Tri‐block copolymers of polyethylene glycol and hyperbranched poly‐3‐ethyl‐3‐(hydroxymethyl)oxetane through cationic ring opening polymerization |
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| Authors: | Martin Rahm Robert Westlund Carina Eldsäter Eva Malmström |
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| Institution: | 1. Department of Physical Chemistry, Royal Institute of Technology (KTH), Stockholm SE‐100 44, Sweden;2. Competence Centre for Energetic Materials (KCEM), Gammelbackav?gen 6, Karlskoga SE‐691 51, Sweden;3. Department of Fiber and Polymer Technology, Royal Institute of Technology (KTH), Stockholm SE‐100 44, Sweden;4. Division of Weapons and Protection, Swedish Defense Research Agency (FOI), Tumba SE‐147 25, Sweden |
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| Abstract: | Tri‐block copolymers of linear poly(ethylene glycol) (PEG) and hyperbranched poly‐3‐ethyl‐3‐(hydroxymethyl)oxetane (poly‐TMPO) are reported. The novel dumb‐bell shaped polyethers were synthesized in bulk with cationic ringopening polymerization utilizing BF3OEt2 as initiator, via drop‐wise addition of the oxetane monomer. The thermal properties of the materials were successfully tuned by varying the amount of poly‐TMPO attached to the PEG‐chains, ranging from a melting point of 54 °C and a degree of crystallinity of 76% for pure PEG, to a melting point of 35 °C and a degree of crystallinity of 12% for the polyether copolymer having an average of 14 TMPO units per PEG chain. The materials are of relatively low polydispersity, with Mn/Mw ranging from 1.2 to 1.4. The materials have been evaluated for usage with the energetic oxidizer ammonium dinitramide. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6191–6200, 2009 |
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| Keywords: | ADN ammonium dinitramide cationic polymerization oxetane polymerization polyether thermal properties TMPO |
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