Synthesis of polycaprolactone: a review

Abstract

Polycaprolactone (PCL) is an important polymer due to its mechanical properties, miscibility with a large range of other polymers and biodegradability. Two main pathways to produce polycaprolactone have been described in the literature: the polycondensation of a hydroxycarboxylic acid: 6-hydroxyhexanoic acid, and the ring-opening polymerisation (ROP) of a lactone: epsilon-caprolactone (epsilon-CL). This critical review summarises the different conditions which have been described to synthesise PCL, and gives a broad overview of the different catalytic systems that were used (enzymatic, organic and metal catalyst systems). A surprising variety of catalytic systems have been studied, touching on virtually every section of the periodic table. A detailed list of reaction conditions and catalysts/initiators is given and reaction mechanisms are presented where known. Emphasis is put on the ROP pathway due to its prevalence in the literature and the superior polymer that is obtained. In addition, ineffective systems that have been tried to catalyse the production of PCL are included in the electronic supplementary information for completeness (141 references).

A Comparison of Gallium and Indium Alkoxide Complexes as Catalysts for Ring-Opening Polymerization of Lactide

“…Metal alkoxide species, M-OR, have been shown to be the true active species in numerous ROP processes. [1][2][3][4][5][6][7][8][9][10][11][12][13][18][19][20][21][22][23][24] For example, in 2004, Lewiński and co-workers reported the first structurally characterized aluminum ε-caprolactone complex, indicating that the Al-Me group has poor reactivity with CL. 77 Thus, in most ROP cases, an alcohol is used as an initiator and is essential in order to start the polymerization.…”

Optically transparent membrane based on bacterial cellulose/polycaprolactone

“…Polycaprolactone (PCL) is a hydrophobic, semi-crystalline polymer; its crystallinity tends to decrease with the increase of the molecular weight. The good solubility of PCL in organic solvents, its low melting point (59-64 °C) and the exceptional blend-compatibility has stimulated an extensive research of the potential application of this material in the biomedical field [12] . The goal of this work was the preparation and characterization of a new optically transparent membrane based on dried bacterial cellulose and polycaprolactone (PCL).…”

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

“…[1][2][3][4] Ring-opening polymerization (ROP) of cyclic esters is mainly mediated by metal complexes which afford faster polymerization rates and greater control over molecular weight of the resulting polymers. [5][6][7][8] Biocompatible metal complexes are important in the production of these polymers, where small amounts of catalyst may inevitably be incorporated.…”