A useful approach toward the synthesis and metal extractions with polymer appended thioalkyl calix[4]arenes

This article describes a convenient method for the synthesis of two new polymeric resins via nucleophilic substitution reactions involving 5,11,17,23-tetrakis[(propylthio)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 4, and 5,11,17,23-tetrakis[(methylthio)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 6, as precursors with Merrifield's resin. The extraction studies were made using both liquid-liquid extraction and solid-liquid batchwise sorption procedures. The calix[4]arene based polymeric resins have high extraction ability toward metal cations and Na₂Cr₂O₇ as compared to their monomeric precursors.     

Synthesis and characterization of chiral polythiophenes: Poly [(R)-(−) and (S)-(+)-2-(3′-thienyl)ethyl N-(3″,5″-dinitrobenzoyl)-α-phenylglycinate]

(R)-(−) (1) and (S)-(+)-2-(3′-Thienyl)ethyl N-(3″,5″-dinitrobenzoyl)-α-phenylglycinate (2) monomers were synthesized, characterized, and polymerized in chloroform using FeCl₃ as an oxidizing agent. Molecular weights of 2.6 × 10⁴ and 3.2 × 10⁴ for poly1 and poly2, respectively, were determined by SEC analysis. FTIR spectra of the polymers indicated the coupling of monomers through the α positions. UV-vis spectra showed absorption bands at λ_max = 226 and 423 nm for poly1 and poly2, ascribed to transitions of side groups and polythiophene backbone, respectively. Poly1 and poly2 remained stable up to 210 °C. At higher temperatures, a two step weight loss degradation process was observed for both polymers by TGA analysis. ¹H NMR, in the presence of Eu(tfc)₃, and optical rotation measurements indicate the chiral properties of the monomers 1 ([α]_D²⁸ = −76.2) and 2 ([α]_D²⁸ = +76.0), and the maintenance of chirality after polymerization (poly1 [α]_D²⁸ = −29.0 and poly2 [α]_D²⁸ = +28.4, c = 2.5 in THF). According to scanning electron microscopic analysis, the polymers are highly porous.     

Propylene polymerisations with novel heterogeneous combination metallocene catalyst systems

Propylene was polymerised with novel combination metallocene catalyst systems prepared by an emulsion-based heterogenisation method in liquid monomer conditions. The catalyst combinations investigated were rac-dimethylsilanylbis(2-methyl-4-phenyl-1-indenyl)zirconium dichloride/rac-[ethylenebis(2-(tert-butyldimethylsiloxy)indenyl)]zirconium dichloride/methylaluminoxane (MAO) (1 + 2) and rac-dimethylsilanylbis(2-methyl-4-phenyl-1-indenyl)zirconium dichloride/rac-dimethylsilanylbis(2-isopropyl-4-[3,5-dimethylphenyl]indenyl)zirconium dichloride/MAO (1 + 3). The effects of polymerisation temperature and hydrogen on catalyst performance and polymer properties, as well as copolymerisation with hexene and ethylene were investigated. Depending on the polymerisation conditions, M_w of polypropylene varied from 144 to 286 kg/mol for 1 + 2 and from 200 to 390 kg/mol for 1 + 3. Combination 1 + 2 produced broader molecular weight distribution (MWD) than 1 + 3, and a bimodal MWD with clearly separated low- and high-M_w polymer fractions was observed with 1 + 2. The two catalyst systems showed similar hydrogen and hexene responses. Each metallocene precursor showed individual response towards the polymerisation conditions, especially polymerisation temperature, suggesting that interaction between the catalyst active sites was negligible in the studied systems.     

