coacervate layer—a reconfiguration that has been described as incompressible “molecular ball bearings” (Klein, 2006). To further investigate the mcfp-1/HA coacervate, we adjusted the mixing ratio (7:3 and 3:7) and found that surface wear protection relied on the careful coordination of the mixing ratio. Although mcfp-1/HA coacervate at a 1:1 mixing ratio protected the surfaces from damage at high loads, mcfp-1/HA coacervate at 7:3 and 3:7 mixing ratios suboptimally protected surfaces, which damaged under only a quarter of the applied load (Figure 4a, 5). In this instance, damage was not due to insufficient adhesion—mcfp-1/HA coacervates with an excess of mcfp-1 or HA had higher and more variable adhesive/cohesive energies. Perhaps these molecules not involved in balanced electrostatic interactions (coacervate formation) become entangled, allowing shear forces to impact and damage the surface. The observation that as adhesion increases, wear protection decreases suggests that adhesion has an optimum for mitigating damage. Mussel byssal cuticle toughness and durability is widely attributed to covalent crosslinks and Ca2+ and Fe3+ complexation (Harrington et al., 2010; Holten-Andersen et al., 2009b). However, our results raise the interesting possibility that maintaining coacervates (fluid component) in all or part of the cuticle matrix could be adaptively beneficial for damage control as well as self-healing (by definition, fluids spontaneously self-heal). The excellent frictional damage mitigation by mcfp-1/HA coacervate reveals a significant untapped potential for coacervates in applications that require both adhesion
coacervate layer—a reconfiguration that has been described as incompressible “molecular ball bearings” (Klein, 2006). To further investigate the mcfp-1/HA coacervate, we adjusted the mixing ratio (7:3 and 3:7) and found that surface wear protection relied on the careful coordination of the mixing ratio. Although mcfp-1/HA coacervate at a 1:1 mixing ratio protected the surfaces from damage at high loads, mcfp-1/HA coacervate at 7:3 and 3:7 mixing ratios suboptimally protected surfaces, which damaged under only a quarter of the applied load (Figure 4a, 5). In this instance, damage was not due to insufficient adhesion—mcfp-1/HA coacervates with an excess of mcfp-1 or HA had higher and more variable adhesive/cohesive energies. Perhaps these molecules not involved in balanced electrostatic interactions (coacervate formation) become entangled, allowing shear forces to impact and damage the surface. The observation that as adhesion increases, wear protection decreases suggests that adhesion has an optimum for mitigating damage. Mussel byssal cuticle toughness and durability is widely attributed to covalent crosslinks and Ca2+ and Fe3+ complexation (Harrington et al., 2010; Holten-Andersen et al., 2009b). However, our results raise the interesting possibility that maintaining coacervates (fluid component) in all or part of the cuticle matrix could be adaptively beneficial for damage control as well as self-healing (by definition, fluids spontaneously self-heal). The excellent frictional damage mitigation by mcfp-1/HA coacervate reveals a significant untapped potential for coacervates in applications that require both adhesion
Miller_dissertation_corrections.docx