Synthesis and gas permeation properties of various Si-containing poly(diarylacetylene)s and their desilylated membranes

Diarylacetylene monomers having trimethylsilyl groups and other substituents (substituted biphenyl, 1a and 1b; trimethylsilylmethylphenyl, 1c-e) were synthesized and polymerized with TaCl₅-n-Bu₄Sn catalyst to produce the corresponding poly(diarylacetylene)s (2a-d). Polymers 2a-c had high molecular weights and were soluble in common organic solvents. Free-standing membranes of 2a-c as well as previously reported 2f-h were prepared by the solution-casting method. Desilylation of these Si-containing polymer membranes was carried out with trifluoroacetic acid to afford 3a, 3b, and 3f-h. Upon desilylation, biphenyl-containing membranes became less permeable (3a, b), whereas fluorene-containing membranes became more permeable (3f-h). In particular, 3h exhibited extremely high gas permeability (PO₂ = 9800 barrers), which is about the same as that of poly(1-trimethylsilyl-1-propyne). Desilylated membranes 3a and 3f-h showed different gas permeability from that of polymers 2i-k which have the identical chemical structures and obtained directly by the polymerization of the corresponding monomers.     

Syndiotactically enriched 1,2-selective polymerization of 1,3-butadiene initiated by iron catalysts based on a new class of donors

A series of phosphoryl (PO) contained compounds: triethylphosphate (a), diethylphenylphosphate (b), ethyldiphenylphosphate (c) triarylphosphates (d and h-m), triphenylphosphine oxide (e), phenyl diphenylphosphinate (f) and diphenyl phenylphosphonate (g) have been prepared. Iron catalysts, which are generated in situ by mixing the compounds with Fe(2-EHA)₃ and AlⁱBu₃ in hexane, are tested for butadiene polymerization at 50 °C. Phosphates donated catalysts have been, unprecedently, found to conduct extremely high syndiotactically (pentad, rrrr = 46.1-94.5%) enriched 1,2-selective (1,2-structure content = 56.2-94.3%) polymerization of butadiene. Introduction of electron withdrawing substituents on phenyl rings oftriphenylphosphate (k-m) remarkably promotes catalytic activity, while bulky substituent isopropyl at 2-position (h) has beneficial influence on regioselectivity. Employment of e, f or g as donor, results in a suppressed monomer conversion, accompanied by deteriorated 1,2-regioselectivity. The effects of polymerization conditions such as reaction temperature, types of cocatalysts and polymerization medium are also investigated by using catalyst system with tri(2,4-difluorophenyl)phosphate (m) as donor. Highly tolerance to polymerization temperature up to 80 °C is observed for the first time in the iron-based catalyst.     

Metallocene-catalyzed synthesis of polyethylenes with side-chain triarylamines: Effects of catalyst structure and triarylamine functionality

The copolymerization of ethylene with 8-triarylamine (TAA) substituted 1-octene monomers (TAA = triphenylamine (M1), N,N-diphenyl-m-tolylamine (M2), N,N-diphenyl-1-naphthylamine (M3)) using various types of group 4 single-site catalytic systems (Cp₂ZrCl₂ (C1), rac-EBIZrCl₂ (C2), rac-SBIZrCl₂ (C3), i-PrCpFluZrCl₂ (C4), Me₂Si(η⁵-C₅Me₄)(η¹-N-^tBu)TiCl₂ (C5)) was investigated to prepare functionalized polyethylene with side-chain TAA groups. The metallocene/methylaluminoxane (MAO) catalytic systems (C1-C4) efficiently lead to the production of high-molecular-weight poly(ethylene-co-M1). While the C4/MAO catalytic system shows the highest comonomer response, the C5/MAO system exhibits the poor compatibility with the M1 comonomer. Copolymerization results of ethylene with M1-M3 using C4/MAO indicate that M1-M3 are well tolerated by both the cationic active species of C4 and MAO cocatalyst, giving rise to the copolymers with high levels of activity and molecular weight. Inspection of the aliphatic region of the ¹³C NMR spectra of the copolymers (P1-P3) having ca. 11 mol% of M1-M3, respectively, reveals the presence of isolated comonomer units with prevailing [EEMEE] monomer sequences in the polymer chain. UV-vis absorption and PL spectra exhibit an apparent low-energy band broadening for P1 and P2 indicative of intrachain aggregate formation. Whereas P2 and P3 undergo completely reversible one-electron oxidation process, P1 shows relatively poor oxidational stability.     

