Lightweight materials by tailoring foam-fiber interactions

We studied surface interactions in simplified fiber-foam systems with the captive bubble and fiber bed methods. The captive bubble technique was used to measure the bubble interaction with different cellulose model surfaces in sodium dodecyl sulfate (SDS) solution. The interaction of a single bubble with real fibers, submerged in SDS solution, was investigated using the fiber bed. Bubbles had clear adhesion to fiber surfaces in water, and the addition of SDS decreased this attraction. At high SDS concentration, the attraction was lost due to wetting transition. However, a smooth cellulose model surface did not attract bubbles even in the absence of surfactant. This suggests that the observed interaction with cellulose nanofibrils and fibers was caused by the presence of hydrophobic regions of the respective surface (e.g. lignin or nanobubbles).