title: Controlling the wettability of hierarchically structured thermoplastics.
abstract: Surfaces play an important role in defining the properties of materials, controlling wetting, adsorption, or desorption of biomolecules, and sealing/bonding of different materials. We have combined microscale features with plasma-etched nanoscale roughness and chemical modification to tailor the wettability of the substrates. Cyclic olefin polymers and copolymers (COPs/COCs) were processed to make a range of surfaces with controlled superhydrophobic or -hydrophilic properties. The hydrophobic properties of the polymers were increased by the introduction of microstructures of varying geometry and spacing through hot embossing. The COC/COP substrates were functionalized by plasma activation in O(2), CF(4), and a mixture of both gases. The plasma etching introduces nanoscale roughness and also chemically modifies the surface, creating either highly hydrophilic or highly hydrophobic (contact angle >150°) surfaces depending on the gas mixture. The influence of geometry and chemistries was characterized by atomic force microscopy, contact angle measurements, and X-ray photoelectron spectroscopy. Measurements of the contact angle and contact angle hysteresis demonstrated long-term stability of the superhydrophobic/superhydrophilic characteristics (>6 months).
authors: ECS-Nano Group, School of Electronics and Computer Science, University of Southampton, University Road, Southampton SO17 1BJ, United Kingdom. bpc@ecs.soton.ac.uk
authors: Barbara
authors: B
authors: Cortese
authors: Hywel
authors: H
authors: Morgan
mesh_terms: D010969:Plastics; D017155:Wettability
chemical_list: D010969:Plastics