From phase structure to mechanical properties: How component selection controls the properties of an amphiphilic polymer conetwork

Amphiphilic polymer conetworks (APCNs) are thin, flexible and breathable matrices with a heterogeneous nano-phase separated morphology, making them ideal candidates for applications such as wearable luminescent solar concentrators (LSCs) for sunlight harvesting. Such materials should possess a well-defined morphology, with domains at the nanoscale that allow the incorporation of luminophores at specific volumes. This improves the efficiency of Förster resonance energy transfer, a feature essential for state-of-the-art LSC systems. Although APCNs have been developed and investigated extensively over recent decades for different applications, we now focus on the specificities of using APCNs for LSCs, and how it influences the design process. We found that the phase ratio of an APCN strongly affects its transition temperature and hence, the extent of its influence on the mechanical properties at room temperature. Similarly, although the chemistry of the hydrophobic domain influences the mechanical properties, the extent of these changes depends on the molecular weights of the precursors. We also demonstrated that Dynamic Mechanical Thermal Analysis (DMTA) a suitable alternative method of investigate in the morphology and phase separation in APCNs for which the phase contrast is too low for small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). In-situ strain SAXS measurements indicated that the macroscopic deformation is reflected at the deformation of the nanoscale domains. Taken together, these results help to design APCNs with tunable morphologies and mechanical properties and suggest alternative characterization methods, which contribute to revealing the full property space of APCNs for applications in energy harvesting and beyond.