Polycaprolactone
From Wikipedia, the free encyclopedia
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 by chemical synthesis from 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 systems such as a RepRap, where it is used for Fused Filament Fabrication (similar to the Stratasys' Fused Deposition Modeling or FDM technique).
Contents |
[edit] 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), or adhesion barrier. It is being investigated as a scaffold for tissue repair via tissue engineering, GBR Membrane. It has been used as the hydrophobic block of amphiphilic synthetic block copolymers used to form the vesicle membrane of polymersomes.
A variety of drugs have been encapsulated within PCL beads for controlled release and targeted drug delivery which have been peer reviewed[1]
The major impurities in the medical grade are toluene (<890 ppm, usually about 100 ppm) and tin (<200ppm).
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.
[edit] Hobbyist and Prototyping
PCL also has many applications in the hobbyist market. Some brand names used in selling it to this market are Shapelock in the US, and Polymorph in the UK. Its physical properties -- a very tough, nylon-like plastic that melts to a putty-like consistency at only 60°C. PCL's specific heat and conductivity are low enough that it isn't hard to handle at this temperature.This makes it ideal for small-scale modeling, part fabrication, repair of plastic objects, and rapid prototyping where heat resistance isn't needed. Though molten PCL readily sticks to many other plastics, if the surface is cooled, the stickiness can be minimized while still leaving the mass pliable.
PCL has been known to become brittle, lose its tensile strength and fall apart after several months so is not suitable for permanent or critical applications.
[edit] References
- ^ Sinha et al, Int. J. Pharm., 278, 2004
[edit] External links
- medical supplier, physical properties, and solvents
- www.designinsite.dk/htmsider/m0954.htm
- Sinha VR, Bansal K, Kaushik R, Kumria R, Trehan A (June 2004). "Poly-epsilon-caprolactone microspheres and nanospheres: an overview". Int J Pharm 278 (1): 1–23. doi:. PMID 15158945.
