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611.
Fluoropolymer materials and architectures prepared by controlled radical polymerizations 总被引:2,自引:0,他引:2
Natanya M.L. Hansen 《European Polymer Journal》2007,43(2):255-293
This review initially summarizes the mechanisms, merits and limitations of the three controlled radical polymerizations: nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP) or metal catalyzed living radical polymerization, and reversible addition-fragmentation chain transfer (RAFT) polymerization. This is followed by two parts, one dealing with homo- and copolymerizations of fluorinated methacrylates and acrylates, and a second where fluorinated styrenes, alone or in combination with other monomers, are the main issues. In these parts, initiators (including multifunctional and macroinitiators), ligands and other reaction conditions as well as some kinetics and conversions are discussed. Numerous possibilities for preparation of a variety of different block copolymers where one or more blocks are fluorinated are devoted particular attention. The advantageous properties and functionalities that can be obtained from these novel fluorinated materials and architectures are especially emphasized. Thus, various amphiphilic, biocompatible or low energy materials, fluorinated nanoparticles and nanoporous films/membranes as well as materials for submicron and nanolevel electronics have been fabricated. In addition, the possible fluorination of various surfaces through surface initiation is highlighted. A final part deals with the use of fluorine containing initiators and macroinitiators, and the applications on the novel materials derived thereof. 相似文献
612.
Early stages of heat deterioration of some siliconcontaining aromatic polyimide thin films with disiloxane groups (I) in their main chains were studied with XPS. It was found that the thermal decomposition of silicon-containing aromatic polyimides takes place at lower temperatures than those not modified with silicon. The low thermal stabilities observed are explained by the easier decomposition of silicon–carbon bonds (e.g. silicon–methylene, silicon–aryl) than other bonds (e.g. carbon–carbon, carbon–oxygen). Particularly, silicon–methylene bonds (II) readily undergo thermal oxidative decomposition and start to decompose at 350°C under aerobic conditions. This starting temperature of thermal decomposition is lower by 100°C than that of the corresponding polyimide not modified with silicon. In the case of polyimide incorporating silicon–aryl bonds (III) instead of silicon–methylene bonds, the decrease in the thermal decomposition temperature is as small as 50°C, and decomposition under aerobic conditions starts at 400°C. 相似文献
613.
Masayuki Iijima Yoshikazu Takahashi Yoshiyuki Oishi Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1991,29(12):1717-1723
A novel method for the preparation of ultrathin films of aromatic polyimides was developed through vapor deposition polymerization from combinations of monomer pairs of either N,N′-bis (trimethylsilyl)-substituted aromatic diamines and pyromellitic dianhydride or aromatic diamines and pyromellitic dithioanhydride. Both diamine component and tetracarboxylic dianhydride component were evaporated simultaneously at a stoichiometric molar ratio under vacuum, giving a deposited film on a substrate, which consisted of a polyamic acid derivative formed by the ring-opening polyaddition. The deposit was then converted to polyimide by thermal imidization at a relatively lower temperature, compared with a conventional method using the parent diamine and tetracarboxylic dianhydride. The properties of polyimide ultrathin films such as thermal stability, chemical resistance, and dielectric behavior were almost the same as those of the polyimide films prepared by a conventional method. 相似文献
614.
Chin-Ping Yang Wen-Tung Chen 《Journal of polymer science. Part A, Polymer chemistry》1993,31(11):2799-2807
Novel aromatic polyimides containing bis(phenoxy)naphthalene units were synthesized from 1,5-bis(4-aminophenoxy)naphthalene (APN) and various aromatic tetracarboxylic dianhydrides by the usual two-step procedure that included ring-opening polyaddition in a polar solvent such as N,N-dimethylacetamide (DMAc) to give poly(amic acid)s, followed by cyclodehydration to polyimides. The poly(amic acid)s had inherent viscosities between 0.72 and 1.94 dL/g, depending on the tetracarboxylic dianhydrides used. Excepting the polyimide IVb obtained from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), all other polyimides formed brown, flexible, and tough films by casting from the poly(amic acid) solutions. The polyimide synthesized from BPDA was characterized as semicrystalline, whereas the other polyimides showed amorphous patterns as shown by the x-ray diffraction studies. Tensile strength, initial moduli, and elongation at break of the APN-based polyimide films ranged from 105–135 MPa, 1.92–2.50 GPa, and 6–7%, respectively. These polyimides had glass transition temperatures between 228 and 317°C. Thermal analyses indicated that these polymers were fairly stable, and the 10% weight loss temperatures by TGA were recorded in the range of 543–574°C in nitrogen and 540–566°C in air atmosphere, respectively. © 1993 John Wiley & Sons, Inc. 相似文献
615.
