Depolymerization kinetics of di(4‐tert‐butyl cyclohexyl) itaconate and Mark‐Houwink‐Kuhn‐Sakurada parameters of di(4‐tert‐butyl cyclohexyl) itaconate and di‐n‐butyl itaconate

Multipulse pulsed laser polymerization coupled with size exclusion chromatography (MP‐PLP‐SEC) has been employed to study the depropagation kinetics of the sterically demanding 1,1‐disubstituted monomer di(4‐tert‐butylcyclohexyl) itaconate (DBCHI). The effective rate coefficient of propagation, k, was determined for a solution of monomer in anisole at concentrations, c, 0.72 and 0.88 mol L^?1 in the temperature range 0 ≤ T ≤ 70 °C. The resulting Arrhenius plot (i.e., ln k vs. 1/RT) displayed a subtle curvature in the higher temperature regime and was analyzed in the linear part to yield the activation parameters of the forward reaction. In the temperature region where no depropagation was observed (0 ≤ T ≤ 50 °C), the following Arrhenius parameters for k_p were obtained (DBCHI, E_p = 35.5 ± 1.2 kJ mol^?1, ln A_p = 14.8 ± 0.5 L mol^?1 s^?1). In addition, the k data was analyzed in the depropagatation regime for DBCHI, resulting in estimates for the associated entropy (?ΔS = 150 J mol^?1 K^?1) of polymerization. With decreasing monomer concentration and increasing temperature, it is increasingly more difficult to obtain well structured molecular weight distributions. The Mark Houwink Kuhn Sakurada (MHKS) parameters for di‐n‐butyl itaconate (DBI) and DBCHI were determined using a triple detection GPC system incorporating online viscometry and multi‐angle laser light scattering in THF at 40 °C. The MHKS for poly‐DBI and poly‐DBCHI in the molecular weight range 35–256 kDa and 36.5–250 kDa, respectively, were determined to be K_DBI = 24.9 (10³ mL g^?1), α_DBI = 0.58, K_DBCHI = 12.8 (10³ mL g^?1), and α_DBCHI = 0.63. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1931–1943, 2007     

Solvay type VCl3 isospecific catalysts

Solvay type S –VCl₃ catalyst has 7% of catalytically active vanadium sites ([C^*]) with k_p (rate constant of propagation) = 31 (M s)^?1 for ethylene polymerization. Addition of a comonomer, propylene of 4-methylpentene-1 (4-MP) significantly raised the ethylene polymerization activity. S –VCI₃ catalyst has very small amounts of catalytically active vanadium for propylene polymerizations: [C] = 0.19% with k_p,i = 857 (M s)^?1 and [C] = 0.45% with k_p,a = 23 (M s)^?1 for isospecific and nonspecific sites, respectively. Addition of a conomer, ethylene or 4-MP. lowered the propylene polymerization activity. S –VCI₃ is more easily reduced to the divalent ion by AIR₃ than S –TiCl₃. Methyl-p-toluate moderates the reducting power of AIR₃; it increase the productivity and stereoselectivity of the S –YiCl₃ catalyst, VCI₃ supported on MgCl₂ (CW–V catalyst) has enhanced rate constant of propylene polymerization but has the opposite effects on the S –TiCl₃ Catalyst. VCI₃ supported on MgCl₂ (CW–V catalyst) has enhances rate constant of propylene polymerization but only a minute fraction of the supported vanadiums are catalytically active: [C] = 0.019% and k_p,i = 1580 (Ms)^?1, [C] = 0.057% and k_p,i = 58 (M s)^?1. This is compared with far greater number of catalytically active titanium sites in the TiCl₃ supported on MgCl₂ catalyst: [C] = 6% and k_p,i = 200 (M s)^?1, [C] = 6% and k_p,a = 16(M s)^?1. Therefore, both the S –VCI₃ and CW–V catalysts are highly stereoselective but low in efficiency with respect to the utilization of the vanadium ion in the catalysis.     