Effects of internal linkage groups of fluorinated diamine on the optical and dielectric properties of polyimide thin films

To investigate the difference of the trifluoromethyl (CF₃) group and ether group affecting the optical property of fluorinated polyimides (PIs), we prepared 4,4′-bis(4-amino-2-trifluoromethylphenoxy)diphenyl ether (4) with three ether groups and 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane (5) with four CF₃ groups with 2-chloro-5-nitrobenzotrifluoride and 4,4′-dihydroxydiphenyl ether or 2,2-bis(4-hydroxyphenol)hexafluoropropane. Two series of organosoluble and light-colored PIs (4a-4c, 5a-5c) were synthesized from 4 and 5 with various aromatic dianhydrides: 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA) (a), 4,4-oxydiphthalic anhydride (ODPA) (b), and 4,4-hexafluoroisopropylidenediphthalic anhydride (6FDA) (c), prepared through a typical two-step polymerization method. These PIs were soluble in amide polar solvents and even in less polar solvents. The glass-transition temperatures (T_g) of 4a-5c were 221-249 °C and the 10% weight-loss temperatures were above 530 °C. Their films had cutoff wavelengths between 339 and 399 nm and yellowness index ranges from 1.95 to 42.60. The dielectric constants estimated from the average refractive indices are 2.59-2.93 (1 MHz). In a comparison of the PI series based on 4, 5, and 4,4′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (6), we found that the CF₃ group and ether group on the diamine had almost same effect in lowering the color, but the ether group had better thermal stability. The color intensity of the three PI series was lowered in the following order: 6 > 4 > 5. The PI 5c, synthesized from diamine 5 and dianhydride c, had six CF₃ groups in a repeated segment and ether group at the same time, so it exhibited the lightest color among the three series.     

Anodic carbon-boron bond cleavage through the intermediacy of electrogenerated bromonium ion

The electrochemical properties of a series of cyclic arylboronic esters, XC₆H₄B(OR)₂ [RR = CH₂CH₂; X = H (1a); p-Me (1b); p-OMe (1c); p-Cl (1d); p-Ph (1e); m-Cl (1f); m-OMe (1g); CF₃ (1h); OMe (1i); 2,6-dimethyl (1j); 1b with RR = (CH₂)₃, (1k); 1b with RR = CMe₂CMe₂, (1m)] has been studied in acetonitrile by cyclic voltammetry (CV) and controlled-potential electrolysis (CPE). The CV of representative examples of aryl borates with different substituents show one irreversible oxidation wave on a Pt cathode, at 1.8-1.9 V (vs. Ag/AgCl), with a negligible substituent effect. The cathodic CPE process led to small amounts of biaryls only, whereas the direct anodic CPE could not be carried out practically due to low currents. However, in the presence of electrogenerated bromonium (or iodonium) ions a C-B bond cleavage does take place to yield the corresponding bromoaryls, brominated phenols, and arylboronic acids as the major products.     

Electrochemical study of stable N-alkoxyarylaminyl radicals

The electrochemical study of N-tert-butoxy-2,4-diphenyl-6-tert-butylphenylaminyl (1a), N-tert-butoxy-2,4-bis(4-chlorophenyl)-6-tert-butylphenylaminyl (1b), N-[2-(methoxycarbonyl)-2-propyl]-2,4-diphenyl-6-tert-butylphenylaminyl (2), and N-tert-butoxy-2,4,6-tris(4-chlorophenyl)phenylaminyl radicals (3) was performed by cyclic voltammetry using acetonitrile as the solvent and Bu₄NPF₆ as the supporting electrolyte. On cathodic scan (100 mV/s), all the radicals gave chemically reversible cyclic voltammograms, and the were determined to be −1.405 V (1a), −1.310 V (2a), −1.282 V (2b), and −1.195 V (3) (versus Fc⁺/Fc), respectively. On anodic scan (100 mV/s), on the other hand, 1a, 1b and 2 showed chemically reversible cyclic voltammograms, but 3 exhibited a partially reversible couple even on a scan rate of 500 mV/s, indicating that the cation species of 3 was less stable. The determined for 1a, 1b, 2 and 3 were 0.220, 0.280, 0.318 and 0.294 V (versus Fc⁺/Fc), respectively. The electrochemical data were compared with those of thioaminyl radicals, the corresponding sulfur analogues of 1-3.     

