Soluble polyimides based on an aromatic diamine containing pendant phenolic group and four different dianhydrides have been synthesized by two-step polycondensation reaction in solution. The polyimides were easily soluble in polar organic solvents and even in less polar solvents and showed high thermal stability, with initial decomposition temperature being above 420 °C. Monte Carlo method was used to calculate conformational rigidity parameters of these polyimides. Some physical properties such as solubility, glass transition temperature and initial decomposition temperature were investigated and compared with those of related polyimides which did not contain any pendant groups based on the same dianhydrides and a diamine without pendant phenolic group. All data were discussed in relation to the rigidity of the chain.
Polyisophthalamides were prepared from aromatic diamines and 5-iminobenzoylisophthalic acid by the Yamazaki method of direct polyamidation catalyzed by triphenylphosphite. The properties of the polymers were measured and compared with the analogous unsubstituted polyisophthalamides. The incorporation of one iminobenzoyl pendant group per repeating unit gave rise to better solubility in strongly polar solvents. Higher content of amide groups per repeating unit allowed the modified polymers to absorb moisture to a greater extent than the parent polyisophthalamides. The glass transition temperatures were raised 20–30 by the presence of the pendant groups and they ranged from 290 to 317°. On the contrary, the substituted polymers showed lower initial decomposition temperatures, as measured by TGA, all of them beginning to decompose at about 410°. The mechanical properties of polymer films seemed not to be greatly affected by the pendant groups and only small differences were observed between substituted and unsubstituted polymers. 相似文献
Using the method of metathesis polymerization carbon-chain homopolymers containing triрhenylsilyl, tritolylsilyl and trithienylsilyl groups in the side chains, as well as their copolymers with additional carbazole-containing units have been synthesized. Photophysical properties of the obtained compounds were investigated. All polymer products show an intense photoluminescence in the blue region of the spectrum. The largest quantum yield (61.4%) was shown by the copolymer with triphenylsilyl and carbazole side groups. 相似文献
A method for preparation of novel fast photocurable polyethers is described. Thus, novel polyether, poly(3-methacryloxy propylene oxide) was obtained in low molecular weights (Mn: 1700 Da) by cationic ring opening polymerization of the epoxy group of glycidyl methacrylate (GMA) in presence of trimethylsilyl trifilate (TMSTF) as initiator. Copolymerization of the monomer with cyclohexene oxide (CHO) in the same reaction conditions yielded copolyethers with methacylate pendant groups. A series of copolymers with various GMA contents (10-100% mol/mol) were prepared using CHO as diluting comonomer. 1H NMR spectra showed that oxirane function of GMA is somewhat less reactive than CHO. Having methacylate pendant groups the resulting waxy polymers underwent rapid photocrosslinking to give glassy hard materials upon UV irradiation at 350 nm, in the presence of benzoin as photoinitiator. Photocuring abilities of the copolymers were investigated by real time FT-IR using in dimethoxyethane solutions (14.7% w/w). The results showed that, 60% double bonds disappear within 150-300 s by irradiation of diluted copolymer solutions with Xenon lamp (150 W). 相似文献
Chemical modifications of polyacrylonitrile (PAN), an inexpensive and commercial homopolymer, to obtain terpolymers containing 1,2,4 or 1,3,4 oxadiazolic pendant groups are described. These new materials are physically and spectroscopically characterized. 相似文献
The synthesis of eighteen crown ether compounds with pendant thioamide, N-alkylthioamide, and N,N-dialkylthioamide groups is reported. The new crown ether compounds are obtained by one-step reactions from the corresponding sym-dibenzo-16-crown-5-oxyacetamides and sym-(propyl)dibenzo-16-crown-5-oxyacetamides with Lawesson's reagent. 相似文献
Miscibility is not always common in blends of homologous polymers that differ in structure but possess the same functional groups. In this study, two methacrylate polymers, which differ by a methylene unit, were found to be miscible in accordance with morphology and thermal transition criteria of polymer miscibility. Miscibility of the pair poly(phenyl methacrylate) and poly‐(benzyl methacrylate) is quite unusual. Interactions between carbonyl units and phenyl rings of these two polymers are discussed. FT‐IR results indicate an intimate mixing state between these two polymers leading to mutual influence in the absorbance wavenumbers for C=O, ether groups and, possibly, phenyl rings. 相似文献
