Title Promoter Affiliations Abstract "The path to to chemically recyclable polymers: catalytic synthesis of 1,3-dioxacycloalkanes and their controlled polymerization to high MW polymers" "Dirk De Vos" "Membrane Separations, Adsorption, Catalysis, and Spectroscopy for Sustainable Solutions (cMACS)" "The transition from a linear economy to a fully circular, closed loop economy goes along two tracks. First, for existing materials, improved recycling techniques are desired; but most current polymer types are hard to recycle to identical chemical building blocks. The alternative is to develop materials that are designed to be easily chemically recycled to their original monomers (‘CRM’). In this PhD, the focus is on such a class of polymers, viz. polyacetals formed from the ring-opening polymerization of 1,3-dioxacycloalkanes, such as 1,3-dioxolane. First, we address the high yield preparation of the monomers from alpha,omega-diols and formaldehyde, using hydrophobic zeolites as the preferred catalysts. Next, solid catalysts are identified for the conversion of 1,3-dioxacycloalkanes to high molecular weight polyacetals, either via ring-opening polymerization (ROP) on Lewis acid sites, or via cationic ROP (CROP). The major asset of the solid catalysts is that they are easy to remove from the product, which impedes spontaneous depolymerization of the material. Double metal cyanides and Lewis acid zeolites are earmarked as platforms to design polymerization catalysts; to understand the catalysts’ action, they are thoroughly characterized, also in catalytic operation, e.g. via X-ray absorption spectroscopy. The physicochemical properties of the high MW polymers are briefly explored, as well as their controlled depolymerization to monomers on Brønsted acid solids." "Polymer chemistry with nature's precision: design of supramolecular sequence defined polymers." "Tanja JUNKERS" "Organic and Bio-polymer Chemistry" "Today, polymer materials are designed with almost unlimited variations in chain length, dispersity, topology, composition and functionality. However the ability to control the exact order and sequence of monomers in a polymer chain is still one of the last major challenges in polymer chemistry. In this project, the aim is to synthesize sequence defined oligomers and polymers that feature the structural definition of biomolecules via combinations of controlled radical polymerization methods, end group modifications, click reactions, and microreactor technology. Initially, commercially available monomers will be used, but in a second step the focus is shifted towards vinyl monomers with side chains capable of forming multiple hydrogen bonds (MHB). These sequence defined oligomers exhibit supramolecular interactions to be used for molecular recognition with complementary sequence defined MHB counterparts. To exploit this recognition property, the synthesized oligomers will be covalently attached to surfaces using a grafting-to approach and subsequently employed as templates to purify statistical mixtures of sequence controlled oligomers stemming from controlled radical insertion reactions. In this manner, purification of sequence controlled oligomers will be significantly simplified, thus removing one of the major hurdles in their synthesis. As such, the project has the potential to considerably facilitate design and up-scale of complex sequence defined materials in future." "O&O project POLCAP : Novel Conductive Polymers for next-gen polymer Capacitors" "Herman Terryn" "Agfa Gevaert, Electrochemical and Surface Engineering, Materials and Surface Science & Engineering, Materials and Chemistry" "The main goal of this project is to understand the role of the polymer in capacitor applications, and therefore to be able to work out a considerable improvement by radically modifying the chemical PEDOT design: PSS.." "Plast-i-Com: Efficientreuse of contaminated polymers and polymer blends through compatibilisation andstabilisation" "Isabel De Schrijver" "R&D Plastic Characterization, Processing & Recycling" "Project goalsOne of the biggest challenges of the industry is to produce in a sustainable way. As a consequence, the reduction, re-use, and upgrade of waste is becoming increasingly important. Moreover, the raising prices of raw materials are pushing the industry to economize on raw materials and energy. Some companies are already experienced in the re-use of intern polymer waste without a significant downgrading of mechanical properties. However, it becomes more difficult when companies have to recycle waste which might be contaminated by amounts of other polymers. In these cases, the recyclates often demonstrate poor mechanical properties, since most polymers are not compatible and therefore difficult to mix homogeneously and with a well-defined fine distribution in one another. In other cases, the presence of another polymer can lead to a severe degradation due to the instability of some materials at high temperatures or a catalytic effect of contaminants on further