A crystalline cyclic (aryl ether ketone) oligomer containing tetramethylbiphenylene moiety

A highly methyl-substituted cyclic (aryl ether ketone) oligomer was success fully synthesized by the reaction of 3,3',5,5'-tetramethyl-4,4'-biphenol (T MBPH) and 4,4'-difluorobenzophenone with the use of a pseudo- high dilution condition. The structure of the cyclic oligomer was characterized by IR, N MR, matrix-assisted laser desorption ionization time-of-flight mass spectro scopy and gel permeation chromatography analyses. From the measurement of w ide angle X-ray diffraction it was revealed that the cyclic oligomer is cry stalline, in contrast to the fact that the corresponding linear polymer is amorphous. The difference in the crystallization behavior is discussed base d on molecular modeling. (C) 1999 Elsevier Science Ltd. All rights reserved .