Magnesium chloride-supported high-mileage catalysts for olefin polymerization XI. Determinations of poly(decene-1) molecular weight chain dimension and thermal transitions

Decene-1 was polymerized with the CW catalyst and fractionated by precipitation technique. Light-scattering and viscometric measurements on these fractions established the relationship [η] = 5.19 × 10^?3 M . The unperturbed mean square end-to-end distance is (〈R〉/M)^1/2 = (6.17 ± 0.34) × 10^?9. Light-scattering data is consistent with a relatively stiff molecule with length of L = 1.75 × 10^?5 cm for poly(decene-1) with MW = 397,000. Its mean square radius of gyration 〈R〉 is 2.79 × 10^?11 cm.² The ratio of L²/〈R〉 = 11 is close to the theoretical ratio of 12 for this kind of macromolecule.     

Synthesis and clustering of supramolecular “graft” polymers

The synthesis and melt rheology of supramolecular poly(isobutylene) polymers bearing statistically distributed hydrogen‐bonding moieties is reported, aiming at understanding the formation of the underlying supramolecular networks for self‐healing polymers. Two different hydrogen bonds were incorporated into a poly(isobutylene) (PIB) copolymer, one based on a (weak) pyridinium/pyridine interaction, the other based on a (stronger) 2,6‐diaminotriazine/thymine interaction. A direct copolymerization based on living cationic polymerization of isobutene and the comonomers 1 , 2 , and 4 in amounts of 1 mol % lead to the copolymers PIB‐ 1 , PIB‐ 2 , and PIB‐ 4 with a content of ～1 mol % of comonomer and molecular weights ranging from ～2000 to 19,000 g mol^?1 (M_w/M_n ～ 1.2–1.5). Subsequent azide/alkyne “click” chemistry enabled the attachment of 2,6‐diaminotriazine‐ and thymine‐moieties to yield the copolymers PIB‐ 5 , PIB‐ 6 , and PIB‐ 7 . Proof of the statistical incorporation of ～1 mol % of hydrogen‐bonding moieties was achieved by ¹H NMR spectroscopy and matrix‐assisted laser desorption ionization measurements. The true presence of a supramolecular network in PIB‐ 1 (pyridinium/pyridine interaction) as well as with 1/1 blends of PIBs interacting via the 2,6‐diaminotriazine/thymine interaction (PIB‐ 5 /PIB‐ 6 ) was proven via the increasing plateau modulus with increasing molecular weights (5.5k, 9.9k, 12.4k, 16k, and 19k). Dynamics of the hydrogen bonds in the melt state was investigated by determining the effective cluster lifetime ( τ ) observing a clear difference in the (weaker) pyridinium/pyridine interaction ( τ ～ 1 s) to the 2,6‐ (stronger) diamintriazine/thymine interaction ( τ ～ 100 s). The so‐generated materials will be useful as a basis for self‐healing polymers, as dynamics plays a major role in such polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Primary radical termination and unimolecular termination in the heterogeneous polymerization of acrylamide initiated by a fluorinated azo‐derivative initiator: A kinetic study

Acrylamide was polymerized in acetonitrile at 82 °C with a perfluorinated azo‐derivative initiator. The polymerization proceeded heterogeneously. Varying amounts of initiator and monomer were used. The activation energy was deduced from three experiments carried out at 59, 71, and 82 °C. The following kinetic law, deviating a great deal from the classical law, was obtained: R ∼ [I₂][M](0.05% < [I₂]_o/[M]_o < 1.00%) and R ∼ [I₂][M](1% < [I₂]_o/[M]_o < 7%). These results can be interpreted in light of the contribution of primary radical termination and the emergence of occlusion. The development of a new kinetic relationship allowed us to confirm the existence of both of these termination reactions. The calculation of the k_prt /k_i · k_p ratio was also achieved. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1834–1843, 2000     

Non‐transition metal‐catalyzed living radical polymerization of vinyl chloride initiated with iodoform in water at 25 °C

