New strategies for patterning: implications for branched macromolecules Sergei S. Sheiko, University of North Carolina at Chapel Hill, DMR Highly branched macromolecules generate immense tension in their covalent skeleton without applying any external force. Furthermore, these molecular tensile machines enable targeted interrogation of specific chemical bonds evoking unique chemical reactions and alteration of electro- optical properties. As a proof-of-concept, we have studied mechanical activation of a single disulfide linker within a large bottlebrush macromolecule. An anti-Arrhenius behavior has been discovered as the bond-scission rate increases with force, while decreases with temperature. The energy potential and activation parameters of the disulfide bond have been accurately measured. This work opens interesting opportunities for the design of mechanically encoded photoresists. Macromolecules (accepted, 08/14/2013) Polymer brushes generate, amplify, and transmit mechanical tension to a disulfide bond, causing its scission under controlled tension and temperature. Anti-Arrhenius Cleavage of Disulfide Bonds 26 °C16 °C 5 °C

Macromolecules typically phase separate unless their shapes and chemical compositions are tailored to explicitly drive mixing. But now research has shown that physical constraints can drive spontaneous mixing of chemically different species. Long-range 2D arrays of intimately mixed and patterned macromolecules, having a variety of molecular architectures and chemistries, have been obtained. This is achieved by exploiting the entropy-driven repulsive interactions between macromolecules anchored on a substrate. The reported entropic templating strategy opens new ways for generating features on sub-100 nm length scales with potential application in lithography, directed self- assembly, and biomedical assays. Nature Materials 12, (2013) Steric repulsion between brush-like macromolecules leads to intercalation, aka perfect mixing, of chemically different polymers and particles. Entropic templating – A new strategy for mixing the immiscible polymers conformational entropy increases New strategies for patterning: implications for branched macromolecules Sergei S. Sheiko, University of North Carolina at Chapel Hill, DMR

Entropic templating – A new strategy for mixing the immiscible polymers Macromolecules typically phase separate unless their shapes and chemical compositions are tailored to explicitly drive mixing. But now research has shown that physical constraints can drive spontaneous mixing of chemically different species. Long-range 2D arrays of intimately mixed and patterned macromolecules, having a variety of molecular architectures and chemistries, have been obtained. This is achieved by exploiting the entropy-driven repulsive interactions between confined macromolecules. The entropic templating strategy opens new ways for generating features on sub-100 nm length scales with potential application in lithography, directed self-assembly, and biomedical assays. Nature Materials 12, (2013) Steric repulsion between brush-like macromolecules leads to intercalation, aka perfect mixing, of chemically different polymers and particles. Mixing the immiscible New strategies for patterning: implications for branched macromolecules Sergei S. Sheiko, University of North Carolina at Chapel Hill, DMR