(Co)polymerization of (−)-menthide and β-butyrolactone with yttrium-bis(phenolates): tuning material properties of sustainable polyesters

• Published in: Polymer chemistry Vol. 11; no. 27; pp. 4426 - 4437
• Main Authors: Adams, Friederike, Pehl, Thomas M, Kränzlein, Moritz, Kernbichl, Sebastian A, Kang, Jia-Jhen, Papadakis, Christine M, Rieger, Bernhard
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 21.07.2020
• Subjects: Block copolymers; Butyrolactone; Catalysts; Elongated structure; Material properties; Mechanical properties; Modulus of elasticity; NMR; Nuclear magnetic resonance; Polyester resins; Polyhydroxybutyrate; Polymer chemistry; Polymerization; Ring opening polymerization; Small angle X ray scattering; Strain analysis; Syndiotacticity; Thermal analysis; Thermogravimetric analysis; Yttrium
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/d0py00379d

Pyridine-based heteroaromatic yttrium-bis(phenolate) complexes were investigated in ring-opening polymerization of racemic β-butyrolactone (rac-BBL) and (−)-menthide. In addition, AB and BAB copolymers from poly((−)-menthide) (PM, block A) and poly(3-hydroxybutyrate) (PHB, block B) were synthesized via sequential addition. BAB copolymers were accessible through introduction of a bifunctional pyrazine initiator enabling chain growth in two directions. Block copolymers were analyzed using thermal analysis, X-ray diffraction, small-angle X-ray scattering, NMR analysis and stress-strain experiments. These measurements confirmed a microphase separation within the semicrystalline BAB materials. Regarding the mechanical behavior, two hot-moldable PHB-based (co)polymers were investigated. The syndiotactic PHB is less brittle than natural PHB, resulting in a lower Young's modulus. Incorporating PM in the structure, the elastic modulus is further lowered with increasing elongation at break. Sustainable thermoplastic elastomers derived from block copolymers of syndiotactic poly(3-hydroxybutyrate) and poly((−)-menthide) were synthesized via yttrium-mediated ring-opening polymerization.