Acrylic copolymers crosslinked by click chemistry: Some aspects of synthesis,curing, and crosslinking

Acrylic polymers bearing pendant azide and propargyl groups were synthesized by chemical transformation of epoxy‐ and carboxylic functional acrylic precursor polymers and were characterized. These copolymers were crosslinked by reacting them in the presence of Cu(I) catalyst via the azide–alkyne click reaction leading to triazole networks. Influence of catalyst concentration on the crosslinking cure kinetics was investigated, and the activation parameters were evaluated. The activation energy decreased from 90 kJ mol^?1 to 25 kJ mol^?1 on catalyzing the cure reaction as estimated by Ozawa method. Differential scanning calorimetric analysis indicated thermal decomposition of the residual azide groups at around 200–220°C, which was catalyzed by Cu(I) with associated activation energy of 130–94 kJ mol^?1. Isothermal cure reaction and decomposition of the azide groups were predicted using these parameters. Estimation of crosslink density by solvent swelling and dynamic mechanical analyses showed a normal crosslinking behavior. While the solvent swelling rate and the equilibrium swelling decreased, the front factor and diffusion coefficient of swelling showed a transition from non‐Fickian to Fickian as the triazole concentration increased in the network. The click reaction offered an alternate means to crosslink acrylate polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1289‐1300, 2013     

Novel poly(orthosilicate)s based on linear aliphatic diols: Synthesis,characterization, and swelling properties

Condensation reactions between tetraethyl orthosilicate and linear aliphatic diol monomers at moderately high temperatures in proper stoichiometric ratios gave crosslinked poly(orthosilicate)s. The synthesized crosslinked polymers were found to be insoluble in common organic solvents, such as tetrahydrofuran, dichloromethane, benzene, and acetone, but did show swelling abilities in these solvents. All of the crosslinked polymers had moderate thermal stability and good, regenerable solvent uptake abilities. The synthesized polymers have been characterized by Fourier transform infrared spectroscopy solid‐state ¹³C‐ and ²⁹Si‐NMR, thermogravimetric analysis, differential scanning calorimetry methods, and elemental analysis. In this report, the synthesis characterization, and swelling properties of crosslinked poly(orthosilicate)s for environmental removal and recovery of organic solvents are presented. The effect of the length of the aliphatic diol monomers on the properties of the synthesized polymers was also examined. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and swelling properties of new crosslinked polyorthocarbonates

Crosslinked polyorthocarbonates were synthesized by the condensation of tetraethyl orthocarbonate and hydroxyl functional monomers. The main goal of this study was to produce a solvent‐absorbent polymer with a high absorption capacity and to use these polymers for the removal of organic solvents from the environment and the recovery of these solvents. The synthesized polymers were characterized by Fourier transform infrared spectroscopy, solid‐state ¹³C‐NMR spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. All of the polymers (except Poly 1 and Poly 2 ) had a high and fast uptake ability for organic solvents, such as tetrahydrofuran, dichloromethane, benzene, and acetone. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Investigation of organic solvent/oil sorption capabilities of phenylene-bridged cross-linked poly(alkoxysilane)s

Phenylene-bridged cross-linked poly(alkoxysilane)s produced by the condensation of 1,4-bis(triethoxysilyl) benzene (BTEB) with different lengths of aliphatic diols in proper stoichiometric ratios were successfully prepared. The synthesized phenylene-bridged poly(alkoxysilane)s were characterized by Fourier transform infrared spectroscopy (FTIR), solid-state ¹³C and ²⁹Si cross polarization magic angle spinning nuclear magnetic resonance (CP-MAS NMR), and thermal gravimetric analysis (TGA). The oil and organic solvent uptake capacity, reusability, absorption and desorption kinetics of cross-linked polymers were examined. The effect of chain length of the linear diol monomers on the polymer-solvent interaction was also investigated. The swelling experiments were conducted in oils such as gasoline, euro diesel and organic solvents such as dichloromethane, tetrahydrofuran, benzene and toluene. All the synthesized polymers have high and fast swelling properties in oils and organic solvents. The reutilize properties of polymer in organic solvents were also investigated.     

