Boundary-controlled imbibition reveals liquid-structure coupling in soft jammed systems

Transport in soft jammed materials is often described as liquid flow through a fixed structure, yet foam imbibition frequently deviates from classical Lucas–Washburn scaling. Here, we investigate liquid imbibition in foams while directly visualizing both liquid penetration and foam motion under controlled boundary conditions. When foam motion is allowed, liquid uptake is accompanied by collective translation of the unimbibed foam, while the penetration relative to the foam matrix follows approximately x rel ∝ t 1/2 . When foam motion is suppressed, compression accumulates ahead of the imbibition front and the apparent propagation becomes slower than t 1/2 . We interpret these behaviors using an effective osmotic driving pressure reduced by a counterpressure generated by foam compression. When the matrix can move, this compression does not accumulate substantially; under a closed boundary, it progressively increases and suppresses further imbibition. These results demonstrate that foam imbibition is governed by coupling between capillary transport and the mechanical response of the foam matrix.