Cyclodextrins Initiated Ring-Opening Polymerization of Lactide Using 4-Dimethylaminopyridine (DMAP) as Catalyst: Study of DMAP/β-CD Inclusion Complex and Access to New Structures

Julie Meimoun (1) , Yupin Phuphuak (1, 2) , Remi Miyamachi (1) , Yong Miao (1) , Marc Bria (3) , Cyril Rousseau (4) , Guilherme Nogueira (1, 5) , Andreia Valente (5) , Audrey Favrelle-Huret (1) , Philippe Zinck (1)

1 UCCS - Unité de Catalyse et Chimie du Solide - UMR 8181
2 Department of Chemistry [Faculty of Science, Naresuan University]
3 IMEC - Institut Michel Eugène Chevreul - FR 2638
4 UCCS Équipe Catalyse Supramoléculaire
5 Centro de Química Estrutural, Faculdade de Ciências da Universidade de Lisboa

Cyclodextrins (CDs) are cyclic oligosaccharides used in many fields. Grafting polymers onto CDs enables new structures and applications to be obtained. Polylactide (PLA) is a biobased, biocompatible aliphatic polyester that can be grafted onto CDs by -OH-initiated ring-opening polymerization. Using 4-dimethylaminopyridine (DMAP) as an organocatalyst, a quantitative functionalization is reached on native α-, β-, γ- and 2,3-dimethyl- β-cyclodextrins. Narrow molecular weight distributions are obtained with the native CDs (dispersity < 1.1). The DMAP/β-CD combination is used as a case study, and the formation of an inclusion complex (1/1) is shown for the first time in the literature, which is fully characterized by NMR. The inclusion of DMAP into the cavity occurs via the secondary rim of the β-CD and the association constant (Ka) is estimated to be 88.2 M−1. Its use as an initiator for ring-opening polymerization leads to a partial functionalization efficiency, and thus a more hydrophilic β-CD-PLA conjugate than that obtained starting from native β-CD. Polymerization results including also the use of the adamantane/β-CD inclusion complex as an initiator suggest that inclusion of the DMAP catalyst into the CD may not occur during polymerization reactions. Rac-lactide does not form an inclusion complex with β-CD.

Mots clés: ring-opening polymerization; rac-lactide; polylactide; cyclodextrin; organocatalysis; DMAP; inclusion complex; polylactide carbohydrate conjugate

Domaines: Catalyse; Chimie; Chimie organique

Julie Meimoun, Yupin Phuphuak, Remi Miyamachi, Yong Miao, Marc Bria, et al.. Cyclodextrins Initiated Ring-Opening Polymerization of Lactide Using 4-Dimethylaminopyridine (DMAP) as Catalyst: Study of DMAP/β-CD Inclusion Complex and Access to New Structures. Molecules, 2022, 27 (3), pp.1083. ⟨10.3390/molecules27031083⟩. ⟨hal-03644807⟩