Top grant: Supramolecular Polymerization Processes

Supramolecular polymers are defined as polymeric arrays of monomeric units that are brought together by reversible and highly directional non-covalent interactions, resulting in polymeric properties in dilute and concentrated solution as well as in the bulk. In the recent past, we have shown that a large variety of supramolecular polymers can be created using a variety of directional interactions. Two main systems are studied. The first class makes use of multiple-hydrogen bonding and the dynamics of the interactions are crucial for the understanding of the molecular and macroscopic properties of these flexible polymers. In less than ten years after their discovery, ureidopyrimidinone-based polymers are close to being commercialized and this is primarily due to the fundamental insights obtained from these flexible and disordered systems. The second class is based on more ordered one-dimensional stacks, making use of pi-pi interactions and/or hydrogen bonding and this class represents the rigid rod supramolecular polymers and therefore a possible candidate for high-end applications, like electronic devices. More recently, the understanding of supramolecular polymers is extended by focusing on the mechanisms of the supramolecular polymerization processes. Next to an open-association model for flexible chains, we have disclosed experimental evidence for the nucleation-growth mechanism for structured one-dimensional polymer arrays. In the research proposed in this TOP-grant proposal, we are aiming at a full understanding at the molecular level of all mechanistic features of supramolecular polymerization processes on the one hand. On the other hand, we will use this knowledge in the design, synthesis, characterization and application of novel functional materials with unprecedented properties. As is well accepted for covalent polymers, the mechanism of formation (step versus chain versus ring-opening polymerization) is leading to the understanding of the polymer properties. We are convinced that the same basic understanding of the mechanism of non-covalent or supramolecular polymerization processes will be as crucial as for covalent polymers or macromolecules. With a firm understanding of the pathways of formation and the dynamics involved (kinetic stability versus thermodynamic equilibrium) these novel materials will open the way to arrive at complex molecular systems based on multiple components. Supramolecular polymerization processes will be investigated by four related but different research topics, in which the two fist ones focus on the mechanism of the polymerization process and the last two are using this knowledge for creating novel materials.