Tough Glass with Mechanical Bonding Network Anchored by High-Mobility Polymers

Abstract

A series of mechanically interlocked supramolecular glasses were prepared from a bio-based cyclic oligosaccharide with small amounts of polymer. The rigid glassy materials were readily thermo-moldable, and their mechanical properties were tuned by the substituents on the oligosaccharide. In the presence of even small amounts (<18 wt %) of polymer, fragile oligosaccharide derivatives turned into tough bio-based plastics, as long as the polymer penetrated through the cyclic molecules. A small difference in acyl substituents on the ring components resulted in a significant difference in the mechanical properties. Bulkier substituents monotonically decreased Young’s modulus and the glass transition temperature (Tg), indicating the predominance of interactions between ring components that maintain the material framework. However, the toughness dramatically changed, independent of the interactions, forming two glasses with the same Young’s modulus and Tg into different materials: brittle and ductile. A clear difference between brittle and ductile glasses was observed in their confined polymer mobility. Analysis of the dynamics revealed that the higher mobility of the polymer was maintained in the material frameworks of ductile glasses compared with that of brittle glasses, whereas a comparable glass prepared from a mixture of the two components of ductile glass was very fragile. These results suggest the necessity of a mechanical bonding network formed by high-mobility polymers so that the confined polymers can work as an anchor rapidly in response to crack formation in the framework