The preparation of a new functionalized cyclopentadienyl ligand bearing a nitrile pendant substituent, (C5H4CMe2CH2CN)? is reported. The corresponding lithium salt of this ligand (1) was prepared by the reaction of in situ lithiated acetonitrile with 6,6-dimethylfulvene. The ligand was subsequently utilized for the synthesis of group 4 metal complexes [(η5–C5H4CMe2CH2CN)2MCl2] (M = Ti, 2; M = Zr, 3; M = Hf, 4), [(η5–C5H5) (η5–C5H4CMe2CH2CN)MCl2] (M = Ti, 7; M = Zr, 8), and [(η5-C5Me5) (η5 C5H4CMe2CH2CN)2ZrCl2] (9). Alternative route to 2 comprised the preparation of half-sandwich complex [(η5–C5H4CMe2CH2CN)TiCl3] (6). The prepared compounds were characterized by common spectroscopic methods and the solid state structures of complexes 2, 3, 4, 7, and 9 were determined by the single-crystal X-ray diffraction analysis. In addition, compound 7 was converted to the corresponding dimethyl derivative [(η5–C5H5) (η5–C5H4CMe2CH2CN)TiMe2] (10) and also treated with the chloride anion abstractor Li[B(C6F5)4] to generate the cationic complex with the coordinated nitrile group, as suggested by the NMR spectroscopy. A formation of yet another cationic complex was observed upon treating compound 10 with (Ph3C)[B(C6F5)4]. 相似文献
We compare two mechanisms that dominate the temperature-dependent changes in electronic structure for poly(3-hexylthiophene-2,5 diyl) (P3HT). Structural changes in the relative orientation and configuration of the aromatic ring backbone are observed to occur over a wide range in temperature and affect the local final state screening in photoemission. There are also changes in conductivity and carrier concentration at lower temperatures leading to altered long-range intramolecular screening of photoholes and final state effects that affect excitation spectroscopies including photoemission. For polyethylenedioxythiophene (PEDOT), temperature-dependent changes in the structure and configuration of the polymer backbone are not as significant, although temperature-dependent final state effects are observed. 相似文献
The influence of the chain conformation on the formation of polymeric supramolecular complexes as well as the influence of the complexation on the conformation of the polymer chain has been studied. The complexation of pyrene into the cavity of β-cyclodextrin (β-CD) was investigated in aqueous solutions of β-CD substituted poly(allylamine) (PAA) under variation of external parameters, i.e. temperature, pH, ionic strength and addition of urea. The observed changes of the complexation constant K for the formation of the 2:1 β-CD/pyrene complex can be explained by a change of the chain flexibility which leads to a variation of the mean distance between neighbouring β-CD-moieties along the polymer chain. The intra-chain association of the decyl group with β-CD in PAA with co-pendant decyl and β-CD is disrupted by the addition of 1-adamantanamine HCl resulting in a more extended structure of the polymer. The β-CD moiety in PAA-CD shows one order of magnitude greater affinity to 2-(p-toluidyl)naphthalene-6-sulfonate than the native β-CD and the affinity increases further by the presence of decyl side groups. 相似文献
Novel liquid crystal materials based on 1,3,5-benzenetrisamide derivatives with three pendant 2-phenyl-5-(mono-, di-, and/or tri-n-alkoxyphenyl)-1,3,4-oxadiazole arms (Ia–c, IIa–c) were prepared. The mesomorphic properties of these compounds were characterised and studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. The formation of a columnar mesophase was found to be dependent on the number of alkoxy side chains. The compounds Ib and IIb, with a total of six alkoxy chains, and compounds Ic and IIc, with nine alkoxy chains, exhibited an enantiotropic hexagonal columnar (Colh) phase with high isotropisation temperatures; however, compounds Ia and IIa with a total of three alkoxy chains formed a crystalline phase. Compounds IIb and c were room temperature liquid crystals. 相似文献
This paper studies the diffusive and sorption steps of several gases across membranes cast from poly(N-phenyl-exo,endo-norbornene-5,6-dicarboximide) chloroform solutions. Chains packing effects on gas transport was investigated by conducting a parallel study on the permeation characteristics of membranes cast from hydrogenated poly(N-phenyl-exo,endo-norbornene-5,6-dicarboximide) chloroform solutions. The permeability coefficients of several gases in the two membranes were measured finding that hydrogenation of the norbornene moieties decreases gas permeability. The transition states approach was used to determine the trajectories of the gases in the two types of membranes from which the diffusion coefficients were obtained. Monte Carlo techniques based on the Widom method were used to simulate gas sorption process as a function of pressure. The values of the solubility coefficients thus obtained undergo a relatively sharp drop at low pressures approaching to a constant value as pressure increases. With the exception of carbon dioxide, pretty good agreement between the experimental and simulated values of the permeability coefficient is found for the gases studied. 相似文献