Isolated and Modified Biopolymers as Biomaterials

Plants are wonderful chemical reactors that fabricate complex macromolecules. These compounds are located in the cell wall (e.g. cellulose, lignin, hemicelluloses and pectin) or they constitute the energy stocks (e.g. starch) and even they have specific functions (e.g. proteins). Most of these biopolymers are useful for making industrial biomaterials. 

The characteristics of the isolated biopolymers depend on their structure. Cellulose and amylose are linear polymers, whereas amylopectin, pectin and hemicelluloses are branched polymers. Pectin and amylopectin contain carboxylic groups, which make interactions with water molecules very important. Amylose has a helix structure, whereas the cellulose molecule looks like a ribbon. The interactions with water and other neighbouring molecules are therefore different. 

In the following paragraphs, we will present the technologies needed to overcome these and other disadvantages. In this way, the natural polymer structure becomes profitable for industrial applications as biomaterials. We have selected only the main biopolymers currently used in commercial products. 

The potential of cellulose can be multiplied after chemical modification. The esterification or the etherification of its hydroxyl groups leads to new biopolymers with very different properties. They will be described later. 

Let us first consider a particular case of the modification of the cellulose molecule regeneration. Two types can be distinguished with and without chemical modification. 

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