Monodisperse oligo(ethylene glycol)s were polycondensed with trimesoyl chloride using triethylamine as HCl acceptor. Despite nearly quantitative conversions and relatively high concentrations (0.4 mol/L), no gelation occurred with tri-and tetra(ethylene glycol), regardless of the feed ratio. With a feed ratio around 1.5/1.0 multicyclic poly(ether esters)s free of end groups were isolated and characterized by 1 H NMR and MALDI-TOF mass spectrometry. At concentrations of 0.2 or 0.4 mol/L di-, penta-, and hexa(ethylene glycol)s yielded gels. At concentrations g 0.2 mol/L exclusively gels were obtained from various R,ω-dihydroxyalkanes. However, soluble multicycles were obtained from 1,8-dihydroxy-3,6-dithiaoctane and from 1,4-bis(2-hydroxyethoxy)-2butyne. The influence of conformational differences on the cyclization tendency is discussed. The multicycles derived from tri-and tetraethylene glycol showed cryptand properties and dissolved Li-, Na-, K-, and Cs-benzoate in tetrahydrofuran.
Back Cover: Multicyclic aromatic poly(ether sulfone)s were prepared from tris(4-hydroxy phenyl)ethane and 4,4'difluoro-or 4,4'-dichlorophenylsulfone as relatively inexpensive examples of a new nanoarchitecture. Depending on the feed ratio, these multicyclic polyethers may contain OH or F(Cl) functional groups allowing for further modification or fixation on functional surfaces. Further details can be found in the Full Paper by M. Garaleh, C. Polefka, G. Schwarz, and H. R. Kricheldorf* on page 747.
Polycondensations of 4,4′‐difluorodiphenylsulfone with tris(4‐hydroxy phenyl)ethane were performed in DMSO with variation of feed ratio and concentration. For feed ratios of 1.0:1.3–1.0:1.5, soluble multicyclic poly(ether sulfone)s were obtained when the monomer concentration was below 0.05 M. The conversions were never complete under standard conditions, and doubling the reaction time yielded perfect multicyclic products free of endgroups; however, a small fraction of the product was crosslinked under these conditions. Quite similar results were obtained with 4,4′‐dichlorodiphenylsulfone at higher temperatures. When K2CO3 was replaced by tertiary amines, conversions and molecular weights were lower. The multicyclic poly(ether sulfone)s were characterized by MALDI‐TOF mass spectrometry, SEC, and DSC measurements. Broad molecular weight distributions with polydispersities in the range of 2.4–3.9 were found, and, surprisingly, two glass transitions were detectable in the DSC heating curves.magnified image
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