Patterned Microstructure Fabrication: Polyelectrolyte Complexes vs Polyelectrolyte Multilayers

Abstract

Polyelectrolyte complexes (PEC) are formed by mixing the solutions of oppositely charged polyelectrolytes, which were hitherto deemed “impossible” to process, since they are infusible and brittle when dry. Here, we describe the process of fabricating free-standing micro-patterned PEC films containing array of hollow or filled microchambers by one-step casting with small applied pressure and a PDMS mould. These structures are compared with polyelectrolyte multilayers (PEM) thin films having array of hollow microchambers produced from a layer-by-layer self-assembly of the same polyelectrolytes on the same PDMS moulds. PEM microchambers “cap” and “wall” thickness depend on the number of PEM bilayers, while the “cap” and “wall” of the PEC microchambers can be tuned by varying the applied pressure and the type of patterned mould. The proposed PEC production process omits layering approaches currently employed for PEMs, reducing the production time from ~2 days down to 2 hours. The error-free structured PEC area was found to be significantly larger compared to the currently-employed microcontact printing for PEMs. The sensitivity of PEC chambers towards aqueous environments was found to be higher compared to those composed of PEM.

Bacteria-Resistant, Transparent, Free-Standing Films Prepared from Complex Coacervates

“…However, recent work has demonstrated that salt can be used to plasticize PECs to enable processing. 41–48 To date, PECs have been extruded into single fibers, 44,49 electrospun into fiber meshes, 41,42 processed into free-standing microchambers, 46 spin-coated into films, 43 cast into films, 45 and 3D-printed into material forms. 50,51…”

Polyelectrolyte–Graphene Oxide Multilayer Composites for Array of Microchambers which are Mechanically Robust and Responsive to NIR Light

“…Recently drop‐casting was also suggested as a more readily available alternative for making the templates . Microchambers may be fabricated via one‐step casting of a polyelectrolyte complex onto, or LbL assembly of PEMs on a template . The latter approach requires significantly longer time but allows layered structures which is specifically advantageous for effective stress transfer in PEGOM nanocomposites.…”

“…Enhanced mechanical properties of PEGOM films could be specifically advantageous for making 3D structures, e.g., an array of microchambers developed recently . Potential applications of these structures include micropackaging of drugs, or sensors for rapid diagnostics of biological fluids, where resilience of the microchambers toward external stresses is required to avoid accidental burst release, the event that could be catastrophic.…”

Surface Micro‐ and Nanoengineering: Applications of Layer‐by‐Layer Technology as a Versatile Tool to Control Cellular Behavior

“…Combining soft‐lithography with LbL can occur in different ways: printing, molding or embossing the PDMS structure on the surface of the multilayer film material or constructing an LbL‐based system above the patterned PDMS substrate. For instance, polyelectrolyte multilayers presenting an array of microgrooves were already produced by layer‐by‐layer assembly on patterned PDMS molds and compared with polyelectrolyte complexes prepared in the same conditions …”