The terpolymer of neodymium‐catalyzed styrene,isoprene, and butadiene: Efficient synthesis of integral rubber containing atactic styrene–styrene sequences and high Cis‐1,4 polyconjugated olefins

The present study focuses on the terpolymer of styrene (St), isoprene (Ip), and butadiene (Bd) synthesized together in cyclohexane at 70°C with neodymium (Nd) compound, alkylaluminum, and chlorinating agent (Cl) rare earth cocatalyst system. The resultants possessed atactic St–St sequences and high cis‐1,4 polyconjugated olefins in macromolecular chains besides controllable composition. The composition of the St–Ip–Bd terpolymers and molecular weight (M_w), molecular weight distribution (M_w/M_n) were controlled through the adjustment of Nd compound, alkylalumium, monomers feed ratio (St/Ip/Bd), and [Nd]/[monomers]. With the inventory rating of St raised from 15% to 55%, the content of St in the terpolymers got increased from 2% to 15%. And the content of the Ip segments and Bd segments in the terpolymers increased from 33% to 56% and from 28% to 54%, respectively, with the proportion of Ip/Bd varied from 1/2 to 2/1. As the [Nd]/[monomers] varied from 1.0 × 10^?3 to 5.0 × 10^?4, the molecular weight increased from 1.3 × 10⁴ to 2.7 × 10⁴. According to the proton nuclear magnetic resonance (¹H‐NMR) and ¹³C‐NMR, it was proved that both microstructures of polybutadiene segments and polyisoprene segments were high cis‐1,4‐configuration. A single glass‐transition temperature was observed in the differential scanning calorimetry curve. POLYM. ENG. SCI., 54:1858–1863, 2014. © 2013 Society of Plastics Engineers     

Mechanistic Insights into the Cytochrome P450‐Mediated Oxidation and Rearrangement of Littorine in Tropane Alkaloid Biosynthesis

During the biosynthesis of certain tropane alkaloids, littorine ( 1 ) is rearranged to hyoscyamine ( 3 ). Recent evidence indicates that this isomerisation is a two‐step process in which the first step is an oxidation/rearrangement to give hyoscyamine aldehyde ( 2 ). This step is catalysed by CYP80F1, a cytochrome P450 enzyme, which was recently identified from the plant Hyoscyamus niger; CYP80F1 also catalyses the hydroxylation of littorine at the 3′‐position. The mechanisms of the reactions catalysed by CYP80F1 were probed with synthetic deutero and arylfluoro analogues of 1 . Measurement of the primary kinetic isotope effects indicates that C3′ hydrogen abstraction is the rate‐limiting step for the oxidation/rearrangement of natural littorine, and for the 3′‐hydroxylation reaction of the unnatural S enantiomer of littorine. The character of the intermediates in the oxidation/rearrangement and hydroxylation reaction was probed with the use of arylfluorinated analogues of (R)‐littorine (natural stereoisomer) and (S)‐littorine (unnatural stereoisomer) as substrates for CYP80F1. The relative conversions of ortho‐, meta‐ and para‐fluorolittorine analogues were used to obtain information on the likely intermediacy of either a benzylic radical or benzylic carbocation intermediate. The data suggest that hydroxylation takes place via a benzylic carbocation intermediate, whereas the product profile arising from rearrangement is more consistent with a benzylic radical intermediate.     

A highly transparent and thermally stable copolymer of 1‐adamantyl methacrylate and styrene

Thermal and optical properties of copolymers of 1‐adamantyl methacrylate (AdMA) and styrene (St) prepared by free radical polymerization in the bulk are investigated. The copolymer forms an azeotrope when the composition is AdMA/St = 55/45 mol%. The glass transition temperature and decomposition temperature of the azeotropic copolymer are 170 and ca 340 °C, respectively. The refractive index increases nonlinearly with St content from 1.522 to 1.591. The light scattering loss at 633 nm is 28.1 dB km^?1, which is less than half of that of polystyrene. The total optical loss including molecular vibrational absorption, which is evaluated using a copolymer‐based optical fiber, is 292–645 dB km^?1 at 500–700 nm. These values correspond to transmittances of 86–93% for a 1 m optical path length. © 2014 Society of Chemical Industry     