Non‐transition metal‐catalyzed living radical polymerization (LRP) of vinyl chloride (VC) in water at 25–35 °C is reported. This polymerization is initiated with iodoform and catalyzed by Na₂S₂O₄. In water, S₂O dissociates into SO that mediates the initiation and reactivation steps via a single electron transfer (SET) mechanism. The exchange between dormant and active propagating species also includes the degenerative chain transfer to dormant species (DT). In addition, the SO₂ released from SO during the SET process can add reversibly to poly(vinyl chloride) (PVC) radicals and provide additional transient dormant ～SO radicals. This novel LRP proceeds mostly by a combination of competitive SET and DT mechanisms and, therefore, it is called SET‐DTLRP. Telechelic PVC with a number‐average molecular weight (M_n) = 2,000–55,000, containing two active ～CH₂? CHClI chain ends and a higher syndiotacticity than the commercial PVC were obtained by SET‐DTLRP. This PVC is free of structural defects and exhibits a higher thermal stability than commercial PVC. SET‐DTLRP of VC is carried out under reaction conditions related to those used for its commercial free‐radical polymerization. Consequently, SET‐DTLRP is of technological interest both as an alternative commercial method for the production of PVC with superior properties as well as for the synthesis of new PVC‐based architectures. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6267–6282, 2004     

Lactide polymerization activity of alkoxide,phenoxide, and amide derivatives of yttrium(III) arylamidinates

In quest of new, single‐site catalysts for cyclic ester polymerizations, a series of mononuclear yttrium(III) complexes of N,N′‐bis(trimethylsilyl)benzamidinate ([L^TMS]⁻) and hindered N,N′‐bis‐(2,6‐dialkylaryl)toluamidinates ([L^Et]⁻, aryl = Et₂C₆H₃, and [L^iPr]⁻, aryl = ⁱPr₂C₆H₃) were synthesized and characterized by X‐ray diffraction: LY(μ‐Cl)₂Li(TMEDA) ( 1 ), LY(OC₆H₂^tBu₂Me) ( 2 ), LY(OC₆H₃Me₂)₂Li(THF)₄ ( 3 ), LY(μ‐O^tBu)₂Li(THF) ( 4 ), L^iPrY[N(SiMe₂H)₂]₂(THF) ( 5 ), LY(THF)(Cl)(μ‐Cl)Li(THF)₃ ( 6 ), and LY[N(SiMe₂H)₂] ( 7 ). Coordination numbers ranging from five to seven were observed, and they appeared to be controlled by the steric bulk of the supporting amidinate and alkoxide, phenoxide, or amide coligands. Complexes 2 – 5 and 7 are active catalysts for the polymerization of D,L ‐lactide (e.g., with 2 and added benzyl alcohol, 1000 equiv of D,L ‐lactide were polymerized at room temperature in less than 1 h, with polydispersities less than 1.5). The neutral complexes 2 , 5 , and 7 were more effective than the anionic complexes 3 and 4 . In addition, the presence of the more hindered amidinate ligands [L^Et]⁻ and [L^iPr]⁻ on yttrium‐amides slowed the polymerizations ( 7 < 5 < Y[N(SiMe₂H)₂]₃). © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 284–293, 2001     

A chiral polymer‐based turn‐on fluorescent sensor for specific recognition of hydrogen sulfate

A new kind of polymeric chemosensor containing chiral naphthaldimine moiety in the side chain was synthesized by the reversible addition‐fragmentation chain transfer polymerization of N‐{[2‐(4‐vinylbenzyloxy)‐1‐naphthyl]‐methylene}‐(S)‐2‐phenylglycinol (VNP). The resulting polymers (PVNP) showed high selectivity for hydrogen sulfate relative to other anions including F^?, Cl^?, Br^?, H₂PO, CH₃CO, and NO in tetrahydrofuran (THF) solution as judged from UV?vis, fluorescence, and circular dichroism spectrophotometric titrations. Compared with its monomer, the polymer has proven to be more attractive for detection of HSO in terms of sensitivity and reproducibility. Upon addition of the anion it gives remarkable spectral responses concomitant with detectable color change from colorless to pale yellow. Furthermore, the HSO‐induced CD or fluorescence signal can be totally reversed with addition of base and eventually recovered the initial state, leading to a reproducible molecular switch with two distinguished “on” and “off” states. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Poly(ionic liquid)s as new materials for CO2 absorption

