Periodic Reporting for period 1 - DoDyNet (Double Dynamics for design of new responsive polymer networks and gels)
Reporting period: 2017-11-01 to 2019-10-31
Within DoDyNet, we would like to address this challenge, inspired by the recent progress made in this field, reached thanks to the development of new types of polymer networks. While different, these new materials share a common concept, which is the combination of at least two distinct dynamic modes within the same material in order to display multiscale viscoelastic responses under the influence of an external stress or deformation field. Consequently, they are characterized by a ‘double’ mechanical behavior, which offers a better balance between the desired properties.
Therefore, we would like to design, synthesize and characterize new double polymer networks, which will allow us to investigate and understand how to control their dynamics by playing with their composition. Based on these results, we would like to develop models to relate the properties of these polymer networks and their architecture. Such fundamental understanding will help us to answer the requests from our industrial partners about developing new materials based on this strategy.
Organization of DoDyNet and Double Dynamics Networks
In order to accomplish our objectives, the institutions in DoDyNet have been chosen in order to cover, all together, the necessary expertise for the project, i.e. a strong expertise in synthesizing responsive networks, the use of many state-of-the art (home-made) measurement techniques, most accurate models, detailed questions and advices from major companies, and large support of visiting experts. Our work packages have been organized in respect to this expertise.
(insert Figure 1)
Dynamics and flow properties of sticky polymer chains:
An example of systems we are studying is the sticky polymer chains. They consist of polymer chains bearing sticky groups along their backbone. Our metallo-supramolecular sticky polymers (Clément Coutouly, UCL), ionomers (Wendy Wang, DTU), reversible covalent sticky chains (Larissa Hammer, ESPCI) and associating block copolymers (Simone Sbrescia, DSM) enter within this category. Statistical tool have been developed to determine the composition of these samples (Yanzhao Li, UCL). Hongwei Liu (UN) has developed simulations which account for End modes and Trapped modes of the Rouse dynamics of unentangled sticky chains in order to understand how these samples can relax their stress when a constant deformation is applied, while Yanzhao Li (UCL) is investigating the role of possible inter-chain entanglements in their relaxation process.
(Insert Figure 2)
Wendy Wang (DTU) has investigated how such materials deform under a large elongational deformation, while Jianzhu Ju (ESPCI) has studied the fracture mechanisms and corresponding structure of associating block-copolymers under large deformations. In parallel, Simone Sbrescia (DSM) investigated how these thermoplastic elastomers could better resist deformation at high temperature.
Next step is to study similar systems containing stickers with two different lifetimes. Preliminary studies have been achieved by Consiglia Carillo (FORTH) in collaboration with our associated partner tesa on DDNs containing both reversible and covalent bonds. An in depth study of these materials should help us understanding how to optimize the stickiness of these pressure-sensitive adhesives!
To utilize DDNs in industry, a number of pre-requisites need to be fulfilled in terms of cost and processing. In this respect, morphological separation along with hydrogen bonded supramolecular associations offers an economically sound approach to introduce DDNs starting from commercial compounds requiring no or little chemical modification.
Beside the industrial impact, we aim at building a strong collaborative network of researchers in the field of polymer gels and networks, taking the consortium of DoDyNet as the starting point for the development of a larger structure. Thanks to the summer school open to researchers outside the consortium, to the presentations of our results at international conferences, or to the active role of the visiting experts, the research performed within DoDyNet starts to have a good visibility, that we would like to enhance even more in the future!