Improving the cleanability of melamine‐formaldehyde‐based decorative laminates

Decorative laminates based on melamine formaldehyde (MF) resin impregnated papers are used at great extent for surface finishing of engineered wood that is used for furniture, kitchen, and working surfaces, flooring and exterior cladding. In all these applications, optically flawless appearance is a major issue. The work described here is focused on enhancing the cleanability and antifingerprint properties of smooth, matt surface‐finished melamine‐coated particleboards for furniture fronts, without at the same time changing or deteriorating other important surface parameters such as hardness, roughness or gloss. In order to adjust the surface polarity of a low pressure melamine film, novel interface‐active macromolecular compounds were prepared and tested for their suitability as an antifingerprint additive. Two hydroxy‐functional surfactants (polydimethysiloxane, PDMS‐OH and perfluoroether, PF‐OH) were oxidized under mild conditions to the corresponding aldehydes (PDMS‐CHO and PF‐CHO) using a pyridinium chlorochromate catalyst. With the most promising oxidized polymeric additive, PDMS‐CHO, the contact angles against water, n‐hexadecane, and squalene increased from 79.8°, 26.3° and 31.4° for the pure MF surface to 108.5°, 54.8°, and 59.3°, respectively, for the modified MF surfaces. While for the laminated MF surface based on the oxidized fluoroether the gloss values were much higher than required, for the surfaces based on oxidized polydimethylsiloxane the technological values as well as the lower gloss values were in agreement with the requirements and showed much improved surface cleanability, as was also confirmed by colorimetric measurements. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40964.     

N,N‐Dimethylformamide as a Methylenating Reagent: Synthesis of Heterodiarylmethanes via Copper‐Catalyzed Coupling between Imidazo[1,2‐a]pyridines and Indoles/N,N‐Dimethylaniline

A new copper‐catalyzed, efficient method for the synthesis of heterodiarylmethanes through the coupling of imidazo[1,2‐a]pyridines with indoles employing N,N‐dimethylformamide as a methylenating reagent has been developed. A library of 3‐(1H‐indol‐3‐ylmethyl)‐imidazo[1,2‐a]pyridine derivatives has been synthesized under aerobic reaction conditions. This protocol is also applicable for the synthesis of (4‐imidazo[1,2‐a]pyridin‐3‐ylmethyl)(phenyl)dimethylamines. The method is highly selective for the hetero‐coupling.

     

Influence of the chemical structure of dithiocarbamates with different R groups on the reversible addition‐fragmentation chain transfer polymerization

Four dithiocarbamates, carbazole‐9‐carbodithioic acid benzyl ester (R1), carbazole‐9‐carbodithioic acid naphthalen‐1‐ylmethyl ester (R2), 2‐(carbazole‐9‐carbothioylsulfanyl)‐2‐methyl‐propionic acid ethyl ester (R3), and (carbazole‐9‐carbothioylsulfanyl)‐phenyl‐acetic acid methyl ester (R4), were synthesized and used to the reversible addition‐fragmentation chain transfer (RAFT) polymerizations of styrene (St), methyl methacrylate (MMA), and methyl acrylate (MA), respectively. The influence of chemical structure of dithiocarbamates with different R groups on the RAFT polymerizations was investigated. The results showed that the four RAFT agents were effective RAFT agents for the polymerizations of styrene or MA, and that the polymerizations were well‐controlled with the characteristics of controlled/“living” polymerization. The polymerization rate of styrene with thermal initiation was markedly influenced by the chemical structures of the group R in dithiocarbamates, and decreased in the order of R3 > R2 > R4 > R1. For the polymerization of MA, the efficiency of RAFT agents was in the following order: R2–R3 > R1 > R4. However, they were not efficient enough to control the polymerization of MMA. The obtained polystyrene (PSt) with carbazole group labeled strongly absorbed UV light at 294 nm and emitted fluorescent light in N,N‐dimethyl formamide (DMF). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 982–988, 2007     

Removal of basic dyes from aqueous solutions using starch‐graft‐acrylic acid copolymers

