Palladium on carbon‐catalyzed direct C—H arylation polycondensation of 3,4‐ethylenedioxythiophene with various dibromoarenes

We have demonstrated a direct arylation polycondensation of 3,4‐ethylenedioxythiophene with 2,7‐dibromo‐9,9‐dioctylfluorene using palladium on carbon (Pd/C) as a catalyst. Pd/C is a low‐cost solid‐supported palladium catalyst, giving one of the effective catalytic systems for direct arylation. The Pd/C‐catalyzed direct arylation polycondensation with acetic acid/potassium carbonate in N,N‐dimethylacetamide furnished a high molecular weight π‐conjugated alternating copolymer of EDOT‐fluorene (M_n = 89,300, M_w/M_n = 3.27) in high yield. The polycondensation of EDOT with various dibromoarenes was also achieved, giving EDOT‐carbazole, EDOT‐dialylamine, and EDOT‐bithiophene polymers. Optical and electrochemical properties of the polymers were also discussed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1183–1188     

SYNTHESIS OF CONDENSATION POLYMERS OF SALICYLIC ACID, FORMALDEHYDE AND ALKYL PRIMARY AMINES AND ITS APPLICATION AS A CATALYST FOR THE HYDROLYSIS OF p-NITROPHENYL ACETATE (PNPA) IN AQUEOUS SOLUTION

As a model of serine hydrolase, the condensation polymers of salicylic acid, formaldehyde and methyl amine, n-propyl amine, n-hexyl amine or n-lauryl amine were prepared by polycondensation catalyzed by sulfuric acid. It was confirmed by potentiometric titration and infrared spectrum that the polymers containing tertiary amino group possess the structure which resembles the internal salt of amino acid in weak basic and weak acidic solution:     

Vanadium(V) complexes containing tetradentate amine trihydroxy ligands as catalysts for copolymerization of cyclic olefins

A series of vanadium(V) complexes bearing tetradentate amine trihydroxy ligands [NOOO], which differ in the steric and electronic properties, have been synthesized and characterized. Single crystal X‐ray analysis showed that these complexes are five or six coordinated around the vanadium center in the solid state. Their coordination geometries are octahedral or trigonal bipyramidal. In the presence of Et₂AlCl, these complexes have been investigated as the efficient catalysts for ethylene polymerization and ethylene/norbornene copolymerization at elevated reaction temperature and produced the polymers with unimodal molecular weight distributions (MWDs), indicating the single site behaviors of these catalysts. Both the steric hindrance and electronic effect of the groups on the tetradentate ligands directly influenced catalytic activity and the molecular weights of the resultant (co)polymers. Other reaction parameters that influenced the polymerization behavior, such as reaction temperature, ethylene pressure, and comonomer concentration, are also examined in detail. Furthermore, high catalytic activities of up to 3.30 kg polymer/mmol_V·h were also observed when these complexes were applied to catalyze the copolymerization of ethylene and 5‐norbornene‐2‐methanol, producing the high‐molecular‐weight copolymers (M_w = 157–400 kg/mol) with unimodal MWDs (M_w/M_n = 2.5–3.0) and high polar comonomer incorporations (up to 12.3 mol %). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1122–1132, 2010     

Coordination Polymers based on the Neutral Ditopic Ligand (C6H4PO(OCH3)2)2 Involving some f‐Block Elements

An improved synthesis using microwave heating affords (C₆H₄PO(OCH₃)₂)₂ in excellent isolated yield (95 %). The ligand properties of this bisphosphonateester were explored towards hard metal centers M²⁺ (M = Ca, UO₂) and M³⁺ (M = La, Ce, Sm, Eu) resulting in coordination polymers, for which the reduction of ionic size of the central metal atom resulted in lower‐dimensional structural motifs as opposed to higher dimensional networks obtained for the larger ions. All coordination polymers were characterized by single‐crystal X‐ray diffraction, IR spectroscopy, and combustion analysis. The ligand was furthermore characterized with multinuclear NMR spectroscopy.     