degradation. Detection of impurities, sorting and separation of different polymers makes the recycling process more expensive and rarely offers a 100% guarantee on the removal of all impurities. Activitites and results Because of the unsatisfactory quality of mixed recyclates, they are recycled into less valuable products (downgrading) or not recycled at all. In the latter case, waste is e.g. deposited into landfill or incinerated with or even without energy recovery. A route to improve processability and to optimize the polymer quality is offered by the so-called “compatibilization”. Polymer blends can be compatibilized by creating an interphase interacting with both polymer phases. Mostly copolymeric compatibilizers or even reactive compatibilisers are proposed. Although these principles have already been known for decennia, compatibilisation is hardly applied on an industrial scale, and certainly not in the processing of recycled polymers. Looking at plastic waste, many streams consist of polymers which are immiscible or so-called not-compatible. Within the project ‘plast-i-com’, it was evaluated whether specific additives, called compatibilizers, could be used to convert non-usable, ‘ready-to-incinerate’ streams into more valuable recyclate materials. This evaluation was approached from three different angles. First of all, a theoretical approach was applied, wherein chemical models were used to predict the compatibilizing efficiency of additives for the studied blends. To this end, solubility parameters were estimated for the polymers of interest, based on the Hoftyzer-Van Krevelen method. Secondly, experimental work was performed to evaluate the actual performance of the additives in different polymer blends. Processing techniques such as injection moulding and textile extrusion were used to produce the desired test samples, whereafter mechanical testing could be performed. Finally, in a third step, numerical simulations were performed of the polymer processing of (non-)compatibilized blends, either in injection moulding or extrusion, using flow and thermal behaviour properties as input data. Based on the company’s interest, different market-relevant blends were selected for evaluation, including polyolefin (PO) blends, PET- and PA contaminated PO blends, PMMA-based blends, as well as other more niche blends. For the polyolefin blends, it seemed that ethylene copolymers were most effective to increase the mechanical properties, whereas for the PET and PA-based blends reactive compatibilizers such as glycidyl methacrylate- (GMA) and maleic anhydride- (MAH) based compatibilizers proved to be very successful. For PE/PA blends for example, the PA contamination resulted in a 4 times lower impact strength compared to pure PE material. On the other hand, as also predicted by the chemical models, MAH-based compatibilizers could increase the impact strength with 200% compared to the non-compatibilized blends. Chemical modelling also showed that for the PP/PET blends the most suitable compatibilizer candidate is not available on the market yet. Nevertheless, existing grades are able to increase the mechanical properties, although to a lesser extent compared to the PE/PA blend. In general, it could be concluded that compatibilizers positively affect the elongation and impact properties of the blends, as well as the morphological distribution of the contaminant phase inside the polymer matrix. The material stiffness on the other hand was most of the times affected in a negative way. In an attempt to restore the stiffness losses, nucleating agent were evaluated, but they only seemed effective in case of virgin non-compatibilized blends. It should also be emphasized that the material source (virgin, post-industrial vs. post-consumer grades) has a significant influence on the final compatibilization success. Next to the mechanical and morphological properties, compatibilizers could also contribute to the esthetical performance of the polymer blend. Apart from evaluating the recycled blends on an end-product performance level, their stability on a processing level could also be considered. In the current project, a research strategy was developed for a company specific case to understand the acceptable variations in viscosity to still end up with the desired end-product quality after injection moulding." "Dynamic polymeric systems as basis for reusable high performance materials and polymer therapeutics" "Filip Du Prez" "Department of Organic and Macromolecular Chemistry" "The aim of this project is to develop new materials based on dynamic polymer networks. On the one hand we focus on developing new chemical and supramolecular strategies for the design of dynamic high performance and reusable polymer networks. On the other hand we aim at exploring the potential of dynamic polymer networks for therapeutic applications." "Dynamic polymeric systems as basis for reusable high performance materials and polymer therapeutics" "Richard Hoogenboom" "Department of Organic and