New Class Of High-performance Polymers Research Articles

Poly(arylene benzimidazole)s as novel high-performance polymers

Series of novel poly(arylene benzimidazole)s (PABIs) was obtained by condensation polymerization of aromatic bifluorides with the monomers of di(benzimidazolyl)benzenes (synthesized by reaction of the isomeric phthalic acids with o-phenylenediamine) via a C–N coupling reaction. The structures of this series of polymers were characterized by Fourier transform infrared, proton nuclear magnetic resonance (1H NMR) spectroscopy and elemental analysis, and the results showed good agreement with the proposed structures. These synthesized polymers exhibited relatively high glass-transition temperatures (Tg>240 °C), good thermal stability with high decomposition temperatures (Td>450 °C) and excellent solubility in organic solvents. On the atomic scale, the molecular simulation results indicated that the PABI polymers exhibited a zigzag molecular chain structure with a high free volume fraction due to the different linkage modes of the monomers in the polymerization process. On the macro level, the PABI polymers possessed high tensile strength with good toughness; the mechanical behavior of the PABI polymers indicates that they can be considered a new class of high-performance polymers. Series of novel PABIs have been obtained by the condensation polymerization of aromatic bifluorides with di(benzimidazolyl)benzenes via a C–N coupling reaction. PABI exhibited zigzag molecular chain structure with a high free volume fraction, and they showed relatively high glass-transition temperatures (Tg>240), good thermal stability with high decomposition temperatures (Td>450) and excellent solubility in organic solvents. The mechanical behavior of the PABI polymers suggested that they can be considered as a new class of high-performance polymers.

Fluorinated poly(aryl thioether)s and poly(aryl sulfone)s derived from 2,3,4,5,6-pentafluorobenzoic acid

Poly(aryl thioether)s (F-PTEs) containing 2,3,5,6-tetrafluoro-1,4-phenylene moiety and polar moiety, such as 1,3,4-ozadiazole, ether ketone, and amide groups, were synthesized by nucleophilic aromatic substitution reaction of aryl fluorides and 4,4′-thiobisbenzenthiol. F-PTEs were amorphous with good thermal properties including high glass transition temperature (Tg) and thermal stability, solubility, and hydrophobicity. F-PTEs were transformed into poly(aryl sulfone)s (F-PSs) by the oxidation reaction with hydrogen peroxide in acetic acid. Because of the sulfone group, the Tgs of the F-PSs were 30–40°C higher than those of the corresponding F-PTEs. F-PSs maintained solubility in polar aprotic solvents and exhibited hydrophobicity in spite of the content of polar sulfone groups due to the highly substituted fluorine atoms. These F-PTEs and F-PSs were a new class of high-performance polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Synthesis and gas permeability of novel fluorinated poly(phenylene-co-naphthalimide)s

A new class of high-performance polymers [poly(phenylene-co-naphthalimide)s] was prepared through the Ni(0) catalytic coupling of N-(4-chloro-2-trifluromethylphenyl)-5-chloro-1,8-naphthalimide and 2,5-dichlorobenzophenone. The resulting copolymers exhibited high molecular weights (high inherent viscosities) and a combination of desirable properties such as good solubility in dipolar aprotic solvents, film-forming capability, and mechanical properties. The glass-transition temperatures of the copolymers ranged from 320 to 403 degrees C and increased as the content of the naphthalimide moiety increased. Tough polymer films, obtained via casting from N-methylpyrrolidone solutions, had tensile strengths of 64-107 MPa and tensile moduli of 3.4-4.7 GPa. The gas permeability coefficients of the copolymers were measured for H-2, CO2, O-2, CH4, and N-2. They showed oxygen permeability coefficients and permeability selectivity of oxygen to nitrogen (permeability coefficient for O-2/permeability coefficient for N-2) in the ranges of 1.39-4.31 and 4.92-5.38 barrer, respectively.

Reduction of the optical loss and optimization of polycyanurate thermosets used in integrated optics

The current infrastructure of the communication has to be expanded rapidly due to the dramatic increase of data, that is transferred via the internet. The optical network technology is the most suitable technology for this demand. Not only glass fibres are required, but also a broad range of optical components like splitters, switches and multiplexers, which are usually produced in silica technology. Polymeric materials are becoming more and more interesting for these applications, since they e.g. promise lower power consumption and lower production costs than their silica based pendants. Polycyanurate ester resins are a relatively new class of high-performance polymers with outstanding properties, for example high thermal stability, low optical loss, low dielectric constant, good adhesion and amazing mechanical properties. This paper focuses on the optical loss of such materials at 1550 nm, in the optimisation for use in integrated optics and for the production of embedded waveguides.

Conformational and electronic band structure analysis of a new type of high performance polybenzothiazole polymers

The energy-band structure and preferred (minimum energy) conformation of the recently synthesized polybenzothiazoles (PBT; AA and AB type), representing a new class of high-performance polymers, were determined by molecular orbital calculations. In the case of the AAPBT chain, the most stable conformation was obtained atφ1 (rotation angle about the bond joining the two bibenzothiazole moieties) = 20° andφ2 (rotation angle about the bond joining the bibenzothiazole group and thep-phenylene group) = 10°. In the case of the ABPBT chain, the corresponding minimum energy rotational angle (φ′) was found to be 20°. These conformations agree fairly well with both theoretical and experimental observations. The calculated axial band gaps were 1.94 and 2.08 eV for the AAPBT and ABPBT polymers, respectively, and these values are close to the corresponding value for polyacetylene, considered a prototype electrically-conducting polymer because of its novel electronic properties and manifold applications.