Synthesis and swelling behaviors of semi‐IPNs superabsorbent resin based on chicken feather protein

A novel chicken feather protein‐g‐poly (potassium acrylate)/polyvinyl alcohol (CFP‐g‐PKA/PVA) semi‐IPNs superabsorbent resin (SAR) based on feather protein, acrylic acid (AA), and polyvinyl alcohol (PVA) was synthesized by graft copolymerization and semi‐interpenetrating technology. The results from FTIR, SEM, and TGA analysis showed that both CFP and PVA reacted with PKA during the polymerization process. The effects of AA, PVA, initiator and crosslinker content on water absorbency of semi‐IPNs SAR were studied. The swelling behavior in various pHs and saline solutions were also investigated. The water absorbency of SAR reached the maximum at pH = 6. The effect of the five cations on swelling had the following order: Al³⁺ > Ca²⁺ > Mg²⁺ > K⁺ > Na⁺. The highest water absorbency in distilled water and 0.9 wt % NaCl solutions were 714.22 and 70.08 g g^?1, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39748.     

Synthesis and swelling properties of crosslinked poly(orthosilicate)s from cyclohexanedimethanols

Condensations of cyclohexanedimethanol derivatives with tetraethyl orthosilicate in the proper stoichiometric ratio produce crosslinked poly(orthosilicate)s. Synthesized crosslinked polymers have swelling abilities in common organic solvents such as tetrahydrofuran (THF), dichloromethane, benzene and acetone. All these polymers are moderately thermally stable and possess solvent uptake abilities that are not only good and fast but are also regenerable. FTIR, solid‐state ¹³C, ²⁹Si‐NMR and thermal methods were used to characterize these synthesized polymers. The effects of different cyclohexanedimethanol derivatives on the properties of polymers were also examined. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122:1182–1189, 2011     

Synthesis and characterization of functionalized acrylic‐acrylamide‐based superabsorbent gels

We have synthesized series of superabsorbent polymers (SAPs) by solution free radical polymerization of acrylic acid (AA), acrylamide (AM) with different functional monomers (FM). Three functional monomers including zwitterionic monomer [3‐(methacryloylamino) propyl] dimethyl (3‐sulfopropyl) ammonium (MPDSA), cationic monomer (3‐acrylamidopropyl) trimethylammonium chloride (APTAC) and anionic monomer 2‐acrylamidoglycolic acid monohydrate (AGAM) were selected to provide different charged groups on the superabsorbents. The effect of reaction parameters, such as degree of neutralization, content of initiator and crosslinker on the swelling capacity were assessed. The water absorbency of the superabsorbent were characterized in the distilled water, 0.9 wt % NaCl solution and the mixed solution containing 60 mg L^?1 CaCl₂ and 30 mg L^?1 MgCl₂, respectively. In addition, the swelling rate and water retention capacity in the soil were also investigated. Finally, the mechanism of different absorbency induced by the variety kinds of functional monomers was studied by XPS and FTIR, and tentative interpretation was presented as well. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of polypropylene glycol-based novel organogels as effective materials for the recovery of organic solvents

In this study, novel hydrophobic organogels were successfully prepared via the aza-Michael addition reaction method using diamino terminated polypropylene glycol and diphenylmethane bismaleimide as monomers, in the presence of a tri-amino functional polypropylene glycol as a crosslinking agent. The chemical structures, surface morphology, and thermal stability of the synthesized organogels were analyzed using Fourier transform infrared spectroscopy and solid-state CPMAS ¹³C-NMR, scanning electron microscope, and thermal gravimetric analysis technique, respectively. The effects of various parameters, such as the monomer ratio, amount of crosslinker, and as well as swelling properties of organogels by solvent absorption tests were studied. According to obtained results, the solvent uptake capacity increased with decreasing crosslinker ratio up to 30 wt%. The maximum solvent absorbency of the synthesized organogels were determined as 730%, 504%, 271%, 224%, 95%, and 17% for dichloromethane, tetrahydrofuran, benzene, acetone, gasoline and diesel oil, under optimum conditions, respectively. In addition, reusability of the organogels was evaluated for 10 cycles, depicting no significant loss in absorbance capacity. The fabricated organogels showed high solvent absorption efficiency with prospects as suitable material for the recovery of a wide range of organic solvents.     

Hydrogel composites based on linear low‐density polyethylene‐g‐poly (acrylic acid)/Kaolin or halloysite nanotubes

Two series of superabsorbent hydrogel composites were prepared using waste linear low‐density polyethylene, acrylic acid, and two types of clays including kaolin and halloysite nanotube (HNT) through emulsion polymerization. The effects of the clay content on Water absorbency were investigated to obtain a high swelling capacity. The prepared samples were characterized using FTIR, SEM, thermogravimetric analysis, XRD, solid‐state ¹³C Nuclear Magnetic Resonance spectroscopy, and ²⁹Si NMR. SEM characterization of the samples showed that the hydrogel composites have more pores and a higher swelling ratio than the clay‐free hydrogels. The hydrogel composite containing kaolin had higher water absorbency compared to the hydrogel composites with HNT. The swelling behavior of the hydrogel composite was investigated in various saline solutions. The hydrogel composite containing 5 wt % kaolin had the highest water absorbency (760 g/g in distilled water). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40101.     

