Synthesis and characterization of high molecular weight polyrotaxanes: towards the control over a wide range of threaded α-cyclodextrins.

Fleury, Guillaume; Brochon, Cyril; Schlatter, Guy; Bonnet, Guillaume; Lapp, Alain; Hadziioannou, Georges · Soft Matter · 2005

basic_science · Level V

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Abstract

This work focuses on the synthesis of polyrotaxanes with high molecular weight template poly(ethylene glycol) PEG (20 kg mol) having various and well-defined amounts of α-cyclodextrins (α-CD) per chain from 3 up to 125. is the complexation degree of the polyrotaxane defined to be the average number of cyclodextrin molecules per template chain. The usual route has been used for high values of , while sparsely complexed polyrotaxanes have been synthesized with an original one pot synthesis in water. Furthermore, a systematic study was carried out to understand and control the complexation degree of the polyrotaxane as a function of the complexation time, the temperature and the initial ratio of α-CD to template polymer. It has been shown that a high temperature thermal plateau leads to the formation of very sparsely complexed (low ) pseudo-polyrotaxanes for which, the threaded α-CD act like nuclei and generate a favourable driving force for the final complexation at lower temperature.