Anita Routaray

Synthesis and Immortal ROP of L-Lactide Using Copper Complex

In the present work, the -ONNO- tetradentate Schiff base ligand N, N′-bis (2-hydroxy-3-methoxybenzaldehyde) propylenediamine, [HMBPD] was synthesized. Further, complexation of this ligand with copper [HMBPD-Cu] was carried out and their reactivity for the ring-opening polymerization (ROP) of lactide (LA) has been studied. This monomeric copper complex is prepared by the reactions of copper solution with one molar equivalent of HMBPD Schiff-base ligand in ethanol under nitrogen atmosphere. This copper complex has been characterized by different spectroscopic methods, which showed square planner geometry. The copper complex is highly active towards ROP of LA. The rate of polymerization is heavily dependent on the initiator used. The copper complex allows controlled ring-opening polymerization as shown by the linear relationship between the percentage conversion and the number-average molecular weight. On the basis of literature reports, a mechanism for ROP of lactide has been proposed.

Retracted Article: Ring-Opening Polymerization of Lactide by Aluminium Catalyst

This review summarizes recent developments in the preparation and use of aluminium catalysts/initiators such as, monometallic aluminium and bimetallic aluminium compounds for the ring opening polymerization of lactide (L-lactide and rac-lactide). The organoaluminium catalysts/initiators have been synthesized and characterized by different spectroscopic techniques, including X-ray crystal structural studies and NMR data. Lactide polymerization has been analyzed by NMR and GPC methods. The present paper emphasizes on the polymerization kinetics and the control exhibited by the different types of aluminium initiators/catalysts. For the cases, where useful properties, such as high molecular weight, narrow PDI, or stereocontrol, have been observed, a more detailed examination of the catalysts/initiators are provided. Keywords Ring-opening polymerization, aluminium catalyst, poly(lactic acid), stereoselective, polydispersity index, living polymerization

Salicylaldimine Copper(II) complex catalyst: Pioneer for ring opening Polymerization of Lactide

AbstractSalicylaldimine copper complex has been synthesized and its reactivity for the ring-opening polymerization (ROP) of lactide has been studied. This monomeric copper complex was prepared by the reaction of copper(II) solution with one molar equivalent of salicylaldimine Schiff-base ligand in methanol under nitrogen atmosphere. This copper complex has been characterized by different spectroscopic methods, which showed square planar geometry. The molecular structure of the salicylaldimine Schiff-base has been determined by X-ray diffraction studies. The complex was tested as the initiator for the ring-opening polymerization of lactide, with variation in diamine group in ligand. The rate of polymerization is dependent on the diamine group in the following order: ethylene > propylene > phenyl. The salicylaldimine copper complex allows controlled ring-opening polymerization as indicated by the linear relationship between the percentage conversion and the number-average molecular weight. On the basis of literature reports, a mechanism for ROP of lactide has been proposed. Graphical AbstractThis article describes the synthesis and characterization of salicylaldimine copper(II) complexes, and their catalytic activity towards ring-opening polymerization of L-lactide.

Retraction: Ring-opening polymerization of lactide by aluminium catalyst

Retraction of ‘Ring-Opening Polymerization of Lactide by Aluminium Catalyst’ by Anita Routaray et al., Catal. Sci. Technol., 2015, DOI: 10.1039/c5cy00454c.