Adel F. Halasa, Ph.D. Matt Gram Synthesis and Characterization of Poly(β-farnesene) Homopolymers and Styrenic Block Copolymers Adel F. Halasa, Ph.D. Matt Gram Kwang SU SEO Institute of Polymer Science The University of Akron/Akron Polymer system Akron, OH USA

7,11-dimethyl-3-methylene-1,6,10-dodecatriene β-Farnesene 7,11-dimethyl-3-methylene-1,6,10-dodecatriene Can be polymerized into the 1,4 and 3,4 microstructures by anionic polymerization. Tg of both the 1,4 and 3,4 microstructures; -76 oC Can be used as an elastomer Triblock copolymers can be polymerized by anionic polymerization of styrene and farnesene Applications Adhesives Toughening agents Oxygen scavenger Crosslinking additives

Experimental β-Farnesene: 97% purity (zingiberene, bisabolene, farnesene exposide, franesol, E,E-farnesol, squalene, ergosterol, and so on) Solvent: cyclohexane Catalyst system: n-BuLi or sec-BuLi with TMEDA Crosslinking agent: dichlorosilane

Synthesis of 1,4-Poly(farnesene) Low MW High MW Mn = 105K, Mw= 147K Mw/Mn = 1.41 Mn = 245K, Mw= 457K Mw/Mn = 1.87

DSC of 1,4 PF 105K 245K Tg = -76.08 oC Tg = -76.62 oC cis-1,4-Polyisoprene: -73 oC trans-1,4-Polyisoprene: -53 oC 3,4-Polyisoprene: 5oC cis-1,4-Polybutadiene: -107 oC trans-1,4-Polybutadiene: -107 oC

Tensile Test of 245K 1,4 PF

Synthesis of 3,4-Poly(farnesene) n-BuLi / TMEDA, Target MW: 50K A B A; Mn = 46K, Mw= 48K, Mw/Mn = 1.04 B; Mn = 97K 90% 3,4 microstructure 10% 1,2 microstructure

DSC of 3,4 PF Tg = -76.09 oC

Vulcanization of 1,4PF 105K 245K the repeat unit in PF systems have three double bonds with two located on the relatively long flexible side chain. These double bonds can easily react with neighboring side chains from the same backbone which would not result in effective crosslinking. The result would be poor physical properties.

Polystyrene-Poly(1,4-farnesene)-Polystyrene PS-1,4PF-Li + dichlorosilane ---------> PS-1,4PF-PS B C A 10% A; Mn = 138K, B; Mn = 63K, C; Mn = 28K 97% 1,4 microstructure

Polystyrene-Poly(1,4-farnesene)-Polystyrene PS-3,4PF-Li + dichlorosilane ---------> PS-3,4PF-PS A B C 33% A; Mn = 172K, B; Mn = 86K, C; Mn = 28K 95% 3,4 microstructure

DSC of PS-1,4PF-PS and PS-3,4PF-PS 3,4PF: -72 oC PS: 94 oC 1,4PF: -76 oC PS: 96 oC

Tensile Test of PS-1,4PF-PS and PS-3,4PF-PS

Tensile Test of purified PS-3,4PF-PS Exhibits strain crystallization which increases the modulus of the material with elongation.

Summary PF with highly selective 1,4 or 3,4 microstructures was efficiently synthesized. High MW PF was synthesized at relatively high monomer concentrations. 1,4 and 3,4 microstructures can be mixed without affecting the Tg. Both 1,4 and 3,4 microstructures are thermally stable above 170˚C. Both 1,4 and 3,4 microstructures exhibited good tack. The PF tri-block exhibits strain crystallization which poly(isoprene) does not. Considering the composition of the triblock, they exhibited good properties. The triblock exhibited promising results as an adhesive.