PEF (Tg = 86 °C, Tm = 235 °C) polymers (Table ) Irrespective of the fact that whether the (-)-α-pinene-based diol monomer (HN (2), HM ( )) is a crystalline solid or a liquid, the synthesized polyester will be crystalline (HN_FDCA (10), HM_FDCA ( )) when the aromatic content of the polyester is increased, as it can increase the possibility of H-bonding that stabilizes the polymer in a particular stereochemical form (syndiotactic/isotactic/atactic) by its planar rigid structure (see the SI, Table ).