Cyclic polyarylates

The polymerization of cyclic low-molar-mass polycarbonates, polyarylates, and PBT to high-molar-mass thermoplastics has been extensively studied by the General Electric Company during the last decade.57,58 Due to very low viscosity, cyclic oligoesters can be processed like thermosetting resins but retain thermoplastic properties in the final state, after polymerization in the presence of suitable... 

Guggenheim, et al demonstrated that the cyclic arylates can be polymerized at elevated temperature (360° C) in the presence of an anionic initiator. The polymerization of a cyclics/polymer mixture, which has a lower melting point, can be carried out at a somewhat lower temperature. The individual cyclics melt at about 385° C with polymerization occurring, even in the absence of catalyst. Polymerization leads to polyaiylates with wt. avg. MW of about 40-60,000, and the expected glass transition temperatures (bisphenol A polyarylate, Tg = 167° C, spirobiindane polyarylate, Tg = 242° C). 

The propensity of this bisphenol to form high yields of cyclic macromers exhibits itself in the condensation reaction of i with 4,4 -dihalo substituted diphenylketones and diphenylsulfones to produce cyclic etherketones and ethersulfones. Polymerization of the polyarylate, polyetherketone and polyethersulfone macromers can also be accomplished in the presence of anionic initiators to produce linear polymers. 

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