gly, Gln‐Val‐Gly‐Gln‐Val‐Glu‐Leu‐Gly, and Val‐Gln‐Ala‐Ala‐Ile‐Asp‐Tyr‐Ile‐Asn‐Gly. Comparative synthetic studies showed that the new resin is superior to divinylbenzene (DVB)‐based resin in the case of the synthesis of hydrophobic peptide sequences. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1290–1296, 2003     

Synthesis and characterization of reinforced acrylic‐based superabsorbents crosslinked with divinylbenzene

A series of superabsorbent polymers were synthesized by an inverse suspension polymerization, with potassium persulfate as the initiator, Span60 as the dispersant, and N,N′‐methylene bisacrylamide (BIS) and divinylbenzene (DVB) as multiple crosslinkers. The synthesis conditions, including the amount of dispersant, concentration of crosslinkers, oil‐to‐water phase ratio (O/W) of the polymerization system, total monomer concentration, and acrylamide (AM) content were studied. The results indicated that there were optima for the following properties: BIS crosslinker concentration (0.075 wt %), O/W (3 : 1), total monomer concentration (37.5 wt %), and AM content (5 wt %). In addition, the particle size had a significant influence on the absorption speed, and the absorption speed increased with decreasing particle size. In comparison with the conventional sample crosslinked only by BIS, the superabsorbent with the same particle size but crosslinked by multiple crosslinkers had the higher absorption rate because of surface crosslinking. It also showed that the salt resistance and antihydrolyzing property of the superabsorbent crosslinked by multiple crosslinkers (BIS and DVB) were enhanced, which was also attributed to surface crosslinking by DVB. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1594–1600, 2006     

Swelling and network parameters of high oil‐absorptive network based on 1‐octene and isodecyl acrylate copolymers

Crosslinked 1‐octene‐isodecyl acrylate copolymers were synthesized and evaluated for oil‐absorbency applications. The copolymer was crosslinked at different concentrations of ethylene glycol diacrylate (EGDA) and EG dimethacrylate (EGDMA) crosslinkers via catalytic initiation or by electron‐beam irradiation at a dose rate 80 kGy. The concentration of both crosslinkers was varied from 0.5 to 2%. The effects of the crosslinking conditions such as crosslinker concentration, method of polymerization and monomer concentrations on the conversion and gel fraction were examined through oil‐ absorption tests using petroleum crude oil. It was found that the oil absorbency was influenced mainly by the degree of crosslinking and the hydrophobicity of the copolymer units. The final equilibrium oil content, volume fraction of the polymer, and swelling capacity were determined at 298 K. The effective crosslinking density, average molecular weight between the crosslinks, and polymer–toluene interaction parameter were determined from stress–strain measurements. The crosslinking efficiencies of EGDA and EGDMA toward copolymers were determined. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 80–91, 2005     

Water‐swelling behavior of hydrophobic porous copolymer resins composed of two kinds of crosslinkers

Hydrophobic, but water‐swellable, porous copolymer resins composed of divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDM) or ethylene glycol diacrylate (EGDA) were prepared by using purified DVB (98.8%) in the presence of toluene as porogen. The EGDM/DVB resins thus obtained, whose polarity was nearly identical to that of the resins based on DVB and methyl methacrylate (MMA) at the same DVB levels, were water‐swellable by direct contact with water up to a DVB content of 64%, whereas the latter did not swell in water at any DVB levels. EGDA is also hydrophobic, but with a polarity greater than that of EGDM. As a result, the EGDA/DVB resins were more water swellable than EGDM/DVB resins, and could also be prepared as water‐swellable materials by using technical DVB (79.3%), besides the use of the purified DVB. All these results were explained on the basis of the network rigidity (crosslinking density) and the polymer polarity of the resins that were formed in the presence of a well‐solvating porogenic solvent. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 997–1004, 2004     

Effect of crosslinking on the positive temperature coefficient stability of carbon black‐filled HDPE/ethylene‐ethylacrylate copolymer blend system

Carbon black‐filled high‐density polyethylene (HDPE)/ethylene ethylacrylate copolymer (EEA) blends were prepared and the effect of crosslinking of the blends on the positive temperature coefficient (PTC) stability was investigated. By irradiation and silane‐crosslinking methods, crosslinked composites with various degrees of crosslinking were obtained. Crosslinking of the matrix polymer led to the disappearance of the negative temperature coefficient (NTC) phenomenon. Also, the PTC intensity increased with an increasing degree of crosslinking. The PTC stability of silane‐crosslinked samples was notably improved at heat cycles of 140°C. This was sufficiently improved by both the silane‐ and radiation‐crosslinking methods when they were treated at 85°C. Therefore, the limiting temperature of self‐regulating heat is about 85°C. Both radiation‐ and silane‐crosslinked samples are thought to be of use to the industry.     

