Polymer Brush Membranes Christopher K. Ober , Cornell University, DMR 1105253

1. Polymer Brush MembranesChristopher K. Ober, Cornell University, DMR 1105253 Polymer brushes are of great interest due to the broad range of future applications that these 2D nanoscale structures make possible.We have recently discovered the robust character of free standing crosslinked polymer brushes. Consequently, the nature of patterned polymer brushes as removable thin films was explored. Both hydrofluoric acid etching and polyvinyl alcohol (PVA) dissolution processes have enabled us to lift off very thin membranes for characterization via AFM and TEM. These intact, self-supporting films less than 50 nm thick suggest that “polymer carpets” can be produced with arbitrary shape and different chemical functions top and bottom. By varying the thickness of the polymer brushes we may achieve different folding properties based on the mechanical properties of the membranes. These films show potential use as “Janus membranes” and other molecular objects. A • Immobilize Initiator • ATRP monomer Spin coat photoresist • Pattern by UV • Develop • Etch • Crosslink by UV • Remove photoresist HF etch B C water (A) Schematic of lifting off polymer brushes via HF etch. (B) Polystyrene (PS) brush (53 nm) on a sacrificial PVA layer can be released by water to give small particles that can fold into different shapes. (C) TEM images of PS show the importance of initiator immobilization concentrations on grown membrane quality (left image 2mM, right image 20mM initiator concentration).

2. Polymer Brush Membrane Lift Off Christopher K. Ober, Cornell University, DMR 1105253 • Outreach activities include hosting REU students and student exchanges (U of Mainz) • Grad student exchanges included the extended research visits of L. Welch to U.Freiburg, Germany; A. Wan to Écoledes Mines, France and B. Wenning to the U of Pisa • Ober has created and maintains the • IUPAC Polymer Education website, an international resource for students and teachers • It continues as one of the Google, Bing and Yahoo top hits for polymer education • Ober led IUPACPolymer Division efforts to celebrate 2011, the International Year of Chemistry (IYC) and coordinated an international writing and video contest on “A World without Polymers”. http://iupac.org/polyedu/