(450g) Combined Magneto- and Optofluidic Assembly of Colloidal Chains of Controllable Length

Combined magneto- and optofluidic
assembly of colloidal chains of controllable length

Because of their unique
characteristics, colloids have been used to investigate the fundamental physics
of soft materials including both equilibrium phase behavior and kinetic
processes. Unlike atoms, colloidal sizes can be conveniently tailored and are
typically large enough to be probed individually with interaction strengths and
effective ranges that can be modulated over several orders of magnitude.
Despite these significant advantages, mostly relatively simple colloidal models
such as spheres have been created; such systems in turn assemble into crystals
of fairly limited symmetry, precluding the study of problems associated with
complex structure. To push towards the synthesis of more complicated colloidal
molecules, we use combined applied magnetic and anisotropic optical fields to fabricate
colloidal chains. In these experiments, thiol-functionalized
magnetic beads were linked via maleimide-functionalized
polyethylene glycol crosslinker. Properties of
assembled chains including flexibility and stability were tuned by varying the linker
length and system temperature during synthesis. With integration of an optofluidic field, chain length and sequence could also be modified
by balancing hydrodynamic shear stress, applied magnetic field, and applied optical
forces.