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Munchen (Germany) are using theMagnetism Reflectometer atORNL's Spallation Neutron Sourceto analyze new functionalnanocomposite thin films they aredeveloping.2As more materialsincorporate nanoparticles, newtechniques are needed to analyzetheir structures on the nanoscale.The thin films combine Fe3O4nanoparticles with matrices of thediblock copolymer poly(styrene-block-n-butyl methacrylate),P(Sdb-nBMA). The componentsself-assemble into a well-orderedstructure that remains stable withup to 10% nanoparticle content.The challenge in making thesenanocomposite thin films is thatwell-controlled placement ofnanoparticles in the diblockcopolymers can be difficult. Bignanoparticle clusters can form, andsometimes the morphology of thediblock copolymer matrix gradual-ly disappears. The researchers usedasymmetric diblock copolymers,which have two unequal blocklengths. They fabricated and stud-ied composite thin films of asym-metric P(Sdb- BMA) diblockcopolymer and large magnetiteFe3O4nanoparticles (10 nm aver-age diameter). Their samples con-tained 5% and 10% volume frac-tions of nanoparticles. High-contrast neutron scatteringperformed with the MagnetismReflectometer showed that beforeannealing, the internal structure ofthe films was not uniform. Bothwith and without nanoparticles,there was a partial phase separationin the asymmetric films. Afterannealing, the neutron reflectome-try showed that a combined, well-organized two-layer structure hadbecome imprinted in the thin films.Furthermore, the structureremained stable after the incorpora-tion of the nanoparticles. "Thestudies demonstrate that the self-assembly of such materials isstrongly influenced by the energiesgenerated between the interfacingmaterials and the surface energiesof the blocks and substrate," saysValeria Lauter, a member of theresearch team. Analyzing NanomaterialsResearchers from Neaspec GmbH inMartinsried, Germany, recentlydeveloped an infrared near-fieldmicroscopy platform that can ana-lyze nanomaterials with a spatial res-olution of about 10 nm. However,analysis using this platform is usual-ly performed with a tunable | OCTOBER 2011 | PLASTICS ENGINEERING |15