In accordance with the nature of the material, medical polymer materials can be divided into two categories: non-degradable and biodegradable. The non-biodegradable materials include: polyethylene, polypropylene, polyacrylate, aromatic polyester, silicone rubber, polyurethane, polyether ether ketone, etc., which can remain stable for a long period of time in the physiological environment, without degradation, cross-linking and physical wear, and has good mechanical properties. These materials are mainly used for human soft and hard tissue repair and manufacture of artificial organs, artificial blood vessels, contact lenses and adhesives. Degradable biomaterials include: collagen, aliphatic polyester, chitin, cellulose, polyamino acid, polyvinyl alcohol, polylactic acid, polycaprolactone, polyphosphoronitrile, etc. These materials can be structurally damaged in the physiological environment and the degradation products can be absorbed by the body through the normal metabolism or discharged, and they are mainly used for drug-releasing carriers and non-permanent implantable devices.
Medical polymer materials are mostly used in the human body, directly related to human life and health, the general requirements for its performance are: ① safety: must be non-toxic or very few side effects. This requires high polymer purity, the production environment is very clean, polymerization additives with little residue, impurity content of ppm level, to ensure that there is no disease, non-toxic transmission conditions. At the same time its polymer compounds themselves, as well as monomer impurities, degradation or wear products do not adversely affect the body. ② Physical, chemical and mechanical properties need to meet the requirements of the design and function required for medical use. Such as hardness, elasticity, mechanical strength, fatigue strength, creep, abrasion, water absorption, solubility, enzyme resistance and in vivo aging. Taking heart valves as an example, it is best to use them for 250,000 hours, requiring particularly good fatigue strength. In addition, it is also required to facilitate sterilization and disinfection, and can withstand wet heat disinfection (120 ~ 140 ° C), dry heat disinfection (160 ~ 190 ° C), radiation disinfection or chemical treatment disinfection, without reducing the performance of the material. Different properties of medical polymer materials can be selected according to their specific conditions of the appropriate sterilization method. ③ Adaptability: including adaptability with other materials in medical supplies, materials and human biocompatibility, blood compatibility and tissue compatibility. Materials implanted in the human body, the requirements of a long period of time on the body fluids have no effect; good compatibility with the blood, no damage to the blood components, does not coagulate, does not dissolve blood, does not form a thrombus; no foreign body reaction, no damage to tissues in the body, not carcinogenic and teratogenic, will not lead to inflammation, necrosis, tissue proliferation and so on. ④Special function: different application areas, the requirements of the material has a certain special function. For example: with the separation of dialysis function of the artificial kidney filtration membrane, artificial lungs with gas exchange membrane, as well as artificial blood with the suction and removal of gas substances, etc., are required to have their own special separation and transmission function. In most cases, the surface chemical composition and structure of the existing polymer materials is difficult to meet the above requirements, usually using surface modification treatment, such as grafting **** poly, in order to improve its anti-coagulant properties. In addition, medical polymer materials also need excellent processing and molding, easy to process into the complex shape of the need.