posted on 2025-02-05, 01:29authored bySophia
J. Melvin, Yunxin Yao, Xiao Huang, Rowina C. Bell, Ryann E. Kemmerling, Ilia Kevlishvili, Angus C. Berg, Ana Paula Kitos Vasconcelos, Alshakim Nelson, Heather J. Kulik, Stephen L. Craig, Rebekka S. Klausen
The tearing of a polymer network arises from mechanochemically
coupled bond-breaking events in the backbone of a polymer chain. An
emerging research area is the identification of molecular strategies
for network toughening, such as the strategic placement of mechanochemically
reactive groups (e.g., scissile mechanophores) in the crosslinks of
a network instead of in the load-bearing primary strands. These mechanically
labile crosslinkers have typically relied on release of ring strain
or weak covalent bonds for selective covalent bond scission. Here,
we report a novel chemical design for accelerated mechanochemical
bond scission based on replacing a single carbon atom in a crosslinker
with a silicon atom. This single-atom replacement affords up to a
two-fold increase in the tearing energy. We suggest a mechanism, validated
by computational modeling, for accelerated mechanochemical Si–C
bond scission based on minimizing the energy required to distort the
starting material toward the transition-state geometry. We demonstrated
the seamless incorporation of these scissile carbosilanes to toughen
3D-printed networks, which demonstrates their suitability for additive
manufacturing processes.