Final Report Summary - SUPOLEN (Supramolecular assembly of polymeric structures: a novel route to enhance soft materials properties) Supramolecular polymeric assemblies represent an emerging, promising class of systems with superior versatility compared to their covalent polymeric counterparts. They offer exciting new opportunities for stimuli-responsive structures exhibiting reversible tunable properties, with applications in foodstuff, coatings, cost-efficient processes or biomedical areas. To explore their potential and define strategies for designing novel materials amenable to contemporary needs, a fundamental understanding of their very complex and diverse multiscale supramolecular structure and dynamics is needed. In this regard, a synergy of synthetic chemistry (including both model and industrial systems), physical experiment and modeling are necessary. The objective of SUPOLEN is to understand how the structure and dynamics of supramolecular polymers are related, in order to be able to control their properties, and develop new materials based on supramolecular interactions. To this end, we focused on specific systems in order to propose a global picture to explain their dynamics and properties. Here are few examples:A. Our first objective was to understand and tailor the structure and dynamics of supramolecular polymers based on well-defined building blocks, mainly monodisperse telechelic linear and star-like polymers, able to associate via metal-ligand association or H bonding. The systematic, thorough study of their behavior allowed us pointing out the main effect on the viscoelastic response and healing properties of structural and external parameters such as the combined effect of the dynamics of the associating groups (strength, position, number and nature) and the internal dynamics of the building blocks (entanglements and architecture), and exploring the role played by external stimuli. These associative polymers allowed building a real toolbox containing various chain architectures (linear or star, telechelic or containing side sticky groups, with a range of molar masses) that can be systematically investigated, as single component or in blends. A detailed investigation of these materials has allowed us to understand their dynamics, and to develop the corresponding mesoscopic models. Similar synergistic approach was then developed at the industrial scales by Solvay, leading to a patent.B. Concerning entangled chains bearing sticky groups along their backbone, we studied the properties of well-defined thermoplastic elastomers (TPEs). Scattering data allowed us to determine the organization of the crystallites formed by the association of the hard blocks. Based on flash DSC measurements, we could further investigate the association dynamics of these systems and demonstrate the possible existence of temperature- and rate-dependent pseudo-equilibrium states in which the hard segments domains are trapped, and to link these states to the linear viscoelastic properties. Based on these results, new dumbbell-shaped thermoplastic elastomers were designed and synthesized, and their behavior was compared to the segmented TPEs. This allowed us to show the importance of both chain connectivity and chain mobility in the flow properties of such TPEs. Mechanical properties of model TPEs were explored, and a corresponding model was developed. C. By studying different supramolecular polymers, it became apparent that failure properties of associating polymers are wide-ranging, leading to ductile and brittle behavior as function of the sticker density and rate of deformation. In order to explore such behavior, the consortium developed a large collaboration in order to study the samples with all available state-of-the-art techniques and methods (in particular, based on the cone-partitioned plate geometry developed by FORTH, the filament stretching rheometer developed by DTU and the failure tests developed by Montpellier). This is certainly an important and new result of the project.D. Several samples from the industrial partners were studied in detail by the ESRs. This has allowed pointing out their main properties, and their relation to structural and external parameters. The output of these studies is a better knowledge of the sample composition needed in order to fulfill specific properties, as well as the design of new materials, which are of direct interest to the industries. Four areas of applications have been investigated: (1) Applications related to thickening aqueous solutions, (2) Development of new bulk thermoplastics applications, (3) Development of new thermoplastic elastomers with improved properties, (4) Development of new healable coatings.These scientific results have been made possible through the multidisciplinarity and complementarity of project partners. Exchange visits and industrial secondments, as well as regular project meetings, have allowed students to collaborate.Besides the research project, students have received high-level training through modules related to polymer science. An elementary module gave students a bird’s-eye view of selected aspects of polymers such as synthesis, dynamics, rheology, light-scattering and industrial applications. Following this, students have had opportunities to follow more advanced courses: computational physics, (hands-on) advanced molecular rheology, light scattering techniques and nuclear magnetic resonance spectroscopy, as well as an advanced module on material failure and mechanical properties. They also have participated in industrial workshops organized at DSM Ahead (Geleen, The Netherlands) and Solvay R&I Center (Paris, France), and have performed industrial secondments. In addition, a summer school has been organized by SUPOLEN. Students received an intense week of high-level lectures with world-class experts in their field. At the end of the project, the ESRs and ERs had to opportunity to present their work during the final international conference of SUPOLEN (20-22 September, Crete, Greece), which was open to a larger audience (75 people participated). The private sector was well represented and very active in Supolen, with major industries in the field. Their contribution was at different levels, including training and applications. Several sets of samples were synthesized by DSM and Solvay, and distributed among the academic partners in order to characterize properties and better understand the link between synthesis-composition-properties-processing. This has allowed pointing out important parameters to take into account in order to produce materials with enhanced properties. Two industrial workshops were organized by DSM in September 2014 and Solvay in March 2017, in order to expose students to research within industry, to market aspects and to future career perspectives. All ESRs performed an industrial secondment, which gave then a unique opportunity to work in an industrial environment. These works have led to interesting results (in some cases published in scientific journals), which were presented during the seventh Supolen meeting. Within Supolen project, new collaborations have started between the academic and industrial partners, which will continue well beyond the project. During the project, dissemination activities were taken on by the students themselves, with newsletters published after every meeting, and youtube videos posted. The main activities were the summer school and the final conference of SUPOLEN, with 75 participants in the field of supramolecular polymers in both activities, the publication of a Special Issue on Associating Polymer (see Journal of Rheology, Vol 61, Issue 6, November 2017), and the production of a brochure addressed to a broad (non-scientific) audience. They also include activities such as a very informative website, the distribution of flyers, the creation of newsletters by the ESRS/ERs, participation in international conferences and a large number of publications.Within SUPOLEN, many contributors were involved. Visiting experts and invited speakers had a large role in training section and as scientific advisers of projects. Many young researchers not directly involved in the project also participated to the meetings, training or conference. Through our dissemination actions, SUPOLEN had large visibility in the scientific community and made the field of supramolecular polymers very active. Today, many industries would like to further develop this area of research.Publications and attendance of conferences also offered a way to disseminate scientific knowledge – to date SUPOLEN has published 37 articles, and presented over 50 contributions to conferences. Project coordinator: Prof. Evelyne van Ruymbeke, Université catholique de LouvainProject website: www.supolen.eu
