Superrepellent Porous Polymer Surfaces by Replication from Wrinkled Polydimethylsiloxane/Parylene F

Abstract

Superrepellent surfaces, such as micro/nanostructured surfaces, are of key importance in both academia and industry for emerging applications in areas such as self-cleaning, drag reduction, and oil repellence. Engineering these surfaces is achieved through the combination of the required surface topography, such as porosity, with low-surface-energy materials. The surface topography is crucial for achieving high liquid repellence and low roll-off angles. In general, the combination of micro- and nanostructures is most promising in achieving high repellence. In this work, we report the enhancement of wetting properties of porous polymers by replication from wrinkled Parylene F (PF)-coated polydimethylsiloxane (PDMS). Fluorinated polymer foam “Fluoropor” serves as the low-surface-energy polymer. The wrinkled molds are achieved via the deposition of a thin PF layer onto the soft PDMS substrates. Through consecutive supercritical drying, superrepellent surfaces with a high surface porosity and a high water contact angle (CA) of >165° are achieved. The replicated surfaces show low roll-off angles (ROA) <10° for water and <21° for ethylene glycol. Moreover, the introduction of the micro-wrinkles to Fluoropor not only enhances its liquid repellence for water and ethylene glycol but also for liquids with low surface tension, such as n-hexadecane.

Influence of Parylene F Coatings on the Wetting Properties of Soft Polydimethylsiloxane (PDMS)

“…The preparation of two sorts of soft PDMS substrates (Bioclear and commercially available two-components SF) was previously reported [37]. Briefly, soft Bioclear substrates were fabricated by mixing a vinylsiloxane prepolymer (XG 0677, DMS V31) and a hydrosiloxane curing agent (HMS 151) with a platinum catalyst, with the precise amounts being previously reported [37]. Commercial soft PDMS substrates were prepared using crosslinked SF mixed at a weight ratio of 50:1 of pre-polymer to crosslinker, respectively.…”

“…The elastic modulus of the PDMS substrates was measured via shear rheology measurements using HAAKE Modular Advanced Rheometer System of type MARS 2 (Thermo Scientific, Germany). The procedure was reported in our previous recent work [37].…”

“…The chemical vapor deposition (CVD) process of parylene F (PF) thin layers was carried out using PDS 2010 Labcoater (Specialty Coating System (SCS), KISKO, Indianapolis, IN, USA). The parameters were previously reported [37]. The PF dimer was vaporized at 150 • C, then transformed to gaseous monomers in the pyrolysis oven at 650 • C and deposited onto the PDMS surfaces at room temperature.…”

Exploring Pore Formation and Gas Sensing Kinetics Using Conjugated Polymer–Small Molecule Blends

“…8−10 Porous polymers have been prepared using both polymeric chemistry and physical methods. 11 Various approaches such as interfacial polymerization, 12 selfassembly with block copolymers, 13−15 and direct molding with hard templates 16,17 have been reported to form porous structures and tailor pore sizes for nonconjugated polymers. However, formation of porous structures with CPs is limited by their inherently rigid nature.…”

“…Porous conjugated polymers (CPs) are versatile platforms for enhancing the mass storage/transfer and detection capabilities of various energy evolution and electro-optical devices such as electrochemical transistors, , gas sensors, − and photocatalytic redox devices. , According to the International Union of Pure and Applied Chemistry, porous materials can be classified into three categories based on their pore size: microporous (<2 nm), mesoporous (2–50 nm), and macroporous (>50 nm). − Porous polymers have been prepared using both polymeric chemistry and physical methods . Various approaches such as interfacial polymerization, self-assembly with block copolymers, − and direct molding with hard templates , have been reported to form porous structures and tailor pore sizes for nonconjugated polymers. However, formation of porous structures with CPs is limited by their inherently rigid nature.…”