Copolymers containing pendant styryltriphenylamine and carbazole groups: Synthesis, optical, electrochemical properties and its blend with Ir(ppy)3

A series of vinyl copolymers (PVKST12-PVKST91) and homoploymer PVST containing pendant hole-transporting 4-(4-oxystyryl)triphenylamine (12-100 mol%) and carbazole chromophores were synthesized by radical copolymerization and employed as host for Ir(ppy)₃ phosphor to tune emission color. They were characterized using the ¹H NMR, FT-IR, absorption and photoluminescence spectra, elemental analysis, GPC, cyclic voltammetric and thermal analysis (DSC, TGA). Their weight-average molecular weights (M_w) and decomposition temperatures (T_d) were 1.46-5.68 × 10⁴ and 356-399 °C, respectively. The HOMO levels of PVKST12-PVKST91 and PVST, estimated from the onset oxidation potentials in cyclic voltammograms, were −5.40 to −5.14 eV, which are much higher than −5.8 eV of the conventional host poly(9-vinylcarbazole) (PVK) owing to high hole-affinity of the 4-(4-oxystyryl)triphenylamine groups. Therefore, copolymers PVKST are effective in reducing hole-injection barrier between the PEDOT:PSS and emitting layer. Electroluminescent devices [ITO/PEDOT:PSS/PVKST:Ir(ppy)₃:PBD/BCP/Ca/Al] using the hole-transporting PVKST as host were fabricated to tune the emission color. Their EL spectra showed a major emission at 515 nm and a minor peak at 435 nm attributed to Ir(ppy)₃ and 4-(4-oxystyryl)triphenylamine, respectively. The C.I.E. 1931 coordinates shift from (0.29, 0.61) for PVK to (0.33, 0.42) for PVST with an increase in 4-(4-oxystyryl)triphenylamine content.     

New host copolymers containing pendant triphenylamine and carbazole for efficient green phosphorescent OLEDs

A series of vinyl copolymers (P1-P6) containing pendant hole-transporting triphenylamine (11-88 mol%) and carbazole chromophores were synthesized by radical copolymerization to investigate the influence of triphenylamine groups upon optoelectronic properties. The copolymers were readily soluble in common organic solvents and their weight-average molecular weights (M_ws) were between 1.41 × 10⁴ and 2.24 × 10⁴. They exhibited moderate thermal stability with T_d = 402-432 °C at 5% weight loss. The emission spectra (both PL and EL) of the blends [P1-P6 with 4 wt% Ir(ppy)₃] showed dominant green emission (517 nm) attributed to Ir(ppy)₃ due to efficient energy transfer from P1-P6 to Ir(ppy)₃. The HOMO levels of P1-P6, estimated from onset oxidation potentials in cyclic voltammeter, were −5.42 to −5.18 eV, which are much higher than −5.8 eV of conventional poly(9-vinylcarbazole) (PVK) host owing to high hole-affinity of the triphenylamine groups. The optoelectronic performances of phosphorescent EL devices, using P1-P6 as hosts and Ir(ppy)₃ as dopant (ITO/PEDOT:PSS/P1-P6:Ir(ppy)₃ (4 wt%):PBD (40 wt%)/BCP/Ca/Al), were greatly improved relative to that of PVK. The best performance was obtained with P4 device, in which the maximum luminance and luminance efficiency were 11?501 cd/m² and 10.6 cd/A, respectively.     

