Browsing by Author "Saleem, Sajid"

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    Realizing surface amphiphobicity using 3D printing techniques: A critical move towards manufacturing low-cost reentrant geometries
    (Elsevier, 2021-01-06) Shams, Hamza; Basit, Kanza; Khan, Muhammad Ali; Saleem, Sajid; Mansoor, Asif
    Amphiphobic surfaces are obtained by lowering the surface energy through changes in surface geometry. These changes can be designed on the surface, thereby altering its wettability, and in turn rendering it amphiphobic. The main geometrical entities behind this phenomenon are reentrant geometries which prevent the solid-liquid interface tension from breaking, thereby resulting in contact angles greater than 90°. The science behind modelling and manufacturing of these reentrant geometries is well established apart from manufacturing them via extrusion-based 3-Dimensional printing processes. This review paper in identifying this gap summarizes various characterization parameters for surface wettability followed by identifying the role of surface reentrant geometries to introduce superamphiphobicity in polymers. The focus of the paper then moves towards achieving amphiphobicity using 3D printing processes where the current state of research is discussed in terms of reentrant profiles and achievement of high static contact angles. Role of the most common yet rarely reported Fused Deposition Modelling technique is discussed in more detail and a preliminary investigation based on characteristics flow and printing parameters used in Fused Deposition Modelling has been presented. The surface amphiphobicity is achieved in a one-step process characterized by high static contact angles with low and high surface tension liquids owing to air entrapment in characteristic layer-by-layer deposition features obtained in Fused Deposition Modelling.
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    Scalable wear resistant 3D printed slippery liquid infused porous surfaces (SLIPS)
    (Elsevier, 2021-10-02) Shams, Hamza; Basit, Kanza; Khan, Muhammad Ali; Mansoor, Asif; Saleem, Sajid
    Surface wettability is a measure of adhesion and repulsion of liquids on a material’s surface, where surface wettability may be altered by creating a new interfacial surface between the base material and the target liquid on top. Where the interface comprises of a liquid that is locked in the pores or ridges of the base material, it is then termed as liquid infused surface (LIS). LIS alters the wettability due to the distinctive properties of the interfacial liquid which now forms the new surface. If the interfacial liquid is repellent towards polar (hydrophobic) and non-polar (oleophobic) liquids, the overall surface becomes slippery (amphiphobic) and prevents any new target liquids from adhering. This phenomenon leads to the definition of slippery liquid infused porous surfaces (SLIPS), where this term not only describes its role but also its fabrication route. Here a two-step facile method is presented to quickly transform any 3D printable polymeric material into robust SLIPS, irrespective of the wettability properties of the original polymer. The complex geometrical porosity required for locking the interfacial liquid is achieved using Fused Deposition Modelling (FDM) setup. Surface wettability characteristics of the 3D printed porous structure are then enhanced by increasing the liquid-adsorption sites where the locking of the infused interfacial (repellent) liquid takes place. The SLIPS demonstrate low rolling-off (sliding) angles with both polar and non-polar solvents of up to 2 degrees with high resistance to mechanical abrasion undergoing sliding frictional wear. The robust SLIPS as produced can be quickly scaled up using existing processes used in the laboratory.