Copoly THF-Oxirane Diols

Linear strictly bifunctional oligomers of THF with molecular weights close to 1000 or 2000 and having two terminal OH groups are prepared in bulk with strong protonic acids (cf. Sect. 6.2). These oligomers are mostly used as soft segments in block copolymers made by polycondensation with diisocyanates or with 1,4-alkylene (ethylene, butylene) terephthalates. 

2-Propylene oxide PO was mostly used as comonomer in the preparation of bifunctional THF copolymers by direct copolymerization process. The required products must have a sufficiently low m.p., uniform structure and the functionality equal to two. It is also desirable to have the same OH end groups, either primary (preferentially) or secondary. 

In this section we first describe the major findings of the copolymerization of THF with 1,2-propylene oxide and then a practical method published by Futamura32 for the synthesis of the bifunctional copolymer of THF and PO. 

THF-PO copolymers obtained by various methods differ in several properties. 

In off-resonance decoupled spectra these C atoms give a distinguishable doublet and a triplet, respectively. The CH2CH2OH end-group (THF as a terminal unit) wasabsent. The ratio between secondary and primary end-groups was independent of Mn and was close to 2 1. 

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