Synthesis and properties of various PPV derivatives with phenyl substituents

New electroluminescent polymers with various phenyl groups, poly[2-dimethyl(octyl)silyl-5-(4-(dimethyl(octyl)silyl)phenyl)-1,4-phenylenevinylene] (P1), poly[2,5-bis(4-(dimethyl(octyl)silyl)phenyl)-1,4-phenylenevinylene] (P2), poly[2,5-bis(9,9-dihexylfluorenyl)-1,4-phenylenevinylene] (P3), and poly[2,5-bis(4-(4-(2-etylhexyloxy)phenyl)phenyl)-1,4-phenylenevinylene] (P4), have been synthesized by the Gilch polymerization. The maximum absorption peaks of P1-P4 appeared at 388-423 nm in THF solution, and are red-shifted to 404-425 nm in solid thin film. The photoluminescence (PL) emission spectra of P1-P4 show a maximum peak at 482-503 nm in THF solution and at 521-549 nm as the solid film state. The emission spectra in the solid film state are more red-shifted over 40 nm, and the full width at half maximum (fwhm) was 30 nm greater than the solution conditions. The polymer light-emitting diodes (PLEDs) with the configuration of ITO/PEDOT/polymer/Al emitted light with maximum peaks at around 517-546 nm. The various phenyl substituents, with intermolecular interactions in the solid film state, can introduce the color tuning and device performance enhancement of the conjugated polymer as an emissive layer in PLED.     

Electrochemical studies of the nickel catecholate complexes for detection of sulphur dioxide gas

Nickel catecholate complexes, bis(diphenylphosphino)ethanenickelcatecholate [(dppe)NiO₂C₆H₃4-R₁] R₁ = CH₃ (1), C(CH₃)₃ (2), H (3) and F (4)] were studied using CV and SWV techniques between −1.5 and +1.5 V at 50 mV s⁻¹ in cathodic and anodic sweeps. Glassy carbon electrode was used with 0.1 M tetrabutylammonium tetrafluroborate (TBATFB) in CH₂Cl₂. Complexes 1-4 before addition of SO₂, showed approximately reversible behaviour (i_pa/i_pc ≈ 1 and ΔE ≈ 77-88 mV); oxidation peaks observed between +313 and +524 mV, reduction peaks between +225 and +436 mV, depending on the substituent on the ligand. Detection limit 0.01 ppm, linear range 0.01-20 ppm, sensitivity 0.02 ppm/mV (with SWV) were obtained. The complexes 1 and 2 could be used as voltammetric sensors while complexes 3 and 4 would be suitable as amperometric sensors, for monitoring industrial SO₂ emissions.     

Synthesis of polystyrene microgel with glucose as hydrophilic segment via controlled free-radical polymerization

4-Vinylbenzyl glucoside peracetate (1) was copolymerized with divinylbenzene (DVB) using 1-phenyl-1-(2′,2′,6′,6′-tetramethyl-1′-piperidinyloxy)ethane (2) as an initiator in m-xylene at 138 °C for 20 h ([DVB]/[2]=28; [DVB]=0.62 mol L⁻¹). The copolymerizations were performed using the mole fraction of 1 in the total feed of 1 and DVB (F₁: [1]/[1]+[DVB]) ranging from 0.11 to 0.38 that produced the polystyrene (PSt) microgel with acetyl glucose, 3, in 46-53% yields. Dynamic laser light scattering (DLS) measurements showed that 3 was stably suspended in toluene as particles with average diameters (d's) ranging from 12 to 22 nm. A static laser light scattering (SLS) measurement gave the average molar mass, M_w,SLS, of 3 that ranged from 9.69×10⁴ to 6.96×10⁵. The numbers of the 1, 2, and DVB units in 3 (N₁, N₂, and N_DVB, respectively) were from 111 to 238, from 17 to 208, and from 350 to 4510, respectively. The deacetylation of 3 was achieved by treatment with sodium methoxide in dry 1,4-dioxane to produce the PSt microgel with glucose as the hydrophilic segment, 4. The solubilities of 4 in toluene, CHCl₃, THF, 1,4-dioxane, pyridine, DMF, DMSO, and H₂O, and the mixture of H₂O and 1,4-dioxane were examined, indicating that a hydrophilic property had been effectively introduced into 4.     