Synthesis and characterization of alternating poly(amide urethane)s from ε-caprolactam, amino alcohols, and diphenyl carbonate

Alternating poly(amide urethane)s from ε-caprolactam, amino alcohols H₂N-(CH₂)_x-OH (x=2-6), and diphenyl carbonate were prepared by polycondensation of α-hydroxy-ω-O-phenylurethanes 4a-e. The degree of oligomerization was adjusted by the conversion. Oligomers with two or three O-phenylurethane end groups and predetermined molecular weight were prepared by polycondensation of the α-hydroxy-ω-O-phenylurethanes 4a-e in the presence of comonomers with O-phenylurethane end groups in a given concentration. In order to prepare oligomers with hydroxyl and carboxyl groups at both chain ends suitable for coupling reactions, chain analogous reactions were performed with amino acids and amino alcohols. The microstructure of the polymers and the nature of end groups was determined by means of ¹H NMR spectroscopy and the molecular weights were determined by means of gel permeation chromatography. The poly(amide urethane)s 5a-e prepared are semicrystalline materials with melting points between 150 and 200 °C.     

Synthesis of hydroxyphenylglycine-derived novel poly(silylenevinylenephenyleneethynylene)s

The hydrosilylation polymerization of d-(−)-p-hydroxyphenylglycine-derived diethynyl monomers 1p and 1m with dihydrosilanes Si1 and Si2 was carried out using RhI(PPh₃)₃ as a catalyst to give optically active novel poly(silylenevinylenephenyleneethynylene)s [(E)-poly(1p-Si1), (E)-poly(1p-Si2), (E)-poly(1m-Si1), (E)-poly(1m-Si2), and (Z)-poly(1p-Si1)] with number-average molecular weights ranging from 2800 to 17,000 in 41-92% yields. Polymers having (E)- and (Z)-olefin moieties were obtained, wherein the (E)-/(Z)-ratios depended on the reaction conditions. The UV-vis absorption edge of (E)-poly(1p-Si1) was positioned at a wavelength longer than that of (Z)-poly(1p-Si1), indicating that (E)-vinylene-linkage extends the conjugation more largely than the (Z)-counterpart. This was also confirmed by fluorescence spectroscopy. Alkaline hydrolysis of ester moieties of these polymers gave the corresponding polymers having carboxy groups. The (E)-polymers showed different solubility in hydrophobic solvents before and after hydrolysis, but the non-hydrolyzed and hydrolyzed (Z)-polymers exhibited the same solubility.     

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.     

Synthesis and properties of cyclopentadithiophene-based poly(silarylenesiloxane) derivatives

Poly(silarylenesiloxane) derivatives with 4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene moiety, bearing dimethyl- (P1), methylphenyl- (P2) and diphenyl- (P3) substituents on silyl moieties, were prepared via polycondensation of the corresponding disilanol monomers, that is, 2,6-bis(dimethylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M1), 2,6-bis(methylphenylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M2), and 2,6-bis(diphenylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M3), respectively. P1-P3 exhibited the good solubility in common organic solvents, such as benzene, toluene, chloroform, dichloromethane, THF, and so on. The glass transition temperatures (T_gs) of P1, P2 and P3 were determined by differential scanning calorimetry to be 56, 97 and 137 °C, respectively, depending on the substituent on the silyl moieties. No melting temperatures (T_ms) of P1, P2 and P3 were observed, suggesting the obtained P1-P3 are amorphous polymers. The temperatures at 5% weight loss (T_d5s) of P1, P2 and P3 were 460, 459 and 479 °C, respectively, indicating that the larger number of phenyl group on the silyl moieties resulted in the better thermostability. Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra by introducing silyl substituents onto 4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene moiety. In addition, the bathochromic shift of the maximum absorption (λ_abs) and the increase in the fluorescence quantum yield (Φ_F) were observed by the introduction of phenyl group onto the silyl moieties.     

