Medical applications poly

An idea of the range of materials and applications for polymers in medicine can be gained from the information in Table 10.1. As can be seen from this table a number of polymers are used in medical applications. One particular such polymer is poly (methyl methacrylate), PMMA. Early on it was used as the material for fabricating dentures later other biomedical applications developed. For example, PMMA is now used as the cement in the majority of hip replacement operations worldwide. 

Martin DP and Williams SF. Medical applications of poly 4-hydroxybutyrate A strong flexible absorbable biomaterial. Biochem Eng J, 2003, 16, 97-105. 

Other types of synthetic biopolymers that have been in use for medical applications for a number of years are polyglycolide, polydioxanone and poly(lactide-co-glycolide). 

An additive system was developed for poly(vinyl chloride) for medical applications. The additives include primary stabilisers (Ca-Zn stearate and Zn stearate), secondary stabilisers (epoxides) and lubricants (ethylene bisamide and high density polyethylene), to improve melt processing and heat stability. The use of the stabilisers resulted in reduced equipment down-time, increased the level of recycled material which could be incorporated, and enhanced the product characteristics, including colour, clarity, blush, aqueous extractables and particle generation. 5 refs. 

Applications to polymer chemistry have also been proposed. Interestingly. the adhesion toward itself. Al or stainless steel, of polythene or TeHon with epoxyresins adhesives is considerably improved by a glow discharge polymerization of methane (or etheiie. ethyne) on the polymer surface, CH4 giving the best results (33). Such a modification of polymer surfaces has also received attention within the scope of modifying poly mer membrane compatibility with blood for medical applications. Various o nic compounds (even CH4 > have been studied in this context, where an ultrathin layer (< 1000 is sufficient to alter blood compatibility 134). 

Schuerch2) reviewed the medical application of synthetic poly-saccharides. Capozza199 reported that the poly-orthoester prepared from 2-ethoxy-4-hydroxymethyl-l,3-diox-olane in the presence of add are useful as slow-release agents for drugs. Poly-2,6,7-trioxabicyclo[2.2.1]heptane VIII showed the same behavior200). 

These results suggest that poly-orthoesters are also useful for medical applications. If hydroxyl or amino groups are incorporated into the skeleton, the corresponding polymers will become more valuable by being more water-soluble. 

Poly(propylene oxide) is typically obtained by base catalyzed anionic polymerization of propylene oxide [12]. Both stereospecific and atactic forms are known. The polymer is used as a soft polyether unit in polyurethane elastomers and foams in polymer electrolytes as surfactants (lubricants, dispersants, antistatic agents, foam control agents) in printing inks, as solubilizers in hydraulic fluids, coolant compositions in various medical applications (protective bandages, drug delivery systems, organ preservation, dental compositions), etc. 

Chitin is known to be biodegradable, biocompatible, and nontoxic. It is used in dmg delivery and bio medical applications. It also used in the purification of water especially for the absorption of toxic dyes. Chitin has limited solubility in solvents but chitosan is readily soluble in acidic aqueous solutions and has more tendency to be chemically modified. Chitosan can readily be spun into fibers, cast into films, or precipitated in a variety of micromorphologies from acidic solutions. Min and Kim have reported on the adsorption of acid dyes from wastewater using composites of PAN/chitosan [52]. Shin et al. has reported on copolymers composed of PVA and poly dimethyl siloxanes cross-linked with chitosan to prepare semi IPN hydrogels for application as biomedical materials... 

Water-soluble polymers. Substituted water-soluble poly-orthoesters can be regarded as polysaccharide analogs, and could have potential medical applications as drugs or as drug carriers. Ionic substituents were introduced In the blcycllc monomers to Improve the solubility of these polymers. 

---