Functional single chain polymer nanoparticles

Nature creates function using well-defined, complex three-dimensional macromolecular structures. The introduction of function due to molecular arrangement is one of the great challenges in Macromolecular Science. Single chain polymer nanoparticles (SCPNs) are macromolecules that underwent intramolecular collapse through covalent and/or non-covalent interactions into 3D shapes with reasonably defined sizes and shapes, mimicking the natural biomolecules’ process. While in the past decade research on SCPNs mostly focused on synthetic pathways towards this architecture, we have started to study molecular functionality in a wide variety of potential applications in which folding provides a differential advantage compared to traditional linear and branched polymers. This work focuses on two possible functions that are affected by folding.

Grubbs` catalysts are well-defined homogeneous catalysts for olefin metathesis reactions. Here we describe a new catalytic SCPN capable of reversible activation of the catalyst as a consequence of conformation, similar to a mechanoenzyme. Linear polymers functionalized with NHC-side chains are prepared and collapsed by double coordination of the Ruthenium complex at high dilution. The dormant catalyst can be activated by removal of a ligand due to mechanical stress. After a few turnovers, intramolecular coordination restores the catalyst to the dormant condition.

In SCPNs, the polymer density is increased by the folding of the polymer, leading to increase in Tg.¹ A major challenge in the development of alkaline fuel cells is the low chemical stability of anion exchange membranes (AEMs), in which quaternary ammonium cationic functional groups are attacked by the hydroxide groups. Here, we present a new molecular strategy to affect the kinetics of the nucleophilic attack, as well as the effect of folding on additional relevant properties such as ion conductivity and water uptake.

1. Galant, O., Bae, S., Wang, F., Levy, A., Silberstein, M. N., & Diesendruck, C. E. (2017). Macromolecules, 50(17), 6415-6420.