Hydrophilic/Hydrophobic Film Patterning by Photodegradation of Self-Assembled Alkylsilane Multilayers and Its Applications

Abstract

While the photopatterning of self-assembled monolayers (SAMs) has been extensively investigated, much less attention has been given to highly ordered multilayer systems. By being both thicker (0.5-2 μm) and more stable (cross-linked) than SAMs, patterned hybrid multilayers lend themselves more easily to the development of technology-relevant materials and characterization. This paper describes a facile two-step UV approach to patterning an alkylsilane multilayer by combining photoinduced self-assembly for multilayer synthesis and photodegradation through a mask for creating patterns within the film. In this second stage, a spatially resolved removal of the alkyl tail via a photooxidation mechanism took place, yielding regular and uniform silica microdomains. The result was a regular array of features (alkylsiloxane/silica) differing in chemical composition (hybrid/inorganic), ordering (crystal-like/disordered), and wettability (hydrophobic/hydrophilic). Such a photopatterned film was of utility for a range of applications in which water droplets, inorganic crystals, or aqueous polymer dispersions were selectively deposited in the hydrophilic silica microwells.

Photoinduced nanostructured organosilica hybrids

“…This approach leads to high degree of condensation of the siloxane network without any thermal treatment and affords the possibility of achieving thin and homogeneous films. This method has already opened opportunities in COOH‐functionalized lamellar organosilica with long‐range molecular ordering and uniform or photopatterning of self‐assembled alkylsilane multilayers . We foresee that the expansion of this approach will be driven by the ability to self‐assemble a broader range of organosilanes with less structural constraints and less efforts on chemical design.…”

Liquid Wells as Self‐Healing, Functional Analogues to Solid Vessels

“…[ 6–8 ] A commonly employed strategy is hydrophilic–hydrophobic chemically patterned surfaces, which allow spatial confinement of aqueous compartments. [ 9–15 ] Development of omniphobic–omniphilic or superoleophobic patterned substrates made it possible to confine droplets of low‐surface‐tension liquids (LSTLs) and significantly improved the capabilities of surface‐templated liquids. [ 16 ] The preparation of omniphobic or superoleophobic surfaces typically requires perfluorinated chemicals for surface modification or lubricant infused surfaces (LISs).…”

Controlled Growth of Organosilane Micropatterns on Hydrophilic and Hydrophobic Surfaces Templated by Vacuum Ultraviolet Photolithography

“…Photolithography is a commonly used technique for engineering the surfaces of materials to be applicable in advanced applications such as cell adhesion, sensing, and electronic devices. − In mask-based lithography, polymers and organic substrates are exposed to light, mainly ultraviolet (UV) light, through the slits of a photomask inducing different chemical conversions. − These chemical conversions result in different interfacial properties at the irradiated domains than at the masked domains. − Vacuum UV (VUV) photolithography, especially using 172 nm VUV light, is commonly used in patterning polymers and self-assembled monolayers (SAMs) due to the high photon energy of the used light. − …”

“…In an ambient environment, the VUV light exposure excites the molecular oxygen and generates active oxygen (O) species such as atomic oxygen species [O] and ozone O 3 . These (O) species can oxidize and dissociate the terminal alkyl moieties at the irradiated domains and generate different oxygenated groups. ,,− Namely, the induced surface modifications after the VUV/(O) treatment were accomplished through successive photofunctionalization and photodegradation processes . In the case of VUV/(O) patterning of alkyl-SAM formed on oxide-free Si substrate, the alkyl moieties would be dissociated and silicon dioxide (SiO 2 ) layers would be formed at the irradiated areas .…”