Syndiospecific living polymerization of 4-methylstyrene with (trimethyl)pentamethylcyclopentadienyltitanium/tris(pentafluorophenyl)borane/trioctylaluminium catalytic system

The polymerization of 4-methylstyrene with the (trimethyl)pentamethylcyclopentadienyltitanium (Cp*TiMe₃)/tris(pentafluorophenyl)borane (B(C₆F₅)₃)/trioctylaluminium (AlOct₃) catalytic system at –20°C was carried out. The number-average molecular weight (M_n) of the polymers increased linearly with increasing monomer conversion. The propagating chain ends were successfully reacted with tert-butyl isocyanate, and the M_n of the polymer determined by ¹H NMR was in good agreement with the M_n determined by GPC measurement. It is concluded that this catalytic system promoted the syndiospecific living polymerization of 4-methylstyrene.     

Synthesis of low polydispersity polybutadiene and polyethylene stars by convergent living anionic polymerization

Star‐shaped polybutadiene stars were synthesized by a convergent coupling of polybutadienyllithium with 4‐(chlorodimethylsilyl)styrene (CDMSS). CDMSS was added slowly and continuously to the living anionic chains until a stoichiometric equivalent was reached. Gel permeation chromatography‐multi‐angle laser light scattering (GPC‐MALLS) was used to determine the molecular weights and molecular weight distribution of the polybutadiene polymers. The number of arms incorporated into the star depended on the molecular weight of the initial chains and the rate of addition of the CDMSS. Low molecular weight polybutadiene arms (M_n = 640 g/mol) resulted in polybutadiene star polymers with an average of 12.6 arms, while higher molecular weight polybutadiene arms (M_n = 16,000 g/mol) resulted in polybutadiene star polymers with an average of 5.3 arms. The polybutadiene star polymers exhibited high 1,4‐polybutadiene microstructure (88.3–93.1%), and narrow molecular weight distributions (M_w/M_n = 1.11–1.20). Polybutadiene stars were subsequently hydrogenated by two methods, heterogeneous catalysis (catalytic hydrogenation using Pd/CaCO₃) or reaction with p‐toluenesulfonhydrazide (TSH), to transform the polybutadiene stars into polyethylene stars. The hydrogenation of the polybutadiene stars was found to be close to quantitative by ¹H NMR and FTIR spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 828–836, 2006     

Facile and Versatile Synthesis of End-Functionalized Poly(phenylacetylene)s: A Multicomponent Catalytic System for Well-Controlled Living Polymerization of Phenylacetylenes

A rhodium-based multicomponent catalytic system for well-controlled living polymerization of phenylacetylenes has been developed. The catalytic system is composed of readily available and bench-stable [Rh(nbd)Cl]₂, aryl boronic acid derivatives, diphenylacetylene, 50 % aqueous KOH, and PPh₃. This system offers a method for the facile and versatile synthesis of various end-functionalized cis-stereoregular poly(phenylacetylene)s because components from aryl boronic acids and diphenylacetylene were introduced to the initiating end of the polymers. The polymerization reaction shows a typical living nature with a high initiation efficiency, and the molecular weight of the resulting poly(phenylacetylene)s can be readily controlled with very narrow molecular-weight distributions (M_w/M_n=1.02–1.09). The experimental results suggest that the present catalytic system has a higher polymerization activity than the polymerization activities of other rhodium-based catalytic systems previously reported.     

