Main methods and processes to synthesise polymers

It was shown in Chapter 1 that life is supported by many natural polymers or macromolecules. Natural polymers have been used for centuries, e.g. natural rubber. Modification of natural polymers permitted new useful goods to be made, but sometimes not very well adapted to everyday life, e.g. the highly flammable celluloid. 

1 Examples of drawbacks encountered when using technical-grade polymers 

For storage of blood, single-use plasticised poly(vinyl chloride) (PVC) bags replaced heavy, breakable glass flasks. However, migration of the plasticiser di-(2-ethylhexyl) phthalate (DEHP) into blood has been observed. Plasticised PVC is still used but is restricted to short-time contact as single-use tubing. 

For the joints of hip prostheses, poly(tetrafluoroethylene) (PTFE, e.g. Teflon ) was tested for its well-known low-friction properties. However, this material does not resist wear under compression, leading to failure of the prosthesis. 

For the main piece of hip prostheses, the use of carbon-fibre-based composites was suggested because of their lightness and excellent mechanical properties. However, debris of carbon fibres was found in the surrounding tissues, leading to the withdrawal of such types of composite for use in living tissues. 

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