A comparison of the oxidizing ability of polystyrene‐supported linear and cyclic polyoxyethylene bound permanganates

The grafting of linear and cyclic polyoxyethylenes into DVB‐crosslinked chloromethylpolystyrene was carried out by treating with polyethyleneglycol (PEG₆₀₀). The complexations of crosslinked polystyrene‐supported linear and cyclic polyoxyethylene with permanganate functions were carried out. With this reagent, primary alcohols and secondry alcohols were converted to aldehydes and ketones and aldehyde to acid. The polymer acts as a reservoir of permanganate functions and releases them slowly as the substrates are being used up. The effect of solvent, molar excess of reagent, time, and temperature on oxidation behavior were investigated by choosing benzoin to benzil conversion as the model reaction. The linear polymeric reagent has greater reactivity than the cyclic polymer due to the greater availability of the reactive sites in the linear polymer than the cyclic polymer. Polymeric reagent could be used in excess to get a good yield without causing any separation problems and over oxidation products. The reagents have advantages of easy separation, regeneration and reuse. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1897–1905, 2005     

Segregation of resin‐bound peptides during solid‐phase synthesis

To compare the segregation ability of 1,4‐butanediol dimethacrylate‐crosslinked polystyrene (BDDMA‐PS) and divinylbenzene‐crosslinked polystyrene (DVB‐PS), a set of difficult sequence peptides characterized by high‐arithmetic‐average β‐sheet stabilizing potential (SP_β) and low‐stepwise arithmetic average random coil conformational parameter (P_c*) were synthesized on both supports (～ 2 mmol Cl g^?1) under identical conditions. The yield and purity of the peptides obtained from BDDMS‐PS resin were higher than from DVB‐PS resin. The synthetic efficiency of the new support was found to be its ability to suppress the aggregation of growing peptide chains by β‐sheet formation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1717–1723, 2002     

Influence of the support structure on the activity,stability, and metal leaching of a polymer‐supported organotin chloride catalyst

Polymer‐supported organotin chlorides have been synthesized by suspension copolymerization of organotin‐functionalized styrenic monomers using a precipitating porogen. Their activities as reducing catalysts have been evaluated in the reduction of bromoadamantane by sodium borohydride. The influence of the length of the spacer arm between the tin atom and the polymer backbone on the activity and the tin leaching of the supported catalyst have been studied. The nature of the alkyl groups (butyl or phenyl) attached on the tin atom plays an important role on the stability toward successive reuse of the supported catalyst. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1297–1308, 2001     

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     

Polyacenaphthylene supported t-butyl chromates: a new class of solid phase oxidizing reagents

Copolymers of acenaphthylene with divinylbenzene were functionalized by incorporating t-butyl chromate groups, and the resulting polymeric reagents were used to oxidize alcohols to carbonyl compounds. Primary and secondary alcohols were oxidized to the corresponding carbonyl compounds in quantitative yields. The extent of oxidation was found to depend on the various reaction parameters including the temperature, nature of the solvent, concentration of the reagent functions, duration of the reaction and the presence of catalyst. © 1998 SCI.     

Polystyrene‐Supported Enantiopure 1,2‐Diamines: Development of a Most Practical Catalyst for the Asymmetric Transfer Hydrogenation of Ketones

Chlorosulfonylated polystyrene, a commodity resin, reacts with enantiopure 1,2‐diamines to afford, in a single step, high loading catalytic resins involving monosulfonylated 1,2‐diamino moieties. These functional polymers form stable (p‐cymene)ruthenium chloride [RuCl(p‐cymene)] complexes that efficiently catalyze (down to S/C=150) the asymmetric transfer hydrogenation (ATH) of alkyl aryl ketones with formic acid‐triethylamine under essentially solvent‐free (down to 0.25 mL mmol⁻¹) reaction conditions. Among these resins, the immobilized version of TsDPEN stands out as a most practical catalyst for ATH: Uniformly high enantioselectivities are achieved with its use at low catalyst loading, and the resin can be recycled with virtually no limits.     

