Nitroalcohol Induced Hydrogel Formation in Amine-Functionalized Polymers.

Certain β-nitroalcohols degrade under basic conditions or upon heating to form formaldehyde. This reaction provides an elegant approach to generate formaldehyde within a system at a desired time using the stimulus of pH or temperature. Using β-nitroalcohols as a delivery agent for formaldehyde, polymer crosslinking can be induced via stimulus. Such an approach is akin to those used to prepare "self-healing" polymers, which have received much attention recently. Herein, we describe the use of certain β-nitroalcohols as a masked formaldehyde delivery system and demonstrate its use as a crosslinking agent of amine functionalized polymers to form hydrogels. We examine the temperature and pH dependence of 2-nitro-1,3-propanediol and 2-(hydroxymethyl)-2-nitro-1,2-propanediol on the rate and extent of gelation and characterize the resulting gel by swelling and FTIR experiments.