Synthesis of sugar‐based macromolecules via sono‐ATRP in miniemulsion

Ultrasound‐mediated atom transfer radical polymerization (sono‐ATRP) in miniemulsion media is used for the first time for the preparation of complex macromolecular architectures by a facile two‐step synthetic route. Initially, esterification reaction of sucrose or lactulose with α‐bromoisobutyryl bromide (BriBBr) is conducted to receive multifunctional ATRP macroinitiators with 8 initiation sites, followed by polymerization of n‐butyl acrylate (BA) forming arms of the star‐like polymers. The brominated lactulose‐based molecule was examined as an ATRP initiator by determining the activation rate constant (k_a) of the catalytic process in the presence of a copper(II) bromide/tris(2‐pyridylmethyl)amine (Cu^IIBr₂/TPMA) catalyst in both organic solvent and for the first time in miniemulsion media, resulting in k_a = (1.03 ± 0.01) × 10⁴ M^?1 s^?1 and k_a = (1.16 ± 0.56) × 10³ M^?1 s^?1, respectively. Star‐like macromolecules with a sucrose or lactulose core and poly(n‐butyl acrylate) (PBA) arms were successfully received using different catalyst concentration. Linear kinetics and a well‐defined structure of synthesized polymers reflected by narrow molecular weight distribution (M_w/M_n = 1.46) indicated 105 ppm wt of catalyst loading as concentration to maintain controlled manner of polymerization process. ¹H NMR analysis confirms the formation of new sugar‐inspired star‐shaped polymers.     

Facile and Versatile Synthesis of End‐Functionalized Poly(phenylacetylene)s: A Multicomponent Catalytic System for Well‐Controlled Living Polymerization of Phenylacetylenes

A rhodium‐based multicomponent catalytic system for well‐controlled living polymerization of phenylacetylenes has been developed. The catalytic system is composed of readily available and bench‐stable [Rh(nbd)Cl]₂, aryl boronic acid derivatives, diphenylacetylene, 50 % aqueous KOH, and PPh₃. This system offers a method for the facile and versatile synthesis of various end‐functionalized cis‐stereoregular poly(phenylacetylene)s because components from aryl boronic acids and diphenylacetylene were introduced to the initiating end of the polymers. The polymerization reaction shows a typical living nature with a high initiation efficiency, and the molecular weight of the resulting poly(phenylacetylene)s can be readily controlled with very narrow molecular‐weight distributions (M_w/M_n=1.02–1.09). The experimental results suggest that the present catalytic system has a higher polymerization activity than the polymerization activities of other rhodium‐based catalytic systems previously reported.     

Influence of molecular weight on the short‐channel effect in polymer‐based field‐effect transistors

In this study, we demonstrate how the intrinsic properties of a polymer can influence the electrical characteristics of organic field‐effect transistors (OFETs). OFETs fabricated with three batches of poly[2‐methoxy,5‐(3′,7′‐dimethyl‐octyloxy)]‐p‐phenylene vinylene (MDMO‐PPV) were investigated. The properties of the polymers were initially investigated using Fourier transform infrared spectroscopy (FTIR), impedance spectroscopy (IS), gel permeation chromotography (GPC), and cyclic voltammetry (CV), respectively. The structure and purity of the polymer batches were found to be very comparable, but the molecular weight (M_n and M_w) and polydispersity (PDI = M_w/M_n), varied between the samples and the HOMO and LUMO levels of the polymers were found to depend on the molecular weight properties. OFETs were then fabricated with the polymers and electrically characterized. It was observed that the channel current and the field‐effect mobility increase with increasing polymer molecular weight. The output characteristics of the transistors, on the other hand, were found to depend on the PDI of the polymer. Saturation of the channel current occurs at higher source–drain voltages and short‐channel behavior was observed to start at longer channel lengths for polymers with a higher PDI. This behavior is observed to be thickness dependent, and the short‐channel behavior was more pronounced for thicker MDMO‐PPV films. These results are explained in terms of influences of chain packing and ordering and high bulk currents on the FET output and transistor parameters. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 117–124, 2012     

