Enantioselective,alternating copolymerization of carbon monoxide and olefins

Enantioselective, alternating copolymerizations of carbon monoxide with styrene, dicyclopentadiene, and methylcyclopentadiene dimer were carried out with a palladium catalyst modified by 1,4‐3,6‐dianhydro‐2,5‐dideoxy‐2,5‐bis(diphenyl phosphino)‐L ‐iditol. Chiral diphosphine was proven to be effective at enantioselective copolymerization. In the copolymers, some of the second double bonds of alternating poly(1,4‐ketone) were carbonylated. Optical rotation, elemental analysis, and spectra of ¹H NMR, ¹³C NMR, and IR showed that the copolymers had isotactic, alternating poly(1,4‐ketone) structures. An oxidant and an organic acid were the promoters of the copolymerization. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2919–2924, 2000     

Rare‐earth‐catalyzed alternating copolymerization of carbon monoxide with styrene

Rare‐earth acetates were used to catalyze the copolymerization reaction of carbon monoxide and styrene. Cupric acetate, 1,10‐phenanthroline, p‐toluenesulfonic acid, and 1,4‐benzoquinone were also added to the catalyst system. The structures of the copolymers obtained were characterized with IR, ¹H NMR, ¹³C NMR, wide‐angle X‐ray diffraction, and elemental analysis methods. The relationship between the catalytic activity and the catalyst composition was studied in detail. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 642–649, 2002; DOI 10.1002/pola.10147     

Alternating copolymerizations of styrene derivatives and carbon monoxide in the presence of a palladium (II) catalyst

A series of styrene derivatives were synthesized from aromatic substances by Friedel-Crafts acylation, reduction, and dehydration. Alternating copolymers of styrene derivatives and carbon monoxide were prepared in the presence of a palladium(II) catalyst. The characterization of the polyketones produced was performed by use of ¹H-NMR, IR, WXRD, and EA methods. The thermal degradation of the regular alternating copolymer of carbon monoxide and styrene (STCO) has been studied by thermal gravimetry (TG). The TG spectra of solid samples were recorded both in nitrogen and in air. The degradation reaction order and activation energy were determined. The photodegradation of STCO was investigated. In addition, the block copolymerization of STCO with methyl methacrylate under UV irradiations was also studied. It is found that the tertiary amine can promote this photopolymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1283–1291, 1997     

Polyoximes based on the alternating carbon monoxide copolymers

A new efficient method for the synthesis of polyoximes was developed based on the oximation of the alternating carbon monoxide copolymer with ethylene or styrene in the polar aprotic solvent.     

Terpolymerization of carbon monoxide, ethylene and styrene in the presence of supported palladium catalyst

Terpolymers of carbon monoxide with ethylene and styrene are synthesized in the presence of supported palladium catalyst in toluene and heptane medium for the first time. The terpolymerization rate exceeds the rate of carbon monoxide and ethylene copolymerization. The maximum terpolymer yield amounts 7.9 g per g of supported catalyst per hour or 321 g per g of palladium per hour. The influence of reaction temperature, pressure, 1.4-benzoquinone amount and co-monomers mole ratio on the yield and the composition of terpolymer have been studied. The NMR ¹³C data obtained testify to a distribution of ethylene and styrene units in terpolymer with the predominance of short blocks at equal contents of comonomer units.     

Regioselective and stereoselective alternating copolymerization of carbon monoxide with functional olefins

Enantioselective, alternating copolymerizations of carbon monoxide with ω‐undecylenic acid, ethyl acrylate, and butyl acrylate were carried out for the first time with a palladium catalyst modified by 1,4:3,6‐dianhydro‐2,5‐dideoxy‐2,5‐bis(diphenylphosphino)‐L ‐iditol. Optical rotation, elemental analysis, and ¹H NMR,¹³C NMR, and IR spectra showed that the copolymers were optically active, isotactic, alternating poly(1,4‐ketone) or poly(spiroketal) structures. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2027–2036, 2001     

Mechanical and thermal properties of ternary alternating copolymers of carbon monoxide with olefins

Thermal properties and the deformational behavior of ternary alternating copolymers of carbon monoxide with ethylene and other olefins (propylene, 1-butene, styrene) with molecular masses of M _n = 1000–35000 and molar fraction of the third comonomer in the polymer chain from 0.02 to 0.70 were investigated. Temperatures of melting and glass transition are significantly affected by the composition of the products. Varying the nature of the third comonomer or the content of its units in the polymer chain and the molecular masses of terpolymers makes it possible to obtain materials with Young’s moduli of 0.003–3.090 GPa and elongations at break of 5–2000%.     

