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.

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Bioinspired antifreeze for ice-free car windows In winter, road users invariably have to deal with it: scratching to clear car windows of ice. Reduced visibility could otherwise lead to serious accidents and hefty fines. Anti-freeze wiper fluid is very effective, but in its current formulation it contains components that are highly flammable, harmful to health if inhaled, and manufactured from a valuable food source. Inspired by antifreeze proteins from polar fish and bacteria, scientists at Eindhoven University of Technology have developed new building blocks to make car windows ice-free without harmful effects on humans and the environment.

Context. Consumers are becoming increasingly sensitive to questions about the ecological footprint and the sustainability under which the global food industry is producing food. Furthermore, whilst staying price sensitive, consumers demand more natural ingredients and healthier products. Reconciling these demands with chemical and physical stability and superior taste of food products is challenging as conventional routes for food manufacturing and processing have been optimised over decades and cannot easily be altered. Therefore, improving and redesigning food products will require better insights in relationships between product structure and functionality. This is especially the case for proteins and polysaccharides, as their functionality at colloidal interfaces and networks predominantly determines the physical and chemical stability of food products. For these biomacromolecules, however, we currently lack powerful techniques to obtain the required insights. For that reason, new non-invasive techniques to localise polysaccharides and proteins at colloidal interfaces and networks with sub-µm precision and sufficient molecular specificity are needed to address the challenges in sustainable food production. Approach. So far, most successful approaches to understand functionality of biomacromolecules in food colloids utilised antibody labelling with fluorescent or gold bead tags in combination with electron- or light microscopy. Such techniques are, however, cumbersome and/or time consuming or provide very limited spatial and temporal resolution thereby hampering their frequent deployment in food research. We aim to: 1. Develop novel labelling approaches based on rapid screening of affimer/aptamer-type ligand libraries for labelling of high-affinity ligands with fluorescent dyes towards biomacromolecule-specific single-molecule localisation microscopies (SMLM) such as PALM, STORM, iPAINT. 2. Develop instrumentation and modalities for high-throughput food screening of real-life food colloids to quantify local biomacromolecuar dynamics with ultrahigh temporal (milliseconds) and spatial resolution (nanometre) using the developed labelling strategies. 3. Demonstrate the potential of the newly developed localisation technologies to establish structure-property relations in complex commercial products using model colloids and real-life food colloids (yoghurt and mayonnaise) as showcase. Implementation. Four target biomacromolecules will be localised at emulsion interfaces and in colloidal dispersion networks, using respectively mayonnaise and yoghurt as real-life demonstrator systems. The work will be carried out by three PhD students: 1. PhD1 (TU/e) Localisation of specific biomacromolecules with non-covalently bound fluorescent tags to achieve ultrahigh spatial resolution in model (transparent) food colloids. 2. PhD2 (WUR) Overcoming optical density of real-life food colloids and assessment of binding and translational dynamics of biomacromolecules with high temporal and spatial resolution. 3. PhD3 (TU/e & WUR) Establishing structure-property relationships in real-life food colloids (yoghurt and mayonnaise) ideally using advanced imaging modalities developed by PhD1 and PhD2. Valorisation. The localisation of biomacromolecules at colloidal interfaces/networks in real-life food colloids will enable detailed understanding of chemical and physical events occurring at interfaces/networks. This is critical for developing structure-property relationships and for redesigning food products without loss of quality and stability. For the mayonnaise showcase, insights in protein functionality at interfaces will enable design of natural lipid oxidation control strategies (Unilever). For the yoghurt showcase, insights in functionality of EPS/casein in hybrid networks will enable optimization of EPS-producing bacterial lactic acid cultures and enzymes (DSM). For Unilever and DSM this will enable (1) a more rapid decision making in the R&D process, thus shortening time-to-market, (2) filing of patents that are firmly underpinned by mechanisms of action and (3) policing of patents by strong microstructural evidence. For Confocal.nl, the joined development of advanced imaging technologies will strengthen their competitiveness in the microscopy market. Instrumental for effective two-way knowledge and technology transfer will be long-term secondments of the PhD students at the industrial laboratories of DSM, Unilever and Confocal.nl. The unique experience of working both in academic and industrial research cultures will be an important asset in the future career of the PhD students.

Using mechanical forces to control the rate and course of chemical reactions is an exciting, but only superficially explored area of research. Traditionally, chemists have used heat ? a source of random kinetic energy ? to help molecules surmount the kinetic barriers to product formation. Currently, catalysts are the chemists favorite tool to increase both reaction rate and product selectivity. When homogeneous catalysts are provided with polymeric substituents, the possibility arises to apply mechanical forces in a highly directional fashion because stress fields in the medium are transmitted to the catalyst by the polymer chains. In one of the conceptually most simple realizations of this principle, mechanical force is used to switch a transition metal catalyst from an inactive dormant state to its active state by mechanical removal of a ligand. On-off switching of catalyst activity by a mechanical trigger has many potential applications, including self-healing materials, immobilized catalysts switched by flow or stress, shear sensors, and surface polymerization induced by friction at the macroscopic as well as at the nanoscale. Recent work in the group of Sijbesma has demonstrated this principle to be very effective in two distinct catalytic systems based on polymeric coordination complexes of N-heterocyclic carbenes (NHCs), which are activated by means of ultrasound in solution. One system, a Ruthenium alkylidene complex, is activated by ultrasound to catalyze a ring closing metathesis reaction or to initiate ring opening polymerization. The other system comprises silver(I) NHC complexes, which liberate free carbenes as active transesterification catalysts. The aim of the current proposal is to enable the group to take full advantage of the unique position created with these findings, and to explore the full scope of catalyst activation by mechanical force. In order to achieve this goal, three topics are defined that will broaden the chemical basis of mechanocatalysis. In the first project, the initial findings in the area of mechanically activated metathesis catalysts will be elaborated, and new dormant catalysts will be developed with tuned activity and improved reversibility of dissociation. Methods will be developed to immobilize the dormant catalysts on surfaces for application in the third project. In the second project, the full scope of mechanochemical activation of NHC organocatalysts will be explored. Focus will be on increasing susceptibility to scission of the dormant catalyst by incorporation in a polymeric network, and on widening the range of chemical transformations, including exploratory studies of alternative NHC-metal complexes in which the liberated metal is the active catalyst. The third project will explore the engineering aspects of applying mechanical forces to the catalyst as effectively as possible. To this end alternatives to ultrasonication such as shear in the solid state will be investigated. Finally, in this project inroads will be made to mechanochemistry at the nanoscale by using AFM on catalyst covered surfaces to induce polymerization.