Fig. 2
SEM images of the outer surface of the hydrogel films. (a) The synthesized hydrogel film, (b) Some agglomerates on the surface of the synthesized hydrogel film, (c–f) The freeze-dried hydrogel films with different magnifications (Figures in panels a and c are reproduced from ref25, licensed under a Creative Commons Attribution 3.0 Unported Licence).