Cobalt‐catalyzed alternating and nonalternating copolymerization of carbon monoxide with aziridine

Catalysts CH₃COCo(CO)₃PPh₃ ( 1 ) and HCo(CO)₃PPh₃ ( 2 ) catalyze the copolymerization of aziridine and carbon monoxide. Catalyst 2 can be conveniently generated in situ via reaction of Na⁺Co(CO)₄, N,N‐dimethylanilinium chloride, and PPh₃. The copolymerization alternates at high catalyst loadings to produce poly(β‐alanine). The end groups of the poly(β‐alanine) product are characterized by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and by comparison of the ¹H NMR spectra of the polymer and a stepwise synthesized model compound. At low catalyst loadings, the polymer product contains both the β‐alanine units and amine units because of nonalternating enchainment of the comonomers. The characterization of the amine units is again supported by comparison of the ¹H NMR spectra of the polymers and the stepwise synthesized model compounds. The molecular weights of the polymers are determined by gel permeation chromatography. The thermal stability of the polymers is probed by differential scanning calorimetry and thermogravimetric analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 376–385, 2003     

α,α‐Dibromotoluene as a monomer for poly (substituted methylene) synthesis: Magnesium‐mediated polycondensation of α,α‐dibromotoluene and magnesium/copper‐mediated copolycondensation of α,α‐dibromotoluene with 1,6‐dibromohexane

α,α‐Dibromotoluene 1 was found to be polymerized by the reaction with excess Mg to give poly(phenylmethylene)s 2 , whose main chains were partially dehydrogenated to carbon–carbon double bonds (C?C). The C?Cs in 2 can be brominated by treatment with Br₂. The polymerization mechanism was presumed to include the formation of Grignard reagents of various species with benzylic C? Br bonds and the nucleophilic attacks of the Grignard reagents to various compounds with benzylic C? Br bonds. Copolymerization of 1 with dichlorodimethylsilane successfully proceeded. Mg/Cu‐mediated copolycondensation of 1 with 1,6‐dibromohexane proceeded to give polymers that have similar compositions to those of random copolymers of ethylene and styrene. © 2006Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5661–5671, 2006     

Facile synthesis of glycerol carbonate from glycerol using selenium‐catalyzed carbonylation with carbon monoxide

The commercial production of glycerol has increased considerably for several years, because of its rising inevitable formation as a by‐product of biodiesel. For the effective utilization of glycerol, a new synthesis of glycerol carbonate (4‐hydroxymethyl‐2‐oxo‐1,3‐dioxolane) that is used as solvents and raw material of plastics from glycerol was explored. By combined the selenium‐catalyzed carbonylation of slightly excess of glycerol with carbon monoxide and potassium carbonate under 0.1 MPa at 20°C for 4 h in DMF with the oxidation of resulting selenocarbonate salt with molecular oxygen (0.1 MPa, 20 °C) for 2 h, glycerol carbonate was obtained in good yields (83–84%). However, sodium hydride to form sodium alkoxide in situ lowered the yield of glycerol carbonate. Use of triethylamine, 1‐methylpyrrolidine, and DBU as bases gave poor results. Furthermore, styrene carbonate was obtained in excellent yield (90%) under similar reaction conditions. The catalytic synthesis of glycerol carbonate was also brought about in the mixed gas atmosphere (carbon monoxide:oxygen = 3:1, 0.1 MPa, 20°C). Glycerol carbonate and styrene carbonate were obtained in reasonable yields (197% and 119%, based on selenium used). © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:541–545, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20640     

Biocompatible polystyrenes containing pendant tetra(ethylene glycol) and phosphorylcholine groups

The synthesis and characterization of styrene‐based polymers and copolymers containing pendant tetra(ethylene glycol) and phosphorylcholine groups is reported. These polymers are obtained via radical polymerization reactions using α,α′‐azobis(isobutyronitrile) as the initiator, and are developed as protective biocompatible coatings for implantable biosensors. Cell morphology studies show that none of the synthesized polymers and copolymers are toxic, and that the rate of cell growth can be tuned by changing the monomer composition. The presence of tetra(ethylene glycol) groups in the coatings lowers the protein adsorption, thereby influencing the rate of cell growth. An equally profound effect is observed when a low percentage of phosphorylcholine groups is present in the polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 468–474, 2001     

High‐temperature ethylene/α‐olefin copolymerization with a zirconocene catalyst: Effects of the zirconocene ligand and polymerization conditions on copolymerization behavior