Macromolecular Chemistry" "The aim of this project is to develop new materials based on dynamic polymer networks. On the one hand we focus on developing new chemical and supramolecular strategies for the design of dynamic high performance and reusable polymer networks. On the other hand we aim at exploring the potential of dynamic polymer networks for therapeutic applications." "Dynamic polymeric systems as basis for reusable high performance materials and polymer therapeutics" "Bruno De Geest" "Department of Pharmaceutics" "The aim of this project is to develop new materials based on dynamic polymer networks. On the one hand we focus on developing new chemical and supramolecular strategies for the design of dynamic high performance and reusable polymer networks. On the other hand we aim at exploring the potential of dynamic polymer networks for therapeutic applications." "Dynamic polymeric systems as basis for reusable high performance materials and polymer therapeutics" "Filip Du Prez" "Department of Organic and Macromolecular Chemistry, Department of Pharmaceutics" "The aim of this project is to develop new materials based on dynamic polymer networks. On the one hand we focus on developing new chemical and supramolecular strategies for the design of dynamic high performance and reusable polymer networks. On the other hand we aim at exploring the potential of dynamic polymer networks for therapeutic applications." "The development of hybrid materials consisting of conjugated polymers and superparamagnetic nanoparticles for maximum Faraday rotation." "Guy Koeckelberghs" "Polymer Chemistry and Materials" "The interesting opto-electronic properties of conjugated polymers make them promising lightweight and easy-to-process materials to be used in advanced applications such as organic photovoltaics, chemical and biological sensors, oLEDs, charge transport and photocatalytic H2 generation. Within this class of materials, poly(thiophene)s, poly(para-phenylene)s and poly(fluorene)s are interesting to study due to their good environmental and thermal stability, processability and the availability of an extensive toolbox for their controlled synthesis.8 This control over the polymerisation is crucial for the production of tailor-made high-end materials with predictable molar masses, narrow dispersities, control over the end-groups and regularity, which have all shown to strongly affect the performance of these materials.Catalyst transfer condensative polymerisation (CTCP), in theory, allows for a controlled polymerisation of these materials, easy block copolymer synthesis via sequential monomer addition and a quantitative and straightforward end-group functionalisation via external initiation or end-capping. Despite the almost two decades of research on this topic, some unclarities still remain concerning the fundamentals of this technique. For instance, a deeper understanding of the CTCP mechanism itself is needed to explain why end-capping is seldom observed to be quantitative, despite there being no obvious difference in catalytic cycle between monomer incorporation and end-capping. Additionally, more research into the synthesis of block copolymers is required to clarify why para-phenylene-thiophene biaryl monomers can be polymerised, while it is generally accepted that it is impossible to incorporate thiophene monomers after para-phenylene units.To gain more insight in these fundamentals of CTCP, thiophene-para-phenylene block copolymers are synthesised. First, the inefficiency of Kumada-Tamao-Corriu CTCP (KCTCP) to incorporate para-phenylene monomers after a thiophene unit is accurately assessed. Second, the seemingly contradicting observation that a para-phenylene unit can be built in after a thiophene unit by using biaryl monomers is investigated and a novel thiophene-para-phenylene-thiophene monomer is polymerised in a controlled manner. Finally, the hypothesis that not a single thiophene unit, but rather a thiophene oligomer dictates the equilibrium between monomer incorporation and an inactive catalyst-chain association state is tested by varying the length of an initial thiophene block. In these studies, the existence of an equilibrium is proven between the incorporation of less electron-rich para-phenylene monomers and a ring-walking state in which the catalyst is associated to the more electron-rich thiophene block. The critical insight is unveiled that this equilibrium shifts towards the associated state with increasing length of the thiophene block. The understanding that not a thiophene unit, but rather a thiophene oligomer governs the catalyst association and hence the CTCP mechanism, is of key importance for further research in this field, not in the least for computational studies where now mostly single units are considered.A second area within the topics of conjugated polymers and CTCP in need for more research is the supramolecular organisation of hybrid nanostructures. The properties of polymeric devices greatly depend on the supramolecular