Kivanc Yuney 《European Polymer Journal》2007,43(6):2308-2320
Two new soluble polymers (naphthalene containing: TH-NPI, perylene containing: TH-PPI) have been synthesized via incorporation of branched chain substituent unit into their backbones. Because of existence of branched alkyl spacer, the polymers showed good solubility in common solvents such as chloroform without sacrificing their stability and caused a red shifted excimer-like emission. Their monomers (TH-NDI and TH-PDI) have been synthesized for comparison. The compounds are characterized by UV-vis, IR, MS, DSC, TGA, CV, GPC and viscosity measurements. Polymers TH-NPI and TH-PPI with inherent viscosities of 0.50 and 0.30 dL/g were obtained corresponding to their molecular weights 40,000 and 17,000 respectively. Thermogravimetric analysis (TGA) showed that TH-NDI, TH-NPI, TH-PDI and TH-PPI are thermally stable up to 380, 445, 512 and 515 °C respectively. The LUMO energy levels of these compounds are calculated as −3.66, −3.71, −3.62 and −3.61 eV respectively. The red-shifted (TH-NPI: 400-650 nm, TH-PPI: 535-800) excimer-like fluorescence in chloroform is attributed to the formation of ground state complexes probably due to intermolecular and intramolecular π-stackings of the polymers in solution. The fluorescence lifetimes, quantum yields and singlet-state energies are presented. 相似文献
616.
617.
The transport properties of a novel porous fluorinated polyimide membrane fabricated by a wet phase inversion process were studied with a stirred dead‐end filtration cell. The porous membrane‐forming solvents were tetrahydrofuran (THF), acetone, N,N‐dimethylacetamide (DMAc), N‐methylpyrrolidone (NMP), N,N‐dimethylformamide (DMF), and dimethylsulfoxide (DMSO). The phase separation phenomena in a ternary system of polyimide/solvent/water were investigated from cloud point curves by a titration method and binary interaction parameters. Solvent–water demixing in the system has been found to play very important roles in determining the structure and surface morphology of the polyimide membrane. The porous fluorinated polyimide membranes showed pore sizes from 4 to 500 nm and permeation properties from ultrafiltration to a microfiltration range. In this study, we particularly focused on fouling of the polyimide membranes, because fouling decreases the flux and increases the resistance. Interestingly, the porous polyimide membrane showed excellent water flux recovery after water cleaning compared with that of the polyethersulfone (PSf) membrane, which suggest that for a 6FDA‐6FAP membrane, the protein–membrane and protein–protein interaction was not so strong compared with those in a PSf membrane. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
618.
A novel sulfonated diamine monomer,1,2-dihydro-2-(3-sulfonic-4-aminophenyl)-4-[4-(4-aminophenoxy)-phenyl]phthalazin- 1-one(S-DHPZDA),was successfully synthesized by direct sulfonation of diamine 1,2-dihydro-2-(4-aminophenyl)-4-[4-(4- aminophenoxy)-phenyl]-phthalazin-1-one(DHPZDA).A series of sulfonated polyimides(SPIs),which can be used as the material of the proton exchange membrane(PEM)for the proton exchange membrane fuel cell(PEMFC),were prepared from 1,4,5,8- naphthalenetetracarboxylic dianhydride(NTDA),S-DHPZDA,and nonsulfonated diamines DHPZDA.The structure of the monomer and polymers were characterized by FT-IR and~1H NMR.The solubility of the S-DHPZDA-based SPIs has been improved due to the induction of the phthalazione moiety.The SPIs membranes have high thermo-stability,predominant swelling resistance with high ion exchange capacity. 相似文献
619.
In this study, polyimide–silica (PI–silica) based hybrid coating compositions were prepared from tetraethoxysilane (TEOS), γ‐glycidyloxypropyl trimethoxy silane (GOTMS), and polyamic acid (PAA) via a combination of sol–gel and thermal imidization techniques. PAA was synthesized from 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) and 3,3'‐Diaminodiphenyl sulfone (DDS) in N‐Methyl‐2‐pyrrolidone (NMP). The silica content in the hybrid coatings was varied from 0 to 20 wt%. The structural characterization of the hybrid coatings was performed using FTIR and 29Si‐NMR spectroscopies. Results from both pendulum hardness and micro indentation test show that the hardness of hybrid coatings improves with the increase in silica content. The tensile tests also demonstrated that the mechanical properties at low silica content are rather striking. Their surface morphologies were characterized by scanning electron microscopy (SEM). SEM studies revealed that inorganic particles were distributed homogenously through the PI matrix. It was also found that, incorporation of the silica domains increased the thermal stability of the hybrid coatings. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
620.
V. N. Artem'eva V. V. Kudryavtsev E. M. Nekrasova V. P. Sklizkova Yu. G. Baklagina N. V. Lukasheva O. P. Shkurko V. P. Borovik 《Russian Chemical Bulletin》1992,41(10):1790-1796
A detailed comparative study of polypyromellitamido acids and polyimides based on 2,5-bis(paminophenyl)pyrimidine and 4,4-diaminoterphenyl was conducted to determine the role of the nitrogencontaining pyrimidine ring in the main chain of the polymers. A model of the layer packing of polyimide chains in crystalline regions was proposed based on the data from x-ray structural analysis and quantum chemical calculations. The existence of tilted packing caused by partial displacement of the solvent molecules bound to the pyrimidine ring of the neighboring macromolecule with higher basicity in pyrimidine-containing polymers was hypothesized.Institute of Macromolecular Compounds, Russian Academy of Sciences, 199004 Saint Petersburg. Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2288–2296, October, 1992. 相似文献