Graft polymers, biodegradable

Chitin, a waste material from crab and shrimp processing, is poly(N-acetyl-D-glucosamine). The de-acetylated form, chitosan, is primarily used in water purification but is also used as a chemical feedstock. For example, chitosan can be depolymerized to the monomer, which is used as a hair-setting agent in shampoo and hair conditioner. In the future, graft polymers of chitosan may form biodegradable films. Already, carboxymethylated chitin is approved as a food wrap. 

Furthermore, this kind of polymer intercalation is proven useful to load drug molecules, such as ibuprofen for controlled drug-deUvery applications [68]. The incorporation of clay layers was observed to control the initial release of drug. It was concluded that a combination of grafting of biodegradable polymeric chains and clay reinforcement can be applied to achieve the desired combination of properties (mechanical, swelling, and controlled) of materials used for biomedical applications, as shown in Figure 2.4. 

Wang, Y., Sun, Z. and liu, W. (2003) Biodegradable materials from starch-grafted polymers. International Application, WO/2003/074604. PCT/ US03/05661. 

Biodegradable polymers and plastics are readily divided into three broad classifications (/) natural, (2) synthetic, and (J) modified natural. These classes may be further subdivided for ease of discussion, as follows (/) natural polymers (2) synthetic polymers may have carbon chain backbones or heteroatom chain backbones and (J) modified natural may be blends and grafts or involve chemical modifications, oxidation, esterification, etc. 

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