Polymerization of the Bacterial Plastics

So far, the following building blocks can be produced microbially for polymerization purposes hydroxyalkanoic acids with many structural variations, lactic acid, succinic acid, (i )-3-hydroxypropionic acid, bioethylene produced from dehydration of bioethanol, 1,3-propanediol, and c/ s -3,5-cyclohexadiene-I,2-diols from microbial transformation of benzene and other chemicals. They have been successfully used for making various bacterial plastics. 

In this chapter, we will give an overview of these bacterial plastics. 

Six types of monomers produced by microbial fermentation are the most common bio-based polymer building blocks (Fig. 1). Among them, hydroxyalkanoates have rich structural variations, n can be 0-5, and R can be alkyl to benzyl. However, 

Except for polymerization of hydroxyalkanoates, which is conducted in vivo, all other monomers are polymerized in vitro by chemical reactions, leading to the formation of PHA, poly(lactic acid) (PLA), poly(butylene succinate) (PBS), PE, poly(trimethylene terephthalate) (PTT), and poly(p-phenylene) (PPP) (Fig. 2). 

Although these plastics are bio-based, their properties are very similar to those of traditional petroleum-based plastics. Like PE based on bioethanol (leading to bioethylene), they are exactly the same as petroleum-based PE (Table 1) 

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