Mesoscopic Network Topology and Permeability of Adaptive Amphiphilic Conetworks

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Polymer model networks with controlled mesh structure and network topology provide a well-defined basis for derivation of systematic relations between structure and properties of these soft and adaptive materials, with a prime view to unravelling the impact of structural defects and inhomogeneities in the networks. A splendid approach of realizing well-defined and nearly defect-free model network structures is the tetra-PEG approach by Sakai et al. from 2008, which is based on click-chemical interconnection of two heterocomplementary four-arm star-shaped PEG precursors. Our research initiative targets at applying this approach to 2 × 2 different types of amphiphilic conetworks (ACN); these are (A) covalently-jointed permanent as well as (B) ionically-jointed reversible ACN, each realized either from (1) two separate hydrophilic and hydrophobic heterocomplementary star-shaped building blocks or from (2) two kinds of heterocomplementary star-shaped building blocks that both exhibit hydrophilic-hydrophobic core–shell morphologies. To derive structure-property relations of these ACN, with a prime view on their potential nano-, micro-, or even macrophase-separated domains and potential ionic cluster structures, it is necessary to conduct a comprehensive structural characterization on different relevant lengthscales. The present project aims at providing such characterization by scattering methods, predominantly static and dynamic light scattering, as well as through investigation of the diffusive penetration of nanoscopic probes through the networks probed by fluorescence recovery after photobleaching. Both allows structural pictures to be derived. These pictures, along with the primary data themselves (scattering curves and diffusive paths) will be correlated to complementary theoretical models of the same data in other sub-projects of our research group to interrelate the resulting material properties (mostly in view of viscoelasticity and selective and switchable permeability) to the network synthesis parameters.