Synthesis, characterization, and high gas permeability of poly(diarylacetylene)s having fluorenyl groups

Diarylacetylenes having fluorenyl groups and other substituents (trimethylsilyl, t-butyl, bromine, fluorine) (1a-1) were polymerized with TaCl₅-n-Bu₄Sn. Monomers 1a-l produced high molecular weight polymers 2a-l (M_w 5.1 × 10⁵-1.3 × 10⁶) in 12-59% yields. All of the polymers were soluble in common organic solvents, and gave tough free-standing membranes by the solution casting method. The onset temperatures of weight loss of polymers 2a-l in air were over 400 °C, indicating considerably high thermal stability. All the polymer membranes showed high gas permeability; e.g., the oxygen permeability coefficient (PO₂) of 2a was as large as 4800 barrers. Membrane 2d possessing two fluorine atoms at meta and para positions of the phenyl ring showed the highest oxygen permeability (PO₂ = 6600 barrers) among the present polymers.     

Homo- and R/S-copolymerizations of chiral methylpropargyl esters carrying pyrene moieties, and optical properties of the formed polymers

Pyrene-functionalized chiral methylpropargyl esters, (R)-3-butyn-2-yl-1-pyrenebutyrate [(R)-1], (S)-3-butyn-2-yl-1-pyrenebutyrate [(S)-1], (R)-3-butyn-2-yl-1-pyrenecarboxylate [(R)-2], and 3-butyn-2-yl-1-pyrenecarboxylate [(R,S)-2] were polymerized with (nbd)Rh⁺[η⁶-C₆H₅B⁻(C₆H₅)₃] to obtain the corresponding polymers with moderate molecular weights (M_n: 10?500-66?500) in good yields (82-97%). All the polymers were soluble in CHCl₃, CH₂Cl₂, and THF. The polarimetric and CD spectroscopic data indicated that poly[(R)-1], poly[(S)-1], and poly[(R)-2] existed in a helical structure with predominantly one-handed screw sense in these solvents. The helical structure of poly[(R)-1] and poly[(S)-1] was stable upon heating and addition of MeOH, while that of poly[(R)-2] changed upon MeOH addition. The copolymerization of (R)-1 with (S)-1 was also conducted to obtain the copolymers satisfactorily. Poly[(R)-1], poly[(S)-1], and poly[(R)-2] emitted fluorescence smaller than the corresponding racemic copolymers. The fluorescence intensity was tuned by the addition of MeOH to THF solutions of the polymers.     

Synthesis, electroluminescence, and photovoltaic properties of dendronized poly(p-phenylene vinylene) derivatives

Two dendronized poly(p-phenylene vinylene) (PPV) derivatives, ED-PPV and BB-PPV, have been successfully synthesized according to the Gilch route. The obtained polymers possess excellent solubility in common solvents, good thermal stability with 5% weight loss temperature of more than 340 °C. The weight-average molecular weight (M_w) and polydispersity index (PDI) of ED-PPV and BB-PPV are in the range of (1.26-2.34)×10⁵ and 1.37-1.45, respectively. Polymer light-emitting diodes (PLEDs) with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al devices were fabricated, and the PLEDs emitted green-yellow light. The turn-on voltages of the PLEDs based on ED-PPV and BB-PPV were approximately 4.3, and 4.5 V, respectively. The PLED devices of ED-PPV exhibited the maximum luminance of about 157 cd/m² at 10.5 V. Photovoltaic cells with the configuration of ITO/PEDOT:PSS/polymer:C₆₀ (1:1)/Al were also fabricated, and the energy conversion efficiency of the devices based on ED-PPV and BB-PPV was measured to be 0.58, and 0.014%, respectively, under the white light at 75 mW/cm².     