Synthesis and properties of helical polyacetylenes containing carbazole

Novel acetylene monomers containing carbazole with chiral menthyl and bornyl groups, 9-(1R,2S,5R)-menthyloxycarbonyl-2-ethynylcarbazole (1), 9-(1S,2R,5S)-menthyloxycarbonyl-2-ethynylcarbazole (2), 9-(1R,2S,5R)-menthyloxycarbonyl-3-ethynylcarbazole (3) and 9-(1S)-bornyloxycarbonyl-2-ethynylcarbazole (4) were synthesized and polymerized with a Rh catalyst to give the corresponding polymers [poly(1)-poly(4)] with moderate M_n value of (11.5-92.2) × 10³ in good yields (77-89%). CD spectroscopic studies revealed that poly(1), poly(2) and poly(4) took predominantly one-handed helical structure in CHCl₃, THF, toluene, and CH₂Cl₂, while poly(3) did not. Addition of methanol to CHCl₃ solutions of poly(1) and poly(2) resulted in the formation of aggregates showing smaller CD signals at 275 and 320 nm. The helical structure of poly(1) and poly(2) was very stable against heating. The polymers emitted fluorescence in 0.40-2.90% quantum yields. Poly(4) exhibited an obvious oxidation peak at 1.10 V. The polymers were thermally stable below 300 °C.     

Synthesis and properties of various poly(diphenylacetylenes) containing tert-amine moieties

The polymerization of diphenylacetylene derivatives possessing tert-amine moieties, such as triphenylamine, N-substituted carbazole and indole, was examined in the presence of TaCl₅-n-Bu₄Sn (1:2) catalyst. A polymer with high molecular weight (M_w = 570 × 10³) was obtained in good yield by the polymerization of diphenylamine-containing monomer 1b, whereas the isopropylphenylamine derivative (1c) gave a polymer with relatively low molecular weight (M_w = 2.4 × 10³). The polymerization of monomer 1d containing cyclohexylphenylamine group did not proceed; however, carbazolyl- and indolyl-containing monomers also produced polymers. Poly(1b), poly(2f) and poly(4b) could be fabricated into free-standing membranes by casting toluene solutions of these polymers. The gas permeability of poly(1b) was too low to be evaluated accurately whereas poly(4b) possessing two chlorine atoms in the repeating unit showed higher gas permeability than that of poly(1b); furthermore, poly(2f) having trimethylsilyl and 3-methylindolyl groups exhibited relatively high gas permeability (). In the cyclic voltammograms of diphenylamino group-containing polymers, poly(1b) and poly(2b), the intensities of oxidation and reduction peaks decreased more than those of carbazolyl-containing poly(2a). The molar absorptivity (?) of poly(1b) at ∼700 nm increased with increasing applied voltage in the UV-vis spectrum.     

Photosensitive poly(benzoxazole) based on precursor from diphenyl isophthalate and bis(o-aminophenol)

A new synthetic method for the preparation of poly(benzoxazole) (PBO) precursor, poly(o-hydroxyamide) (7) from bis(o-aminophenol) (5) and diphenyl isophthalate (6) has been developed. Polymer 7 was prepared by the polycondensation of 5 and 6 in 1-methyl-2-pyrrolidinone (NMP) at 185-205 °C. Model reactions were carried out in detail to elucidate appropriate conditions for the formation of 2-hydroxybenzanilide (3) from o-aminophenol (1) and phenyl benzoate (2). The photosensitive (PBO) precursor based on polymer 7 containing a 22% of benzoxazole unit and 30 wt% 1-{1,1-bis[4-(2-diazo-1-(2H)naphthalenone-5-sulfonyloxy)phenyl]ethyl}-4-{1-[4-(2-diazo-1(2H)naphthalenone-5-sulfonyloxy)phenyl]methylethyl}benzene (S-DNQ) showed a sensitivity of 110 mJ cm⁻² and a contrast of 5.0 when it was exposed to 436 nm light followed by developing with a 2.38 wt% aqueous tetramethylammonium hydroxide solution at room temperature. A fine positive image featuring 8 μm line and space patterns was observed on the film of the photoresist exposed to 200 mJ cm⁻² of UV-light at 436 nm by the contact mode.     

