Biomass- and calcium carbide-based recyclable polymers†
Biomass is a renewable source of valuable feedstock for the chemical industry of the future. A promising approach to the utilization of valuable components of biomass is the synthesis of monomers and polymers, if the overall technology is designed for a clean cycle without pollution of the environment with newly created polymers. In this work, we have developed a methodology for the recycling of polymers based on biomass and calcium carbide. First, we modified a series of biomass-derived terpene alcohols with calcium carbide followed by polymerization of the isolated vinyl ethers. Then, to study the recycling potential, the obtained polymers were subjected to pyrolysis at moderate temperatures (200–450 °C). The pyrolysis products were analyzed using TGA-MS, GC-MS, and NMR, and it was found that the polymers can be transformed quite easily. The products of the pyrolysis consisted of the starting terpenols, as well as the corresponding non-toxic ketones or aldehydes: up to 87% of the starting alcohol or up to 100% of the total sum of alcohol + aldehyde or alcohol + ketone (GC-yields). Then, the reaction mixture was hydrogenated and resulted in the formation of starting alcohol only. According to the studied pathway of polymers re-building, a terpene fragment attached to the main polyethylene chain through an oxygen atom promotes the transformation of the obtained polymers. Thus, the products of pyrolysis are environmentally friendly and can be reused in the further synthesis of monomers. The developed system has shown a unique assembling/disassembling ability and advances the concept of reusable bio-derived high value-added materials.