A series of imidazolium‐based ionic liquid monomers and their corresponding polymers (poly(ionic liquid)s) were synthesized, and their CO₂ sorption was studied. The poly(ionic liquid)s had enhanced CO₂ sorption capacities and fast sorption/desorption rates compared with room temperature ionic liquids. The effects of the chemical structures, including the types of anion, cation, and backbone of the poly(ionic liquid)s on their CO₂ sorption have been discussed. In contrast to room temperature ionic liquids, the polymer with PF anions had the highest CO₂‐sorption capacity, while those with BF or Tf₂N^? anions had the same capacities. The CO₂ sorption and desorption of the polymers were fast and reversible, and the sorption was selective over H₂, N_2, and O₂. The measured Henry's constants of P[VBBI][BF₄] and P[MABI][BF₄] were 26.0 bar and 37.7 bar, which were lower than those of similar room temperature ionic liquids. The preliminary study of the mechanism indicated that the CO₂ sorption of the polymer particles was more absorption (the bulk) but less adsorption (the surface). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5477–5489, 2005     

Chiral recognition in molecular and macromolecular pairs of (S)‐ and (R)‐1‐cyano‐2‐methylpropyl‐4′‐ {[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐4‐ carboxylate enantiomers

(S)‐1‐Cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐ 4‐carboxylate [ (S)‐11 ] and (R)‐1‐cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐4‐carboxylate [( R)‐11 ] enantiomers, both greater than 99% enantiomeric excess, and their corresponding homopolymers, poly[ (S)‐11 ] and poly[ (R)‐11 ], with well‐defined molecular weights and narrow molecular weight distributions were synthesized and characterized. The mesomorphic behaviors of (S)‐11 and poly[ (S)‐11 ] are identical to those of (R)‐11 and poly[ (R)‐11 ], respectively. Both (S)‐11 and (R)‐11 exhibit enantiotropic S_A, S, and S_X (unidentified smectic) phases. The corresponding homopolymers exhibit S_A and S phases. The homopolymers with a degree of polymerization (DP) less than 6 also show a crystalline phase, whereas those with a DP greater than 10 exhibit a second S_X phase. Phase diagrams were investigated for four different pairs of enantiomers, (S)‐11 /( R)‐11 , (S)‐11 /poly[ (R)‐11 ], and poly[ (S)‐11 ]/poly[ (R)‐11 ], with similar and dissimilar molecular weights. In all cases, the structural units derived from the enantiomeric components are miscible and, therefore, isomorphic in the S_A and S phases over the entire range of enantiomeric composition. Chiral molecular recognition was observed in the S_A and S_X phases of the monomers but not in the S_A phase of the polymers. In addition, a very unusual chiral molecular recognition effect was detected in the S phase of the monomers below their crystallization temperature and in the S phase of the polymers below their glass‐transition temperature. In the S phase of the monomers above the melting temperature and of the polymers above the glass‐transition temperature, nonideal solution behavior was observed. However, in the S_A phase the monomer–polymer and polymer–polymer mixtures behave as an ideal solution. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3631–3655, 2000     

Anthracene‐ and thiophene‐containing MEH‐PPE‐PPVs: Synthesis and study of the effect of the aromatic ring position on the photophysical and electrochemical properties

