Wettability assisted selective deposition of polystyrene nanoparticles on glass fibers

© 2018 Elsevier B.V. This work presents a concept for creating different chemistries along thin, micrometer sized fibers to be used as substrates for selective localization of nanoparticles. Glass fibers have been surface modified to introduce hydrophilic and hydrophobic regions along their length. Dynamic contact angle measurements using the Wilhelmy technique shows a marked change in the wetting behavior, confirming the transition in chemical functionality along the fiber. These fibers were then used as substrates to localize polystyrene nanoparticles from an aqueous dispersion at the air-water interface via a dip-coating method. Low contact angles and faster de-wetting allowed the particles to predominantly confine onto the hydrophilic regions of the glass fibers, indicating that both the fiber surface properties as well as the curvature of the fiber influences the profile of the particle carrying fluid meniscus. Our results also indicate a velocity-dependent particle deposition morphology and image quantification analysis revealed a significantly higher density of nanoparticles to be deposited at higher withdrawal velocities.status: publishe

Patterned glass fiber surfaces – Route to interface modification?

Fiber reinforced composites (FRCs) have demonstrated tremendous growth and attention owing to their outstanding mechanical properties such as high strength, specific stiffness, fatigue and toughness, combined with their low density and cost.[1] Recent research has focused much attention towards tailoring the physico-chemical properties of the fiber-matrix interface. It is well known that the interface plays a crucial role in determining the thermo-mechanical and fracture behavior of the composite, thus defining its overall durability. Shear stress transfer between the matrix and reinforcement occurs by a combination of mechanical inter-locking, physical adhesion and chemical bonding.[2] Physical adhesion of a surface is controlled by its surface free energy, which in a composite is associated to the thermodynamic work of adhesion between the fiber and matrix. The present study describes the surface modification of glass fibers by micro patterning and its effects on the physical properties. Among the variety of fibrous reinforcements available, glass fibers have been chosen for this study owing to the balance between thermo-mechanical properties, intrinsic hydrophilicity, and cost. The process of micro patterning is described as follows: as the first step, a thin layer of an hydrophobic photo sensitive resin is coated on the surface of the fibers. When exposed to ultra-violet (UV) light through a photo mask, the resin dissolves, thus rendering a patterned surface exhibiting selective wettability. Surface morphology of patterned fibers has been observed using Scanning Electron Microscopy (SEM). The effect of patterning on dynamic wetting properties of the fiber surface has been studied using Wilhelmy technique. Single fiber fragmentation tests are performed to elucidate the mechanical behavior of such patterned fibers.status: publishe