| 摘要 |
<p>High molecular weight (Mw > 25,000, preferably > 50,000; ninh up to 3) linear atactic poly (3-hydroxyoxetane) (PHO) are made by polymerizing the trimethylsilyl ether of 3-hydroxyoxetane with a coordination catalyst, or preferably with a cationic catalyst such as i-Bu3Al-0.7 H2O, followed by hydrolysis. The new polymer is atactic, highly crystalline, has a melting point of 155<o>C, is devoid of measurable end groups, has a two-peak <1><3>C-NMR, and can be readily compression molded at 200<o>C to a film which can be drawn at room temperature to give enhanced strength. Isotactic high molecular weight PHO(mp = 223<o>C; DELTA Hf = 25.6 cal/g) and branched high molecular weight PHO are also prepared.</p> |
