Following the objectives of the proposal, a new chemical reaction network was successfully developed (Figure 1). The chemical reaction network converts carboxylates into metastable anhydrides in aqueous media upon consumption of carbodiimide fuels. The anhydrides rapidly hydrolyze to the original carboxylates, therefore, closing the cycle.
The reactions involved work in buffered water at pH values around pH=6. The carboxylate precursor carries negative charges under the described conditions which are neutralized by the formation of the anhydride. This hydrophobization process driven by our chemical reaction network is a crucial step since it changes completely the solubility of the precursor and induces the self-assembly of the anhydride product.
The next step was the design and synthesis of precursor building blocks able to self-assemble into hydrogels. As described in our proposal we satisfactory used small peptide molecules endowed with aromatic motifs, ß-sheet amino acid directors and carboxylate groups as building blocks for our chemical reaction network. When combining the chemical reaction network previously described with the appropriate building blocks, temporary hydrogels were obtained. Crucially, the lifetimes of these hydrogels could be predicted and tuned by controlling the amount of fuel and/or precursor present in the chemical reaction network. Also relevant was to discover the reusability of these materials by the addition of subsequent batches of fuel.
Due to the versatility of the chemical reaction network, other different fuels and precursor building blocks were explored therefore developing other types of dissipative materials (Figure 2). Particularly interesting were the formation of temporary colloids upon self-assembly and their application for the sequentially release of hydrophobic agents and the formation of spherulites and their use for temporary inks. The applications of all these materials were possible due to the dissipative nature of the system. Most likely such applications could not be achieved by using the classical thermodynamic materials developed so far.
The main results have been published in two papers: "Non-equilibrium dissipative supramolecular materials with a tunable lifetime" (Nat Commun 2017) and "Self-selection of dissipative assemblies driven by primitive chemical reaction networks" (Nat Commun 2018). Both publications were followed by press releases in TUM news.
The results of this research have been presented in several scientific meetings and international conferences. For instance, I had the opportunity to make oral presentations in "Suprachem 2019" (February 2019, Würzburg), "Women in Science" (2018, Erlangen) and during the "Gordon Research Seminar" (May 2017-Les Diablerets). Poster contribution was also possible in "Molecular Origins of Life 2018" (October 2018, Munich), in the "International Symposium of Macrocyclic and Supramolecular Chemistry" (2018, Quebec) and during the Young Chemist Researchers 2017 (2017, Badajoz).
I was also invited to give a talk at the Universitat Jaume I 2018 (Castellón-Spain).
The dissemination of the results was also expanded to the general public by the performance of outreach activities. For instance, I co-organise an exhibition activity included at the "Open Door Day" at TUM (2018-Garching) and a science communication event called "15x4 Share your knowledge" sponsored by sponsored the Marie Curie Alumni Association (February 2019, Munich)
