Isotactic poly(1‐hexene sulfone)s by stereoselective anionic ring‐opening polymerisation

Abstract

BACKGROUND: Poly(olefin sulfone)s have been shown to form helical regions and to display main-chain liquidcrystalline behaviour in the bulk when they possess long side-chains. It is believed that increasing the tacticity of the backbone could enhance their liquid-crystalline behaviour. This study aims to produce tactic poly(olefin sulfone)s by stereospecific ring-opening polymerisation.RESULTS: Tactic polythiranes were successfully obtained from a racemic mixture of thirane monomers using a series of chiral catalyst systems. The isotactic placement (P i ) was determined using 13 C NMR analysis of carbons in or near the backbone. The polysulfides were oxidised by peracetic acid to their corresponding polysulfones. Powder X-ray diffraction studies showed that the isotactic polysulfones formed more ordered structures than their atactic analogues, an effect attributed to a tightening of the helical pitch. CONCLUSIONS: Tactic poly(1-hexene sulfone)s have been prepared for the first time by stereoselective ringopening polymerisation.

Polymers and Sulfur: what are Organic Polysulfides Good For? Preparative Strategies and Biological Applications

“…It is worth mentioning that, in contrast to the “monomer route” (i.e., the use of sulfone‐containing monomers), at the beginning of the '70s a “polymer route” to polysulfones was proposed (Figure 3), which allowed to convert preformed aromatic polysulfides into the corresponding polysulfones by the help of hydrogen peroxide 59. Literature offers a number of later examples of this approach, which has been applied to the oxidation of aliphatic [such as poly(thietane),75 poly(ethylene sulfide)153, 154 and poly(hexene sulfide)155] and aromatic55, 57, 156 polysulfides to polysulfones. It is noteworthy that the “polymer route” may be the only way to produce main‐chain aliphatic polysulfones with the narrow MW dispersion typical of “living” chain polymerisation mechanisms, since the synthesis of sulfone‐contained strained rings (analogous to episulfides) is generally non‐trivial 157…”