Preparation of urea-poly(tetrahydrofuran) complexes and their application for fractionation of oligomers

Abstract

Abstract:The synthesis of the urea channel inclusion complexes of poly(tetrahydrofuran) 3) (PTHF) is described. These complexes could be obtained in the form of single crystals for Mn < 1700 g/tool of PTHF as the guest, and they exhibit a hexagonal unit cell (a = 8.20(2) it, c= 11.05(3) A) 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 and M. 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 MwJMn = 1.02 were obtained from commercial PTHF samples.Successive fractionation was applied also on product mixtures from otigomer synthesis, as demonstrated for the separation of the dodecamer H-(o -(CH2)4 -)12OH.

Polyurethane Urea Elastomer Having Monodisperse Poly(oxytetramethylene) as a Soft Segment with a Uniform Hard Segment

“…Materials. Monodisperse PTMG was prepared by fractionation of commercial PTMG (PTG 1000SN, Hodogaya Chemical Co. Ltd.) according to the literature . Polydisperse PTMG (Terathane 2000) was obtained from DuPont Chemical Co. Other reagents are commercially available and used as received.…”