Exploring Structure‐Property Relationship on a Nanoscale for Tailoring Films of Amphiphilic Polymer Co‐Networks

ABSTRACT Amphiphilic polymer co‐networks (APCNs) provide a large toolbox for tuning coatings important for applications such as bio‐interfaces. Therefore, we investigate the influence of network composition and environmental conditions on the structure and mechanical and adhesive properties of thin films composed of hydrophobic tetra‐PCL and hydrophilic tetra‐PEG stars of varying sizes. State‐of‐the‐art atomic force microscopy (AFM) techniques, including phase imaging, fast quantitative static indentation, and dynamic indentation, provide insights into the structure‐property‐relationship on various length scales. PEG‐rich networks exhibit amorphous morphologies with spherical nanodomains and elastic moduli of a few MPa, while PCL‐rich networks form semicrystalline cylindrical arrangements with moduli up to several hundred MPa in water. Temperature‐dependent measurements in water revealed a strong hysteresis of elastic moduli while shifting the melting/crystallization transitions or preventing crystallization in PEG‐rich networks. All networks displayed predominantly elastic behavior. Co‐networks in non‐selective solvent conditions are overall softer, less adhesive, and structurally more homogeneous. These results establish a predictable correlation of network composition, physical and chemical environment, structure, and properties, which makes them suitable for a rational design of amphiphilic systems for various applications.