Hydrolysable materials are very important for their wide applications ranging from drug delivery, tissue engineering to plastics and packaging. These materials usually contain hydrolysable bonds in their backbone, such as ester, anhydride, orthoester, ketal, imine, and so on. Here, we will report the design of a new hydrolysable material based on hindered urea bonds(HUBs), which can reversibly dissociate to bulky amines and isocyanates. The latter species can undergo irreversible hydrolysis, shifting the equilibrium to favor the dissociation of urea bonds and eventually the complete degradation of the polyureas. Kinetic studies of small molecule model compounds show that more bulky HUBs lead to faster hydrolysis, so is the trend in polymers. After that, we prove polyureas bearing hindered urea bonds(pHUBs), whether in the form of a linear polymer, organogel or hydrogel, can be completely degraded by water under ambient condition. Because of the simplicity of the reaction, low cost of the starting materials, the versatility of the structures, and easy tunability of the degradation profiles, pHUBs are likely to find extensive applications.

Hydrolysable polyureas based on hindered urea bonds

253rd National Meeting (2017)

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