Performance improvement of polybenzoxazine by alloying with polyimide: effect of preparation method on the properties

Polymer alloys of polyimide and polybenzoxazine were prepared from the combination of a bifunctional benzoxazine monomer, 6,6′-(1-methylethylidene)bis(3,4-dihydro-3-2H-1,3-benzoxazine) (B-a) and a soluble polyimide (PI) or its precursor, poly(amide acid) (PAA), that was synthesized from oxydianiline (ODA) and bisphenol A di(phthalic anhydride) ether (BPADA). It was observed from DSC that the onset temperature for the curing exotherm of B-a in the blend with PAA was remarkably lowered compared with that of pristine B-a, while the curing temperature of B-a in the blend with PI was almost the same as that of pristine B-a. The cast films of PI/B-a or PAA/B-a were thermally treated at 150, 200 and 240 °C for 2 h each, affording deep wine, transparent films. The PI component in the polymer alloy films from PI/B-a dissolved thoroughly. On the other hand, the polymer alloy films from PAA/B-a were not soluble at all in NMP. The polymer alloy films from both PI/B-a and PAA/B-a showed only one glass transition temperature (T_g) from their viscoelastic analyses. The T_g values remarkably increased as the content of PI increased. The thermal stabilities of both films from PI/B-a and PAA/B-a increased as the PI component increased in the similar manner.     

Aromatic diamine-based benzoxazines and their high performance thermosets

Four high-purity aromatic diamine-based benzoxazines (13-16), which could not easily be synthesized by traditional approaches, were successfully synthesized by a facile, widely useful three-step synthetic method using four typical aromatic diamines - 4,4′-diamino diphenyl methane (1), 4,4′-diamino diphenyl sulfone (2), 2,2-bis(4-(4-aminophenoxy)phenyl)propane (3), and bis(4-(4-aminophenoxy)phenyl)ether (4), respectively, as starting materials. The structures of the monomers (5-16) were confirmed by ¹H, ¹³C, ¹H-¹H and ¹H-¹³C NMR spectra. Their high performance thermosets, P(13-16), were obtained by thermal curing of benzoxazines (13-16), and their properties were studied and compared with polymer derived from bis(3,4-dihydro-2H-3-phenyl-1,3-benzoxazinyl)methane (F-a), a typical aromatic biphenol-based benzoxazine. Among the benzoxazines, 13 and F-a are constitutional isomers, but the T_g value and 5% decomposition temperature of P(13) are 53 and 111 °C, respectively, higher than those of P(F-a), demonstrating the power of the molecule-approach to enhance the thermal properties. Because of the large varieties of aromatic diamines, this approach can increase the molecule-design flexibility of benzoxazines.     

Helical conformation of the copolymers of l-proline derivatives based propargylether and chiral N-propargylamide

The novel acetylene monomers, l-proline derivatives based propargylethers PR (PA, PC, and PL) were synthesized by alkylation of Boc-hydroxyproline with propargyl bromide and acylation of achiral amine. The homopolymers of the novel acetylene monomer exist in no regulated higher order structure in solvents because of the lack of hydrogen bond and the unique ring structure in the pendant. Consequently, the copolymerization of l-proline-derived chiral propargylether PR with the l-alanine-derived N-propargylamide (LA) was formed and the chiroptical properties of the formed copolymers were examined. We conclude that (1) N-H of the amide group at 2-position in proline play an important role in the formation of helical conformation of poly(LA₈₈-co-PR₁₂); (2) improving the amount of PC of poly(LA-co-PC) changes the conformation of the copolymer in CHCl₃ and perturbs the leadership of LA; (3) the conformation of poly(LA₇₅-co-PC₂₅) remarkably changes with changing temperature and PC obtains the leadership in the competition on the conformation of poly(LA₇₅-co-PC₂₅) in CHCl₃ with the improvement of temperature.     

