Regioselective and Anisotropic Multi-Patching of Small Microparticles via a Polymer Brush-Assisted Microcontact Printing (µCP)

We developed a method for fabricating anisotropic monodisperse silicon dioxide (SiO2) patchy microspheres. The protocol utilizes a modified microcontact printing (µCP) technique, employing a polydimethylsiloxane (PDMS) elastomer with a regularly grooved surface topography as a stamp. The stamp’s microscale channels create a confined environment for the SiO2 microspheres, as they match the particle dimensions (~4 µm). Our solid-phase µCP routine allows for the transfer of functional trialkoxysilanes from the elastomer stamp to the particles exclusively at their contact faces. By applying a second stamp to the exposed side of the particles, a fourth patch with different chemical information is added. This fabrication process, compatible with various follow-up chemistries, adds patches with adjustable characteristics. The method is suitable to fabricate particles possessing a C4v and C2v symmetry. Importantly, the protocol is easily adaptable to other particle dimensions and surface chemistries, indicating significant potential in the field of anisotropically functionalized spherical colloidal particles.