Stereoregulation in cationic polymerization. III. High isospecificity with the bulky phosphoric acid [(RO)2PO2H]/SnCl4 initiating systems: Design of counteranions via initiators
✍ Scribed by Makoto Ouchi; Masanori Sueoka; Masami Kamigaito; Mitsuo Sawamoto
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 200 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0887-624X
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✦ Synopsis
In the cationic polymerization of isobutyl vinyl ether (IBVE) with binary initiating systems consisting of a protonic acid as an initiator and a Lewis acid as an activator/catalyst, phosphoric acid derivatives [(RO) 2 POOH] coupled with SnCl 4 gave highly isotactic poly(IBVE)s, whereas those with a bulky substituent (R), [C 4 H 9 CH(C 2 H 5 )CH 2 O] 2 POOH ( 7) and (n-C 10 H 21 ) 2 POOH (8), led to the highest isotacticity [meso dyad (m) ϭ 86%]. In contrast, isospecificity was lower with IBVE-HCl and CF 3 COOH under the same conditions. From the effects of the polymerization temperature (Ϫ78 to 0 °C), it was concluded that the high isospecificity with 7 and 8 was due to an enthalpic factor.