Fast‐swelling superabsorbent polymers with polymerizable macromolecular surfactant as crosslinker

Fast‐swelling superabsorbent polymers (SAPs) have been prepared by micellar cross‐linking copolymerization of acrylic acid and acrylamide using polymerizable macromolecular surfactants (PMSs) as multifunctional crosslinkers, with a foaming technique. Sodium bicarbonate (NaHCO₃)/acetone and Pluronic F127 were used as foam (or porosity) generators and stabilizer, respectively. It has been found that the PMSs with different polyethylene glycol (PEG) chain length have little effect on the swelling rate of the SAPs, while the foam generators are crucial. In addition, the monomer concentration and the concentration of the PMS are important to the fast swelling rate of the SAPs. For a balance of a relatively fast‐swelling rate, high water absorbency under load and low cost in drying, a monomer concentration of above 50%, 0.08% PMS, and 5% NaHCO₃ are preferable. The water absorbency of SAP prepared under optimal conditions could reach half of equilibrium water absorbency in 30 seconds and the saline water absorbency under load could reach 18.4 g/g. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44173.     

Oil absorbents based on styrene–butadiene rubber

Four oil absorbents based on styrene–butadiene (SBR)—pure SBR (PS), 4‐tert‐butylstyrene–SBR (PBS), EPDM–SBR network (PES), and 4‐tert‐butylstyrene‐EPDM‐SBR (PBES)—were produced from crosslinking polymerization of uncured styrene–butadiene rubber (SBR), 4‐tert‐butylstyrene (tBS), and ethylene–propylene–diene terpolymer (EPDM). The reaction took place in toluene using benzoyl peroxide (BPO) as an initiator. Uncured SBR was used as both a prepolymer and a crosslink agent in this work, and the crosslinked polymer was identified by IR spectroscopy. The oil absorbency of the crosslinked polymer was evaluated with ASTM method F726‐81. The order of maximum oil absorbency was PBES > PBS > PES > PS. The maximum values of oil absorbency of PBES and PBS were 74.0 and 69.5 g/g, respectively. Gel fractions and swelling kinetic constants, however, had opposite sequences. The swelling kinetic constant of PS evaluated by an experimental equation was 49.97 × 10^?2 h^?1. The gel strength parameter, S, the relaxation exponent, n, and the fractal dimension, d_f, of the crosslinked polymer at the pseudo‐critical gel state were determined from oscillatory shear measurements by a dynamic rheometer. The morphologies and light resistance properties of the crosslinked polymers were observed, respectively, with a scanning electron microscope (SEM) and a color difference meter.     

Effect of the polymerization conditions on the swelling of a copolymer of AA/AMPS/BA via experimental design

To study the effect of the polymerization conditions on swelling, a copolymer was synthesized from the monomers acrylamide (AA), 2‐acrylamido‐2‐methyl‐propanosulfonic acid (AMPS) and N,N‐methylenobisacrylamide (BA) as crosslinker by an inverse emulsion technique. The conditions were: concentration of organic solvent, s (an isoparaffinic hydrocarbon, commercially Isopar M), concentration of emulsifier, e (sorbitan trioleate, commercially Tween 85), and reaction temperature, T. These three variables (factors) were explored to achieve highest water absorbency, a 2³ factorial experimental design having been applied to find the main and two‐factor interaction effects of those variables on the swelling capacity. A predictive model including the factors for the swelling is proposed, allowing for the estimation of absorbency capacity in this type of copolymers. The results show that the optimum values of the variables given by the experimental design were s = 8.1, e = 1.0, and T = 49°C, with predicted swelling capacity of 1041 and experimental of 1014. The variables are relevant, with a preponderance of s, and the effect of the square of temperature is also significant. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

High oil‐absorptive composites based on 4‐tert‐butylstyrene‐EPDM‐divinylbenzene graft polymer

