Novel thermally crosslinkable fluorine‐containing poly(arylene ether ketone)s comprised of 2,3,5, 6‐tetrafluoro‐1,4‐phenylene moiety were synthesized by the termination of polymer chain ends with propargyl ether groups in order to improve solvent resistance. Crosslinking reaction occurred over 250°C through the formation of both chromen ring and polyene structure. This structure change brought about not only the outstanding solvent resistance but also the increase in glass transition temperature (Tg). The cured films also exhibited excellent thermal stability, transparency and hydrophobicity derived from fluorine atoms. Copyright © 2004 John Wiley & Sons, Ltd.
Fluorine‐containing poly(aryl ether 1,3,4‐ozadiazole)s were synthesized by the nucleophilic aromatic substitution reaction of 2,5‐bis(2,3,4,5,6‐pentafluorophenyl)‐1,3,4‐oxadiazole and various bisphenols in the presence of potassium carbonate. The polymerizations were carried out at 30 °C in 1‐methyl‐2‐pyrrolidinone to avoid the gelation caused by a crosslinking reaction at para and ortho carbons to the 1,3,4‐oxidiazole ring. The obtained polymers were all para‐connected linear structures. The obtained fluorine‐containing poly(aryl ether 1,3,4‐ozadiazole)s showed excellent solubility and afforded tough, transparent films by the solution‐casting method. They also exhibited a high glass transition temperature depending on the molecular structure, and the glass transition temperature could be controlled by the bisphenols in the range of 157–257 °C. They showed good thermal stability and excellent hydrophobicity due to the incorporation of the 2,3,5,6‐tetrafluoro‐1,4‐phenylene moiety. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2855–2866, 2007
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
ABSTRACT:2,3,4,5,6-Pentafluorobenzonitrile (PFBN) is a valuable intermediate and it is available as a commercial product. In this paper, synthesis and characterization of novel fluorinated poly(ether nitrile)s (PEN) derived from PFBN is reported. Novel fluorinated PENs containing fluorine atoms in the main chain and pendant phenoxy group (2F-PEN) are synthesized by aromatic nucleophilic substitution reaction, of which M0 ranges from 1.77 X 10 4 to 5.16 X 104. The obtained PENs show excellent solubilities in common solvents, and 2F-PEN(6FBA) and 2F-PEN(DPE) can be cast as tough transparent films. These polymers have high thermal stabilities with the 5% weight loss temperature in the range 509-5620C and the Tg of 142-235°C, which is highly dependent on the structures.KEY WORDS Poly(ether nitrile) / Fluorine-Containing Polymer I 2,3,4,5,6-Pentafluorobenzonitrile / Nucleophilic Aromatic Substitution/ Thermal Stability/ High Tg I Solubility/ The high-performance fluorinated polymers have been receiving considerable attention as interesting advanced materials for applications as films, coatings for optical and microelectronics devices, gas separation membranes and so on. 1 -3 The incorporation of fluorine atoms into polymer chains leads to polymers with increased solubility, flame resistance, thermal stability and glass transition temperature, while also leading to decreased color, crystallinity, dielectric constant and moisture absorption. Owing these advantages, poly(aryl ether ketone)s (PEK) containing hexafluoroisopropylidene units had been prepared and studied for use in aerospace and electronic applications. 4 Recently, PEKs containing 2,3,5,6-tetrafluoro-l,4-phenylene moieties were synthesized from perfluorobenzophenone. 5 2,3,4,5,6-Pentafluorobenzoic acid (PFBA) is a valuable intermediate for pharmaceuticals, pesticides, perfumes, cosmetics and so on, and it is available as a commercial product. The authors had reported the synthesis and characterization of novel fluorinated PEKs containing 2,3,5,6-tetrafluoro-1,4-phenylene moieties derived from PFBA. 6 • 7 These fluorinated PEKs showed excellent thermal stability and solubility into common organic solvents. Moreover, the films of these PEKs possess outstanding transparency and low dielectric constants. Therefore they are expected to use a optical and electronic materials and the application study is currently underway.2,3,4,5,6-Pentafluorobenzonitrile (PFBN) is a raw material of PFBA and its commercial availability is much higher than PFBA. 2,6-Difluorobenzonitrile is commonly used as a monomer for poly(ether nitrile)s (PEN) 8 and other types of fluorinated PENs had been previously synthesized from 2,4,5,6-tetrafluoroisophthalonitrile and bisphenols by interfacial polycondensation. 9 However, polymers derived from PFBN have not be reported 290 to our knowledge. In this paper, synthesis and characterization of novel fluorinated PEN derived from PFBN is reported.
ABSTRACT:Fluorine-containing poly(aryl ether ketone)s (PEKs) derived from 2,3,4,5,6-pentafluorobenzoic acid (PFBA) exhibit outstanding solubility, thermal stability, low dielectric constant, low moisture absorption and high transparency. Hence, they are expected to be available for optical and electric materials. In such applications, excellent solubility is of great advantage for making thin film and coating. Contrary to this advantage, this is of disadvantage from a point of solvent resistance. Thermally cross-linkable fluorine-containing PEKs terminated with phenylethynyl moiety (PEK-PEP) are synthesized to improve the solvent resistance in this study. Cross-linking reaction occurs over 320• Cand it brings about not only the outstanding solvent resistance but also the increase of T g . Relationship between the cross-linking density and T g can be fundamentally interpreted by configurational entropy theory. Furthermore, the cured PEK-PEPs possess excellent thermal stability with the 10% weight loss temperature in the range from 544 to 598• C.
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