Synthesis and curing behavior of alkyl-substituted poly(aryl ether ketone)s having a crosslinkable styryl group at chain ends

Crosslinkable alkyl-substituted poly(aryl ether ketone)s (PEKs) bearing a styryl group at both chain ends were synthesized by nucleophilic substitution reaction of 1,1′-(p-phenyl-enedioxy)bis[2-methyl-4-(4-fluorobenzoyl)benzene] with an excess aromatic diol in the presence of a base, followed by the reaction of the terminal phenol group with chloromethylstyrene. The aromatic diols used in this study were hydroquinone and resorcinol. The molecular weight of the polymer determined by GPC and ¹H NMR agreed with each other and close to the theoretical value calculated from the feed ratio. The polymer was soluble in N,N-dimethylacetamide and tetrahydrofuran, but insoluble in acetone and methanol. From DSC analysis, the polymer was thermally crosslinked around 220°C. The addition of dicumyl peroxide as a radical generator in the polymer decreased the curing temperature. The cured polymer showed high thermal stability up to 420°C under nitrogen. © 1997 John Wiley & Sons, Inc.     

Synthesis of linear and star-shaped phosphorus-containing telechelic polymers via living cationic ring-opening polymerization using a halobenzene/nickel(II) bromide catalyst

This paper reports a living cationic ring-opening polymerization of 2-phenyl-1,3,2-dioxaphosphorinane (a six membered cyclic phosphonite, 1) initiated by a new catalyst system of a halobenzene with NiBr₂. The polymerization proceeded in a living nature to produce a poly(phosphinate) 2. The polymerizations of seven-and five-membered cyclic phosphonites with this catalyst system are also described. The kinetic analysis of the polymerization of 1, initiated with this catalyst system, has successfully been carried out. The difference of the nature in the polymerizations of five-, six-, and seven-membered monomers is discussed. Syntheses of linear and star-shaped telechelic polymers using di-, tri-, tetra-, and hexahalobenzenes as a catalyst component are disclosed.     

Enzymatic polymerization to artificial hyaluronic acid using a transition state analogue monomer

Artificial hyaluronic acid has been synthesized in vitro via enzymatic polymerization catalyzed by testicular hyaluronidases, which is the first successful example of the hyaluronic acid synthesis via non-biosynthetic pathways. The novel GlcAβ(1→3)GlcNAc oxazoline derivative was designed and synthesized as a transition state analogue monomer for the hyaluronidase catalysis. The oxazoline monomer was efficiently recognized by the enzymes at pH 7.1 to 9.0 and the polymerization reaction proceeded in a regio- and stereo-selective manner to give rise to artificial hyaluronic acid with molecular weight higher than 15000. These results strongly suggest that the transition state of these testicular hyaluronidases catalysis corresponds to a sugar oxazolinium ion.     

Precision enzymatic polymerization to polyesters with lipase catalysts

Ring-opening polymerization of lactones with different ring-size has been achieved via lipase catalysis. Small-size (4-membered) and medium-size lactones (6- and 7-membered) as well as macrolides (12-, 13-, 16-, and 17-membered) were subjected to the lipase-catalyzed polymerization. The polymerization behaviors strongly depended on the lipase origin and the ring-size of the lactones. In using Pseudomonas family lipases as catalyst, the polymerization of macrolides showing much lower anionic polymerizability proceeded much faster than that of ϵ-caprolactone. The enzymatic polymerizability of the lactones was evaluated by Michaelis-Menten kinetics. V_max increased as a function of the ring-size, whereas K_m values were not so different with each other. The granular immobilized lipase derived from Candida antarctica. showed the extremely efficient catalysis in the polymerization of ϵ-caprolactone. Single-step synthesis of methacryl- and ω-alkenyl-type polyester macromonomers was achieved by the lipase-catalyzed polymerization of 13-membered lactone in the presence of vinyl esters acting as terminator. Lipase also catalyzed a polycondensation of dicarboxylic acid and glycol in the aqueous medium, in which the dehydration took place in water.     

New crystalline polymers: poly(2,5‐dialkyl‐1,4‐phenylene oxide)s

New heat‐reversibly crystalline poly‐(alkylated phenylene oxide)s are described. the oxidative polymerization of 2,5‐dimethylphenol catalyzed by (1,4,7‐triisopropyl‐1,4,7‐triazacyclononane) copper dichloride produced poly(2,5‐dimethyl‐1,4‐phenylene oxide), which showed heat‐reversible crystallinity with a high melting point at ca. 300°C, although the isomeric polymer, poly(2,6‐dimethyl‐1,4‐phenylene oxide), never recrystallizes once melted. The polymerization of 2,5‐diethylphenol and 2,5‐dipropylphenol gave the polymers consisting of 1,4‐phenylene oxide units; the latter polymer possessed heat‐reversible crystallinity, however, the former one did not.     

A new crosslinkable polyphenol from a renewable resource

Cardanol, a major component obtained by thermal treatment of cashew nut shell liquid, is a phenol derivative mainly having a C15 unsaturated hydrocarbon chain with 1–3 double bonds at the m‐position. We polymerized cardanol using an Fe‐salen complex as the catalyst to give a soluble polyphenol containing the unsaturated alkyl group in the side chain. The polymer was subjected to hardening by a cobalt naphthenate catalyst or thermal treatment, yielding crosslinked film with high gloss surface.