Polycaprolactone
Polycaprolactone (PCL) is a biodegradable polyester with a low melting point of around 60°C and a glass transition temperature of about −60°C. PCL is derived from the chemical synthesis of crude oil. It can be prepared by ring opening polymerization of ε-caprolactone using a catalyst such as stannous octanoate. Polycaprolactone has good water, oil, solvent and chlorine resistance.
This polymer is often used as an additive for resins to improve their processing characteristics and their end use properties (e.g.: impact resistance). Being compatible with a range of other materials, PCL can be mixed with starch to lower its cost and increase biodegradability or it can be added as a polymeric plasticizer to PVC.
Polycaprolactone is also used for splinting, modeling, and as a feedstock for prototype Fused Deposition Modeling systems such as RepRap.
Biomedical Applications
PCL is degraded by hydrolysis of its ester linkages in physiological conditions (such as in the human body) and has therefore received a great deal of attention for use as an implantable biomaterial. In particular it is especially interesting for the preparation of long term implantable devices, owing to its degradation which is even slower than that of polylactide.
PCL is an Food and Drug Administration (FDA) approved material that is used in the human body as (for example) a drug delivery device, suture (sold under the brand name Monocryl or generically), adhesion barrier and is being investigated as a scaffold for tissue repair via tissue engineering.
A variety of drugs have been encapsulated within PCL beads for controlled release and targeted drug delivery which have been peer reviewed.[citation needed]
The major impurities in the medical grade are toluene (<890 ppm, usually about 100 ppm) and tin (<200ppm).
Degradation time in open air is very short. In Sweden there has been an attempt to produce PCL bags, but they degraded before reaching the customers.
In Odontology or Dentistry (as composite named Resilon™) is used in root canal filling. It performs like gutta-percha, has the same handling properties, and for re-treatment purposes may be softened with heat, or dissolved with solvents like chloroform. Similar to gutta-percha, there are master cones in all ISO sizes and accessory cones in different sizes available.