Temporally programmed polymer - solvent interactions using a chemical reaction network

Abstract

Chemical reaction networks (CRNs) that operate under constant influx of energy enable artificial materials to autonomously respond to their environment by activation and deactivation of intermolecular interactions. Generally, their activation can be driven by various energy sources, yet their deactivation to non-interacting building blocks remains largely limited to hydrolysis and internal pH change. To achieve control over deactivation, we developed a new CRN that enables reversible formation of positive charges on a tertiary amine substrate, which are removed using nucleophilic signals that control the deactivation kinetics. Incorporation of the CRN in a polymer material leads to a temporally programmed transition from collapsed and hydrophobic to solvated, hydrophilic polymer chains by controlling polymer-solvent interactions. Depending on the layout of the CRN, we can create stimuli-responsive or autonomously responding materials. This concept will not only offer new opportunities in molecular cargo delivery but also pave the way for next-generation interactive materials.

Signal responsive transient coacervation in complex coacervate core micelles

“…To operate the reaction cycle we studied two different allyl acetate fuel molecules; diethyl(αacetoxymethyl) vinylphosphonate (DVP) 35 and methyl 2-(acetoxymethyl)acrylate (ME), 36 the latter of which we found to be more reactive due to its stronger electron withdrawing R group.…”

“…To achieve this behaviour, threonine (Thr), a relatively weak, primary amine nucleophile was selected based on our earlier work. 35 After trialling various concentrations of fuel, Thr, P1 and PSS, the following were found to be most optimal. First, we prepared pH 7.4 buffered solutions containing P1 (4 mM), PSS (4 mM) and Thr (32 mM) in triplicate.…”

“…Reaction of this adduct with a competing nucleophile is then able to regenerate the starting tertiary amine, completing the cycle. 35 The allyl acetate fuel is essentially an activated Michael acceptor, which have been shown to have reactivities spanning many orders of magnitude for triggered release of good leaving groups (such as tertiary amines). 36 In this work, we demonstrate the utility of the allyl acetate CRN to achieve reversible unimer to C3M transitions by transient quaternization of tertiary amine functionalised polymers mixed with a polyanion.…”

Signal responsive transient coacervation in complex coacervate core micelles

“…To operate the reaction cycle we studied two different allyl acetate fuel molecules; diethyl(αacetoxymethyl) vinylphosphonate (DVP) 35 and methyl 2-(acetoxymethyl)acrylate (ME), 36 the latter of which we found to be more reactive due to its stronger electron withdrawing R group.…”

“…Reaction of this adduct with a competing nucleophile is then able to regenerate the starting tertiary amine, completing the cycle. 35 The allyl acetate fuel is essentially an activated Michael acceptor, which have been shown to have reactivities spanning many orders of magnitude for triggered release of good leaving groups (such as tertiary amines). 36 In this work, we demonstrate the utility of the allyl acetate CRN to achieve reversible unimer to C3M transitions by transient quaternization of tertiary amine functionalised polymers mixed with a polyanion.…”