4‐tert‐Butylstyrene‐EPDM‐divinylbenzene graft polymer (PBED) was prepared by graft crosslinking polymerization in toluene using BPO as an initiator. Gel and sol of PBED were isolated by extraction with tetrahydrofuran (THF). Sol PBED can be reused as oil absorbent through cross‐linking by ultraviolet irradiation. After swelling in oil, crosslinked polymers have poor gel strength to be taken out of oil wholly at high absorbency, although they possess strong mechanical strength in their dry states. As known, composite technique is one of the useful methods for material reinforcement. Fibres, sponges and non‐woven fabrics were used as reinforcers or supporters in this work. Oil absorbency was measured by method ASTM (F726‐81) and swelling kinetics of the composite was evaluated by an experimental equation. The gel strength parameter S, the relaxation exponent n, and the fractal dimension d_f of polymer and some composites in pseudo‐critical gel state were determined from oscillatory shear measurements by a dynamic rheometer. Mechanical properties and the morphologies of some composites were measured with a tensile tester and scanning electron microscopy, respectively. © 2001 Society of Chemical Industry     

A Study of the Synthesis and Properties of AM/AMPS Copolymer as Superabsorbent

Summary: A new superabsorbent polymer, PAMA, has been prepared in an aqueous solution using acrylamide (AM) and 2‐acrylamido‐2‐methyl‐propanesulfonic acid (AMPS) as monomers, potassium persulfate (PPS) as initiator, and N,N′‐methylenebisacrylamide (NMBA) as cross‐linker. The absorbing properties and water retention of PAMA have been investigated. It is found that the absorbency of PAMA can reach 2 451 and 119 g · g^?1 in distilled water and in 0.9 wt.‐% NaCl solution, respectively. This copolymer also can absorb a large amount of pure methanol (277 g · g^?1), a property that has not been reported for the other superabsorbent polymers in the literature. The swelling behavior of PAMA in some water/organic solvent mixtures and water retention of PAMA in sand have been investigated.

Water retention of the PAMA in sand at 80 °C. 1) Sample containing PAMA; 2) Sample without PAMA.     

Studies on polyurethanes and polyurethane–ureas derived from divalent metal salts of mono(hydroxybutyl) hexolate

Divalent metal salts of mono(hydroxybutyl)hexolate [M(HBH)₂), M=Ca²⁺, Mn²⁺or Pb²⁺] were synthesized by the reaction of 1,4‐butanediol, 5,6,7,8,10,10‐hexachloro‐3a,4,4a,5,8,8a,9,9a‐octahydro‐5,8‐methanonaphtho‐[2,3‐C]‐furan‐1,3‐dione and divalent metal acetates. Hexamethylene bis [N′‐(1‐hydroxy‐2‐methyl‐prop‐2‐yl)urea] (HBHMPU) and tolylene 2,4‐bis[N ′‐(1‐hydroxy‐2‐methyl‐prop‐2‐yl)urea] (TBHMPU) were synthesized by reacting 2‐amino‐2‐methyl‐propan‐1‐ol with hexamethylene diisocyanate (HMDI) and tolylene 2,4‐diisocyanate (TDI), respectively, in toluene solvent. Flame‐retardant metal‐containing polyurethanes were synthesized by the solution polymerization of HMDI with M(HBH)₂ and the polyurethane–ureas by reacting HMDI with 1:1 mixture of M(HBH)₂ and HBHMPU or TBHMPU, respectively, in DMSO as solvent. The polymers have been characterized by elemental analysis, solubility, viscosity and IR and ¹H NMR spectroscopy. The thermal stability of the polymers has been studied by thermogravimetry. The flame‐retardant property of the polymers has been investigated by measuring limiting oxygen index values. © 2000 Society of Chemical Industry     

Regioselective substitution of 2‐isocyanatoethylmethacrylate onto cellulose

Cellulose is a well‐known versatile polymer that presents a wide range of material properties via the substitution and grafting reactions of its hydroxyl groups. Because of their commercial potential, combinations of cellulose and vinyl polymers have been examined with various grafting methods. In this study, the condensation reactions of regioselective and nonregioselective substitution with 2‐isocyanatoethylmethacrylate were performed in a homogeneous solvent system of dimethyl acetamide/lithium chloride. The successful substitution was confirmed by Fourier transform infrared spectroscopy, ¹H‐NMR, cross‐polarization/magic angle spinning ¹³C‐NMR, thermogravimetric analysis, and X‐ray diffraction. The substituted celluloses showed excellent thermal stability and a different polymorph with a depressed cellulose–intrinsic polymorphic phase. The 2‐isocyanatoethylmethacrylate side chain seemed to expand the intermolecular distance with enhanced chain mobility and trigger the formation of a novel crystalline polymorph with a dramatically improved thermal stability. This investigation provided us with a useful understanding of the modification of cellulose with spatial distribution control for advanced future applications requiring a combination of cellulose with vinyl polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Copolymers of glycerol and propylene glycol diglycidyl ethers with aromatic dithiols

