Poly(ether-sulfone)s having an identical backbone were prepared by four different methods. First, silylated bisphenol A (BSBA) was polycondensed with 4,4′-difluorodiphenyl sulfone (DFDPS) and K 2CO3 in N-methylpyrrolidone with variation of the temperature. Second, analogous polycondensation were conducted using CsF as catalyst (and no K2CO3). Third, CsF-catalyzed polycondensations BSBA and DFDPS were conducted in bulk up to 290°C. Fourth, free bisphenol was polycondensed with DFDPS or 4,4′-dichlorodiphenyl sulfone and K2CO3 in DMSO with azeotropic removal of water. MALDI-TOF mass spectroscopy revealed that the first method mainly yielded cyclic poly(ether-sulfone)s which were detected up to masses around 13 000 Da. These and other results suggest that these polycondensations take a kinetically kontrolled course at tempeatures e145°C. This interpretation is also valid for the fourth method where high yields of cycles were obtained with DFDPS. With the less reactive 4,4′-dichlorodiphenyl sulfone lower conversions, lower molecular weights and lower fractions of cycles were found. In contrast to KF (resulting from K 2CO3) CsF cleaves the poly(ether sulfone) backbone at temperatures > 145°C. Smaller amounts of smaller cycles were found in these CsF-catalyzed polycondensations which were in this case the result of thermodynamically controlled "back-biting degradation".

Two series of kinetically controlled polycondensations were conducted yielding polyamides of aliphatic dicarboxylic acids. First, the bis(trimethylsilyl) derivatives of 1,3-diaminobenzene, 4,4‘-diaminodiphenylmethane, 1,12-diamino-4,9-dioxadodecane, and 1,12-diaminododecane were polycondensed with dicarboxylic acid dichlorides in N-methylpyrrodidone below 0 °C. After optimization of the reaction conditions mainly cyclic polyamides were detectable in the MALDI−TOF mass spectra (up to 13 000 Da) of the semiaromatic polyamides in contrast to the Carothers−Flory theory. In the case of silylated aliphatic diamines, side reactions of the acid chlorides prevented a complete conversion of the amino groups, so that the reaction products mainly consisted of cycles and linear chains having two amino end groups. Second, normal interfacial polycondensations were performed either with 1,6-diaminohexane and adipoyl chloride or with 1,12-diaminododecane and decane-1,10-dicarbonyl chloride. When the loss of acid chloride groups by hydrolysis was compensated by an excess of dicarboxylic acid dichlorides cyclic polyamides were again the main reaction products up to masses of 4000−5000 Da. A new version of the “Carothers equation” taking into account the role of cyclization in kinetically controlled step-growth polymerizations is discussed.

The hydrolytic polycondensation of bisphenol‐A bischloroformate in NaOH/CH2Cl2 was studied using triethylamine as the catalyst. Reaction conditions were optimized towards high molar masses. The isolated polycarbonates were characterized by means of SEC and MALDI‐TOF mass spectrometry. The fraction of cyclic polycarbonates strongly increased with higher molecular weights and in the best sample only cycles were detectable (up to 50 000 Da). The largest cycles can compete with cyclic DNS of microorganisms.

Interfacial polycondensations of bisphenol A with triphosgene were conducted in the CH2Cl2/aqueous NaOH system. Four different catalysts were compared:  triethylamine, triethylbenzylammonium chloride (TEBA-Cl), tetrabutylammonium hydrogen sulfate, and tetraphenylphosphonium chloride. Triethylamine yielded mixtures of cyclic polycarbonates and OH-terminated polycarbonates. The fraction of cycles and the molecular weights increased with lower concentrations of this catalyst. When the pseudo-high-dilution method was applied, samples containing ≥95 mol % of cycles were obtained, and the average molecular weights were varied over a broad range via the feed ratio of triethylamine. Fractionation of one sample allowed the detection of cyclic polycarbonates up to 28 000 Da. The three phase transfer catalysts gave quite different product mixtures when compared under identical conditions. The highest fraction of cycles and the highest molecular weights were obtained with Ph4PCl. The fraction of cycles increased with higher feed ratios of Ph4PCl in contrast to triethylamine. Bimodal mass distributions were found for all samples with a high content of cyclic polycarbonates, whereas the frequency distributions were monomodal.

The phosgenation of bisphenol A with diphosgene in the CH2Cl2/NaOH system was studied using the pseudo‐high‐dilution method either with triethylamine, with triethylbenzyl ammonium chloride (TEBA‐Cl), or with tetraphenylphosphonium chloride as catalyst. For Ph4PCl, only low‐molecular‐weight polycarbonates containing various by‐products were obtained. With the TEBA catalyst, the fraction of cycles and the average molecular weights increased with higher feed ratios of the catalyst. Both the fraction of cycles and the molecular weights steeply decreased at higher temperatures. With triethylamine as catalyst both the fraction of cycles and molecular weight passed through a maximum at low catalyst concentration, when the feed ratio of triethylamine was varied. Higher temperatures favored slightly lower fractions of cycles and lower molecular weights. Samples containing ≥ 95 mol‐% of cycles were obtained. The cycles were identified by matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry up to 22 000 Da in the case of virgin samples, and up to 55 000 Da after fractionation by size exclusion chromatography (SEC). Selected samples were characterized by SEC measurements and evaluated by the triple‐detection method. High polydispersities and a tendency towards a bimodal mass distribution were found, when triethylamine was used as catalyst.