  We use a coarse-grained model of DNA-functionalized particles to understand
the role of DNA chain length on their self-assembly. We find that the
increasing chain length for a given particle size decreases the propensity to
form ordered crystalline assemblies, and instead, disordered structures start
to form when the chain length exceeds a certain threshold, which is consistent
with the previous experiments. Further analysis of the simulation data suggests
weakening interparticle interactions with increasing chain length, thereby
shifting the suitable assembly conditions to lower temperatures at which
assembly dynamics are unfavorable. This highlights a complex interplay between
thermodynamics and dynamics, which we suggest can be modulated by changing the
system parameters such as DNA grafting density, resulting in successful
crystallization of particles with longer DNA chain lengths. Our results
highlight the power of computational modeling in elucidating the fundamental
design principles and guiding the assembly of nanoparticles to form complex
nanostructures.
