Isospecific Polymerization of 1-Phenyl-1,3-butadiene and Its Copolymerization with Terpene-Derived Monomers

The transition from fossil-based materials to biobased alternatives has become a critical research focus, particularly in the polymer sector, due to environmental concerns such as rising CO2 levels and microplastic pollution. This work explores the stereospecific polymerization of 1-phenyl-1,3-butadiene (1PB), a bioderived monomer from cinnamaldehyde, using a titanium [OSSO]-type catalyst activated by MAO. The polymerization exhibited high 3,4-regioselectivity and isotacticity (mmmm > 99%) with a maximum yield of 65% at 80 °C. Post-polymerization hydrogenation reduced the glass transition temperature (Tg) from ≈80 °C to ≈17 °C, highlighting the impact of double bond removal on polymer flexibility. Additionally, copolymerizations of 1PB with natural terpenes β-ocimene (O) and S-4-isopropenyl-1-vinyl-1-cyclohexene (IVC) were conducted, yielding multiblock copolymers PPBO and PPBI, respectively, with tunable thermal properties. These copolymers showed partial cross-linking reactions and consequent presence of two glass transition temperatures (Tg). For PPBO copolymers, the low Tg values tended to significantly decrease as the terpene content increased, whereas for the PPBI copolymers, the low Tg values showed minimal changes due to the similar Tg of their homopolymers. These findings demonstrate the potential of renewable monomers for producing sustainable polymers.