Towards Bioelastomers via Coordination Polymerization of Renewable Terpenes Using Neodymium-Based Catalyst Systems

Abstract

Syntheses of biolestomers through the coordination polymerization of terpenes, such as ocimene (Oc), β-myrcene (My) and trans -β-farnesene (Fa), using catalyst systems based on neodymium versatate (NdV 3 ) are reported in this work. All polymerization products were characterized by size exclusion chromatography, differential scanning calorimetry and nuclear magnetic resonance in order to determine their macromolecular, thermal and structural characteristics. The NdV 3 in combination with diisobutylaluminum hydride as cocatalyst and diethylaluminum chloride (DEAC) as halogen source was found effective for Oc polymerizations providing polyocimenes with molecular weights ( M n ) in the order of 20 to 57 Kg/mol, broad molecular weight distributions ( M w / M n ) since 3.8 until 8.2, preferably cis -1,4 content (61-69 %) and glass transition temperatures ( T g ) in the range of-30 to-26 °C. On the other hand, the same NdV 3 but now activated by modified methylaluminoxane and DEAC was found considerably active in My and Fa polymerizations, affording polymyrcenes and polyfarnesenes with M n between 155 and 243 Kg/mol, as well as M w / M n ranging between 3.1-3.9 and 1,4 content values were found higher than 94 % for this subfamily of polyterpenes, being the 3,4 content the complement for completing 100 %. Moreover, it was demonstrated that T g of polyterpenes studied depends on the size of pendant group, shifting it towards lower temperatures as increasing the size of the pendant group.