Courtesy : iupac.org
Green materials
Sustainable materials are products that are manufactured with energy reducing processes, the materials themselves are derived from sustainable sources, or the material’s carbon footprint is reduced. Minimizing the energy consumption at each of these phases is the goal to creating sustainable materials, where waste is the last resort of production processes. University of Minnesota’s Center for Sustainable Polymers (CSP) thinks about it as “meeting the needs of the present without compromising the ability of future generations to meet their needs.” One of these materials that is on the forefront of green technology is polymers, traditionally petroleum based, and engrained in nearly every facet of our lives.
Traditional polymers follow the process of fossil fuels being converted into chemical monomers, small units that make up long carbon chains, and then finally those monomers are converted into polymer materials. These products generally can be recycled, incinerated, or thrown away in landfills which is unfortunately the most economical option for most users. Sustainable polymers are produced from a renewable feedstock, i.e. not fossil fuels; biomass is a renewable, biodegradable, sustainable option for new polymer products however traditional synthesis techniques do not achieve the same product so some clever design must be invoked.
One of the most popular of these bio based polymers is polylactic acid or PLA; its starting materials are harvested mainly from corn starch and sugar cane, two crops that are very available world wide. The simple synthesis is shown here, and from its two steps, it can be inferred as to why PLA is such a popular sustainable polymer. The starting material, lactic acid, can be converted into a cyclic monomer wherein the ring opening process will induce the polymerization. This polymer can be produced at an incredibly high rate at large volumes making it a fantastic material to mass produce simple items. PLA is commonly found in many products including plastic cups, bags, and other low stress application. However, when compared to fossil fuel based polymers, bio based polymers are deficient in strength and crystallinity which is where much of the efforts are being directed to achieve the same, if not better, structural properties of the non-sustainable polymers.
