Preparation and characterization of cyclic poly(oxypropylene)

✍ Scribed by Ga-Er Yu; Prash Sinnathamby; Tao Sun; Frank Heatley; Colin Price; Colin Booth

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 424 KB
• Volume: 18
• Category: Article
• ISSN: 1022-1336
• DOI: 10.1002/marc.1997.030181212

✦ Synopsis

Abstract

Poly(propylene glycol) [α‐hydro‐ω‐hydroxypoly(oxypropylene)] of number‐average molar mass M̄~n~ ≈ 2000 g · mol^−1^ (PPG2000) was cyclised with high conversion (ca. 75%) by reaction with dichloromethane in the presence of powdered KOH. The cyclic product was separated from chain extended polymer by preparative GPC, giving an overall yield of polymer (M̄~n~ ≈ 2000 g · mol^−1^, narrow molar mass distribution) in excess of 50%. Characterisation by analytical GPC and ^13^C NMR spectroscopy confirmed cyclisation. DEPT and ^1^H‐coupled NMR spectra were used to show that the links in cyclic poly(oxypropylene) were 77% single acetal, 12% double acetal and 11% triple acetal (or higher). This complexity probably results from competitive reaction with water introduced with KOH.