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Facile and Efficient Modification of Polystyrene-block-poly(methyl methacrylate) for Achieving Sub-10 nm Feature Size

Nanofabrication based on block copolymer self-assembly is one of the most promising methods for producing nanopatterns with a sub-10 nm feature size. Although polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) has been widely studied as a suitable template for nanofabrication, the insufficient incompatibility between the PS and PMMA blocks makes it difficult to achieve a microphase separation with the domain spacing of less than ca. 20 nm. We now present a simple and efficient method for the postpolymerization modification of PS-b-PMMA for effectively increasing the incompatibility between the two blocks, so that microphase separation can be achieved even at a low degree of polymerization. The ester–amide exchange reactions of PS-b-PMMA with primary and secondary amines were performed to introduce a small number of methacrylamides into the PMMA block to increase its hydrophilicity. The results of small-angle X-ray scattering measurements performed on bulk samples showed that the modified PS-b-PMMA se...