Toughening Brittle Bio‐P3HB with Synthetic P3HB of Engineered Stereomicrostructures

• Published in: Angewandte Chemie (International ed.) 2023-12, Vol.62 (49), p.e202311264-n/a
• Main Authors: Zhang, Zhen, Quinn, Ethan C., Olmedo‐Martínez, Jorge L., Caputo, Maria Rosaria, Franklin, Kevin A., Müller, Alejandro J., Chen, Eugene Y.‐X.
• Format: Article
• Language: English
• Subjects: Biodegradability; Biodegradable Polymer; Biodegradation; Blending; Brittleness; Ductility; Light transmittance; Mechanical properties; Melt temperature; Modulus of elasticity; Molecular weight; Mono-Material Product Design; P3HB Blend; Poly(3-Hydroxybutyrate); Product design; Stereomicrostructure; Tensile strength
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202311264

Poly(3‐hydroxybutyrate) (P3HB), a biologically produced, biodegradable natural polyester, exhibits excellent thermal and barrier properties but suffers from mechanical brittleness, largely limiting its applications. Here we report a mono‐material product design strategy to toughen stereoperfect, brittle bio or synthetic P3HB by blending it with stereomicrostructurally engineered P3HB. Through tacticity ([mm] from 0 to 100 %) and molecular weight (Mn to 788 kDa) tuning, high‐performance synthetic P3HB materials with tensile strength to ≈30 MPa, fracture strain to ≈800 %, and toughness to 126 MJ m−3 (>110× tougher than bio‐P3HB) have been produced. Physical blending of the brittle P3HB with such P3HB in 10 to 90 wt % dramatically enhances its ductility from ≈5 % to 95–450 % and optical clarity from 19 % to 85 % visible light transmittance while maintaining desirably high elastic modulus (>1 GPa), tensile strength (>35 MPa), and melting temperature (160–170 °C). This P3HB‐toughening‐P3HB methodology departs from the traditional approach of incorporating chemically distinct components to toughen P3HB, which hinders chemical or mechanical recycling, highlighting the potential of the mono‐material product design solely based on biodegradable P3HB to deliver P3HB materials with diverse performance properties. The longstanding mechanical brittleness issue associated with stereoperfect biological or synthetic P3HB is solved through blending it with synthetic P3HB with specifically engineered stereomicrostructures, which not only drastically enhances the toughness by >156× and optical clarity but also largely maintains its otherwise desirably high elastic modulus, tensile strength, melting temperature.