This contribution reports on the synthesis and characterization of thiophene‐ ( P1 , P2 , and P3 ) and anthracene‐ ( P4 and P5) containing PPE‐PPV copolymers. The thermostable, soluble and film‐forming polymers were fully characterized by NMR, IR and ELEM . ANAL .; they exhibit high molar masses with polydispersity indices below 2.5. The position of the thiophene in the polymeric backbone has insignificant influence on the spectroscopic properties of the polymers. In contrast, the anthracene‐containing polymers reveal position dependent optical properties. A constant bathochromic shift of 50 nm was observed going from P4 , where anthracene is surrounded by two double bonds, to P5 , where anthracene is at the bridge between a triple bond and a double bond, as well as from P5 to P6 where anthracene is surrounded by two triple bonds. This correlates to the decrease of the observed anthracene band around 255 nm going from P4 through P5 to P6 , amounting to the degree of contribution of the anthracene unit to the main chain conjugation. The phenomenon known as CN‐PPV effect was observed in the case of P4 [Φ_f (solution) = 3%, Φ_f (solid) = 13%]. Electrochemical studies carried out under absolute inert conditions revealed lower electrochemical band gap energies, E , than E . © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2243–2261, 2009     

Synthesis and polymerization of racemic and optically active substituted ß-propiolactones. V. α-methyl ß-propiolactone

R(+) and S(?) enantiomers of α-methyl β-propiolactone (MPL) have been synthesized from the corresponding α-methyl β-hydroxymethylpropionates and racemic MPL from methyl methacrylate. The optical purity and absolute configuration of these lactones were determined using ¹H-NMR spectroscopy after complexation with a chiral compound: 2,2,2-trifluoro-1-(9-anthryl)-ethanol. Optical purities of 100% were obtained for both the S(?) ([α₀] = ?10.4°, c = 1.3 g/dL in CHCl₃) and the R(+) ([α₀] = +10.5°, c = 1.0 g/dL in CHCl₃) enantiomers. The corresponding racemic and optically active polylactones [poly(MPL)] were prepared by anionic polymerization, in bulk and in solution, as well as poly(MPL)s of intermediate optical purities. The polymers thus obtained are optically active ([α₀] = 16.2° in CHCl₃ for the optically pure polymer, S configuration) and exhibit significant differences. For example, the racemic poly(MPL) is soluble in several organic solvents such as tetrahydrofuran, benzene, CCl₄, CH₂Cl₂, hexafluoroisopropanol, and CHCl₃, whereas the optically active poly(MPL)s are soluble in CHCl₃ and hexafluoroisopropanol only. Moreover, racemic poly(MPL) is amorphous whereas optically active poly(MPL)s are semicrystalline for optical purities larger than 51%. Melting temperatures and enthalpies of fusion of the semicrystalline polylactones vary with optical purity whereas glass transition temperatures remain invariant for all polymers, at about ?28°C. The poly(MPL) of highest optical purity exhibits a melting temperature of 95°C and an enthalpy of fusion of 61 J/g.     

Mass spectrometric evidence for collisionally induced removal of H2 from monoanions of 10B nido‐carborane derivatives investigated by electrospray ionization quadrupole linear ion trap and Fourier transform ion cyclotron resonance mass spectrometry

Some newly synthesized ¹⁰B nido‐carborane derivatives, i.e., 7,8‐dicarba‐nido‐undecaborane monoanions ([7‐Me‐8‐R‐C₂B₉H₁₀]^‐K⁺, R = H, butyl, hexyl, octyl and decyl), have been fully characterised and examined by electrospray ionization and Fourier transform ion cyclotron resonance mass spectrometry with liquid chromatographic separation (LC/ESI‐FTICR‐MS). These boron‐containing compounds exhibit abundant molecular ions ([M]^?) at m/z 140.22631 [CB₉H₁₄]^?, m/z 196.28883 [CB₉H₂₂]^?, m/z 224.32032 [CB₉H₂₆]^?, m/z 252.35133 [CB₉H₃₀]^? and m/z 280.38354 [CB₉H₃₄]^? at the normal tube lens voltage setting of ?90 V, which was an instrumental parameter value selected in the tuning operation. Additional [M–nH₂]^? (n = 1?4) ions were observed in the mass spectra when higher tube lens voltages were applied, i.e., ?140 V. High‐resolution FTICR‐MS data revealed the accurate masses of fragment ions, bearing either an even or an odd number of electrons. Collision‐induced dissociation of the [M–nH₂]^? ions (n = 0–4) in the quadrupole linear ion trap (LTQ) analyzer confirmed the loss of hydrogen molecules from the molecular ions. It is suggested that the loss of H₂ molecules from the alkyl chain is a consequence of the stabilization effect of the nido‐carborane charged polyhedral skeleton. Copyright © 2009 John Wiley & Sons, Ltd.     

