Synthesis of biodegradable poly-epsilon-caprolactone microspheres by dispersion ring-opening polymerization in supercritical carbon dioxide

in Biomacromolecules (2008), 9(11), 3141-3149

A series of fluorinated diblock and triblock copolymers of poly(ε-caprolactone) and poly(heptadecafluorodecylacrylate) were prepared by combining ring-opening polymerization of ε-CL and atom transfer ... [more ▼]

A series of fluorinated diblock and triblock copolymers of poly(ε-caprolactone) and poly(heptadecafluorodecylacrylate) were prepared by combining ring-opening polymerization of ε-CL and atom transfer radical polymerization of the acrylate. These copolymers with well-controlled molecular weight and composition were characterized by 1H NMR spectroscopy and used as stabilizers for the dispersion ring-opening polymerization of ε-CL in supercritical carbon dioxide. The effect of composition and architecture of the polymeric stabilizers on the stabilization of PCL microspheres was investigated. Finally, purification of PCL was successfully implemented by reactive supercritical fluid extraction of the tin catalyst. [less ▲]

Supercritical carbon dioxide, a tool for the dispersion ROP of lactone and PCL foaming: Part A

Poster (2008, June 02)

Aliphatic polyesters, namely polylactide (PLA) and poly-ε-caprolactone (PCL) are biodegradable and biocompatible materials that find applications as resorbable suture (PLA) and drugs delivery vectors (PCL ... [more ▼]

Aliphatic polyesters, namely polylactide (PLA) and poly-ε-caprolactone (PCL) are biodegradable and biocompatible materials that find applications as resorbable suture (PLA) and drugs delivery vectors (PCL). Nevertheless, these polymers were mainly prepared by ring opening polymerization using aluminum alkoxide or tin alkoxide initiators in organic media. Recently, the use of supercritical carbon dioxide as polymerization medium was proposed as a potential alternative to the use toxic organic solvents. Nevertheless, due to the non-solubility of PCL in this medium, the growing chains rapidly precipitate during their synthesis leading to the formation of a bulky material that is typical of a precipitation polymerization. This work aims at investigating the dispersion ring-opening polymerization (ROP) of ε-caprolactone in the presence of fluoropolymer-based stabilizers, that were prepared by combining the ring opening polymerization of ε-caprolactone and atom transfer radical polymerization of heptadecafluorodecylacrylate (AC8) and so, stabilizing PCL micrometric particles in supercritical carbon dioxide. In practice, the ROP of CL was initiated by dibutyltin dimethoxide in the presence of PCL-b-PAC8 diblock stabilizers of differents molecular weight and composition. After 24h at 40°C, PCL was collected as a powder that consists of small-sized microspheres. Finally, post-polymerization purification of PCL (removal of tin catalyst that may lead to toxicological problems) was demonstrated to be quite feasible by supercritical fluid extraction (SFE) leading to the preparation of PCL with low catalytic residues. The second goal of this work aims at reporting on the use of sc CO2 for the preparation of foams of poly(epsilon-caprolactone) (PCL), that could be useful in the packaging sector and/or the biomedical sector as potential scaffolds for tissue engineering but also as substitutes for polystyrene thermoformed trays. The method that consists of saturating a polymer with a compressed or supercritical fluid, such as carbon dioxide followed by depressurization and polymer expansion was investigated. Indeed, no residual product is left in the foam, no toxic gas is produced and no resort to hydrocarbon solvents is required. Moreover, CO2 is cheap, non-toxic, recyclable, non-flammable and the technology of CO2-assisted foaming can be used in either a batch mode or in a continuous mode within a high-pressure extruder. [less ▲]

Use of supercritical carbon dioxide for polym/clay nanocomposites preparation and foaming

Poster (2007, August 31)

Polymerization of (L,L)-lactide and copolymerization with epsilon-caprolactone initiated by dibutyltin dimethoxide in supercritical carbon dioxide

in Journal of Polymer Science Part A-Polymer Chemistry (2005), 43(13), 2777-2789

Ring-opening polymerization (ROP) of (L,L)-lactide (LA) has been initiated by dibutyltin dimethoxide in supercritical carbon dioxide (SC CO2). Polymerization is controlled and proceeds at quasi the same ... [more ▼]

Ring-opening polymerization (ROP) of (L,L)-lactide (LA) has been initiated by dibutyltin dimethoxide in supercritical carbon dioxide (SC CO2). Polymerization is controlled and proceeds at quasi the same rate as in toluene, which indicates that the reactivity of the propagating species is not impaired by parasitic carbonation reaction. Random copolymerization of LA with P-caprolactone (CL) has also been studied in sc CO2, and the reactivity ratios have been determined as 5.8 +/- 0.5 for LA and 0.7 +/- 0.25 for CL. These values have to be compared to 0.7 +/- 0.25 for LA and 0.15 +/- 0.05 for CL in toluene. Good control on ROP of CL and LA in SC CO2 has been confirmed by the successful synthesis of diblock copolymers by sequential polymerization of CL and LA. [less ▲]

Synthesis and foaming of polymer nanocomposites and microspheres in supercritical CO2

Poster (2005, June 01)

Contribution of supercritical CO2 to the preparation of aliphatic polyesters and materials thereof

in Macromolecular Symposia (2004), 217

This paper is a short review of the most recent achievments of CERM in the synthesis of poly (ε-caprolactone) (PCL) and polylactides (PLA) in supercritical carbon dioxide (sc CO2) In addition to the ... [more ▼]

This paper is a short review of the most recent achievments of CERM in the synthesis of poly (ε-caprolactone) (PCL) and polylactides (PLA) in supercritical carbon dioxide (sc CO2) In addition to the rrtacromolecular engineering of these aliphatic polyesters, nanocomposites and PCL microspheres have been prepared with the assistance of this supercritical fluid. [less ▲]

Noncovalent functionalization of multi-walled carbon nanotubes by pyrene containing polymers

in Chemical Communications (2003), (23), 2904-2905

Multi-walled carbon nanotubes (MWNTs) have been solubilized in water and in various organic solvents by noncovalent side-wall functionalization by pyrene containing polymers.

Polymer functionalized multi-walled carbon nanotubes

Poster (2003, May 16)

Ring-opening polymerization of epsilon-caprolactone in Supercritical Carbon Dioxide

in Macromolecules (2001), 34(4), 775-781

The ring-opening polymerization of ε-caprolactone (CL) initiated by dibutyltin dimethoxide was studied in supercritical carbon dioxide at 40 °C, under a pressure of 210−215 bar. The polymerization is ... [more ▼]

The ring-opening polymerization of ε-caprolactone (CL) initiated by dibutyltin dimethoxide was studied in supercritical carbon dioxide at 40 °C, under a pressure of 210−215 bar. The polymerization is controlled as assessed by the linear dependence of Mn,SEC on conversion and of ln([CL]0/[CL]) on time. Moreover, there is a good agreement between Mn,SEC and Mn,calc, at least until 20 000 g/mol. The apparent rate constants of polymerization in different media increase as follows: sc CO2, CFC-113, toluene, bulk. The kinetic order in initiator for the polymerization in solution and in sc CO2 was extracted from the slope of ln kapp vs ln [Sn]0. It appears to depend on the initiator concentration in solution, which is not the case in sc CO2. [less ▲]