Publications

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

We have developed a generalized model of particle-substrate interactions describing both adhesion and wetting behavior. Using a combination of the molecular dynamics simulations and scaling analysis we have shown that the crossover between adhesion and wetting-like behavior for a particle with size Rp and shear modulus Gp interacting with a substrate of shear modulus Gs is determined by the dimensionless parameter β ∞ γ∗(G∗ Rp)-2/3W-1/3, where G∗ = GpGs/(Gp + Gs) is the effective shear modulus, W is the work of adhesion between particle and substrate, and γ∗ = Wgr + γp(1-2gr) + γspgr2 is the effective surface tension of the particle/substrate system with γp and γs being surface tensions of particle and substrate, γsp - surface tension of the particle-substrate interface, and gr = Gp/(Gp + Gs). This parameter β is proportional to the ratio of elastocapillary length γ∗/G∗ and contact radius a, β ∞ γ∗/G∗a. In the limit of small values of the parameter β < 1, when the contact radius a is larger than the elastocapillary length γ∗/G∗, our model reproduces Johnson, Kendall, and Roberts results for particle adhesion on elastic substrates (adhesion regime). However, in the opposite limit, β > 1 (a < γ∗/G∗), the capillary forces play a dominant role and determine particle-substrate interactions (wetting regime). Model predictions are in a very good agreement with simulation and experimental results.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Microtubules (MTs) are biological polymer filaments that display unique polymerization dynamics, and serve as inspiration for developing synthetic nanomaterials that exhibit similar assembly-derived behaviours. Here we explore an assembly process in which extended 1D nano-arrays (NAs) are formed through the directed, head-to-tail self-assembly of MT filaments. In particular, we demonstrate that the elongation of NAs over time is due to directed self-assembly of MTs by a process that is limited by diffusion and follows second-order rate kinetics. We further described a mechanism, both experimental and through molecular dynamics simulations, where stable junctions among MT building blocks are formed by alignment and adhesion of opposing filament ends, which is followed by formation of a stable junction through the incorporation of free tubulin and the removal of lattice vacancies. The fundamental principles described in this directed self-assembly process provide a promising basis for new approaches to manufacturing complex, heterostructured nanocomposites.