Effect of polymer characteristics on Beckmann rearrangement of polymer supported ketoximes

Beckmann rearrangement has been carried out in polymeric oximes synthesised from rigid styrene–divinylbenzene copolymer and flexible styrene–hexanediol diacrylate (HDODA) copolymer. Oxime functions were incorporated into these polymers through a series of polymer‐analogous reactions. First the polymers were subjected to Friedel‐Crafts acylation reactions with low molecular weight acid chlorides to give a set of polymeric ketones. These polymeric ketones were converted to oximes by treating with hydroxylamine hydrochloride in the presence of pyridine. The oximes were subjected to rearrangement under acidic conditions into substituted amides. The polymeric amides obtained were characterised by IR spectroscopy and chemical degradative analysis. The rearrangement in the macromolecular matrices were found to follow the same mechanistic path as in the low molecular weight analogues. The rate of rearrangement was found to be faster in the HDODA crosslinked polystyrene system. © 2002 Society of Chemical Industry     

Modification of porous suspension‐PVC particles by stabilizer‐free aqueous dispersion polymerization of absorbed monomers

The modification of porous PVC particles by an in‐situ stabilizer‐free polymerization/crosslinking of a monomer/crosslinker/peroxide solution absorbed within the PVC particles is presented. The modifying crosslinked polymers are polystyrene (PS) crosslinked with DVB (divinyl benzene), polymethyl methacrylate (PMMA) crosslinked with ethylene glycol dimethacrylate (EGDMA), and styrene‐MMA copolymer crosslinked with DVB. The modified PVC particles characterization includes polymerization yield, non‐extractables, ¹³C solid‐state CPMAS NMR, porosity measurements and also morphology and dynamic mechanical behavior (DMTA). The levels of nonextractable fractions found and ¹³C solid‐state CPMAS NMR results are indicative of low chemical interaction in the semi‐IPN PVC particles. Particle porosity levels and SEM observations indicate that styrene and MMA mainly polymerize within the PVC particles' bulk and just small amounts in the pores. MMA polymerization in the PVC pores is as crusts covering the PVC pore surfaces, whereas styrene polymerization in the PVC pores is by filling the pores. Dynamic mechanical studies show that tanδ and the storage modulus curves are influenced by the incorporation of PS and XPS but not by the incorporation of PMMA and XPMMA.     

Poly(vinyl acetate)/polyacrylate semi‐interpenetrating polymer networks. II. Thermal,mechanical, and morphological characterization

The thermal, dynamic mechanical, and mechanical properties and morphology of two series of semi‐interpenetrating polymer networks (s‐IPNs) based on linear poly(vinyl acetate) (PVAc) and a crosslinked n‐butyl acrylate/1,6‐hexanediol diacrylate copolymer were investigated. The s‐IPN composition was varied with different monoacrylate/diacrylate monomer ratios and PVAc concentrations. The crosslinking density deeply affected the thermal behavior. The results showed that a more densely crosslinked acrylate network promoted phase mixing and a more homogeneous structure. The variation in the linear polymer concentration influenced both the morphology and mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Monodisperse plum‐like sulfonated PGMA‐DVB microspheres as a new ion exchange resin

Monodisperse plum‐like crosslinked poly(glycidyl methacrylate‐co‐divinyl benzene) (PGMA‐DVB) microspheres were prepared by dispersion polymerization using glycidyl acrylate as monomer and divinyl benzene as crosslinking agent, and then sulfonated by sulfonation process with phosphorus pentoxide to increase the grafting ratio. The morphology and composition of microspheres were characterized by scanning electron microscope with energy dispersive analysis of X‐rays (SEM‐EDX), Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), and BET surface area analyses. The average sizes of PGMA microspheres and PGMA‐DVB microspheres were 2.18 and 2.52 μm, respectively. The effect of DVB content on the properties of microspheres was investigated and the experimental results indicate that the microspheres prepared with DVB content have crinkled surface with large specific surface area, and with the increase of the DVB content, the average size of the microspheres become larger and the particle size distribution become wider. The as‐prepared sulfonated PGMA‐DVB microspheres were used to remove the copper (II) ion in solution and the maximum adsorption capacity was 75.08 mg/g. This work provides an effective but simple method for a controllable preparation of polymer microspheres with rough surface and high specific surface area, and it could be a new kind of ion exchange resin after sulfonation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44994.