Figure 2.

ZnO tetrapods are pressed and sintered into an interconnected ZnO network and embedded into an Acrylamide solution, which is then allowed to polymerize. (A) Phase contrast image of the ZnO network in the PAAm hydrogel. The ZnO network dissolves when the PAAm sample is incubated in hydrochloric acid (HCl). (B, C) both present time arrays starting from the left that recorded the dissolution process. (B) Entire process shown macroscopically. (C) Phase contrast images of the last stages of the hydrolysis, recorded microscopically every 15 min at the center of the tablet, showing that the nontransparent ZnO structures dissolve completely. The ZnO structures leave an interconnected network of microchannels in the PAAm gel, as shown in a phase contrast image in D.