Multi-Scale Thermal Stability of a Hard Thermoplastic Protein-based Material
2015 Victoria Latza, Paul A. Guerette, Dawei Ding, Shahrouz Amini, Akshita Kumar, Ingo Schmidt, Steven Keating, Neri Oxman, James C. Weaver, Peter Fratzl, Ali Miserez, and Admir Masic, Nature Communications, No. 6, Article number 8313. Pp. 1-8
Although thermoplastic materials are mostly derived from petro-chemicals, it would be highly desirable, from a sustainability perspective, to produce them instead from renewable biopolymers. Unfortunately, biopolymers exhibiting thermoplastic behaviour and which preserve their mechanical properties post processing are essentially non-existent. The robust sucker ring teeth (SRT) from squid and cuttlefish are one notable exception of thermoplastic biopolymers. Here we describe thermoplastic processing of squid SRT via hot extrusion of fibres, demonstrating the potential suitability of these materials for large-scale thermal forming. Using high-resolution in situ X-ray diffraction and vibrational spectroscopy, we elucidate the molecular and nanoscale features responsible for this behaviour and show that SRT consist of semi-crystalline polymers, whereby heat-resistant, nanocrystalline b-sheets embedded within an amorphous matrix are organized into a hexagonally packed nanofibrillar network. This study provides key insights for the molecular design of biomimetic protein- and peptide-based thermoplastic structural biopolymers with potential biomedical and 3D printing applications.