Hierarchical Organization of Poly(ethylene oxide)-block-poly(isobutylene) and Hydrophobically Modified Fe2O3 Nanoparticles at the Air/Water Interface and on Solid Supports

Langmuir monolayers and Langmuir−Blodgett (LB) film morphologies of block copolymers and hydrophobically modified iron oxide nanoparticles were studied by surface pressure−mean molecular area (π−mmA) measurements and by tapping mode atomic force microscopy (AFM). The amphiphilic diblock copolymers consisted of a hydrophilic poly(ethylene oxide) (PEO) block and a hydrophobic poly(isobutylene) (PIB) block. The π−mmA isotherm of PEO97-b-PIB37 (the subscripts refer to the respective degrees of polymerization) at the air/water interface had an extended plateau reflecting the extension of PEO chains into the water subphase at a surface pressure of 10 mN·m−1, which is absent for the more hydrophobic PEO19-b-PIB130. Iron oxide (Fe2O3) nanoparticles capped with oleic acid ligands as the shell were dispersed in the amphiphilic block copolymers at the air/water interface to prevent macroscopic aggregation of the particles. When the nanoparticles were mixed with PEO97-b-PIB37, using a particle to polymer chain ratio ...