Polycaprolactone

ALAKANANDA P M

• Polycaprolactone (PCL) is a biodegradable polyester

• The monomer is caprolactone.

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• PCL is hydrophobic in nature.

• They are semicrystalline polymer and its crystallinity tends to decrease with increasing molecular weight

• PCL is soluble in chloroform, benzene, toluene, cyclohexanone at room temperature. It has a low solubility in acetone and is Insoluble in alcohol, petroleum ether and diethyl ether.

• The polymer has a melting point of only 60°C, which means it can be shaped by hand after a few minutes in hot water.

• PCL can be reheated and reshaped again and again. It feels like nylon when hardened.

• Elastic Modulus is 1.2 GPa

• Elongation at Break is300 %

• Tensile Strength:10 Mpa

• glass transition temperature is about −60 °C

• 1.145 g/cm3 density.

• PCL is non-hazardous

• PCL is resistant to water, oil and chlorine.

• Polycaprolactone is sold under the names Shapelock (US), Polymorph (UK), Instamorph, PlastiMake (AUS) etc.

• The material is delivered as granules that can be easily melted in hot water and shaped.

• Non-toxic

• biodegradable in soil

• broad miscibility

• mechanical compatibility with many polymers and

• good adhesion to a broad spectrum of substrates.

• PCL did not have the mechanical properties to be applied in high load bearing applications

• exceptional blend-compatibility

• Firmicutes and Proteobacteria can degrade PCL.

• Penicillium sp. can degrade high density PCL; though not as quickly as thermotolerant Aspergillus.

• Species of clostridium can degrade PCL under anaerobic conditions.

Synthesis of polycaprolactone• Caprolactone is prepared industrially by BaeyeR-Villiger

oxidation of cyclohexanone with peracetic acid

• rearrangement of cyclic keton takes place forming a lactone.

• PCL is prepared by the ring opening polymerisation of the cyclic monomer ε caprolactone and was studied as early as the 1930s .

• Catalysts such as stannous octoate are used to catalyze the polymerisation and low molecular weight alcohols can be used to control the molecular weight of the polymer.

Application

Biomedical application: it is especially interesting for the preparation of long term implantable devices, owing to its degradation which is even slower than that of polylactide.

• SUTURES: A block copolymer of PCL with glycolide, offering reduced stiffness compared with pure polyglycolide under the trade name Monacryl.

• WOUND DRESSING: PCL has been utilized as an ultra thin film for dressing wounds and has also been used as a release vehicle for the chemical antiseptic chlorohexidine .

• CONTRACEPTIVE DEVICES. PCL is a highly desirable candidate for this role owing to its slow degradation, biocompatability and FDA approval. PCL microspheres as an injectable implant system for the controlled delivery of contraceptive steroids.

DENTISTRY : • In dentistry (as composite named Resilon) is used as a

component of "night guards" (dental splints) and in root canal filling.

• It performs like gutta-percha, has similar handling properties, and for retreatment purposes may be softened with heat, or dissolved with solvents like chloroform.

• .The major difference between the polycaprolactone-based root canal filling material (Resilon and Real Seal) and gutta-percha is that the PCL-based material is biodegradable but gutta-percha is not.

DRUG DELIVERY:• Their ease of shaping and ease of manufacture enable appropriate pore sizes for

the controlled delivery of drugs.

• PCL is suitable for controlled drug delivery due to a high permeability to many drugs, excellent biocompatibility and its ability to be fully excreted from the body once bioresorbed.

• Biodegradation of PCL is slow in comparison to other polymers, so it is most suitable for long-term delivery extending over a period of more than one year.

• PCL Microspheres are mainly used for drug delivery.

• Administration of medication via such systems is advantageous because microspheres can be ingested or injected; they can be tailored for desired release profiles and in some cases can even provide organ-targeted release

TISSUE ENGINEERING:

• As scaffold candidates, the following characteristics are desirable:

three dimensional and highly porous structures with an interconnected pore network for cell growth and flow transport of nutrients and metabolic waste.

biocompatible and bioresorbable with a controllable degradation resorption rate to match cell/tissue growth in vitro and/or in vivo.

suitable surface chemistry for cell attachment, proliferation and differentiation. mechanical properties to match those of the tissues at the site of implantation

• PCL is an incredibly versatile bioresorbable polymer and by way of its superior rheological properties it can be used by

almost any polymer processing technologies to produce an enormous array of scaffolds

• Polycaprolactone may find use as an extrusion aid

• die lubricant

• mold release agent

• pigment and filler dispersion aid

• polyester segments in urethanes and block polyesters.

• It is also used in housing applications.

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