Sep 3, 2021
Tom Mason
Professor Thomas Mason and graduate student Tianren Yu have designed and lithographically created novel lock-and-key colloidal polymers.
 
Their paper, entitled “Brownian lithographic polymers of steric lock-and-key colloidal linkages”, has been published in Science Advances on September 3, 2021. Yu is the first-author and Mason is the senior and corresponding author.
A dendritic polylithomer of lock-and-key colloidal tiles figure
A dendritic polylithomer of lock-and-key colloidal tiles: 
design (left) and optical microscope image after release (right).
 
Mason’s group has created novel lithographic polymers, or ‘polylithomers’, of lock-and-key colloidal tiles that have entirely steric bonds. When released from a substrate, these chains of tiles (i.e. linkages) fluctuate in a plane as a consequence of Brownian excitations and imposed anisotropic depletion attractions; Yu and Mason have tracked the fluctuating conformations of tiles to the sub-monomer scale using optical microscopy. They have designed and demonstrated several different new types of polymer structures that, as far as they know, have not been synthesized previously using either molecular or colloidal monomers. These new colloidal polymers have controllable semi-flexibility and extensibility through the geometrical design of the steric bonds via lithographic mutation of sub-tile features. Their Sciences Advances article covers the powerful idea of using lithography to bypass programmed molecular interactions and instead to program mobile, flexible, bonded colloidal superstructures by direct geometrical design. Moreover, this approach for producing polylithomers advances the field of lithographically pre-assembled monolayers, which was invented by Mason’s group (published in Nature in 2018), yet previously demonstrated only for purely convex shapes that were not interlocking. Beyond reporting these exciting advances in materials science, Mason’s group has also extended real-space video colloidal particle tracking methods to handle lock-and-key colloids, which represents a major technical advance in particle tracking.
 
Mason is a professor of physical chemistry and a professor of soft matter physics at UCLA; he leads an interdisciplinary research group in pre-assembled and self-assembled soft matter, lithography, nanoemulsions, and microrheology. Tianren Yu is a third-year physical chemistry graduate student. He received his bachelor’s degree in chemistry at Nanjing University.  For more information about research in Mason's group, visit this website.
 
Penny Jennings, UCLA Department of Chemistry & Biochemistry, penny@chem.ucla.edu.