Copolymerizations of ethylene and α‐olefin with various zirconocene compounds at a high temperature were carried out to study the relationship between the ligand structure of zirconocene compounds and the copolymerization behavior. All of the indenyl‐based zirconocene compounds in combination with dimethylanilinium tetrakis(pentafluorophenyl)borate/triisobutylaluminum produced only low molecular weight copolymers at a high temperature, regardless of the substituents and bridged structures of the zirconocene compounds. However, zirconocene compounds with a fluorenyl ligand gave rise to a significant increase in the activity and molecular weight of the copolymers by the selection of a diphenylmethylene bridge structure even at a high temperature. Ethylene/1‐hexene copolymers obtained with the fluorenyl‐based catalysts contained inner double bonds accompanied by the generation of hydrogen, presumably because of a C H bond activation mechanism. The contents of the inner double bonds were significantly influenced by the polymerization conditions, including the 1‐hexene feed content, polymerization temperature, and ethylene pressure. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4641–4648, 2000     

Preparation of poly(styrene‐co‐acrylonitrile)‐grafted multiwalled carbon nanotubes via surface‐initiated atom transfer radical polymerization

The in situ grafting‐from approach via atom transfer radical polymerization was successfully applied to polystyrene, poly(styrene‐co‐acrylonitrile), and polyacrylonitrile grafted onto the convex surfaces of multiwalled carbon nanotubes (MWCNTs) with (2‐hydroxyethyl 2‐bromoisobutyrate) as an initiator. Thermogravimetric analysis showed that effective functionalization was achieved with the grafting approach. The grafted polymers on the MWCNT surface were characterized and confirmed with Fourier transform infrared spectroscopy and nuclear magnetic resonance. Raman and near‐infrared spectroscopy revealed that the grafting of polystyrene, poly(styrene‐co‐acrylonitrile), and polyacrylonitrile slightly affected the side‐wall structures. Field emission scanning electron microscopy showed that the carbon nanotube surface became rough because of the grafting of the polymers. Differential scanning calorimetry results indicated that the polymers grafted onto MWCNTs showed higher glass‐transition temperatures. The polymer‐grafted MWCNTs exhibited relatively good dispersibility in an organic solvent such as tetrahydrofuran. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 460–470, 2007     

Olefin polymerization by cyclopentadienyltris(dimethylamido)titanium(IV) complexes

Several titanium(IV) complexes of the type Cp′Ti(NMe₂)₃ [Cp′ = cyclopentadienyl ( 1 ), (dimethylaminoethyl)cyclopentadienyl ( 2 ), indenyl ( 3 ), and pentamethylcyclopentadienyl ( 4 )] were prepared, and their catalytic properties in the polymerization of α‐olefins were examined. Complexes 1 and 2 catalyzed the polymerization of ethylene in the presence of methylaluminoxane with a much higher activity than 3 or 4 . Complexes 3 and 4 polymerized ethylene with an activity similar to that of CpTiCl₃ ( 6 ). The preactivation of 2 , 3 , or 4 with trimethylaluminum (TMA) resulted in an increase in ethylene polymerization activities. Also, 1 and 2 were successfully used as ethylene/1‐hexene copolymerization catalysts, producing polymers with various amounts of 1‐hexene incorporation, depending on the amount of 1‐hexene in the feed mixture. Complex 1 likewise effectively polymerized styrene with a higher activity and higher syndiospecificity than the other three catalysts. Complexes 3 and 4 polymerized styrene with low syndiospecificity, whereas 2 produced only atactic polystyrene. The preactivation of 3 or 4 with TMA resulted in an increase in styrene polymerization activities and increased the syndiotacticity percentage of the polymers produced. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 313–319, 2001     

Surface covalent encapsulation of multiwalled carbon nanotubes with poly(acryloyl chloride) grafted poly(ethylene glycol)

Multiwall carbon nanotube (MWNT) was grafted with polyacrylate‐g‐poly (ethylene glycol) via the following two steps. First, hydroxyl groups on the surface of acid‐treated MWNT reacted with linear poly(acryloyl chloride) to generate graft on MWNT; secondly, the remaining acryloyl chloride groups were subjected to esterification with poly(ethylene glycol) leading the grafted chains on the surface of MWNTs. Thus obtained grafted MWNT was characterized using Fourier transform infrared spectrometer, transmission electron microscopy, and X‐ray photoelectron spectroscopy. Thermogravimetric analysis showed that the weight fraction of grafted polymers amounted to 80% of the modified MWNT. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6880–6887, 2006     

Anionic polymerization of o‐substituted styrene derivatives: Control of reactivity and stereochemistry by aminomethyl group

