2 research outputs found
Synergistic Stiffening in Double-Fiber Networks
Many
biological materials are composite structures, interpenetrating
networks of different types of fibers. The composite nature of such
networks leads to superior mechanical properties, but the origin of
this mechanical synergism is still poorly understood. Here we study
soft composite networks, made by mixing two self-assembling fiber-forming
components. We find that the elastic moduli of the composite networks
significantly exceed the sum of the moduli of the two individual networks.
This mechanical enhancement is in agreement with recent simulations,
where it was attributed to a suppression of non-affine deformation
modes in the most rigid fiber network due to the reaction forces in
the softer network. The increase
in affinity also causes a loss of strain hardening and an increase
in the critical stress and stain at which the network fails
Reversible Temperature-Switching of Hydrogel Stiffness of Coassembled, Silk-Collagen-Like Hydrogels
Recombinant protein polymers, which
can combine different bioinspired
self-assembly motifs in a well-defined block sequence, have large
potential as building blocks for making complex, hierarchically structured
materials. In this paper we demonstrate the stepwise formation of
thermosensitive hydrogels by combination of two distinct, orthogonal
self-assembly mechanisms. In the first step, fibers are coassembled
from two recombinant protein polymers: (a) a symmetric silk-like block
copolymer consisting of a central silk-like block flanked by two soluble
random coil blocks and (b) an asymmetric silk-collagen-like block
copolymer consisting of a central random-coil block flanked on one
side by a silk-like block and on the other side a collagen-like block.
In the second step, induced by cooling, the collagen-like blocks form
triple helices and thereby cross-link the fibers, leading to hydrogels
with a thermo-reversibly switchable stiffness. Our work demonstrates
how complex self-assembled materials can be formed through careful
control of the self-assembly pathway