Graft copolymerization of acrylic acid (AA) onto starch was carried out with ceric ammonium nitrate as initiator under nitrogen atmosphere. The grafting percentages (GP%) of starch‐graft‐AA (St‐gr‐AA) copolymers were determined. When the AA molar concentrations were 0.3 and 0.5 mol/L, GP% of St‐gr‐AA copolymers were 10.5% (St‐gr‐AA‐1) and 14% (St‐gr‐AA‐2), respectively. St‐gr‐AA copolymers have been used for the adsorption of basic dye (Safranine T) from aqueous solutions. Effects of various parameters such as treatment time, initial pH of the solution (pH = 2–6), initial dye concentration (50– 500 mg/L), and GP% of starch graft copolymers were investigated.Basic dye removal capacities of the copolymers increase along with the augment of initial concentration of the adsorbate, GP% of the copolymers, and pH. The adsorption capacities for St‐gr‐AA‐1 and St‐gr‐AA‐2 reach 116.5 and 204 mg/g, respectively. Equilibrium adsorption data were obtained and fitted very well to Freundlich model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Halogeno‐modified polystyrene: monomer reactivity ratios,thermal behaviour and flammability

Chemical modification based on incorporation of flame retardants into polymer backbones was used in order to reduce flammability of polystyrene (PSt). The halogeno‐substituted styrenes: 4‐chlorostyrene (ClSt), 4‐bromostyrene (BrSt) and 2,3,4,5,6‐pentafluorostyrene (5FSt) were applied as reactive flame retardants. Homo‐ and copolymers of these halogeno‐substituted styrenes and styrene (St) were synthesized with various feed ratios using free radical bulk polymerization with azobisisobutyronitrile as a initiator. This yielded series of (co)polymers with various amounts of included ClSt, BrSt and 5FSt (5–50 mol% of modified St). Copolymer compositions were determined using ¹H NMR spectroscopy. The relative reactivity ratios of the used comonomers were determined by applying conventional linearization methods. The Jaacks (J) method was used for systems including BrSt and ClSt monomers whereas the Fineman–Ross method was additionally used to confirm the values of reactivity ratios of St–5FSt. The reactivity ratios of comonomer pairs obtained from J plots were 0.75 and 0.38 (St–ClSt), 1.65 and 0.46 (St–BrSt), 0.44 and 0.42 (St–5FSt). Glass transition temperature and thermal stability of obtained (co)polymers were determined using differential scanning calorimetry and thermogravimetric analysis (TGA), respectively. The thermal degradation kinetic of PSt, PClSt, PBrSt and P5FSt was studied applying TGA. Kinetic parameters such as thermal decomposition activation energy (E) and frequency factor (A) were estimated using Ozawa and Kissinger models. The resulting activation energies estimated using these two methods were quite close. The values of activation energy (kJ mol^?1) increased in the following order: PClSt (E(O) = 216.1) < PSt (E(O) = 219.9) < PBrSt (E(O) = 224.7) < P5FSt (E(O) = 330.9). A pyrolysis combustion flow calorimeter was applied as a tool for assessing the flammability of the synthesized (co)polymers. © 2014 Society of Chemical Industry     

Synthesis,Characterization, and Antimicrobial Activity of Silver(I) and Copper(II) Complexes of Phosphate Derivatives of Pyridine And Benzimidazole

Two silver(I) complexes—{[Ag(4‐pmOpe)]NO₃}_n and [Ag(2‐bimOpe)₂]NO₃—and three copper(II) complexes—[Cu₄Cl₆O(2‐bimOpe)₄], [CuCl₂(4‐pmOpe)₂], and [CuCl₂(2‐bis(pm)Ope]—were synthesized by reaction of silver(I) nitrate or copper(II) chloride with phosphate derivatives of pyridine and benzimidazole, namely diethyl (pyridin‐4‐ylmethyl)phosphate (4‐pmOpe), 1H‐benzimidazol‐2‐ylmethyl diethyl phosphate (2‐bimOpe), and ethyl bis(pyridin‐2‐ylmethyl)phosphate (2‐bis(pm)Ope). These compounds were characterized by ¹H, ¹³C, and ³¹P NMR as well as IR spectroscopy, elemental analysis, and ESIMS spectrometry. Additionally, molecular and crystal structures of {[Ag(4‐pmOpe)]NO₃}_n and [Cu₄Cl₆O(2‐bimOpe)₄] were determined by single‐crystal X‐ray diffraction analysis. The antimicrobial profiles of synthesized complexes and free ligands against test organisms from the ATCC and clinical sources were determined. Silver(I) complexes showed good antimicrobial activities against Candida albicans strains (MIC values of ～19 μM ). [Ag(2‐bimOpe)₂]NO₃ was particularly active against Pseudomonas aeruginosa and methicillin‐resistant Staphylococcus epidermidis, with MIC values of ～5 and ～10 μM , respectively. Neither copper(II) complexes nor the free ligands inhibited the growth of test organisms at concentrations below 500 μg mL^?1.     

