Kinetics of the ring‐opening polymerization of D,L‐lactide using zinc (II) octoate as catalyst

Abstract

The kinetics of ring-opening polymerization of D,L-lactide with 2-ethylhexanoic acid zinc (II) salt as catalyst and methanol as co-catalyst at different temperatures is investigated. A previously proposed kinetic model accounting for reactions such as activation, propagation, chain transfer, transesterification and thermal non-radical random chain scission has been applied to simulate the experimental results of conversion and average molecular weights. The relevance of some side reactions, mainly transesterifications and chain scission, has been verified all over the studied temperature range and the corresponding rate constants have been estimated.

Use of Micro- and Nano-ZnO particles as Catalysts for the Microwave-Assisted Polymerization ofD,L-lactide

“…Regarding the production of PLA, ring-opening polymerization (ROP) of D,L-lactide catalyzed by tin (II) 2-ethylhexanoate is the most employed technique due to its high yield and control over molecular weight and molecular weight distribution of the resulting PLA [1][2][3]. However, catalyst by-products (tin alkoxides) and degradation products (hydroxides and oxides) are cytotoxic, limiting PLA in some applications specially, in the biomedical area [4]. Therefore, there is a need to develop novel and innocuous initiation systems.…”

“…Therefore, there is a need to develop novel and innocuous initiation systems. In this context, several catalysts based on metals of I and II groups of the periodic table have been used, either as organometallic compounds, metal complexes or metal oxides [4]. Zinc oxide (ZnO) (and its by-products), is considered as safe and it has been proved as a suitable catalyst for the D,L-lactide polymerization, however, good yields have been achieved at long reaction times (72-192 hours) [5].…”

Vanadium(v) phenolate complexes for ring opening homo- and co-polymerisation of ε-caprolactone, l-lactide and rac-lactide

“…Interaction of [VO(OtBu) 3 ] with the ethylidene-bridged diphenol 2,2 0 -ethylidenebis(4,6-di-tert-butylphenol), 2,2 0 -CH 3 CH…”

“…Given the bio-applications of PLA and PCL type polymers, there is a drive to develop syntheses using new catalysts that offer advantages over the established stannous octoate, 3 yet which possess low toxicity. Furthermore, the properties associated with PLA and PCL can be quite different, as typied by their differences in elasticity, and so there is a drive to produce 3-Cl/LA co-polymers of varying composition (and properties).…”

Optimizing the bulk copolymerization of D,L-lactide and glycolide by response surface methodology

“…Moreover, the mathematical model obtained provides a useful tool to select quickly and effortlessly the proper experimental conditions to achieve the desired properties of the polymer as a previous step in the synthesis and impregnation of biodegradable scaffolds [11,12] without having to carry out complex mathematical calculations based on a rigorous theoretical model. Considering that this work represents only a practical approach in order to estimate the properties of the synthesized PLGA for a further step of impregnation, the rigorous study of the reactions that are taking place is not an end in itself (unlike other specific mechanistic or kinetic studies [10,[13][14][15][16]) so that this model of 'black box' is only a practical method to choose a set of conditions for the polymerization process.…”