Synthesis and polymerization of N‐(4‐tetrahydropyranyl‐oxyphenyl)maleimide

N‐(4‐Tetrahydropyranyl‐oxy‐phenyl)maleimide (THPMI) was prepared and polymerized by radical or anionic initiators. THPMI could be polymerized by 2,2′‐azobis(isobutyronitrile) (AIBN) and potassium tert‐butoxide. Radical polymers (poly(THPMI)r) were obtained in 15–50% yields for AIBN in THF at 65°C after 2–5 h. The yield of anionic polymers (poly(THPMI)a) obtained from potassium tert‐butoxide in THF at 0°C after 20 h was 91%. The molecular weights of poly(THPMI)r and poly(THPMI)a were M_n = 2750–3300 (M_w/M_n = 1.2–3.3) and M_n = 11300 (M_w/M_n = 6.0), respectively. The difference in molecular weights of the polymers was due to the differences in the termination mechanism of polymerization and the solubility of these polymers in THF. The thermal decomposition temperatures were 205 and 365°C. The first decomposition step was based on elimination of the tetrahydropyranyl group from the poly(THPMI). Positive image patterns were obtained by chemical amplification of positive photoresist composed of poly(THPMI) and 4‐morpholinophenyl diazonium trifluoromethanesulfonate used as an acid generator. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 341–347, 1999     

Extension of the chain‐end,free‐volume theory for predicting glass temperature as a function of conversion in hyperbranched polymers obtained through one‐pot approaches

Compared with linear polymers, more factors may affect the glass‐transition temperature (T_g) of a hyperbranched structure, for instance, the contents of end groups, the chemical properties of end groups, branching junctions, and the compactness of a hyperbranched structure. T_g's decrease with increasing content of end‐group free volumes, whereas they increase with increasing polarity of end groups, junction density, or compactness of a hyperbranched structure. However, end‐group free volumes are often a prevailing factor according to the literature. In this work, chain‐end, free‐volume theory was extended for predicting the relations of T_g to conversion (X) and molecular weight (M) in hyperbranched polymers obtained through one‐pot approaches of either polycondensation or self‐condensing vinyl polymerization. The theoretical relations of polymerization degrees to monomer conversions in developing processes of hyperbranched structures reported in the literature were applied in the extended model, and some interesting results were obtained. T_g's of hyperbranched polymers showed a nonlinear relation to reciprocal molecular weight, which differed from the linear relation observed in linear polymers. T_g values decreased with increasing molecular weight in the low‐molecular‐weight range; however, they increased with increasing molecular weight in the high‐molecular‐weight range. T_g values decreased with increasing log M and then turned to a constant value in the high‐molecular‐weight range. The plot of T_g versus 1/M or log M for hyperbranched polymers may exhibit intersecting straight‐line behaviors. The intersection or transition does not result from entanglements that account for such intersections in linear polymers but from a nonlinear feature in hyperbranched polymers according to chain‐end, free‐volume theory. However, the conclusions obtained in this work cannot be extended to dendrimers because after the third generation, the end‐group extents of a dendrimer decrease with molecular weight. Thus, it is very possible for a dendrimer that T_g increases with 1/M before the third generation; however, it decreases with 1/M after the third generation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1235–1242, 2004     

Mesomorphic and luminescent properties of side chain nematic liquid-crystalline polymers containing Ir(III)

Iridium-containing liquid-crystalline polymers were obtained by graft copolymerisation using poly(methylhydrogeno)siloxane, 1-methyl-4-(4-(4-vinylcyclohexyl)cyclohexyl)benzene (M₁) and an iridium complexes monomer (Ir-M₂). The series of polymers contained different molecular fractions of Ir-M₂ from 0% to 1.2%. All of these polymers showed mesomorphic behaviours. The introduction of small amount of iridium ions endowed liquid-crystalline polymers with luminescent properties. The chemical structures were characterised by IR and ¹H NMR. The mesomorphic properties and phase behaviour were investigated by differential scanning calorimetry, thermal gravimetric analysis, polarising optical microscopy and X-ray diffraction. With an increase of iridium complexes units in the polymers, the glass transition temperature (T_g) did not change significantly; the isotropic temperature (T_i) decreased. All polymers showed typical nematic marble textures, which was confirmed by X-ray diffraction. The temperatures at which 5% weight loss occurred (T_d) were greater than 300°C for the polymers. The introduction of iridium complexes units did not change the liquid-crystalline state of polymer systems. With Ir³⁺ ion contents ranging between 0.6 and 2.4 mol%, luminescent intensity of polymers gradually increased.     