architecture governed by interchain interactions, which are extensively investigated for homo- and block copolymers. For more advanced structures such as hybrids of conjugated polymers and inorganic nanoparticles, much less research is conducted, despite their potential to improve the performance of applications such as hybrid photovoltaics, which could be used in low-cost, lightweight and flexible devices for the production of green energy. Further, hybrid materials based on conjugated polymers and gold nanoparticles have proven to be interesting for nonlinear optics, such as third harmonic generation and two-photon emission, and can be used to enhance the properties of organic electronic devices such as oFEDs and polymer based transistor memory devices. In this dissertation, we aim to synthesise hybrids of performant conjugated polymers and interesting nanoparticles. Stalling further progress in this field is also the lack of a conductive linker between the organic and inorganic phase of these materials, which could significantly improve the charge separation in these devices and improve their efficiency. Therefore, we aim to synthesise hybrids of performant conjugated polymers and interesting nanoparticles. A novel universal catechol linker is developed and tested in different catalyst transfer condensative polymerisations. First, a new catechol-based external initiator is developed to be used in KCTCP. Here, also an equilibrium is demonstrated between interaction with the novel catechol-based initiator group and a chain-associated state for Ni catalysts in the KCTCP of poly(3-alkylthiophene). This equilibrium shifts towards the association with the initiator group when branched side-chains are used, confirming that branching weakens the polymer-catalyst association. A similar effect is not found for when using a Pd catalyst and it is reasoned that the soft Pd is less prone to interaction with the hard oxygen atoms on the catechol group compared to the harder Ni. It is demonstrated that the new catechol-based initiator can be employed in the controlled synthesis of poly(thiophene) via KCTCP and that well-defined materials with predetermined end-groups can be obtained. Subsequently, the catechol-functionalised poly(thiophene) is coupled to magnetite nanoparticles and the supramolecular organisation of the obtained hybrid materials is investigated. It is observed that the ordering of the polymer is hampered by the attachment to the magnetite nanoparticles.Next, the versatility of this catechol-based initiator group is demonstrated by the development of a novel external Pd initiator for Suzuki-Miyaura CTCP (SCTCP). The polymerisation of a fluorene monomer is proven to be controlled and again tailor-made polymers are obtained. The catechol-functionalised poly(fluorene) is coupled to gold nanoparticles and the supramolecular organisation is investigated. Also here, the macromolecular ordering of the polymer is hindered by the coupling to the nanoparticles.These insights yield a deeper understanding of catalyst transfer condensative polymerisations, allowing for the further development of controlled production methods for well-defined and tailor-made conjugated polymer materials for innovative applications such as hybrid photovoltaics. The newly developed catechol-based initiators can potentially be used as a universal coupling tool between different conjugated polymers and various nanoparticles." "In situ investigation of surface-supported dynamic covalent twodimensional polymers" "Steven De Feyter" "Molecular Imaging and Photonics, Northwestern University" " Few consumer goods can rival (one-dimensional) polymers in terms of societal and industrial relevance (around 300 megatons are produced every year). Two-dimensional (2D) polymers, and among them single-layer covalent organic frameworks, are one-molecule thick sheets of a crystalline and robust material endowed of a periodic array of nanopores. By tuning the building-blocks, a wide set of potential applications, ranging from superthin membranes to advanced electronics, open up. Because of this attractive perspective, such functional materials are broadly investigated today. Unfortunately, their synthetic processes are still far from performing as well as for standard polymers. This envisioning project deals with the use of surfaces to template the formation of extended networks of such sophisticated 2D polymers. Scanning Probe Microscopy techniques will be used to scrutinize in situ reaction products so as to get a better understanding of the polymerization process. New synthetic approaches are explored to achieve the next generation of this type of materials, and to conceive customized versions of 2D polymers with a well-defined size and shape. First steps towards the upscaling and interfacing of these systems will be given. These exciting novel 2D polymers, that could outrank graphene, are not only of interest by themselves, but they also nanostructure and functionalize the surfaces they are adsorbed on. "