  We comparatively analyzed imbibition of polystyrene (PS) into two
complementary pore models having pore diameters of about 380 nm and
hydroxyl-terminated inorganic-oxidic pore walls, controlled porous glass (CPG)
and self-ordered porous alumina (AAO), by X-ray computed tomography and EDX
spectroscopy. CPG contains continuous spongy-tortuous pore systems. AAO
containing arrays of isolated straight cylindrical pores is a reference pore
model with a tortuosity close to 1. Comparative evaluation of the
spatiotemporal imbibition front evolution yields important information on the
pore morphology of a probed tortuous matrix like CPG and on the imbibition
mechanism. To this end, pixel brightness dispersions in tomographic 3D
reconstructions and 2D EDX maps of infiltrated AAO and CPG samples were
condensed into 1D brightness dispersion profiles normal to the membrane
surfaces. Their statistical analysis yielded positions and widths of the
imbibition fronts without segmentation or determination of pore positions. The
retardation of the imbibition front movement with respect to AAO reference
samples may be used as a descriptor for the tortuosity of a tested porous
matrix. The velocity of the imbibition front movements in CPG equaled
two-thirds of the velocity of the imbibition front movements in AAO. Moreover,
the dynamics of the imbibition front broadening discloses whether porous
matrices are dominated by cylindrical neck-like pore segments or by nodes.
Independent single-meniscus movements in cylindrical AAO pores result in faster
imbibition front broadening than in CPG, in which a morphology dominated by
nodes results in slower cooperative imbibition front movements involving
several menisci.
