“Sandwich” Microcontact Printing as a Mild Route Towards Monodisperse Janus Particles with Tailored Bifunctionality

Abstract

A “sandwich” microcontact printing method is reported. A monolayer of porous epoxy polymer microspheres is transformed into Janus particles with distinct functionality on each face by reaction with amine functional fluorescent dyes, carbohydrates, and magnetic nanoparticles.

Porous polymer particles—A comprehensive guide to synthesis, characterization, functionalization and applications

“…This porogen was found to be the most successful porogen among others in yielding skin-free macroporous particles [221]. More interestingly, these isotropic particles underwent a reactive "sandwich" microcontact printing procedure, which produced anisotropic beads with two different faces, referred to as Janus particles [222].…”

“…In addition, there are directional methods that are being used to form chemical patches on surface of particles such as microcontact printing [387][388], etching [389], laser- [390] or UV-induced deposition [391], projection lithography [392], metal deposition [393][394] and temporary masking one side of particles while modifying the other [395][396]. Most of these methods are waiting to be explored for porous particles.…”

Vertical Hydrodynamic Focusing and Continuous Acoustofluidic Separation of Particles via Upward Migration

“…A mixture of two different‐sized particles (larger green and smaller red) was injected through the first of the two inlets at a flow rate of Q 1 , and a sheath fluid in the form of deionized (DI) water was introduced through the second inlet at a flow rate of Q 2 . The purpose of the sheath flow was to pinch the sample mixture in the lower streamlines using the DI water flowing in the upper streamlines to create a vertical double‐layered flow while hydrodynamically focusing the particles close to the bottom of the microchannel 49, 50. The first of the two outlets was used to pump out the fluid at a flow rate of Q 3 by applying a negative pressure, while the remaining fluid was collected through the second outlet, which was open to the atmosphere, with a flow rate of Q 4 .…”

Ordered arrays of pumpkin-shaped Janus particles with tailored surface morphologies via microcontact hot embossing

“…Compared with synthesis approaches for the preparation of Janus particles, the post-modification strategy seems to be more straightforward, in that it can be applied to almost any particles for customized topologies [18]. For example, evaporation deposition of metal film on the exposed surface of the pre-immobilized particles is such a common method, which is amenable to a wide range of particle materials [19,20].…”

“…Those techniques provide us a novel perspective for the post-modification of particles in a simple way, while concerned researches are limited. For instance, there have been some reports [18,20,[23][24][25][26][27][28] on the asymmetric post-modification of particles via μCP, which mainly utilizes an elastomeric stamp (typically poly(dimethylsiloxane) (PDMS)) to transfer inks onto the contacted surface. Here, Cayre et al used μCP to generate Janus microparticles with dipolar surface charge distribution and further extended this technique to produce asymmetrically coated colloid particles by printing one colloidal monolayer on a latex particle monolayer of opposite charges [23,24].…”