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 (<i>mmmm</i> > 99%) with a maximum yield of 65% at 80 °C. Post-polymerization hydrogenation reduced the glass transition temperature (<i>T</i> _g) 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 <i>S</i>-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 (<i>T</i> _g). For PPBO copolymers, the low <i>T</i> _g values tended to significantly decrease as the terpene content increased, whereas for the PPBI copolymers, the low <i>T</i> _g values showed minimal changes due to the similar <i>T</i> _g of their homopolymers. These findings demonstrate the potential of renewable monomers for producing sustainable polymers.