Two new inorganic-organic hybrid single pendant hexadecavanadate derivatives with bifunctional electrocatalytic activities

Two new supramolecular assembly hexadecavanadate derivatives of H₂[Cd(phen)₃]₂{[Cd(H₂O)(phen)₂](V₁₆O₃₈Cl)}·2.5H₂O 1 (phen = 1,10′-phenanthroline) and H₂[Cd(bipy)₃][Cd(H₂O)(bipy)₂]{[Cd(H₂O)(bipy)₂](V₁₆O₃₈Cl)}·1.5H₂O 2 (bipy = 2,2′-bipyridine), have been prepared under mild hydrothermal conditions and structurally characterized by IR, XPS spectra, TG analyses and single-crystal X-ray diffraction. Compounds 1 and 2 are constructed from single pendant [CdL₂] (L = phen, 1 and L = bipy, 2) modified hexadecavanadates. The hybrids 1 and 2 were used as solid bulkmodifier to fabricate bulk-modified carbon paste electrodes (CPEs) (1-CPE and 2-CPE) by direct mixing. The electrochemical behaviors and electrocatalysis of 1-CPE and 2-CPE indicate bifunctional electrocatalytic activities toward both the oxidation and reduction of nitrite. Furthermore, their electrocatalytic activities toward the reduction of bromate and oxidation of ascorbic acid are also studied in 1 M H₂SO₄ aqueous solutions.     

Syntheses of group 4 transition metal complexes bearing 2-pyridinethiolate ligands and their catalytic activities for ethylene polymerization

Titanium bis(2-pyridinethiolate) complexes, Ti(6-R-SPy)₂(NMe₂)₂ (6-R-SPy = 6-R-2-pyridinethiolate, 3a: R = H; 3b: R = Me; 3c: R = Ph; 3d: R = C₆H₄-4-Me; 3e: R = C₆H₄-4-t-Bu; 3f: R = C₆H₃-3,5-Me₂), and the titanium bis(2-pyridinolate) complexes, Ti(6-Ph-OPy)₂(NMe₂)₂ (6-Ph-OPy = 6-phenyl-2-pyridinolate, 8) were prepared by treating Ti(NMe₂)₄ with 2 equiv. of 6-R-2-pyridinethiol or 6-Ph-2-pyridinol. The cis-configuration of the diamido moieties in the pseudo octahedral geometry was elucidated by X-ray crystallography for 3a. Reaction of M(NMe₂)₄ (M = Ti, Zr) with 4 equiv. of 2-pyridinethiol cleanly gave tetrakis(pyridinethiolate) complexes, M(6-H-SPy)₄·THF (6: M = Ti; 7: M = Zr). The triangular dodecahedral geometries of 6 and 7 were also revealed by X-ray crystallography. These complexes catalyzed ethylene polymerization upon activation with MAO (methylaluminoxane) or MMAO (modified MAO). The catalytic activities of titanium bis(6-aryl-pyridinethiolate) systems were found to be remarkably higher than that of titanium bis(6-methyl-pyridinethiolate) system. Among the complexes synthesized in this study, Ti[6-(C₆H₃-3,5-Me₂)-SPy]₂(NMe₂)₂ (3f)/MMAO showed the highest activity (1200 kg/Ti-mol h atm) for ethylene polymerization at 60 °C under atmospheric pressure. In contrast, the activity of the corresponding 6-aryl-pyridinolate system 8/MMAO was rather low (9.3 kg/Ti-mol h atm). Both the N-S chelating structure and the bulky aryl substituents are essential for the high activities of the 6-aryl-pyridinethiolate complexes.     

