Synthetic polymers from renewable monomers

Synthetic Green Polymers from Renewable Monomers... 

Natural monomers and polymers have complex structure and properties, which with proper modifications could be a substitute for today s high-performance plastic materials. Existing biodegradable polymers can be blended with different materials with the aim to reduce cost and to tailor the product for specific applications. NR and almost all other natural resources are discussed and possible modifications and the applications of these natural polymers as well as polymers from natural monomers are analyzed in this review. Further studies are required to improve the performance of these materials so that synthetic polymeric materials can be replaced by polymers derived from these renewable materials. 

The beginning of the twentieth century witnessed the birth of a novel class of materials, the synthetic polymers based on monomers derived from fossil resources, but the progress associated with them was relatively slow up to the Second World War and did not affect substantially the production and scope of the naturally based counterparts. Some hybrid materials, arising from the copolymerization between both types of monomers were also developed at this stage as in the case of the first alkyd resins. Interestingly, both monomers used in the first process to synthesize nylon in the late 1930s were prepared from furfural, an industrial commodity obtained from renewable resources, in a joint venture between Quaker Oats and DuPont. 

Generally, polymers from renewable resources have different origins such as natural (e.g., polysaccharides - namely cellulose and starch, which are produced in large amounts protein gums), synthetic (e.g., polylactic acid, PLA) derived from natural monomers, and microbial (e.g., polyhydroxybutyrate, PHB) [1, 5] The main components of biomass are cellulose, lignin, hemicelluloses and extractives and, as a nonwood structural component, starch. 

Commercial polymers generated totally or partially from renewable resources will remain a very small component in the production of plastics, rubbers, and fibers, in the near future. However, their importance and marketability will continue to grow. They provide environmental and potentially economic advantages over their counterpart generated entirely from fossil raw materials. In addition, they offer more readily desirable properties such as biodegradability and biocompatibility that are more difficult to achieve with synthetic polymers. With extensive ongoing research and development pertaining to new catalysts that will enable the incorporation/ modification of renewable monomers into feedstocks as well as the development of new metabolic microbial pathways for the bio-production of monomers, the field will continue to advance to achieve production costs of polymers from renewable resources that are reasonably competitive. 

Th. Heinze and K. Petzold, Cellulose chemistry Novel products and synthetic paths, in M. N. Belgacem, A. Gandini (Eds.), Monomer, Polymers and Composites from Renewable Resources, Elsevier Ltd, Oxford, 2008, pp. 434-368. 

Overall, the recent developments highlighted in this chapter have documented increasing academic and industrial efforts in the utilization of biomass-derived renewable monomers for the production of synthetic polymers that offer sustainable alternatives to the current petroleum-based polymers. Furthermore, some of the sustainable polymers also exhibit enhanced or unique materials properties over the polymers derived from the depleting resources. Such efforts will continue in the future, with an emphasis being placed on making biomass-derived polymers not only renewable but also technically and economically practicable and competitive. 

Polylactic acid (PLA), the structure of which is shown in Figure 7.10, is a polyester fibre in which there has been recent interest because of its environmental credentials. PLA may be derived from renewable resources, such as cornstarch, and it is biodegradable. PLA may be coloured using certain disperse dyes, although the dyes do not exhaust as well as on PET, mainly because of its aliphatic character. Acrylic fibres are synthetic fibres based essentially on the addition polymer polyacrylonitrile, the essential structure of which is illustrated in Figure 7.11. However, most acrylic fibres are rather more complex and contain within their structure anionic groups, most commonly sulfonate (-SOs ), but also carboxylate (-CO2 ) groups either as a result of the incorporation of co-polymerised monomers in... 

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