ISSN:
1435-1536
Keywords:
Poly(tetrahydrofuran)
;
urea-inclusions-complexes
;
fractionation
;
oligomers
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The synthesis of the urea channel inclusion complexes of poly(tetrahydrofuran)) (PTHF) is described. These complexes could be obtained in the form of single crystals forM n ≤ 1700 g/mol of PTHF as the guest, and they exhibit a hexagonal unit cell (a=8.20(2) Å,c=11.05(3) Å) very similar to the wellknown urea-n-alkane complexes. X-ray investigations, elemental analysis and density measurements suggest an all trans zig-zag conformation of the polymer chain. The formation of the complexes was exploited for the purpose of fractionation of PTHF, making use of the correlation between temperature of crystallization andM n of the included polyether chain. The distribution and the molecular weights of the fractions, obtained by extractive crystallization, were determined by reversed phase HPLC analysis and vapour pressure osmometry (VPO). Narrow fractions with Mw/Mn=1.02 were obtained from commercial PTHF samples. Successive fractionation was applied also on product mixtures from oligomer synthesis, as demonstrated for the separation of the dodecamer H-(o-(CH2)4-)12OH.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01412786
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