A detailed study of the self-assembly ability of triblock coil-rod-coil copolymers containing a rigid di(styryl)-anthracene segment covalently linked to oxadiazole-based blocks and their binary blends with oxadiazole-based homopolymers is presented here. The self-organized microdomains seem to pack into a fascinating ordered hexagonal structure obtained at a critical concentration without any significant influence of the sample preparation method, based on evidence obtained by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence microscopy studies. The compatibilization efficiency of these coil-rod-coil copolymers in polymer blends composed of an electron-accepting polyoxadiazole and a luminescent polyanthracene-based pair was studied by atomic force microscopy (AFM). The common feature of all observed morphologies is the compatibilizing function of the rod-coil molecule, which intercalates between the incompatible domains to prevent the formation of well-defined phase separated nanostructured surfaces. 相似文献
Aromatic polyethers containing polar pyridine units in the main chain have been synthesized using different difluoride monomers. Copolymers of 2,5-(4′,4″dihydroxy biphenyl)-pyridine and 3,3′,5,5′-tetramethyl-[1,1′-biphenyl]-4,4′-diol with bis(4-fluorophenyl) sulfone or phenyl phosphine oxide difluoride or decafluorobiphenyl (PTMPySF, PTMPyPO, PTMPyDF) were synthesized. These polymeric structures despite their common structural characteristics, showed totally different behavior in terms of solubility and acid doping ability. Blends of these copolymers have been prepared in order to be evaluated in terms of fuel cell relevant parameters like acid doping ability and conductivity. In most cases flexible membranes were obtained by solution casting. The acid doping ability was controlled based on the blend constituents and composition. The doped membranes exhibited high conductivity values, in the range of 10−3 S/cm at room temperature which is increased at 2.5 × 10−2 S/cm at temperatures up to 180 °C. 相似文献
Newly designed PS/PEO alternating branched polymacromonomers have been obtained by polycondensation of alpha-dicarboxy-functionalized polystyrene and alpha-dihydroxy-functionalized polyethyleneoxide. 4-[3,5-Bis(methoxycarbonyl)phenoxymethyl]benzyl bromide was used as atom-transfer radical polymerization (ATRP) initiator for the synthesis of alpha-dicarboxy functionalized polystyrenes. These macromonomers possess low polydispersities and molecular weights in the range of 7000 to 100,000, as proved by gel permeation chromatography (GPC) and 1H NMR. Alpha-dihydroxy functionalized polyethyleneoxide (PEO) was synthesized by treatment of monofunctionalized PEO with 3,5-bis(benzyloxy)benzoyl chloride. Polycondensation of the alpha-dicarboxy PS with the alpha-dihydroxy PEO in solution or in bulk resulted in alternating PS/PEO polymacromonomers, which were effectively purified from the unreacted macromonomers and characterized by using 1H NMR, GPC, thermal analysis, and optical microscopy. Light-scattering measurements in organic solvents like THF or dioxane have shown that these polymacromonomers form stable micelles. 相似文献
Blends composed of sulfonated polysulfone (SPSF) and poly(ethylene oxide)-grafted-polyethersulfone (PEO-g-PES) in different compositions have been prepared and studied in terms of fuel cell relevant parameters like thermal behaviour, water uptake and ionic conductivity. Moreover, spectroscopic characterization (FT-IR) has also been conducted in order to elucidate their miscibility and to investigate the influence of polymer blending on the crystallinity level of the individual components. These blends exhibit very good mechanical properties, a very high water uptake and a high ionic conductivity (4 × 10−3 S/cm) at ambient temperatures and they are amorphous, a property that facilitates their use as polymer electrolytes in fuel cells. 相似文献
Summary: Novel poly(aryl ether sulfone) copolymers containing 2,5‐biphenylpyridine and tetramethyl biphenyl moieties were synthesized by polycondensation of 4‐fluorophenyl sulfone with 2,5‐(4′,4″ dihydroxy biphenyl)pyridine and tetramethyl biphenyl diol. Copolymers with different molecular weights and different monomer compositions were obtained. These copolymers exhibit excellent film‐forming properties, mechanical integrity, and high modulus up to 250 °C, high glass transition temperatures (above 280 °C) as well as high thermal stability up to 400 °C. In addition to the above properties required for PEMFC application, this novel material shows high oxidative stability and acid doping ability, enabling proton conductivity in the range of 10−2 S · cm−1 above 130 °C.
Synthesis of copolymers with high acid uptake and ionic conductivity. 相似文献