Synthesis of Wholly Aromatic Polyketones

Abstract

The structural design strategy and the synthetic approaches for the wholly aromatic polyketones and the monomers are described. Electrophilic aromatic aroylation substitution polycondensation and aromatic coupling polycondensation have been investigated as synthetic routes for wholly aromatic polyketones by the author's group. Acyl-acceptant arene molecules as the electrophilic aromatic aroylation substitution polycondensation type monomers and the aromatic nuclei for bis(chlorobenzoylated) compounds as the aromatic coupling polycondensation one were designed and synthesized employing 2,2 0 -dioxybiphenyl, 2,2 0 -dioxy-1,1-binaphtyl, and o-terphenyl skeletons. Determining factors for monomers, which enable regioselective polycondensation, are also discussed. The properties of polyketones are also discussed briefly on the basis of polymer repeating unit structures. Aromatic polyketones are a group of aromatic polymers having ketonic carbonyl groups as the major linkage in the aromatic polymer main chain. Though there have been reported many examples of aromatic polyketones, almost all of them belong to the category of ''aromatic poly(ether ketone)s.'' [1][2][3][4][5] In fact, the term ''aromatic polyketone'' is generally apt to be regarded identical to ''aromatic poly(ether ketone).'' As a representative material of this category of aromatic polymer, PEEK Ò (1), a poly(ether ether ketone), is well-known super engineering plastics showing superior thermal stability, mechanical strength, and chemical resistance. Figure 1 shows the structure of PEEK Ò (1). The repeating unit of the polymer is composed of three 1,4-phenylene moieties bonded with two ether linkages and one ketonic carbonyl group. The structure suggests that PEEK Ò (1) might have properties more attributable to aromatic ether rather than aromatic ketone.On the other hand, aromatic polymers that have main chain structure composed of only aromatic rings and ketonic carbonyl groups are another type of aromatic polyketones (Figure 2). 6 The authors' group has been investigating the synthesis of aromatic polyketones free from main chain hetero linkages, wholly aromatic polyketones, during recent one and a half decades. Contrary to aromatic poly(ether ketone)s, wholly aromatic polyketones were seldom reported before.Prior to discussion of synthetic chemistry of wholly aromatic polyketones, the overview of aromatic polyketones including aromatic poly(ether ketone)s is briefly summarized to discriminate between aromatic poly(ether ketone)s and wholly aromatic polyketones.Aromatic polyketones are obliged to have copolymer structure composed of aromatic rings and ketonic carbonyl groups. From this point, aromatic polyketones are regarded as polyarylenes bearing inserted carbonyl groups. These polymers are classified into wholly aromatic polyketones or others according to the absence or presence of hetero linkages in the main chain. Aromatic poly(ether ketone) is the representative polymer of the latter type.As a natural consequence of the structural characterist...

Palladium-Catalyzed Homo- and Copolymerization of Polar Monomers: Synthesis of Aliphatic and Aromatic Polymers

“…Thus, our next goal was the copolymerization of aryne equivalents with carbon monoxide to produce aromatic polyketones/polyketals. 97 Although aromatic polyketones, 98,99 bearing main chains consisting of alternating arylene and carbonyl groups, are important as superengineering plastics, 100102 the range of accessible ones is narrow. In particular, aromatic polyketones bearing o-arylene units have been elusive.…”

Synthesis of High Molecular Weight Polyetherethersulfone‐Allyl Copolymers of Controlled Glass Transition

“…The latter is now the main method used, and is performed at high temperature (180 °C) in DMAc . The synthetic route involving the Friedel–Crafts polycondensation suffers from low reactivity and poor selectivity compared to nucleophilic aromatic substitution …”

“…[ 10 ] The synthetic route involving the Friedel-Crafts polycondensation suffers from low reactivity and poor selectivity compared to nucleophilic aromatic substitution. [ 11 ] A PEES copolymer in which double bonds were regularly inserted along the backbone was recently developed by our group, and can be synthesized either by using acyclic diene metathesis polymerization or regular polycondensation reaction. [ 12 ] This double bond is easily modifi ed, and can provide an alternate route to the direct modifi cation of PES on aromatic ring, [13][14][15][16] or to modifi cation via copolymerization with other polymeric blocks.…”

Synthesis and properties of novel poly(aryl ether ketone)s containing both 2,6‐naphthylene moieties and amide linkages in the main chains

“…PEEK) suffer from poor creep behavior above their relatively low glass transitions, the synthesis of novel semicrystalline PAEKs with increased T g is of high interest. The introduction of a variety of stiff and bulky groups such as biphenyl or naphthalene into the polymer backbone is one of the common approaches for increasing T g because it offers good advantages concerning the stability and thermal resistance of the resulting polymer . The copolymerization of PEEK was also investigated in order to improve its glass transition temperature ( T g ), and processability at high temperatures, and to obtain low‐cost materials, but the improvement of T g is not so marked for those reported PEEK copolymers.…”

“…The introduction of a variety of stiff and bulky groups such as biphenyl or naphthalene into the polymer backbone is one of the common approaches for increasing T g because it offers good advantages concerning the stability and thermal resistance of the resulting polymer. [24][25][26][27][28][29] The copolymerization of PEEK was also investigated in order to improve its glass transition temperature (T g ), and processability at high temperatures, and to obtain low-cost materials, [30][31][32][33] but the improvement of T g is not so marked for those reported PEEK copolymers. Shibata et al [34] reported the synthesis of the block copolymers of the PEEK and the poly(aryl ether sulfone) containing biphenylene moieties (PEBS).…”