Palladium complex embedded crosslinked polystyrene nanofibers as a green and efficient heterogeneous catalyst for coupling reactions

A simple and green chemical modification coupled with electrospinning technique has been developed to incorporate tetrakis(triphenylphosphine)palladium [Pd(PPh₃)₄] inside crosslinked polystyrene nanofibers (Pd@CPS) as an efficient and stable heterogeneous palladium catalyst. The catalytic activities and recyclabilities of the prepared Pd@CPS catalyst have been evaluated by using Suzuki and Heck reactions of various aromatic halides separately with phenylboronic acid and alkenes. The Pd@CPS exhibited high-catalytic activities for the Suzuki and Heck reactions of aromatic iodides to afford the products in excellent yields (coupling yields >88%). The catalytic activities and the nanofiber structure remained essentially unchanged even after recycling for five times. The high activities and stabilities of the prepared Pd@CPS catalyst can be attributed to the ultrafine fiber and embedment of palladium active species inside the nanofibers.     

Study on ethylene (co)polymerization and its kinetics catalyzed by a reversible crosslinked polystyrene‐supported metallocene catalyst

A well‐defined linear polystyrene with cyclopentadienes groups was prepared and characterized. The cyclopentadienes groups performed a Diels–Alder reaction to form the reversible crosslinking of the support. In olefin polymerization the crosslinked active species transformed noncrosslinked active species via MAO. The influence of the reversibility of network on olefin polymerization was investigated. The polystyrene‐supported metallocene catalyst showed high activity and stable polymerization process in olefin polymerization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1632–1636, 2005     

Polymer‐supported iminodiacetamides for selective mercury extraction

A new polymeric resin with iminodiacetamide functions has been prepared for the selective extraction of mercuric ions. This polystyrene sulfone amide‐based resin with a 9.6 mmol g^?1 amide content is able to selectively sorb mercury over many metal ions, including Cd(II), Zn(II), Fe(III), and Pb(II). Among these, Cd(II) and Zn(II) ions are not sorbed at all, and Fe(III) and Pb(II) ions show only trace absorptions (0.58 and 0.17 mmol/g, respectively) under the same conditions. The selectivity of the resin, its high mercury loading capacity (4.23 mmol g^?1), and its ability to regenerate via acetic acid make it a promising material for the large‐scale selective separation of mercuric ions from aqueous mixtures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1316–1321, 2003     

Mechanical,thermal and degradation properties of jute fabric – reinforced polypropylene composites: Effect of potassium permanganate as oxidizing agent

Mechanical properties of jute fabrics‐reinforced polypropylene composites were measured with reference to fiber loading and found highest at 45% by the weight of jute fabrics. Jute fabrics were treated with potassium permanganate in acid (oxalic acid and sulphuric acid) and alkaline (KOH) media in order to investigate the oxidizing effect on the properties of the composites. Solutions of oxalic acid, sulphuric acid, and KOH were prepared in water as 1.0–10.0% w/v, 0.1–2.0% v/v, and 1.0–10.0% w/v, respectively, where percentage of KMnO4 was maintained at 0.01% w/v. Among the treatments, 5.0% oxalic acid treated jute composite showed better mechanical performance. Thermogravimetric (TG/DTG) data of PP, jute fabrics and composites showed that thermal degradation temperatures of composites shifted to higher temperature regions compared to PP or jute fabrics. The treatment of jute fabrics improves thermal stability of the composites. Treated jute composites were found less degradable in soil, water and simulated weathering conditions and also found less water sensible compared to control composite (45% w/w jute fabrics). POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Ethylene polymerization with a silica‐supported iron‐based diimine catalyst

