Ring opening polymerization of $\varepsilon$-caprolactone in the presence of wet $\beta$-cyclodextrin: Effect of the operative pressure and of water molecules in the $\beta$-cyclodextrin cavity - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue RSC Advances Année : 2016

Ring opening polymerization of $\varepsilon$-caprolactone in the presence of wet $\beta$-cyclodextrin: Effect of the operative pressure and of water molecules in the $\beta$-cyclodextrin cavity

Résumé

The ring opening polymerization (ROP) of $\varepsilon$-caprolactone (CL) in the presence of $\beta$-cyclodextrin ($\beta$-CD) was performed in batch reactors both at room pressure and with the reaction system pressurized with CO$_2$, N$_2$ or Ar. Significant enhancements of the polymerization rate was observed when the ROP was carried out with wet $\beta$-CD under pressure. For example, after 24 hours at 120° C with a $\beta$-CD/CL molar ratio of about 1/100, the monomer conversion increased from 4 to 98–99% when the pressure was changed from 0.1 to 12.5–13.0 MPa independent of the nature of the compressing gas. MALDI-TOF analyses indicated that a major fraction of polymer chains obtained in pressurized systems was initiated by water molecules. The collected results suggest that at 12–13 MPa wet b-CD can catalyse both the ring opening of $\varepsilon$- caprolactone and the polymerization of the obtained linear species and that high energy water molecules located inside the cavity of the cyclic oligosaccharide must play a role in initiating the polymerization. The trend of number average molecular weight and the results of MALDI-TOF analyses obtained in polymerizations performed for long reaction times and in a hydrolysis test of commercial poly($\varepsilon$- caprolactone) indicate that wet $\beta$-CD can work as an artificial lipase enzyme under the adopted conditions.

Domaines

Chimie

Dates et versions

hal-01688082 , version 1 (19-01-2018)

Identifiants

Citer

A. Galia, O. Scialdone, T. Spanò, M.G. Valenti, B. Grignard, et al.. Ring opening polymerization of $\varepsilon$-caprolactone in the presence of wet $\beta$-cyclodextrin: Effect of the operative pressure and of water molecules in the $\beta$-cyclodextrin cavity. RSC Advances, 2016, RSC Advances, 6, pp.90290-90299. ⟨10.1039/c6ra20211j⟩. ⟨hal-01688082⟩
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