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.     

Polybinaphthyls incorporating chiral 2,2′-binaphthyl and isoquinoline moieties by Sonogashira reaction

Polymers P-1, P-2, P-3, P-4 and P-5 were synthesized by the polymerization of 5,8-bis(ethynyl)isoquinoline (M-1) with (R)-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthyl ((R)-M-2), (S)-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthyl ((S)-M-2), (R)-6,6′-dibromo-2,2′-bisbutoxy-1,1′-binaphthyl ((R)-M-3), (S)-6,6′-dibromo-2,2′-bisbutoxy-1,1′-binaphthyl ((S)-M-3), and rac-6,6′-dibromo-2,2′-bisbutoxy-1,1′-binaphthyl (M-4) under Sonogashira reaction, respectively. Both monomers and polymers were analyzed by NMR, MS, FT-IR, UV-vis spectroscopy, DSC-TGA, fluorescence spectroscopy, GPC and circular dichroism (CD) spectroscopy. CD spectra of polymers P-1 and P-2, P-3 and P-4 are almost identical except that they gave opposite signals at each wavelength. The long wavelength CD effect of P-1 and P-2 can be regarded as the more extended conjugated structure in the repeating unit and the helical backbone in the polymer chain. All five polymers have strong blue-green fluorescence due to the efficient energy migration from the extended π-electronic structure of the repeating unit of the polymers to the chiral binaphthyl core and are expected to provide understanding of structure-property relationships of the chiral conjugated polymers.     

Highly active and trans-1,4 specific polymerization of 1,3-butadiene catalyzed by 2-pyrazolyl substituted 1,10-phenanthroline ligated iron (II) complexes

A new family of iron (II) complexes (2a–h) bearing tridentate 2-pyrazolyl substituted 1,10-phenanthroline ligands were successfully prepared and characterized by IR spectroscopy, elemental analysis, and mass spectra. Complexes 2a–f and 2h were further confirmed by the X-ray crystallographic analysis. 2a, 2b, 2e, and 2f adopted distorted trigonal bipyramidal configuration. 2c displayed a distorted octahedron formed by six coordinated nitrogen atoms of the two ligands. Linked by two bridged chloride atoms, complex 2d was a centrosymmetric dimmer, and complex 2h adopted a six-coordinate distorted octahedral geometry due to the coordination of two solvent molecules. These complexes activated by alkylaluminum were examined in butadiene polymerization. In combination with AlⁱBu₃, complexes 2a–c exhibited high catalytic activity (73.5%–94.3%) at 20 °C, whereas other complexes exhibited much lower activity. Interestingly, the activity and selectivity of the complexes increased as increasing polymerization temperature. In particular, 2b and 2c displayed both high activity (99% and 80%, respectively) and trans-1,4 selectivity (95.6% and 96.2%, respectively) at 60 °C. The trans-1,4 selectivity of 2b varied as alkylaluminum used as a cocatalyst, in the following order: AlⁱBu₃ > AlOct₃ > AlEt₃ > AlMe₃, whereas much lower trans-1,4 selectivity was observed in the cases of using MAO and MMAO.     

