Synthesis and ring-opening polymerization of macrocyclic aryl ketone oligomers

A series of macrocyclic aryl ketone oligomers were prepared by the reaction of phthaloyl dichloride or isophthaloyl dichloride with various bridge-linking electron-rich aromatic hydrocarbons 3a-d under pseudo-high dilution conditions in the presence of Lewis base via Friedel-Crafts acylation reaction. Detailed structural characterization of these oligomers confirmed the cyclic nature by a combination of MALDI-TOF-MS, GPC, and H-1 NMR analyses. These cyclic ketone oligomers have high solubility in organic solvents and the cyclic oligomers derived from phthaloyl dichloride are amorphous. The cyclic ketone oligomers readily undergo anionic ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator, producing linear, high molecular weight poly(ether ketone)s. Moreover, the isothermal chemorheology of the ring-opening polymerization of cyclic oligomers 4a and 4b was also investigated. The results show that the shear viscosity of the molten reactive mixture is lower than 10 Pa at a constant shear rate of 0.05 rad/sec and increases slowly in the initial stage of ring-opening polymerization. Copyright (C) 2009 John Wiley & Sons, Ltd.