A supported iron‐based diimine catalyst (SC) was prepared by immobilization of 2,6‐bis[1‐(2,6‐diisopropylphenylimino)ethyl]pyridine iron chloride (I) on silica and employed in ethylene polymerization. The kinetic behavior of ethylene polymerization with SC was studied. The effects of the Al/Fe molar ratio, reaction temperature, and cocatalyst on the catalytic activity as well as the melting temperature, molecular weight, and morphology of the polymers obtained were also investigated. The results showed that good catalytic activities can be obtained even with a small amount of the cocatalyst methylaluminoxane (MAO) or triethylaluminum (AlEt₃). The polyethylenes obtained with a supported catalyst had higher molecular weight, higher melting temperature, and better morphology than those obtained with a homogeneous catalyst. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 466–469, 2003     

Novel nanocomposite of poly(acrylonitrile‐co‐glycidyl methacrylate) crosslinked with Jeffamine‐functionalized multiwalled carbon nanotubes as gel polymer electrolytes

Multiwalled carbon nanotubes (MWCNTs) were functionalized with α,ω‐diamino poly(propylene oxide) (Jeffamine) of different molecular weights and crosslinked with poly(acrylonitrile‐co‐glycidyl methacrylate) [P(AN‐GMA)] to prepare a novel nanocomposite for applications in gel polymer electrolytes (GPEs). The synthesized copolymer was characterized by ¹H‐NMR, Fourier transform infrared, and thermal analysis. Scanning electron microscope observation revealed that the Jeffamine‐functionalized MWCNTs distributed uniformly in the nanocomposite membrane. The mechanical behaviors of the nanocomposite membranes were investigated. It was found that the crosslinked nanocomposite membranes of P(AN‐GMA) and Jeffamine‐functionalized MWCNTs exhibited much higher mechanical strength than the counterpart nanocomposite obtained by physical blending. Moreover, the weight content and molecular weights of Jeffamine had an effect on the mechanical properties of the nanocomposites. Differential scanning calorimeter measurements showed that the crosslinked nanocomposite membranes were amorphous. GPEs based on the nanocomposite were prepared and characterized by complex impedance measurements. The GPE based on the nanocomposite of P(AN‐GMA) crosslinked with 6 wt % of MWCNTs functionalized by Jeffamine D400 showed an ionic conductivity of about 3.39 × 10^?4 S cm^?1 at 25°C, which is much higher than the counterpart nanocomposite of physically blended P(AN‐GMA) and MWCNTs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Hydrogen‐containing silicone resin as the crosslinking agent of heat‐curable silicone rubber

The hydrosilation‐cured vulcanizates (HCV) of silicone rubber were prepared by using hydrogen‐containing silicone resin (HSR) as the crosslinking agent. The influences of both the amount and structure of HSR on hydrosilation‐curing silicone rubber (HCSR) were discussed. The results indicate that HSR is a good crosslinking agent for HCSR. The tensile strength, tearing strength, elongation at break, and hardness of the vulcanizates can reach 9.6 MPa, 37.8 kN/m, 870% and 56 SHA, respectively. The aging stability of the vulcanizates can be improved greatly. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3066–3069, 2003     

Vinyl‐containing silicone resin as the crosslinking agent of heat‐curable silicone rubber

Heat‐curable silicone rubber (HCSR) was prepared by using vinyl‐containing silicone resin (VSR) as the crosslinking agent instead of polyvinylsilicone oil (C gum). Mechanical properties and crosslink density of the vulcanizates were measured. The results indicate that VSR is a good crosslinking agent for HCSR. The tensile strength, tearing strength, elongation at break, and hardness of the vulcanizate can reach 10.2 MPa, 29.1 kN/m, 720%, and 58 SHA, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3123–3127, 2002; DOI 10.1002/app.10054     

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     

Use of epoxidized rubber seed oil as a coupling agent and a plasticizer in silica‐filled natural rubber compounds

