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

A method for fabricating anisotropic monodisperse silicon dioxide (SiO2) patchy microspheres is developed. In the protocol, we utilize 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). The solid-phase µCP routine allows for the transfer of functional trialkoxysilanes from the 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, resulting in particles with four equidistant patches along the particle equator. This fabrication process, compatible with a manifold follow-up chemistry, adds patches with adjustable characteristics. Consequently, a polymeric material containing the nucleobase adenine, is successfully added to the patches, which enables interactions with materials that possess its complementary base uracil. 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 chemistry, possessing significant potential in the field of anisotropically functionalized spherical colloidal particles.