Chemical Amplification of Subthreshold Base Triggers to Drive Sol-Gel Transitions in Polymers

Chemical amplification has been widely applied in applications ranging from stimuli sensing to advanced photoresists, but it is rarely utilized to drive productive mechanical property changes. Here, we demonstrate the use of a base amplifier to drive the gelation of a functional polymer solution, in response to a subthreshold base trigger through a mechanism whereby the trigger drives a dramatic increase in the base concentration driven by base amplification, resulting in complexation of Fe(III) and polymer-bound catechol groups and subsequent gelation of the polymer solution. The concomitant crystallization of dibenzofulvene, which is a byproduct of base amplification, led to significant stiffening of the resultant gel and an unexpected temperature-sensitive change of gel stiffness.