Deciphering the three-dimensional morphology of free-standing block copolymer thin films by transmission electron microscopy

作者：Allen Frances I^*; Ercius Peter; Modestino Miguel A; Segalman Rachel A; Balsara Nitash P; Minor Andrew M

来源：Micron, 2013, 44: 442-450.

DOI：10.1016/j.micron.2012.09.010

• Electron tomography
• Energy-filtered TEM
• Block copolymer morphology
• PS-b-PEO thin films
• Salt doping
• Casting solvent

Block copolymer thin films with distinct morphologies are prepared by spin casting a nominally lamellar assay of poly(styrene-block-ethylene oxide) from a variety of solvents with and without salt doping. The 3-D morphologies of free-standing thin-film regions, which are obtained by casting directly onto holey substrates, are investigated in detail using various energy-filtering transmission electron microscopy techniques and by electron tomography. Surface characterization is achieved by atomic force microscopy. Our results demonstrate that in order to fully characterize the unique 3-D morphologies of the block copolymer thin films, a multi-method approach is required. When casting from a binary solvent, an unexpected layered honeycomb-type morphology is revealed, which likely results from an expansion of the poly(ethylene oxide) phase. A dramatic effect of selective cation coordination on the morphology of the as-cast block copolymer films is also directly observed. Published by Elsevier Ltd.

• 出版日期2013-1