The effect of various catalysts on the monomer reactivity ratios in oxidative copolymerization of styrene and α‐methylstyrene

Oxidative copolymerizations of styrene (St) with α‐methylstyrene (AMS) have been studied under 100 psi (690 kPa) oxygen pressure at 50 °C in the presence of various catalysts, namely 2,2′‐azobisisobutyronitrile, cobalt(II) phthalocyanine pyridine complex and cobalt(II) tetraphenylporphyrin pyridine complex. The rates of copolymerization reactions (R_p) are obtained from oxygen consumption versus time plots. The reactivity ratios are computed with the Fineman–Ross and Kelen–Tüdös methods, using copolyperoxide compositions obtained from ¹H NMR analysis. The effects of these catalysts on R_p, molecular weight and monomer reactivity ratios have been examined. Using all three catalysts, the comonomer incorporation in the copolyperoxide chain is controllable over a wide range by adjusting the comonomer feed ratios. The reactivity ratio results indicate that incorporation of St or AMS in the copolyperoxides is independent of initiating system. © 2014 Society of Chemical Industry     

Synthesis of a photo‐patternable cross‐linked epoxy system containing photodegradable carbonate units for deep UV lithography

Bis(2‐(oxiran‐2‐ylmethyl)‐1,3‐dioxoisoindolin‐5‐yl) carbonate and polymers containing 9‐anthracenylmethylmethacrylate (AMMA), p‐tert‐butoxy styrene (PTBS), and methacrylic acid (MAA) monomeric units were synthesized with the aim of developing a novel photo‐patternable cross‐linked epoxy system. The oxirane groups in bis(2‐(oxiran‐2‐ylmethyl)‐1,3‐dioxoisoindolin‐5‐yl) carbonate were reacted with the carboxylic acid in the polymer to generate a cross‐linked epoxy film, and the photo degradation of the cross‐linked film was achieved through decomposition of the carbonate groups in the cross‐linked film by deep UV irradiation. Because the copolymer containing anthracene groups has relatively high reflective index and absorption at 248 nm, this cross‐linked system can be applied to patternable bottom antireflective coating materials for deep UV lithography applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Stereoselective Modulation of P‐Glycoprotein by Chiral Small Molecules

Inhibition of drug efflux pumps such as P‐glycoprotein (P‐gp) is an approach toward combating multidrug resistance, which is a significant hurdle in current cancer treatments. To address this, N‐substituted aryloxymethyl pyrrolidines were designed and synthesized in their homochiral forms in order to investigate the stereochemical requirements for the binding site of P‐gp. Our study provides evidence that the chiral property of molecules could be a strategy for improving the capacity for interacting with P‐gp, as the most active compounds of the series stereoselectively modulated this efflux pump. The naphthalene‐1‐yl analogue (R)‐2‐[(2,3‐dichlorophenoxy)methyl]‐1‐(naphthalen‐1‐ylmethyl)pyrrolidine) [(R)‐ 7 a ] emerged foremost for its potency and stereoselectivity toward P‐gp, with the S enantiomer being nearly inactive. The modulation of P‐gp by (R)‐ 7 a involved consumption of ATP, thus demonstrating that the compound behaves as a P‐gp substrate.     

Melt grafting of maleic anhydride onto polypropylene with 1‐decene as a second monomer

