Using Fluoropolymers In Biomedical Applications

A fluoropolymer is a fluorocarbon-based polymer that has multiple carbon-fluorine bonds. Fluoropolymers boast of high resistance to bases, acids, and solvents. They also share fluorocarbons' properties and thus are not as susceptible to the Van Der Waals forces as hydrocarbons. This typically gives them their non-stick and friction-reducing properties.

Fluoropolymers have exceptionally low surface energy, a low coefficient of friction, and are highly water repellent thanks to the strong, polar bond of carbon and fluorine. These remarkably popular industrial application materials have high chemical resistance, outstanding dielectric properties, and are highly biocompatible. Therefore, they are the top choice for several medical applications, ranging from flexible tubing to catheters.

Characteristics and Properties of Fluoropolymers

• Exceptional thermal stability Most fluoropolymers can work continuously at temperatures as high as 290°C and as low as -270°C. 
• Low coefficient of friction Depending on the fluoropolymer type, load, and sliding speed, the low co-efficiency of friction ranges from 0.02 to 0.2.
• Non-stick characteristics Fluoropolymers have poor adherence to other substances.
• Low surface energy Fluoropolymers are poorly wettable by both oil and water.
• Chemical inertness Fluoropolymers cannot be affected by most solvents and other chemicals.
• Outstanding electric properties Fluoropolymers boast of electric resistance, electric strength, and a low dissipation factor.  

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Production Methods

Fluoropolymers are produced from thermoplastic resins similar to polyethylene. This method involves replacing some hydrogen atoms attached to the carbon chain with fluorine or fluorinated alkyl. Some of the fluoropolymer family groups are also produced through industrial processes that give these materials their burn and chemical resistance characteristics. For example, homopolymers like PTFE are created through the polymerization of identical monomer units. In contrast, copolymers are produced by chaining two different monomers to allow for the creation of many other fluoropolymer types, such as PVDF.

Common Uses in Medical Devices and Life Sciences

Fluoropolymers are steadily replacing other plastics in medical applications due to their ability to meet the next-generation devices' biocompatibility and physical requirements. Some key attributes of fluoropolymers include their USP class certification, electric properties, chemical inertness, lubricity, biocompatibility, low binding to process equipment, and high purity with low extractability. Fluoropolymers, including PTFE and PVDF, are widely used in:

• Microporous membranes
• Accessory equipment, such as pumps, tubing, and fittings
• Medical catheters, such as multi-lumen catheter and guiding catheter

The Best Method of Sterilization

It is essential to know how different types of fluoropolymers perform under each sterilization method. Some can discolor, while others may warp if treated incorrectly. The FDA regulates four types of sterilization of medical devices made from natural polymers. These include autoclave, dry heat, ethylene oxide, and irradiation methods. The effectiveness and suitability of each method depend on the specific properties of the polymer material being sterilized.

Fluoropolymer devices can be sterilized using physical sterilization methods, such as autoclaving. This method combines heat, humidity, and pressure to clean tools thoroughly. Most autoclave sterilization takes between 15 minutes and an hour, depending on the force used and the deep cleaning needed.

Fluoropolymers can also be sterilized using radiation sterilization. Ideally, devices are exposed to a strong gamma radiation source to kill contaminants. Irradiation can also use electric beam sterilization, which leverages cathode rays to kill contaminants.

Currently, one of the best and popular methods of sterilizing fluoropolymers is the use of gamma-ray radiation. Gamma-ray radiation has many advantages over the other standard techniques and may soon be the industry's only method of choice. It is a highly efficient, cost-effective, and fast way of sterilizing fluoropolymer medical devices.