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That is, the polymer is unstable in a water based environment. This is the prevailing mechanism for the polymers degradation. This occurs in two stages. 1. Water penetrates the bulk of the device, attacking the chemical bonds in the amorphous phase and converting long polymer chains into shorter water-soluble fragments.
Vinyl polymers are subject of several structural variations, which greatly expands the range of polymers and their applications. With the exception of polyethylene, vinyl polymers can arise from head-to-tail linking of monomers, head-to-head combined with tail-to-tail, or a mixture of those two patterns. Additionally the substituted carbon center in such polymers is stereogenic (a "chiral center")
Gelatin polymer is often used on dressing wounds where it acts as an adhesive. Scaffolds and films with gelatin allow for the scaffolds to hold drugs and other nutrients that can be used to supply to a wound for healing. As collagen is one of the more popular biopolymers used in biomedical science, here are some examples of their use:
In the biomedical sciences, PVDF is used in immunoblotting as an artificial membrane (usually with 0.22 or 0.45-micrometre pore sizes), on which proteins are transferred using electricity (see western blotting). PVDF is resistant to solvents and, therefore, these membranes can be easily stripped and reused to look at other proteins.
EVA is also used in biomedical engineering applications as a drug-delivery device. The polymer is dissolved in an organic solvent (such as dichloromethane). Powdered drug and filler (typically an inert sugar) are added to the liquid solution and rapidly mixed to obtain a homogeneous mixture.
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Other applications include its use in photoresist materials, dielectric materials for energy storage, water-resistant adhesives and antimicrobial coatings. PVP, when mixed with a polyelectrolyte , has been demonstrated to moderately inhibit the growth of microorganisms.
The biodegradable polymers used in biomedical applications typically consist of hydrolyzable esters and hydrazones. These molecules, upon external stimulation, go on to be cleaved and broken down. The cleaving activation process can be achieved through use of an acidic environment, increasing the temperature, or by use of enzymes. [82]