Ortho‐substituted styrenes, such as 2‐(N,N‐dimethylaminomethyl)styrene ( 1 ), 2‐(1‐pyrrolidinylmethyl)styrene ( 2 ), and 2‐[(S)‐2‐(1‐pyrrolidinylmethyl)‐1‐pyrrolidinylmethyl]styrene ( 3 ), were synthesized, and the effects of the ortho‐substituents on the polymerizability and stereoregularity of the obtained polymers using the anionic method were examined. The bulkiness and coordination of the ortho‐substituted amino groups to the counter cation significantly affected the polymerizability and stereochemistry of the obtained polymers. The anionic and radical polymerizations of 2 with a less hindered ortho‐substituent afforded polymers in good yields, whereas those of 1 and 3 resulted in lower yields. The anionic polymerization of 3 bearing an optically active diamine derivative at the ortho‐position with n‐butyllithium in toluene at 0 °C gave a polymer with a high stereoregularity and stable regular conformation based on the stereoregular backbone structure. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4088–4094, 2000     

Graft copolymers of polyethylene by atom transfer radical polymerization

Poly(ethylene‐g‐styrene) and poly(ethylene‐g‐methyl methacrylate) graft copolymers were prepared by atom transfer radical polymerization (ATRP). Commercially available poly(ethylene‐co‐glycidyl methacrylate) was converted into ATRP macroinitiators by reaction with chloroacetic acid and 2‐bromoisobutyric acid, respectively, and the pendant‐functionalized polyolefins were used to initiate the ATRP of styrene and methyl methacrylate. In both cases, incorporation of the vinyl monomer into the graft copolymer increased with extent of the reaction. The controlled growth of the side chains was proved in the case of poly(ethylene‐g‐styrene) by the linear increase of molecular weight with conversion and low polydispersity (M_w /M_n < 1.4) of the cleaved polystyrene grafts. Both macroinitiators and graft copolymers were characterized by ¹H NMR and differential scanning calorimetry. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2440–2448, 2000     

In situ compatibilization of PET/PS blends through carbamate‐functionalized reactive copolymers

To investigate the effect of reactive compatibilization in the immiscible poly(ethylene terephthalate) (PET)/polystyrene (PS) blend, poly(styrene‐co‐methacryloyl carbamate) (PSM) was synthesized as a reactive compatibilizer. The interfacial reaction of the carbamate group in PSM with OH/COOH in PET was confirmed by atomic force microscopy. The interfacial roughness developed rapidly with an increase in the methacryloyl carbamate (MAC) content and then leveled off above the optimum content (3.8 wt %). These results were well‐reflected in the interfacial adhesion, morphology, and mechanical properties of the PET/PS blends, showing a maximum value at the optimum MAC content. The existence of a maximum value is believed to stem from a reciprocal relationship between the sufficient formation of in situ copolymer and the fast diffusion rate of reactive polymers at the interface. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1396–1404, 2000     

Copolymerization of ethylene/carbon monoxide by a cationic hydridoaquopalladium complex

The cationic hydridoaquopalladium (II) complex, trans-[(PCy₃)₂Pd(H)(H₂O)]⁺BF^?₄, is an excellent catalyst for the ethylene/carbon monoxide alternating copolymerization in the presence of a bidentate phosphorus ligand and p-toluenesulphonic acid. © 1995 John Wiley & Sons, Inc.     

Polystyrene with dendritic branching by convergent living anionic polymerization. II. Approach using vinylbenzyl chloride

Vinylbenzyl chloride (VBC) has been used as a coupling agent in Convergent Living Anionic Polymerization to produce polymers with dendritic branching. The slow addition of a stoichiometric amount of VBC to living polystyrene chains allows the coupling to proceed through macromonomer formation followed by vinyl addition. Changing the reaction conditions produced two types of structures. Star‐shaped polymers with a hyperbranched core were made by the continuous slow addition of VBC alone, and chain‐extended hyperbranched structures with varied molecular weight between branch points were produced by the slow addition of VBC mixed with different amounts of styrene monomer. The extent of growth of the two different types of structures ranged from 2.4 to 2.6 generations for the case of VBC added alone, corresponding to an average of 5.3 to 6.1 arms attached to the hyperbranched core, and from 3.2 to 4.2 generations for polymers produced from the addition of VBC mixed with styrene. Relatively low polydispersities were obtained for all samples. The highly branched nature of the polymers was reflected in the low intrinsic viscosity relative to linear polystyrene and in the dependence of glass‐transition temperature on the molecular weight relative to the number of end groups. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4289–4298, 2000