Genipin Cross-Linked Chitosan-Polyvinylpyrrolidone Hydrogels: Influence of Composition and Postsynthesis Treatment on pH Responsive Behaviour

Figure 4

(a)–(c) SEM images of samples polymerised at 30, 40, and 50°C, respectively, with no postsynthesis manipulation; (d)–(f) samples polymerised at 30, 40, and 50°C, respectively, and continuously frozen for 72 h; (g)–(i) samples polymerised at 30, 40, and 50°C, respectively, and subjected to three freeze-thaw cycles (24 h freezing and 3 h thawing).

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