Monomers derived from renewable recourses have the potential to become the biobased alternatives for petroleum derived chemicals in the production of polymers. Glycerol, the byproduct of biodiesel refining, and propylene glycol derived from glycerol are promising candidates which can be used in the synthesis of polymers as they are or after chemical modification. The new copolymers of glycerol and propylene glycol diglycidyl ethers with aromatic dithiols were synthesized and investigated in this study. Their chemical structures were confirmed by IR, ¹H‐NMR spectroscopy, and gel permeation chromatography. The dependencies of the mechanical, thermal properties, swelling in the different solvents, biodegradability, and bioresistance of synthesized copolymers on their chemical structures were studied. The properties of some synthesized copolymer films were found to be comparable with those of commodity polymer films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4367–4374, 2013     

Poly(acrylamide‐co‐maleic acid) hydrogels for removal of Cr(VI) from aqueous solutions,Part 1: Synthesis and swelling characterization

The swelling behavior of poly (acrylamide‐co‐maleic acid) hydrogels has been investigated in distilled water at 30°C. The gels were characterized with respect to structural parameters, Fourier transform infrared, and thermogravimetric analysis. The gels showed fair pH‐dependent swelling and exhibited double “s”‐shaped curve between equilibrium water uptake and pH of the swelling media. The two pK_a values, as determined from the curve, were found to be 2.46 and 6.58. The activation energy of the water uptake process for plain and acid containing gels was found to be 7.93 and 3.26 kJ mol^?1 respectively. Similarly, the enthalpy of mixing between dry polymer and solvent showed positive values, thus indicting endothermic nature of the process, and the values increased from 10.06 to 16.29 kJ mol^?1 with increase in acid content from 2.1 × 10^?1 to 4.7 × 10^?1 mM respectively. There was an optimum initiator concentration 24.0 × 10^?2 mM and reaction temperature 60°C at which gels synthesized showed maximum absorbency. The dilution of the reaction mixture resulted in the formation of hydrogels with enhanced absorbency. Finally, the gels with varying content of monomer acid in the feed mixture showed different swelling behavior when studied in the medium of pH 1.0 and 7.0. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2759–2769, 2006     

Improving properties of superabsorbent composite induced by using alkaline protease hydrolyzed‐sericin (APh‐sericin)

A series of superabsorbent polymer composites based on sericin hydrolyzed with alkaline protease (AP) were prepared by grafting with acrylic acid (AA) and acrylamide (AM). The properties of the superabsorbent polymers (SAP) by using hydrolyzed sericin with different amount of alkaline protease (nAPh‐sericin) were compared. It was found that the polymer prepared from 5APh‐sericin (the mass ratio of AP to sericin was 5.0 mg g⁻¹) showed the highest graft percentage and water absorbency, this phenomenon may be attributed to the change of molecular weight of resulting sericin molecules. The molecular structure of the grafted polymers was proved by thermal gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) measurements. Comparing with PAA‐AM (poly AA‐co‐AM) and 0APh‐sericin/PAA‐AM polymer, 5APh‐sericin/PAA‐AM polymer had the most excellent water retention capacity and enzyme degradability. The morphological features of the polymers with different drying methods were evidenced by SEM images. The water absorbencies of 5APh‐sericin/PAA‐AM polymer prepared with freeze‐drying were 896 g g⁻¹ in deionized water, 424 g g⁻¹ in tap water, and 83 g g⁻¹ in 0.9 wt% aqueous NaCl solution. POLYM. COMPOS., 35:509–515, 2014. © 2013 Society of Plastics Engineers     

Synthesis and properties of styrene copolymers. Preparation of film‐modified electrodes to detect Pb2+ ions

Organic solvent‐soluble polymers containing different functional groups able to coordinate metal ions from low concentration were synthesized to build complexing polymer film modified electrodes. Poly(acetamide acrylic acid‐co‐styrene) and poly(itaconic acid‐co‐styrene) were synthesized by radical polymerization. The copolymers were characterized by Fourier transform infrared and ¹H NMR spectroscopy, electron scanning microscopy, and thermal analysis. The molecular weight and molecular weight distribution were determined by size exclusion chromatography. These complexing polymers have been used in the preparation of complexing modified electrodes (CME) by spin coating. The CME have been tested for the detection of metal ions using the chemical preconcentration‐anodic stripping technique. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2380–2385, 2006