My article, written with Dylan Domaille, appears in Chemistry of Materials. Check it out here: http://pubs.acs.org/doi/abs/10.1021/cm5007789. We demonstrated predictable control of the material properties of the hydrazone crosslinked hydrogel by varying bath pH. The abstract is below:

Rheological and small molecule kinetic studies were performed to study the formation and hydrolysis of the bis-aliphatic hydrazone bond. The rate of gelation was found to correspond closely with the rate of bond formation and the rate of gel relaxation with the rate of hydrolysis, indicating that small molecule kinetic studies can play an important role in material design. Furthermore, unlike aryl or acyl hydrazone bonds, the bis-aliphatic hydrazone bond forms rapidly under physiological conditions without requiring aniline catalysis yet maintains a pH-dependent rate of hydrolysis. These results suggest the bis-aliphatic hydrazone bond should find use alongside existing bioorthogonal click chemistries for bioconjugation, biomaterial synthesis, and controlled release applications.