Bioplastics from Lipids

International Digital Laboratory, WMG, University of Warwick, United Kingdom 

The prominence of lipids in the chemical industry is growing year on year and they are now one of the major renewable feedstocks used in a chemist s synthetic toolbox. They are readily obtained in different parts of the planet and can be easily modified to produce a wide range of chemical precursors for polymer production. However, many associate the commercial use of lipids in areas such as biodiesel, lubricants and paint formulations and not with the largely investigated use of polymers. This chapter aims to define loosely what a lipid is, and highlight the main areas where they have been employed in bioplastics production to date. 

It is challenging to give an accurate, succinct definition of what a lipid is. Most commonly, lipids are thought of as fatty acids and the related triglycerides, but even this does not include the mono- and di-substituted glycerol compounds. In general terms, lipids can be considered to be fatty acids, their derivatives and any other compounds that may have a similar behaviour, functionality or biosynthetic pathway. They are often hydrophobic, soluble in hydrocarbon or aromatic solvents and insoluble in water. 

Bio-Based Plastics Materials and Applications, First Edition. Edited by Stephan Kabasci. 2014 John Wiley Sons, Ltd. Published 2014 by John Wiley Sons, Ltd. 

Chain can have no (saturated), one (monounsaturated) or multiple (polyunsaturated) double 

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All naturally occurring lipids from botanical sources (plants) or zoological sources (animals and humans) could potentially be used in the production of bioplastics. They have the same chemical structure and function in a very similar manner. Cholesterol (and its related esters) and fatty acids are commonly found in zoological sources, although the fats tend to be of a heavily saturated nature. It is feasible to create other products such as biodiesel from extreme sources including liposuction fat. However, a lack of volume and more importantly ethical approval have prevented their uptake further. The remainder of this chapter will focus on the use of triglycerides from plants and their related compounds for bioplastics production. 

Plants are used as the main sources of lipids for bioplastics production. Often used as energy storage in plants [1], triglycerides are mainly found in the seeds although they can also be observed in other parts, such as tubers [2], although this is a rare case. Some bioplastics have been synthesized from fish oils [3] but the lack of reliability in supply, cost and questions of the true sustainability of this route have restricted investigations in this area. 

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