A novel synthesis of polyethers with pendant hydroxyl groups by polyaddition of bis(oxetane)s with bis(phenol)s

The polyaddition of 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene (BEOB) with 3,3′,5,5′-tetrachlorobisphenol A (TCBPA) was examined with or without catalysts. High molecular weight polymer (polymers 1) (M_n = 13,600) with pendant primary hydroxyl groups was obtained in a 99% yield without any gel products when the reaction was performed with 5 mol % of tetraphenylphosphonium bromide as a catalyst in NMP at 160°C for 96 h. However, when the reaction was carried out without a catalyst under the same conditions, a low molecular weight polymer (M_n = 3200) was obtained in a 51% yield. The structure of the resulting polymer was confirmed by IR, ¹H-NMR, and ¹³C-NMR spectra. In this reaction system, it was also found that tetraphenylphosphonium iodide and crown ether complexes such as 18-crown-6 (18-C-6)/KBr and 18-C-6/KI have high catalytic activity. Polyadditions of 1,4-bis[(3-methyl-3-oxetanyl)methoxymethyl]benzene with TCBPA and BEOB with 3,3′,5,5′-tetrabromobisphenol-S were also examined, and corresponding polymers (polymers 2 and 3) were obtained in good yields. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2781–2790, 1999     

Catalytic properties of spinel-type complex oxides in oxidation reactions

The catalytic activity of M^IM^II ₂O₃ spinel-type complex oxides (M^I = Cu, Ni, Mn, Zn, Mg, Co, M^II = Co, Cr, Al) in the oxidation of CO and ethylbenzene has been investigated. The Co-containing catalysts were more active than the Cr- and Al-containing catalysts. The nature of the cation influenced the catalytic activity. Higher activities were observed for the catalysts containing two transition elements. A correlation between the catalytic and adsorption properties was established.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1730–1732, October, 1994.     

Amino acid‐based bioanalogous polymers. Synthesis,and study of regular poly(ester amide)s based on bis(α‐amino acid) α,ω‐alkylene diesters,and aliphatic dicarboxylic acids

The purpose of this research was to synthesize new regular poly(ester amide)s (PEAs) consisting of nontoxic building blocks like hydrophobic α‐amino acids, α,ω‐diols, and aliphatic dicarboxylic acids, and to examine the effects of the structure of these building block components on some physico‐chemical and biochemical properties of the polymers. PEAs were prepared by solution polycondensation of di‐p‐toluenesulfonic acid salts of bis‐(α‐amino acid) α,ω‐alkylene diesters and di‐p‐nitrophenyl esters of diacids. Optimal conditions of this reaction have been studied. High molecular weight PEAs (M_w = 24,000–167,000) with narrow polydispersity (M_w/M_n = 1.20–1.81) were prepared under the optimal reaction conditions and exhibited excellent film‐forming properties. PEAs obtained are mostly amorphous materials with T_g from 11 to 59°C. α‐Chymotrypsin catalyzed in vitro hydrolysis of these new PEA substrates was studied to assess the effect of the building blocks of these new polymers on their biodegradation properties. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 391–407, 1999     

Polymerization of ethylene in the presence of novel single-site titanium phenolate catalytic systems

The polymerization of ethylene has been studied in the presence of novel catalytic systems based on various sterically hindered phenol precursor complexes of titanium containing grafted phenoxyammonium ligands. The presence of the grafted ammonium salt in the phenolate ligand leads to an increase in the activity of the catalyst and originates single-site catalytic systems. As evidenced by IR and ¹³C NMR studies and DSC measurements, the resulting polymers are linear, possess a narrow molecular-mass distribution (M _w/M _n = 2–4), and are characterized by a wide range of thermal properties.     

