Fig. 4
From: Self-folding of thick paper via continuous solution supply analyzed by FTIR spectroscopy
Time evolution of the through-thickness concentration and time–depth heat maps for the inkjet method and the filter-paper method. (a) Time evolution of the concentration at each depth for the inkjet method. Immediately after printing, the surface-layer concentration drops sharply, while the mid-depth region remains low throughout. (b) Time–depth heat map for the inkjet method. Penetration in the thickness direction is minimal, and the penetration front remains stalled. (c) Time evolution of the concentration at each depth for the filter-paper method. The concentration gradually increases from the mid-depth to the deep region and remains high after the transition to the Free Reaction Phase. (d) Time–depth heat map for the filter-paper method. Owing to the Loading Penetration Phase, a wide high-concentration region across the thickness is established at \(\:t=0\:s\), and the penetration front continues to advance despite evaporation-induced concentration decrease.