The influence of 1‐decene as the second monomer on the melt‐grafting behavior of maleic anhydride (MAH) onto polypropylene (PP) was studied with differential scanning calorimetry and Fourier transform infrared spectroscopy. We found that the value of the grafting degree increased from 0.68% for pure MAH‐g‐PP to 1.43% for the system with a 1‐decene/MAH molar ratio of 0.3, whereas the maximum value with styrene (St) as the second monomer was 0.98% under an St/MAH molar ratio of 1.0. Compared with the contribution of St/MAH‐g‐PP to the peeling strength between the PP and polyamide (PA) layer for a PP/PA laminated film, the introduction of 1‐decene/MAH‐g‐PP increased the peeling strength from 180 g/15 mm to 250 g/15 mm. 1‐Decene inhibited the chain scission behavior of PP. 1‐Decene reacted with MAH to form a 1‐decene/MAH copolymer or the Alder‐ene reaction product before the two monomers grafted onto PP. The grafting of the reactive product onto PP greatly improved the grafting degree of MAH. What is more, because of the similar chemical structures of 1‐decene and PP, the affinity of 1‐decene with PP was higher than that of St. Compared with St, the introduction of less 1‐decene led to a higher grafting degree and higher peeling strength. Therefore, we concluded that 1‐decene was more effective for improving the grafting degree of MAH onto PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Sesquiterpene Synthases Cop4 and Cop6 from Coprinus cinereus: Catalytic Promiscuity and Cyclization of Farnesyl Pyrophosphate Geometric Isomers

Sesquiterpene synthases catalyze with different catalytic fidelity the cyclization of farnesyl pyrophosphate (FPP) into hundreds of known compounds with diverse structures and stereochemistries. Two sesquiterpene synthases, Cop4 and Cop6, were previously isolated from Coprinus cinereus as part of a fungal genome survey. This study investigates the reaction mechanism and catalytic fidelity of the two enzymes. Cyclization of all‐trans‐FPP ((E,E)‐FPP) was compared to the cyclization of the cis–trans isomer of FPP ((Z,E)‐FPP) as a surrogate for the secondary cisoid neryl cation intermediate generated by sesquiterpene synthases, which are capable of isomerizing the C2? C3 π bond of all‐trans‐FPP. Cop6 is a “high‐fidelity” α‐cuprenene synthase that retains its fidelity under various conditions tested. Cop4 is a catalytically promiscuous enzyme that cyclizes (E,E)‐FPP into multiple products, including (?)‐germacrene D and cubebol. Changing the pH of the reaction drastically alters the fidelity of Cop4 and makes it a highly selective enzyme. Cyclization of (Z,E)‐FPP by Cop4 and Cop6 yields products that are very different from those obtained with (E,E)‐FPP. Conversion of (E,E)‐FPP proceeds via a (6R)‐β‐bisabolyl carbocation in the case of Cop6 and an (E,E)‐germacradienyl carbocation in the case of Cop4. However, (Z,E)‐FPP is cyclized via a (6S)‐β‐bisabolene carbocation by both enzymes. Structural modeling suggests that differences in the active site and the loop that covers the active site of the two enzymes might explain their different catalytic fidelities.     

UV‐ and thermally triggered ring‐opening metathesis polymerization for the spatially resolved functionalization of polymeric monolithic devices

Porous polymeric monolithic supports were prepared via electron beam‐triggered free radical polymerization using a mixture of ethyl methacrylate and trimethylolpropane triacrylate in 2‐propanol, 1‐dodecanol and toluene. Bicyclo[2.2.1]hept‐5‐en‐2‐ylmethyl acrylate (1) was grafted onto these monolithic supports in a spatially resolved way with the aid of masks using both electron beam‐ (EB) and UV‐triggered free radical polymerization. The thus immobilized norborn‐2‐ene‐containing graft polymers were further treated with the 2^nd‐generation Grubbs initiator, i.e., RuCl₂(PCy₃)(IMesH₂)(CHPh) (4) (IMesH₂ = 1,3‐dimesitylimidazolin‐2‐ylidene), and then reacted with bicyclo[2.2.1]hept‐5‐en‐2‐ylmethyl pyrene‐1‐carboxylate (2). Alternatively, monoliths completely grafted with poly‐ 1 were surface grafted with 2 in a spatially resolved way in the presence of a latent, UV‐triggerable precatalyst, i.e., [Ru(IMesH₂)(CF₃COO)(t‐BuCN)₄⁺ CF₃COO^?] (5). Finally, to demonstrate the utility of this chemistry, a 2^nd‐generation Grubbs initiator‐based approach was used to prepare a trypsin‐functionalized monolith‐containing chip device that allowed for the online digestion of N‐α‐benzoyl‐L ‐argininethylester hydrochloride. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of poly(acrylonitrile‐co‐p‐trimethylsilylstyrene) and poly(acrylonitrile‐co‐p‐trimethylsilylstyrene‐co‐styrene)

