Characterization of amphiphilic arborescent graft polymers at the air/water interface

Two amphiphilic arborescent copolymers with a polyethylene (PEO)-d4 content of either 8 or 43% w/w were prepared. Rearrangements of the relatively flexible polystyrene side chains during evaporation of the spreading solvent explained why the copolymer behaves like a typical small molecular amphiphile in the Langmuir force balance experiments. The length of the PEO chain segments was shown to have a major impact on the aggregation of the molecules at the air/water interface. Most significantly, copolymers containing long PEO segments were shown to aggregate reversibly to ribbon-like structures under the influence of pressure. Reversibilty of the association process was observed even after extended compression intervals.