Faculty of Engineering, Hokkaido University, Sapporo, Japan
Takuya Isono is an Associate Professor at the Faculty of Engineering at Hokkaido University in Japan. He earned his Ph.D. degree in polymer chemistry from the Graduate School of Chemical Sciences and Engineering at Hokkaido University in 2014. During his Ph.D. studies from 2012 to 2014, he was a JSPS research fellow (DC1). After completing his Ph.D., he began his research career as an Assistant Professor at the Faculty of Engineering at Hokkaido University in 2014. Since April 2021, he has held his current position at Hokkaido University. His expertise is in precise polymer synthesis, and his research interests are currently centred on organocatalytic polymerization, bio-based polymers, block copolymers, and topological polymers. He has received scientific awards for his research, including the Inoue Research Award for Young Scientists from the Inoue Foundation for Science in 2016, the Polymer Research Encouraging Award from the Society of Polymer Science, Japan in 2020, and the Research Encourage Award from the Chemical Society of Japan in 2021.
Polysaccharides and their derivatives have long been utilized as thermoplastics and fibers. However, despite the long history of utilizing polysaccharides in commodity polymers, their range of applications has been limited due to their intrinsically hard and rigid properties. Here, we report that the integration of a rubbery hydrophobic polymer and oligo/polysaccharide hard segments into a block copolymer (BCP) can create a novel bio-based elastomer, in which the microphase-separated carbohydrate hard domains act as a physical cross-link for the rubbery chains.
A series of “hard-b-soft-b-hard” BCPs consisting of maltooligosaccharides (maltose, maltotriose, maltotetraose, and maltohexaose; A block) and poly(δ-decanolactone) (PDL; B block), with ABA-, A2BA2-, A3BA3-, A(BA)2-, and A2(BA)2-type architectures, were synthesized by combining living ring-opening polymerization and click reaction. To understand the correlation between the BCP molecular structure and material properties, the BCPs were designed to have comparable molecular weights (around 12 kg mol-1) and total numbers of glucose units (12). Morphological analysis revealed the formation of body-centered-cubic sphere and hexagonally close-packed cylinder (HEX) morphologies depending on the branched architecture (interdomain distance 9.7−14.4 nm). While the PDL homopolymer is a viscous liquid due to its low Tg and amorphous nature, all BCPs exhibited elastomeric properties, confirming that the oligosaccharide blocks segregated to form the hard domains to cross-link the rubbery PDL chains. Tensile testing revealed that the mechanical properties of the BCPs were mainly determined by the microphase-separated structure and less affected by the length of each oligosaccharide chain. The HEX-forming A2BA2– and A3BA3-type BCPs exhibited Young’s moduli of ∼6 MPa, which is comparable to well-known styrene-based thermoplastic elastomers. These results demonstrate that oligosaccharides are a sustainable alternative to the petroleum-derived synthetic hard segments (e.g., polystyrene), thereby opening up a new avenue for fully bio-based soft material design.
©fbpol2024 – Legals notices – Webdesign : chrisgaillard.com