Synthesis of 1,9-bis[glycidyloxypropyl]penta(1′H,1′H,2′H,2′H-perfluoroalkylmethylsiloxane)s and copolymerization with piperazine

A series of 1,9-bis[glycidyloxypropyl]pentasiloxanes (IV-VI) were prepared by the platinum catalyzed hydrosilylation of 1,9-dihydridodecamethylpentasiloxane (I), 1,9-dihydrido-3,5,7-tris(3′,3′,3′-trifluoropropyl)heptamethylpentasiloxane (II), and 1,9-dihydrido-3,5,7-tris(1′H,1′H,2′H,2′H-perfluorooctyl)heptamethylpentasiloxane (III) with allyl glycidyl ether. Subsequently, IV-VI were copolymerized with piperazine to form high molecular weight copoly(carbosiloxane)s (VII-IX). The structures of the 1,9-bis[glycidyloxypropyl]penta-siloxanes (IV-VI) and copoly(carbosiloxane)s (VII-IX) were determined by ¹H, ¹³C, ²⁹Si, and ¹⁹F NMR as well as IR spectroscopy. The molecular weight distributions (M_w/M_n) of VII-IX have been characterized by gel permeation chromatography and their thermal properties measured by differential scanning calorimetry and thermal gravimetric analysis.     

Polybinaphthyls incorporating chiral (R) or (S)-2,2′-binaphthyland oxadiazole moieties by Stille reaction

Chiral polymers P-1 and P-2 were prepared by the polymerization of (R)-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthyl ((R)-M-1) and (S)-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthyl ((S)-M-1) with 2,5-bis[(4-tributylstannyl)phenyl]-1,3,4-oxadiazole (M-2) via Pd(PPh₃)₄ catalyzed Stille coupling reaction. 1,3,4-Oxadiazole unit not only has high electron affinity, high thermal and oxidative stability, but also serves as a good chromophore. Polymers have strong blue fluorescence due to the efficient energy migration from the extended π-electronic structure of the polymers to the chiral binaphthyl core and can be expected to have potential application in the materials of fluorescent sensors. Circular dichroism (CD) spectra of polymers P-1 and P-2 are almost identical except that they gave opposite signals at each wavelength. The long wavelengths CD effect of P-1 and P-2 can be regarded as the more extended conjugated structure in the repeating unit and a high rigidity of the polymer backbone.     

Tyrosine-based poly(m-phenyleneethynylene-p-phenyleneethynylene)s. Helix folding and responsiveness to a base

The Sonogashira-Hagihara polymerization of 3′,5′-diiodo-N-α-tert-butoxycarbonyl-l-tyrosine methyl ester (1) and 3′,5′-diiodo-N-α-tert-butoxycarbonyl-O-methyl-l-tyrosine methyl ester (2) with para-diethynylbenzene (3) was carried out to obtain optically active poly(m-phenyleneethynylene-p-phenyleneethynylene)s [poly(1) and poly(2)] with M_n’s ranging from 9900 to 15,000 in 80-87% yields. Poly(1) exhibited intense CD signals in DMSO and THF, but did not in CH₂Cl₂, indicating that it took a predominantly one-handed helical conformation in the former two solvents. On the other hand, there was no evidence for poly(2) to take a helical structure in these solvents. Poly(1) turned the CD sign at 390 nm from plus to minus in DMSO/H₂O = 9/1 (v/v) by the addition of NaOH. Alkaline hydrolysis of ester moieties of poly(1) and poly(2) gave the corresponding polymers having carboxy groups [poly(1a) and poly(2a)]. Poly(1a) and poly(2a) increased the CD intensity by the addition of NaOH.     

Synthesis and gas permeability of new polynorbornene dicarboximide with fluorine pendant groups

The new exo-N-3,5-bis(trifluoromethyl)phenyl-7-oxanorbornene-5,6-dicarboximide (TFmPhONDI, 2), was synthesized and polymerized via ring opening metathesis polymerization (ROMP) using tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazolilydene][benzylidene] ruthenium dichloride (I) to produce the corresponding PTFmPhONDI (3). Gas permeability, diffusion and solubility coefficients of PTFmPhONDI (3) were determined by transient permeation for five gases He, CO₂, O₂, N₂ and CH₄. The larger gas permeability and diffusion coefficients of 3 compared to polynorbornene dicarboximides without fluorine pendant groups were attributed to a lower polymer chain packing due to the effect of the CF₃ groups in the lateral phenyl moiety pending at positions 3 and 5.