Copolymerization of acrylonitrile (AN) with p‐trimethylsilylstyrene (TMSS) was carried out at 60°C in bulk and in solution in the presence of 2,2′‐azobisisobutyronitrile (AIBN). The reactivity ratios of AN (M₁) and TMSS (M₂) were determined to be r₁ = 0.068 and r₂ = 0.309. The effects of the AIBN concentration and that of the chain transfer agent CCl₄ on the molecular weights (MWs) of the copolymers were investigated. An increase in the concentrations of AIBN or CCl₄ in solution led to a decrease in MW. Poly(AN‐co‐TMSS‐co‐St) was synthesized in solution using AIBN as the initiator. The molar fraction of AN was 0.415, while the molar ratio of TMSS/St varied from 1 : 1 to 1 : 9. The transition temperatures and thermal and thermooxidative stabilities of poly(AN‐co‐TMSS) and poly(AN‐co‐TMSS‐co‐St) were investigated. The differential scanning calorimeter technique was used to determine the compatibility of the poly(AN‐co‐TMSS) and poly(AN‐co‐TMSS‐co‐St) with commercial poly(AN‐co‐St). All the blends show a single glass transition temperature, which indicates the compatibility of the blend components. The surface film morphology of the blends mentioned above was examined by X‐ray photoelectron spectroscopy. The data obtained indicate that the silicon‐containing copolymer is concentrated in the surface layer. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1920–1928, 2000     

Effects of the cosurfactant 1‐butanol and feed composition on nanoparticle properties produced by microemulsion copolymerization of styrene and methyl methacrylate

The concentration of the cosurfactant 1‐butanol (BuOH) determined the polymer weight and size for a series of poly(styrene‐co‐methyl methacrylate)s (P(St‐co‐MMA)) synthesized by the free‐radical (o/w) microemulsion technique. A factorial design established the levels of the experimental conditions for the polymerization i.e., concentration of the surfactant, sodium dodecyl sulfate (SDS); concentration of the cosurfactant, BuOH; temperature and ratio of the styrene (St) to methyl methacrylate (MMA). An increase in the weight‐average molecular weight (M_w) and number‐average molecular weight (M_n) was observed in the P(St‐co‐MMA) series with an increase in BuOH concentration from 1 to 5 wt %. These effects could arise from the micellar aggregation induced by interfacial BuOH. The unique micellar conditions could be exploited to synthesize copolymers of varying molecular weight and size. Additionally, the composition of the copolymers was virtually templates of the feed composition. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Polymer‐Supported,Carbon Dioxide‐Protected N‐Heterocyclic Carbenes: Synthesis and Application in Organo‐ and Organometallic Catalysis

The synthesis of a resin‐supported, carbon dioxide‐protected N‐heterocyclic carbene (NHC) and its use in organocatalysis and organometallic catalysis are described. The resin‐bound carbon dioxide‐protected NHC‐based catalyst was prepared via ring‐opening metathesis copolymerization of 1,4,4a,5,8,8a‐hexahydro‐1,4,5,8‐exo,endo‐dimethanonaphthalene ( DMNH6 ) with 3‐(bicyclo[2.2.1]hept‐5‐en‐2‐ylmethyl)‐1‐(2‐propyl)‐3,4,5,6‐tetrahydropyrimidin‐1‐ium‐2‐carboxylate ( M1 ), using the well‐defined Schrock catalyst Mo[N‐2,6‐(2‐Pr)₂‐C₆H₃](CHCMe₂Ph)(OCMe₃)₂ and was used for a series of organocatalytic reactions, i.e., for the trimerization reaction of isocyanates, as well as for the cyanosilylation of carbonyl compounds. In the latter reaction, turn‐over numbers (TON) up to 5000 were achieved. In addition, the polymer‐supported, carbon dioxide‐protected N‐heterocyclic carbene served as an excellent progenitor for various polymer‐supported metal complexes. It was loaded with a series of rhodium(I), iridium(I), and palladium(II) precursors and the resulting Rh‐, Ir‐, and Pd‐loaded resins were successfully used in the polymerization of phenylacetylene, in the hydrogen transfer reaction to benzaldehyde, as well as in Heck‐type coupling reactions. In the latter reaction, TONs up to 100,000 were achieved. M1 , as a non‐supported analogue of poly‐M1‐b‐DMNH6 , as well as the complexes PdCl₂[1,3‐bis(2‐Pr)tetrahydropyrimidin‐2‐ylidene]₂ ( Pd‐1 ) and IrBr[1‐(norborn‐5‐ene‐2‐ylmethyl)‐3‐(2‐Pr)‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidine](COD) ( Ir‐1 ) were used as homogeneous analogues and their reactivity in the above‐mentioned reactions was compared with that of the supported catalytic systems. In all reactions investigated, the TONs achieved with the supported systems were very similar to the ones obtained with the unsupported, homogeneous ones, the turn‐over frequencies (TOFs), however, were lower by up to a factor of three.     

