Macrocycles 32. Syntheses of Cyclic Poly(Ether Ketone)s of Bisphenol-A

Abstract

%!3484& Two classes of poly(ether ketone)s were prepared from bisphenol-A, namely by polycondensation with 11 1 1 -difluorobenzophenone or with 2,6-difluorobenzophenone and 1 1 -tert.butyl-2,6-difluorobenzophenone. Two different synthetic methods were compared. First, polycondensations of the free bisphenol-A in DMSO or sulfolane with azeotropic distillation of water. Second, polycondensations of bistrimethylsilyl bisphenol-A in 2-methylpyrrolidone. The second approach gave higher yields and higher molecular weights (31 values up to 85000 Da and 32 values up to 190000 Da). The matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectra revealed that the fraction of cyclic oligomers and polymers systematically increased with higher molecular weights. A few polycondensations of silylated 4-tert.butylcatechol with 11 1 1 -difluorobenzophenone confirmed the trends observed for silylated bisphenol-A. Under optimum conditions cyclic poly(ether ketone)s were detectable in the MALDI-TOF mass spectra up to molecular weights of 18 000 Da.'$ (83& Polycondensation, poly(ether ketone)s, cyclic polymers, bisphenol-A, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) !"#!Quite recently we have demonstrated [1-4] that the classical theory of step-growth polymerizations as it was elaborated by Carothers [5] and Flory [6, 7] is partially misleading because it ignores the role of cyclization reactions. In agreement with the calculations of Stepto and coworkers [8] or Gordon and coworkers [9] it was found that in kinetically controlled polycondensations (no equilibration reactions) cyclization competes with chain growth at any concentration (also in bulk) and at any stage of the polycondensation. Therefore, a clean polycondensation conducted up to 100% conversion should yield 100% cyclic reaction products.

Synthesis and characterization of organo‐soluble poly(ether ether ketone)s and poly(ether ether ketone ketone)s containing pendant pentadecyl chains

“…It is well known that conventional poly(ether ether ketone) derived from bisphenol‐A and 4,4′‐difluorobenzophenone can not be dissolved in common organic solvents. 42 In sharp contrast, the PEEKs and PEEKKs containing pendant pentadecyl chains reported in the present study were soluble in common organic solvents such as chloroform, dichloromethane, tetrahydrofuran, and pyridine at room temperature. All polymers were soluble upon heating in polar aprotic solvents such as N , N ‐dimethylacetamide, 1‐methyl‐2‐pyrrolidinone and N , N ‐dimethylformamide.…”

Structural Analysis of Linear PEEK via MALDI-TOF Mass Spectrometry

“…Figure shows a smoothed representation of the MALDI-TOF mass spectra obtained, listing only the main ion peaks. The isotopic distributions obtained experimentally by this technique were in good agreement with the predicted values, as demonstrated for the trimer, tetramer, and pentamer in Figure …”

“…This method, while useful, is an indirect way of characterizing the polymer that requires an extra synthetic step with harsh reaction conditions, in particular the use of the strong acid TFA. MALDI-TOF mass spectrometry has also been used for the analysis of cyclic PEEK oligomers that are soluble in common organic solvents …”

Reversible, Nondegradative Conversion of Crystalline Aromatic Poly(ether ketone)s into Organo-Soluble Poly(ether dithioketal)s

“…This experiment again confirms that the dithioketalization of PEEK is complete and free from cross-linking or chain degradation and that the molecular weight calculated by GPC is representative of the materials. There are a few examples of chain-end analysis by MALDI-TOF MS of poly(ether ketone)s, supporting the exclusive formation of cyclic polymers during step-growth polymerization under strict kinetic conditions . However, these studies were limited to amorphous, soluble polyketones, and the indirect characterization of dithioketal derivatives might extend the scope of the materials examined.…”