Drying dissipative structures of the aqueous suspensions of palygorskite and tungstic acid particles

Macroscopic and microscopic dissipative structural patterns during dryness of the aqueous suspensions of palygorskite (PGK, needle-like shaped) and tungstic acid (TA, plate-like) have been studied on a cover glass. The coexistence of the broad ring of the hill accumulated with the particles and the round hills is observed around the outside edges of the dried film and in the center, respectively. These patterns differ from those of the suspensions of spherical particles. Furthermore, the spoke-like patterns, which have been observed for the suspensions of the spherical particles so often, are not observed at all for PGK and TA suspensions. These characteristic macroscopic patterns of PGK and TA are quite similar to those of the fractionated and monodispersed bentonites (plate-like) reported previously Yamaguchi et al. (Colloid Polymer Sci 283:1123, 2005). Wrinkled and/or branch-like fractal patterns are observed in the microscopic scale, which are quite similar to those of bentonites. “Shape information” of the colloidal particles is clarified to be “transferred” to the drying patterns via the convectional and sedimentary patterns during the course of dryness.