Synthesis and properties of a ternary polyacrylate copolymer resin for the absorption of oil spills

A high‐oil‐absorption resin of a ternary copolymer for the absorption of oil spills was successfully prepared by suspension polymerization, and characterizations of the oil‐absorption resin were also examined in this study. The high‐oil‐absorption resin, a ternary copolymerized long‐chain polyacrylate with styrene (St), butyl methacrylate (BMA), and stearyl methacrylate (SMA) as the monomers and synthesized by suspension polymerization, was introduced. The oil‐absorption resin of St/BMA/SMA was characterized by Fourier transform infrared spectrometry. The particle morphology of the resin was observed by scanning electron microscopy. The effects of different polymerization technological parameters, such as the mass ratios of the monomer, the benzoyl peroxide initiator, and the crosslinking agent of divinylbenzene; the sort and concentrations of the dispersing agent of hydroxyl ethyl cellulose, sodium dodecyl benzene sulfonate, and gelatin, and the polymerization temperature, on the oil absorbency of St/BMA/SMA are discussed in detail. The optimum polymerization conditions of the St/BMA/SMA copolymer were obtained as follows: m_St/m_monomer = 50 wt %, m_BMA/m_{soft monomer} = 60 wt %, m_water/m_oil = 3:1, m_DVB/m_monomer = 1.0 wt %, m_BPO/m_monomer = 1.5 wt %, m_HEC/m_monomer = 0.07 wt %, m_SDBS/m_monomer = 0.03 wt %, m_gelatin/m_monomer = 0.14 wt % (where m is the mass), temperature = 85°C. With increasing content of these factors, the oil absorbency increased at first and then decreased. Compared with binary copolymer St/BMA prepared in previous research, the highest oil absorbencies to dichloromethane were 12.80 and 23.00 g/g in the St/BMA and St/BMA/SMA copolymers, respectively. St/BMA/SMA had a higher oil absorbency and faster oil‐adsorbing rate than St/BMA. The oil absorption in the oil–water mixture and the recovery of the resin were also studied in detail. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40180.     

Improving thermal and flame‐retardant properties of epoxy resins by a novel reactive phosphorous‐containing curing agent

In an attempt to improve thermal and flame‐retardant properties of epoxy resins efficiently, a new reactive phosphorus‐containing curing agent called 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐yl‐(phenylimino)‐(4‐hydroxyphenyl)me‐thane (DOPO‐PHM) was synthesized and was combined with 4,4′‐diaminodiphenyl methane (DDM) to co‐cure epoxy resins (E51), which covalently incorporated halogen‐free DOPO organ groups into the epoxy networks. The chemical structure of this curing agent was confirmed by FTIR, 1D, and 2D NMR spectra. A reaction mechanism during the preparation was proposed, and the electron effect on the stabilization of the carbocation was discussed. Various DDM/DOPO‐PHM molar ratios were used to get the materials with different phosphorus contents. Their dynamic mechanical, thermal, and flame‐retardant properties were evaluated by dynamic mechanical thermal analysis, thermogravimetric analysis, and limiting oxygen index (LOI) respectively. All samples had a single T_g, showing that these epoxy resins were homogeneous phase for long‐term use in spite of adding DOPO‐PHM. Both char yields (under nitrogen and air atmospheres) increased with the increasing of phosphorus content and the LOI values increased from 24.5 for standard resin to 33.5 for phosphorus‐containing resins, indicating the significant enhancement of thermal stability and flame retardancy. POLYM. ENG. SCI., 54:1192–1200, 2014. © 2013 Society of Plastics Engineers