Supramolecular Structures, organization and surface behavior at interfaces

The surface behavior of Supramolecular Structures as inclusion complexes ^[1] were studied. The inclusion complexes (ICs) obtained from the threading of α-cyclodextrin (α-CD) with poly(ε-caprolactone) (PEC) and derivatives as precursor homopolymers were prepared and characterized by ¹H-NMR and FT-IR Microscopy. In order to investigate the influence of the chemical structure of the other precursor homopolymers as poly(ethylene oxide) (PEO) and poly(tetrahydrofuran) (PTHF), the inclusion complexes (ICs) were also obtained from the threading of α-cyclodextrin (α- CD) with these polymers. Surface pressure-area isotherm (π-A) at the air-water interface were determined by the Langmuir Technique for all the ICs and their polymers. Due to solubility reasons, different spreading solvents were used. In a set of control experiments, it was observed that the spreading volume did not influence significantly the isotherms for any polymeric systems studied. It was found that the hydrophobic and hydrophilic balance changes with the increasing of the methylene and hydroxyls groups number in the chemical structures of the precursor polymers involved in the ICs. The degree of hydrophobicity of the different supramolecular systems was also estimated from the determination of the surface free energy (SE) values using the wettability measurements.[2] In order to describe the experimental behavior of the ICs and the precursor polymers, molecular dynamics simulation (MDS) were performed. The radial distribution functions (RDF) between water molecules and hydrophilic and hydrophobic moieties of the polymeric systems studied were analized. By this way it was possible to visualize the orientation and the organization of these supramolecular structures at the air-water interface.