To obtain good reinforcement by silica filler in nonpolar rubbers, it is almost essential to use coupling agents, such as bis(triethoxy silyl propyl) tetrasulfane (TESPT). Chemicals that can interact with the silanol groups on the silica particles and reduce their network formation are also expected to enhance reinforcement. We made a comparative evaluation of TESPT, epoxidized rubber seed oil (ERSO), and their combination as a coupling agent and a plasticizer in silica‐filled natural rubber compounds. The results indicate that compounds containing ERSO showed physical and mechanical properties between that of TESPT and naphthenic oil. The action of ERSO in the improvement of the properties was expected to be bifunctional and similar to that of TESPT; that is, it caused the hydrophobation of silica, which increased its degree of dispersion and the formation of chemical bonds with the rubber, thereby ensuring strong polymer–filler interactions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3531–3536, 2004     

Emulsion polymerization of styrene with Iso‐octyl‐3‐mercaptopropionate as chain transfer agent

Four batch and unseeded emulsion polymerizations of styrene were investigated, which included isooctyl 3‐mercaptopropionate (iOMP) as chain transfer agent (CTA). This compound was analyzed by ¹³C NMR and GC/MS, resulting in a mixture of over 10 isomers. Because of different reactivities of the CTA isomers, the produced polystyrenes presented broad and bimodal molecular weight distributions (MWDs). A mathematical model was adjusted to the measurements, and the measured MWDs were adequately predicted when assuming the CTA as a binary mixture of high but different reactivities. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Packaging technology for improving shelf‐life of fruits based on a nanoporous–crystalline polymer

The ability of films with an active layer of nanoporous–crystalline syndiotactic polystyrene (s‐PS) to prolong shelf‐life, not only of climacteric but also of non‐climacteric fruits, is discussed. Studies on oxygen and carbon dioxide concentrations in the environment of packaged fruits as well as in s‐PS active layers have been combined. Reported results indicate that prolonged shelf‐life can be associated with large increases and decreases of carbon dioxide and oxygen concentrations inside the package, respectively. These data are consistent with a higher barrier offered to both gases by nanoporous–crystalline s‐PS layers. This barrier phenomenon is due to reduction of gas diffusivity typical of nanoporous–crystalline polymer films, which is further enhanced by orientation, parallel to the film plane, of crystalline planes of closely packed s‐PS helices. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46256.     

Thermally stable bromobutyl rubber with a high crosslinking density based on a 4,4′‐bismaleimidodiphenylmethane curing agent

The development of thermally stable bromobutyl rubbers has been a challenge in rubber chemistry and engineering. In this circumstance, 4,4′‐bismaleimidodiphenylmethane (BMI) was newly applied as a novel crosslinking agent for thermally stable brominated isobutylene–isoprene rubber (BIIR) with a high crosslinking density. With oscillating disk rheometry and differential scanning calorimetry, the curing characteristics of BIIR were systematically investigated with respect to the content of BMI. We found that BMI alone could crosslink BIIR at higher temperature, and a corresponding possible chemical reaction mechanism was proposed. With the introduction of zinc oxide, the curing reaction of BIIR with BMI was significantly accelerated, and the resulting vulcanizate provided a higher state of curing with excellent overcure reversion stability even at a temperature of 190 °C for 2 h. The content of the dicumyl peroxide (DCP) reaction accelerator was also optimized to be BMI/DCP = 1:0.05 on the basis of considerations of the curing rate, scorch safety, maximum rheometric torque, and reversion resistance at 160 °C. Compared with the conventional sulfur‐cured BIIR, the BMI‐cured BIIR exhibited a higher crosslinking density with a superior low compression set property at elevated temperatures and an excellent thermal stability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44092.     

Polyurethane‐ and Polystyrene‐Supported 2,2,6,6‐Tetramethyl‐ piperidine‐1‐oxyl (TEMPO); Facile Preparation,Catalytic Oxidation and Application in a Membrane Reactor

In this contribution, the facile synthesis of two new polymer‐supported 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)‐ and polystyrene (PS)‐based TEMPO catalysts are prepared in a one‐step reaction from commercially available compounds. Both polymer‐supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co‐oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane‐supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated.