Synthesis, Characterization, and Intramolecular End-to-End Ring Closure of α-Isopropylidene-1,1-dihydroxymethyl-ω-diethylacetal Polystyrene-block-polyisoprene Block Copolymers
✍ Scribed by Michel Schappacher; Alain Deffieux
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 139 KB
- Volume
- 203
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Abstract
Cyclic polystyrene‐block‐polyisoprenes of controlled dimensions have been synthesized for the first time by the direct coupling of α‐isopropylidene‐1,1‐dihydroxymethyl‐ω‐diethylacetal‐heterodifunctional linear polystyrene‐block‐polyisoprene precursors previously prepared by living anionic polymerization. Cyclization is achieved under high dilution by intramolecular coupling of the polymer ends under acid catalyst conditions. Using this strategy polystyrene‐block‐polyisoprene macrocycles of controlled chain dimensions are prepared in high yield (> 90%). Pure cycles were finally recovered by flash chromatography. The synthesis and characterization of both the linear α,ω‐heterodifunctional polystyrene‐block‐polyisoprenes block copolymers precursors and of the corresponding cyclized chain architectures are reported.
200 MHz ^1^H NMR spectrum (CDCl~3~) of cyclized polystyrene‐block‐polyisoprene copolymer (M~n~ = 12 000).
magnified image200 MHz ^1^H NMR spectrum (CDCl~3~) of cyclized polystyrene‐block‐polyisoprene copolymer (M~n~ = 12 000).