Anionic polymerization of N-substituted maleimide. V. A study on the kinetic features of anionic polymerization of N-phenylmaleimide

The kinetic feature of the anionic polymerization of N-PMI was investigated in THF. The polymerization system initiated with lithium tert-butoxide was revealed to be so-called “slow-initiation” system. The rate constant of the initiation reaction, k_i, was obtained to be 4.2 × 10^?3 (L mol^?1 s^?1) at ?72°C. The apparent rate constants of the propagation reaction, k, at ?72°C were individually obtained from each slope of the first-order plots in the later stages of the polymerizations for four different initiator concentrations. Each k is fairly close to that of initiation rate around 10^?3. The propagation reaction was concluded to be dominated by ion-pair mechanism from the analysis of the kinetic data and the results of the addition effects of crown ether and common salt.     

Kinetics and mechanism of the cationic polymerization of trioxane. I. Crystallization during polymerization

Cationic polymerizations of trioxane in 1,2‐ethylene dichloride and benzene were heterogeneous and reversible. Phase separation accompanying with crystallization occurred during the polymerization. Three morphological changes were found in the course of the polymerization as were investigated by dilatometry and precipitation method. Based on the findings of morphological changes and three reversible processes for the polymerization, a rate equation was proposed to describe the polymerization. The proposed rate equation was fairly good in describing the experimental data, and kinetics constants including K_p, K_d, K_p′, K_d′, M, M, and K_dis/K_cr for the polymerization at 30, 40, and 50°C in 1,2‐ethylene dichloride and benzene were obtained. Factors that affected the kinetics constants were discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 483–492, 1999     

Magnesium chloride supported high-mileage catalysts for olefin polymerization. X. Effect of hydrogen and catalytic site deactivation

The effect of H₂ on propylene polymerization initiated by a MgCl₂/EB/PC/AlEt₃/TiCl₄–3 AlEt₃/MPT catalyst was studied. Hydrogen increases significantly the initial rate during the early stage of the polymerization to give a higher yield of polymer than reactions without H₂. But H₂ reduces the yield toward the latter stages so that the net effect on the total yield can be quite small. There is no appreciable effect of H₂ on either the isotacticity index or polydispersity of the products. It decreases molecular weight proportional to (p_H2)^1/2. The chain transfer by H₂ resulted in a decrease of total metal polymer bond concentration with time of polymerization. The rate constants of hydrogen chain transfer for the two kinds of isospecific and nonspecific sites are = 5.1 × 10^?3, = 2.7 × 10^?3, = 7.5 × 10^?3, = 4.4 × 10^?3, in units of torr^1/2 sec^?1 at 50°. Hydrogen assists in the deactivation of the catalytic sites as does propylene; rates of the former and the latter vary with (p_H2)^1/2 and [C₃H₆]^1/2, respectively, with k = (12.1 ± 0.9) M^?1 torr^?1/2 sec^?1 and k = (65.3 ± 3.3) M^?3/2 sec^?1 at 50° and A/T = 167. The mechanism for deactivation of catalytic sites are discussed.     

