What is the use of polyurethane in the medical world?

Polyurethane resin flooring is a type of polymer used for various purposes in the medical world due to its many benefits. This property of polyurethane has expanded its application in multiple sectors of life.
Due to its hygienic form in the form of elastomers, this polymer has many applications in the manufacture of tank covers, scraps, and packaging in the food and pharmaceutical industries, in the manufacture of gloves, domestic resin flooring , and other surgical and operating room equipment, heart, and other artificial organs, etc.

Polyurethane and medical elastomers
Polyurethane elastomers are a family of bulk copolymers that have found essential applications in the industrial and medical fields. The reaction between aliphatic diisocyanates and glycols resulted in the production of polyurethane with plastic and fibrous properties.
Subsequently, polyurethane was obtained using aromatic and glycolic diisocyanates with very high molecular weight, an essential family of thermoplastic elastomers. The properties of urethanes vary from rigid thermosetting materials to soft elastomers.
Thermoplastic polyurethanes are used to manufacture critical implantable devices because it has good mechanical properties such as tensile strength, toughness, abrasion resistance and resistance to degradation, and good biocompatibility which puts them in the group of materials suitable for medical applications.
Polyurethane elastomers have high mechanical flexibility, high tensile strength, and a very low tendency to drop in elasticity. Laboratory studies have shown that urethane elastomers have high chemical and mechanical properties for vascular prostheses compared to other polymers used in cardiovascular implants.
The most important feature of this group of polymers is that it results in a stable structural reaction. In short, polyurethane is used in various forms such as foam products, films, and elastomers.
Synthetic vessels smaller than 6 mm are often not used due to clot accumulation and damage to the brain and other organs, but nitric oxide prevents clots from forming. Polyurethane releases nitric oxide in combination with water. Nitric oxide prevents blood platelets from sticking together and increases the number of blood vessels.
It also increases the number of guanosine monophosphate (GMP) cycles in cells, which increases the activity of enzymes and increases gene expression in cells.
Applications of polyurethane Using polyethers as polyols in the synthesis of polyurethane can be prepared long-term implants in:
Artificial Heart, Artificial Kidney, Artificial Lung, Hemoperfusion, Artificial Pancreas, Blood Filters, Catheters, Artificial Vessels, Artery or Vein Bypass, Gingival Tooth Implants (Dental Implants, Artificial Tooth Overdenture), Diseases Kidney vessels such as renal artery aneurysm, renal infarction, and renal thrombosis), wound healing (bed sores or pressure ulcers, diabetic ulcers), fluid delivery or removal, vascular pressure display, angioplasty, vascular occlusion, aortic and coronary artery surgery, valves Triple and double heart pacemakers (surgical valve repair, surgical valve replacement, and balloon valve correction) are used.
The effect of a chemical structure and surface morphology on polyurethane compatibility blood In the late 1980s, several chemists studied the surface structure and morphology of polyurethanes, and gradually new surface coating methods with the bonding of other materials to the surface of polyurethanes to improve blood adaptation was invented. In recent years, the chemical composition of polyurethanes to improve blood compatibility has undergone many changes.
These include the synthesis of polyurethane-aura with soft hydrophilic parts. Cooper also investigated the relationship between the chemistry of polyols and the blood compatibility of polyurethanes on different samples of polyurethanes with various polyols such as PEO, PTMO, PB polybutadiene, and PDMS.
These polyurethanes were prepared by the two-step polymerization method and coated on polyethylene pipes, and then placed inside the dog’s body to determine their clotting response. Polyurethane with PDMS polyol showed the lowest flocculation compared to other samples.
The hydrophobic nature of PDMS improves the hydrophobicity of the PDMS base polyurethane surface. It thus justifies its improvement in blood compatibility compared to other cases, and the initial adhesion of platelets increases with increasing hydrophilicity of the polyols. Therefore, it should be said that the compatibility blood of polyurethanes will depend a lot on its constituents and various factors such as microphage separation, water surface heterogeneity.
The use of sulfonates with coatings such as heparin plays a significant role in altering the blood’s response to these substances. A researcher named SANTERRE synthesized sulfonate-based polyurethanes with different sulfur groups (1.3% -1.4%). In samples with sulfonate groups, clotting time was increased more.

Application of polyurea
Application of polyurea

Properties of medical polyurethane

  1. The highest coefficient of thermal conductivity among excellent and mineral insulators;
  2. Lack of water and moisture absorption;
  3. Reasonable price specially for resin flooring for homes ;
  4. Hygiene and no skin allergies;

Methods for improving the surface properties of polyurethanes
Since the blood compatibility of a biomaterial depends directly on its surface chemistry, a change in surface condition will significantly help solve compatibility blood problems.
Materials that have shown satisfactory results in improving blood compatibility include polyurethane sulfonate, bonding of acrylamide and diacrylamide surface with polyurethane, and binding of phosphorylcholine to polyurethane surface using UV and The bond of propyl sulfate – propylene oxide (PEO-SO3), noted.
In recent years, many researchers have used heparin bonding to their surface to increase the blood compatibility of biomaterials with satisfactory results.

Degradation of polyurethanes in the body
In polyurethane medicine, the compounds responsible for the breakdown of polymers in the body include water, salts, peroxides, and enzymes. In general, molecules such as vitamins and free radicals accelerate degradation throughout the matter. Polymer degradation in media fluid (plasma and tissue) generally involves the following steps:

  1. Media absorption at the polymer surface;
  2. Adsorption of media to the polymer mass;
  3. Chemical reactions with unstable bonds in the polymer;
  4. Transfer of degradation products from polymer matrix and adsorption of degradation products from polymer surface.

The effect of hydrophilicity on the rate of degradation of polyurethanes in medicine
One of the leading medical problems of implanting polyurethane resin floors in animal testing is their tendency to calcare and degrade. Most polyurethane implants are degraded by hydrolysis in animal testing. Biodegradable elastomers are used in cardiovascular implants, scaffolds for tissue engineering, repair of articular cartilage, artificial skin, and replacement and replacement of spongy bone grafts.
Hydrophilic materials, such as hydrogens, are used as a barrier to tissue adhesion. Materials with low hydrophilicity cause most cells to adhere, which is suitable for tissue engineering scaffolding. The reaction of biodegradable polyurethane with osteoblasts, chondrocytes, and macrophages The use of biodegradable polymers is a significant advance in medical research in medicine.
Biodegradable materials have numerous applications in medicine and surgery, and these materials are designed to be destroyed in invivo. The general notion of biocompatibility is based on the reaction between a substance and the biological environment. An inflammatory response often characterizes tissue and cell responses.
In tissue engineering, biodegradable polymer matrices and scaffolds are used as cell carriers to regenerate defective tissues. In general, implants should not cause abnormal tissue responses and produce toxic substances or carcinogenic effects in tissues. New research on biodegradable polyurethanes shows good compatibility. Although polyurethanes activate macrophages, they do not have toxic or carcinogenic effects on the body.
In animal test research, biodegradable polyurethane foam has shown good biocompatibility. In a new study to evaluate the biocompatibility of biodegradable polyester urethane foam, the results show that osteoblasts and macrophages can xenophagize and degenerate the degradation products. Degradation products in low concentrations affect growth and yield. It does not leave osteoblasts.
Chondrocytes and osteoblasts generally proliferated in biodegradable foam and retained their phenotype. This shows that these scaffolds are helpful for bone repair steps.

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