Understanding Processing-Structure-Property Relationships in Spun Spidroin-Mimetic Fibers Using Molecular Dynamics...

Considering the tensile and elongational forces involved in natural silk spinning, silk fiber production resembles drawing processes in conventional fiber manufacturing. Understanding how protein sequence and "drawing" conditions govern molecular structure and mechanical properties is essential for the rational design of silk materials. Here, we employ a coarse-grained molecular dynamics model to simulate the self-assembly of spidroin-mimetic chains with varying β-sheet-forming (hard) segment contents under different spinning strains and times. The simulations reveal distinct degrees of macromolecular alignment and β-sheet nanocrystal formation. Uniaxial tensile simulations show that spinning strain, rather than time, predominantly dictates mechanical performance through its impact on nanoscale structure. The results show that spidroin-like macromolecules with low hard segment content are the best candidates for achieving simultaneous strengthening and toughening through increased spinning strain. These findings establish design guidelines for optimizing silk performance through the coordinated control of sequence architecture and spinning conditions.