Terpenes as renewable monomers for biobased materials

Abstract: With the ambition to decrease the utilization of fossil fuels, a development of those raw materials that today only are seen as waste products is necessary. One of those waste products is turpentine. Turpentine is the largest natural source of terpenes in the world today. The main components are the terpenes α-pinene, β-pinene and 3-carene.  In this project, different polymerisation techniques have been evaluated to polymerise limonene with the aim to make a material out of the green raw material, turpentine. Limonene is a terpene that can be found in turpentine. It has a planar structure and should work as a model for other terpenes.   Previous work on polymerising terpenes has focused on succeeding with performing polymerisations of terpenes utilizing the techniques of cationic polymerisation and radical polymerisation. However, this has been done without the aim to make a material out of the polymers. In this project, on the other hand, the main focus has been to obtain a polymer that can be used as a basis for a material. Techniques that have been applied are: radical polymerisation, cationic polymerisation and thiol-ene polymerisation.  In this study, attempts to homopolymerise limonene and also copolymerise it with other synthetic monomers, such as styrene, have been performed with both radical polymerisation and cationic polymerisation. The procedure for the radical polymerisation has been conducted following the work by Sharma and Srivastava. [1] Even though several articles have been published about radical copolymerisations of limonene with other synthetic monomers, the radical polymerisations have not succeeded in this project. Further, the technique of thiol-ene chemistry has shown that limonene can be used in polymerisations; limonene reacts spontaneously with 2-mercaptoethyl ether forming a viscous polymer. The obtained polymers have been characterized with proton nuclear magnetic resonance(1H-NMR), size exclusion chromatography (SEC), matrix-assisted laser desorption ionization-time of flight mass spectroscopy (MALDI-TOF MS), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy.