Mesoscale Polymer Ribbon Arrays: Biofilm-Inspired, Flexible, Fibrillar Adhesives

Biofilm formation and surface fouling cause many problems in aqueous environments. Thin, filamentous pili are one of the many tools leveraged by bacteria to adhere to numerous surface topographies and chemistries. These micron-long, nanometer-wide organelles create multiple points of flexible, adhesive contact with nearby substrates. To create a synthetic analog of this system, we turn to high aspect-ratio mesoscale polymer ribbons. These nanometer-thick and millimeter-long structures exhibit geometrically driven, environmentally sensitive 3D conformations in aqueous environments. Although single-ribbon dynamics are well-explored, it is essential that we understand the impact of environmental factors on the conformation of multi-ribbon systems, as this will likely dictate interactions with nearby surfaces. Using flow coating, we deposit fluorescent poly(tert-butyl methacrylate) ribbon arrays onto glass substrates coated with a poly(sodium styrene sulfonate) sacrificial layer. We probe the morphology of the ribbon arrays released into acidic, basic, and pH neutral environments as a function of time with confocal microscopy and machine vision techniques. We correlate these relationships to the capillary-driven adhesion of ribbon arrays to perfluorodecalin droplets using cantilever deflection. This work elucidates the underlying design principles of flexible, fibrillar underwater adhesives, and informs the development of future systems.