Ring-opening polymerization of six-membered cyclic esters catalyzed by tetrahydroborate complexes of rare earth metals

Catalytic behavior of tetrahydroborate complexes of rare earth metals, Ln(BH₄)₃(THF)_x (1: Ln = La, x = 3; 2: Ln = Pr, x = 2; 3: Ln = Nd, x = 3; 4: Ln = Sm, x = 3; 5: Ln = Y, x = 2.5; 6: Ln = Yb, x = 3), for ring-opening polymerization (ROP) of six-membered cyclic esters, δ-valerolactone (VL) and d,l-lactide (d,l-LA), was studied. The controlled polymerization of VL with 1-6 proceeded in THF at 60 °C. The catalytic activities of these complexes for the ROP of VL were observed to be in order of the ionic radii of the metals: 1(La) ≥ 2(Pr) ≥ 3(Nd) > 4(Sm) > 5(Y) > 6(Yb). The obtained polymers were demonstrated to be hydroxy-telechelic by ¹H NMR and MALDI-TOF MS spectroscopy. The controlled ROP of d,l-LA also proceeded by these complexes. The activities of these complexes for the d,l-LA ROP were also in order of the ionic radii of the metals.     

Synthesis and properties of organosoluble polyimides based on 1,1-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]cyclohexane

New aromatic diamine with cyclohexane cardo group substituted with trifluoromethyl group in the side chain, 1,1-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]cyclohexane (II), was prepared through the nucleophilic substitution reaction of 1,1-bis(4-hydroxyphenyl)cyclohexane and 2-chloro-5-nitrobenzotrifluoride in the presence of potassium carbonate, to yield the intermediate dinitro compound I, followed by catalytic reduction with hydrazine and Pd/C to afford the diamine II. Fluorinated polyimides (IVa-g) were prepared from the II with various aromatic dianhydrides via thermal or chemical imidization of poly(amic acid). These polyimides had inherent viscosity ranging from 0.72 to 1.16 dl/g and showed excellent solubility in a variety of organic solvents. They were soluble in a concentration of 10% in the amide polar solvent, and 1-5% in the other testing solvents. IV films showed good mechanical properties, excellent thermal stability. The 10% weight loss temperature was above 476 °C in nitrogen or air, and the glass transition temperature was recorded at 214-278 °C. In comparison of the IV series with the analogous nonfluorinated polyimides (V series) based on 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane (II′), IV series revealed better solubility, lighter-colored and lower dielectric constants and moisture absorptions. Their films had cut-off wavelengths in the range of 364-414 nm, b^* value (a yellowness index) ranging from 3.3 to 66.3, dielectric constants of 3.02-3.55 (1 MHz), with moisture absorption of 0.16-0.36 wt%.     

Poly(7-oxanorbornenes) carrying 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) radicals: Synthesis and charge/discharge properties

TEMPO-containing 7-oxanorbornene monomers 1-4 (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxy) were synthesized and polymerized via ring-opening metathesis using a ruthenium carbene catalyst. Monomers 1 and 3 gave polymers with number-average weights of 80?100 and 112?200 in 85 and 96% yields, respectively, whereas monomers 2 and 4 did not provide high molecular weight polymers. Poly(1) and poly(3) were soluble in common solvents including CHCl₃, CH₂Cl₂ and THF, while insoluble in hexane, diethyl ether and MeOH. They were thermally stable up to ca. 240 °C according to the TGA measurements in air. The secondary batteries utilizing the present polymers as cathode-active material demonstrated reversible charge/discharge processes, whose discharge capacities were 107 and 92.8 A h/kg, and displayed excellent high-rate charge and discharge properties. These cells demonstrated excellent cycle life, e.g., the discharge capacities of poly(1) and poly(3) showed less than 10% decrements even after 100 cycles.