  In order to allow the simultaneous transport of hydrophilic and hydrophobic
substances, polymeric networks with finely distributed hydrophilic and
hydrophobic components are very suitable. When designing new soft materials
like coatings, in addition to the structure in the volume phase, the structure
at the interface plays a critical role. In this study, two alternating
tetra-arm star polymers poly({\epsilon}-caprolactone) (tetra-PCL-Ox) and
amino-terminated poly(ethylene glycol) (tetra-PEG-NH2) form an amphiphilic
co-polymer network. They serve as a model system for controlling and
understanding the structure-property relationship at the interface of ACN gels.
The correlation between different synthesis strategies for gel films and their
resulting properties will be described. Through various spin coating
techniques, control over film thickness and roughness is achievable and
highlights differences to macroscopic gel samples. Atomic force microscopy
(AFM) measurements reveal the effect of solvents of different polarities on the
swelling ability and surface structure. This correlates with AFM investigations
of the mechanical properties on ACN gel films, demonstrating a strong effect on
the resulting elastic modulus E, depending on the presence or absence of a good
solvent during synthesis. Furthermore, a higher E modulus is obtained in the
presence of the selective solvent water, compared to the non-selective solvent
toluene. This observation is explained through selective swelling of the
tetra-arm star polymers displaying a different hydrophobicity.
