Highly fluid repellent have application in many industries ranging from marine to biomedical due to their self-cleaning antifouling properties. The development and implementation of these superhydrophobic (water contact angle >150 degrees ) and superoleophobic (oil contact angle > 150 degrees ) surfaces were studied in this thesis. We focused our studies on paper as a substrate for these superhydrophobic and superoleophobic surfaces. Cellulose based paper is a biodegradable, inexpensive material that is ideal for disposable use applications. Applying an oxygen plasma etching technique combined with the deposition of a fluoropolymer from a pentafluoroethane precursor, superhydrophobic paper can be attained. This superhydrophobic paper is functionalized by printing wax islands onto the surface, thereby creating areas of high fluid adhesion. These wax functionalized sheets are used to sample droplets from bulk droplets, with the sampled volume being controlled by the hysteresis of the wax island. Disposable biomedical devices can be envisioned from these wax designs. While these superhydrophobic surface excel at repelling water, they continue to readily absorb water. Formation of paper that is both superhydrophobic and superoleophobic, or superamphiphobic, is accomplished through a combination of steps: mechanical fiber refining, solvent exchange processing and plasma treatment. The fiber refining creates nano-scale fibrils that are separated in the solvent processing. Subsequent plasma treatment of oxygen etching and fluoropolymer deposition creates superamphiphobic paper, exhibiting contact angles of > 150 degrees for water, ethylene glycol, motor oil and n-hexadecane. Further studies were conducted to increase the strength of these superamphiphobic sheets by using layered paper. Development of superhydrophobic paper from a hydrophilic diamond-like carbon surface coating was also demonstrated. When combined with oxygen plasma etching, diamond-like carbon coated paper sheets attain superhydrophobic properties similar to fluoropolymer coated sheets. Based on the knowledge gained from the studies on paper, superhydrophobic surfaces are created on 304 and 316 stainless steels. Samples are etched in hydrofluoric acid and then passivated in nitric acid to create the necessary surface structure. Deposition of fluoropolymer onto the etched samples yields superhydrophobic properties.

Raspberry-like polystyrene particles were fabricated through the covalent linkage of small epoxy-functionalized polystyrene particles (PS-GMA) with large amino-functionalized polystyrene particles (PS-NH2). These covalent bonds yielded more stable and robust particle clusters than would be anticipated from non-covalent interactions. While the structures of these raspberry-like particles provided them with a dual-scale hierarchical roughness and re-entrant sites, they were further functionalized with a fluorinated random copolymer to provide them a low surface tension. The fluorinated random copolymer used to functionalize these raspberry-like particles was poly(glycidyl methacrylate20%)-co-2(perfluorooctyl)ethyl methacrylate80%)25 or P(GMA20%-co-FOEMA80%)25, where the subscript 25 denotes the total number of the respective GMA and FOEMA units, while the subscript 20% and 80% denote the molar fractions of GMA and FOEMA, respectively. The epoxy groups of the GMA units could react with the amino groups of the raspberry-like particles, thus incorporating the fluorinated polymer onto the surfaces of the raspberry-like particles. In addition, the FOEMA component provided the particles with enhanced amphiphobicity. Subsequently, these fluorinated raspberry-like particles were cast onto glass slides to demonstrate their superamphiphobic properties. These coatings exhibited superhydrophobic behavior when they were tested against water droplets. Additionally, the oil-repellency of these coatings was tested against various liquids, including diiodomethane, cooking oil, and hexadecane. The coatings exhibited superoleophobic behavior against diiodomethane and cooking oil, as well as highly oleophobic behavior against hexadecane. This work demonstrates a simple and efficient route for the fabrication of superamphiphobic surfaces. Additionally, these surfaces are among the first examples of coatings prepared via self-assembly techniques that exhibited high repellency against hexadecane. These materials could have potential in various applications that require protection of a surface against wetting by either water or oils. / Thesis (Master, Chemistry) -- Queen's University, 2013-10-18 12:36:39.039

Dropp-genereringstekniker är viktiga för industrier som läkemedelsindustrin, livsmedelsindustrin, kosmetikindustrin etc. Traditionella droppgenereringstekniker är dock begränsade i mängden av material som kan processas till droppform. Ett exempel inkjet som är en väletablerad teknik för att generera droppar med hög hastighet (1-10 kHz) och precision (10-20 μm), men kan bara stöta ut vätskor med låga viskositet, ungefär 10-100 gånger viskositeten av vattnet. Akustophoretisk utskrift motiv är att övervinna denna materialbegränsning och har framgångsrikt avkopplat dropputstötning från bläckviskositet. Metoden utnyttjar ickelinjära akustiska krafter för att skriva ut en stor mängd av material med hög kontroll, med viskositet som sträcker sig över fyra storleksordningar (0,5 mPa · s till 25 000 mPa · s). Emellertid är utstötningen baserad på bildandet av en hängande droppe, och i den aktuella prototypen begränsas materialpaletten av akustophoretisk utskrift genom sprider sig över munstycket, vilket begränsar den minsta tillåtnas ytspänningen till ungefär 60 mN / m. I detta arbete införs en munstycksbeläggningsteknik för att expandera mängden av utskrivbara material, med tillåtna ytspänningar så låga som 25 mN / m. Genom att utnyttja generera nanostrukturer med låg ytenergi på munstyckspetsen, tillverkas superavstötande beläggning. Grunden för nanostrukturerna genererades med hjälp av sot från ett paraffin-vaxljus. Ett robust tillverkningsprotokoll har etablerats, och beläggningen fysikaliska egenskaper och prestanda har karaktäriserats. Tre nya tillämpningsområden undersöktes, vilket demonstrerade noviteten hos denna nya metod. Detta arbete banar vägen för en ny uppsättning material som ska behandlas i en droppe-per droppe metodik. / Droplet generation techniques are essential for industries such as the pharmaceutical, food industry, cosmetic industry, etc. However, traditional droplet generation techniques are limited in the palette of materials that can processed in a droplet form. For example, inkjet which is a well-established technology to generate droplets of high speed (1-10 kHz) and precision (10-20 μm), but can only eject fluids with low viscosities, roughly 10-100 folds the one of water. Acoustophoretic printing aims to overcome this material limitation and have successfully decoupled droplet ejection from ink viscosity. The method harnesses nonlinear acoustic forces to print a wide range of materials on demand, spanning over four orders of magnitudes (0.5 mPa·sto 25,000 mPa·s). However, the ejection is based on the formation of a pendant drop, and in the current prototype, the material palette of acoustophoretic printing is limited by nozzle wetting, limiting the allowable minimum surface tension to about 60 mN/m. In this work, a nozzle coating technique is introduced in order to expand the material window by processing fluid with a surface tension as low as 25 mN/m. By leveraging self-assembling of nanostructures on the nozzle tip, superamphiphobic coating is successfully manufactured by using a candle soot template.A robust manufacturing protocol has been established, and the coating characterized in its physics and performance.