New side chain ferroelectric liquid crystalline polymers based on (2S, 3S)-2-chloro-3-methylpentanoic acid: synthesis and phase behaviour

The synthesis of four new chiral mesogenic monomers (M₁–M₄) and side chain ferroelectric liquid crystalline polymers containing (2S, 3S)-2-chloro-3-methylpentanoate is described. The chemical structures and phase behaviour of the monomers and polymers obtained in this study were characterised by Fourier transform infrared, proton nuclear magnetic resonance, polarising optical microscopy, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The selective reflection of light was investigated with ultraviolet/visible (UV/Vis). Their structure–mesomorphism relationships were discussed. M₁ and P₁ all showed a chiral smectic C (SmC*) phase. M₂ and M₃ revealed a SmC* phase and cholesteric phase, while their corresponding polymers P₂ and P₃ revealed a SmC* phase and smectic A (SmA) phase. M₄ only exhibited a cholesteric phase, whereas the corresponding polymers P₄ showed a SmA phase. Moreover, the selective reflection of light shifted to the long-wavelength region at the SmC* phase range and to the short-wavelength region at the cholesteric range with increasing temperature, respectively. The results seemed to demonstrate that the tendency towards melting temperature (T_m), glass transition temperature (T_g), isotropic temperature (T_i) and mesophase range for the monomers and polymers increased by increasing the mesogenic core rigidity or the number of phenyl ring. The polymerisation effect could lead to higher liquid crystalline to isotropic phase transition temperature, wider mesophase range and more ordered smectic phase formed. In addition, all the obtained polymers had a very good thermal stability and the corresponding T_d increased by increasing the number of phenyl ring.     

Controlling grafting density and side chain length in poly(n‐butyl acrylate) by ATRP copolymerization of macromonomers

Atom transfer radical polymerization (ATRP) was used for the preparation and subsequent copolymerization of two acryloyl‐terminated poly(n‐butyl acrylate) macromonomers with different degrees of polymerization (DP_nBA = 25 and 42). Homopolymerization of the higher molecular weight macromonomer ( MM1 ; PnBA₄₂‐A, M_n = 5600, DP_MM = 42, M_w/M_n = 1.18) resulted in preparation of a densely grafted polymer with a narrow molecular weight distribution (M_w/M_n = 1.14), but with the limited degree of polymerization DP = 12. The ultimate degree of homopolymerization for the lower molecular weight macromonomer ( MM2 ; PnBA₂₅‐A, M_n = 3400, DP_MM = 25, M_w/M_n = 1.20) was higher, and DP increased from 12 to 22. The limited DP could be because of progressively increasing steric congestion for macromonomers in approaching the growing chain ends of densely grafted polymers. When MMs were copolymerized with nBA, the reactivity of MM was nearly the same as that of nBA monomer irrespective of the differences in the degree of polymerization of the MMs and the initial molar ratio of nBA to MM. Well‐defined graft polymers with different lengths of backbone and side chains, and different graft density were successfully prepared by “grafting through” ATRP. Tadpole‐shaped and dumbbell‐shaped graft polymers were also synthesized by ATRP. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5454–5467, 2006     

(Diisopropylamido) bis (methylcyclopentadienyl) lanthanides as single-component initiators for polymerization of methyl methacrylate

It was first found that (diisopropylamido)bis(methylcyclopentadienyl)lanthanides (MeC₅H₄)₂LnN(i-Pr)₂(THF) (Ln = Yb ( 1 ), Er ( 2 ), Y ( 3 )) exhibit extremely high catalytic activity in the polymerization of methyl methacrylate. The reactions can be carried out over a quite broad range of polymerization temperatures from -78 to 40°C. The catalytic activity of the complexes increases with an increase of ionic radii of the metal elements, i.e. Y > Er > Yb. The results of GPC (gel permeation chromatography) indicate that the number-average molecular weights (M_n) of polymers obtained exceed 100 × 10³ and the molecular weight distribution (M_w/M_n) becomes broad with the increase of temperature. Furthermore highly syndiotactic PMMA (87.7%) can be obtained by lowering the reaction temperature to −78°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1593–1597, 1998