1. 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

2. 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

3. 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

4. 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

5. 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

6. Tensile Test of 245K 1,4 PF

7. 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

8. DSC of 3,4 PF
Tg = oC

9. 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.

10. 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

11. 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

12. 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

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

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

15. 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.