Natural Product Polymers

While the relatively young polymer industry was learning much from the modification of natural polymers, production figures were small. As the purely synthetic polymers came on stream, the range of valuable applications for plastic materials rapidly increased. Today, the annual mass of polymeric... 

The Coll-R is a sirolimus-eluting biocompatible, biodegradable collagen matrix designed for intra-operative perivascular implantation around the graft-venous anastomosis [25]. This natural polymer product was tested in 12 patients requiring... 

The main raw material required for the production of viscose is ceUulose (qv), a natural polymer of D-glucose (Fig. 1). The repeating monomer unit is a pair of anhydroglucose units (AGU). CeUulose and starch (qv) are identical but for the way in which the ring oxygen atoms alternate from side to side of the polymer chain (beta linkages) in ceUulose, but remain on the same side (alpha linkages) in starch. 

There are a number of factors that favor the use of natural polymers as a source for polymer production. The concerns of environmental pollution, tensions in the Persian Gulf countries regarding oil, the fear of a possible future depletion of oil, etc., give credence to the move toward a bio-based material policy [8,21]. The... 

Another natural polymer that needs a fresh look into its structure and properties is bitumen [123], also called asphaltines, that are used in highway construction. Although a petroleum by-product, it is a naturally existing polymer. It primarily consists of polynuclear aromatic and cyclocaliphatic ring systems and possesses a lamellar-type structure. It is a potential material that requires more study, and high-performance materials such as liquid crystalline polymer (LCP) could be made from it. 

Probably the most promising polymeric drug carrier system involves polysaccharide molecules. These are natural polymers and are often biodegradable to products that are useful to the host or easily eliminated by the host. Dextrans have been the most extensively used polysaccharide for macromolecular prodrug preparations (79). These materials are biocompatible and the in vivo fate is directly related to their molecular weight. Moreover these macromolecules can be easily targetted to the hepatocytes with D-mannose or L-fucose (20). 

Synthetic products, e.g., polyethylene oxides(104), polyacrylates, polyacrylamides, and polyetherglycols were in competition with natural polymers like starch, guar, cellulose derivatives, alignates, carrageenan, and locust bean gum. The basic physical and structural properties of the various polysaccharide thickeners have been compiled and reviewed by numerous authors and editors(105-109). 

The natural polymers in common use are cellulose, lignin, chitin, starch and guar gum. The natural products had complete... 

Natural polymers are far more complex materials, being exclusively "organic", that is, products of life (cellulose, proteins, DNA,...). Nevertheless, as nature seems to have formed (size, weight, hardness, etc.) several natural polymers (wood, bones, ivory, etc.) in such a way as to be almost immediately usable by our ancestors, they were most probably the bases of the first human tools. The commonly widespread conception that polymers are the youngest "materials" in the historical world is not true, but, strictly speaking, only applies to synthetic polymers, which were discovered about 100 years ago, early in the XXth century. 

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