Electrochemical synthesis of PEDOT derivatives bearing imidazolium‐ionic liquid moieties

Novel poly(3,4‐ethylenedioxythiophene) (PEDOT) polymers bearing imidazolium‐ionic liquid moieties were synthesized by electrochemical polymerizations. For this purpose, new functional monomers were synthesized having an 3,4‐ethylenedioxythiophene (EDOT) unit and an imidazolium‐ionic liquid with different anions such as tetrafluoroborate (BF), bis(trifluoromethane)sulfonimide ((CF₃SO₂)₂N^?), and hexafluorophosphate (PF). Next, polymer films were obtained by electrochemical synthesis in dicholoromethane solutions. Obtained polymers were characterized, revealing the characteristics of PEDOT in terms of electrochemical and spectroelectrochemical properties, FTIR, ¹H NMR, and AFM microscopy. Interestingly, the hydrophobic character of electropolymerized films could be modified depending on the anion type. The hydrophobicity followed the trend PF > (CF₃SO₂)₂N^? > BF > pure PEDOT as determined by water contact angle measurements. Furthermore, the polymers could be dissolved in a range of polar organic solvents such as dimethylformamide, propylene carbonate, and dimethyl sulfoxide making these polymers interesting candidates for wet processing methods. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3010–3021, 2009     

Aromaticity of ionic structures: Investigation and application of NICS value and 4n + 2 rule

At DFT/B3LYP/6‐31G** theoretical level, C₆H and C (n = 0, ?2, and +2), C₆H and C (n = 0, ±2, ±4, and ±6), C₆H (n = 0–6), as well as C₆H₆‐A and C₆‐A (A = Be, B, N, O, Mg, Al, Si, S, and Fe) structures were investigated. Comparing NICS values of C₆H and C (n = 0, ?2, and +2), we discovered that C₆H, C₆H were antiaromatic, and C₆H₆, C₆, C, C had aromaticity with negative NICS values. According to research of C₆H and C (n = 0, ±2, ±4, ±6), C₆H (n = 0–6), we sustained that their σ and π orbit were different and the locations of electrons were difficult to confirm in ionic structures. Thus, neither 4n + 2 rule nor NICS values can precisely estimate the aromaticity of ionic structures. Besides, through WBI (NBO) research of C₆H₆‐A and C₆‐A (A = Be, B, N, O, Mg, Al, Si, S, and Fe) structures, we found that C₆H₆ was easy to accept electrons, contrarily, C₆ was prone to bestowing electrons. Moreover, C₆H₆ took the symmetrical carbon atoms form feeble interaction or bond, and C₆ used all carbon atoms to impact with other atom. C₆H₆ generated two contrapuntal single bonds with oxygen, sulfur, and nitrogen atoms, whereas C₆ molecule formed double bond with oxygen and nitrogen atoms, two conjoint single bonds with sulfur atom. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Theoretical study of one‐electron bonds in a series of high‐spin lithium–beryllium–hydrogen clusters: “Valence shell single‐electron repulsion” rule and electron localization function analysis

A series of high‐spin clusters containing Li, H, and Be in which the valence shell molecular orbitals (MOs) are occupied by a single electron has been characterized using ab initio and density functional theory (DFT) calculations. A first type (⁵Li₂, ⁿ⁺¹LiH_n+ (n = 2–5), ⁸Li₂H) possesses only one electron pair in the lowest MO, with bond energies of ～3 kcal/mol. In a second type, all the MOs are singly occupied, which results in highly excited species that nevertheless constitute a marked minimum on their potential energy surface (PES). Thus, it is possible to design a larger panel of structures (⁸LiBe, ⁷Li₂, ⁸Li, ⁴LiH⁺, ⁶BeH, ⁿ⁺³LiH (n = 3, 4), ⁿ⁺²LiH (n = 4–6), ⁸Li₂H, ⁹Li₂H, ²²Li₃Be₃ and ²²Li₆H), single‐electron equivalent to doublet “classical” molecules ranging from CO to C₆H₆. The geometrical structure is studied in relation to the valence shell single‐electron repulsion (VSEPR) theory and the electron localization function (ELF) is analyzed, revealing a striking similarity with the corresponding structure having paired electrons. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007