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 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 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), 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 [Sinha et al, "Int. J. Pharm.", 278, 2004 ]

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.

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 a temperature at which it can easily be handled and molded with bare hands [Though 60°C sounds too hot to handle, and 60°C water can cause burns, PCL's specific heat and conductivity are low enough that it isn't hard to handle at this temperature.] -- make 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.

References

External links

* [http://www.absorbables.com/properties.htm medical supplier, physical properties, and solvents]
* [http://www.designinsite.dk/htmsider/m0954.htm www.designinsite.dk/htmsider/m0954.htm]
* [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T7W-4C82NG4-1&_user=10&_handle=V-WA-A-W-WU-MsSAYWW-UUA-U-AAWBEWYWBC-AAWACUEUBC-WWZDBZDZZ-WU-U&_fmt=summary&_coverDate=06%2F18%2F2004&_rdoc=1&_orig=browse&_srch=%23toc%235069%232004%23997219998%23503354!&_cdi=5069&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=bc1489995bc09fb14dce73cae00160b3 Peer Reviewed Paper by Sinha et al] .
* [http://www.sep.org.uk/downloads/flow_small.pdf Go with the flow. Peter Hollamby, 2005]