Teresa Napolitano

Enabling Strategies in Organic Electronics Using Ordered Block Copolymer Nanostructures

Today’s lithographic techniques for carving silicon into circuit patterns are unable to achieve the future target of the semiconductor industry of fabricating ultrahigh density memory devices made of memory cells just few tens of nanometers apart. [ 1 ] The primary metric for gauging progress in the various semiconductor integrated circuit technologies is, indeed, the spacing, or pitch, between the most closely spaced wires within a dynamic random access memory (DRAM) circuit. The circuit components on today’s silicon chips are more than 100 nm across and modern DRAM circuits have 140 nm pitch wires and a memory cell size of 0.0408 μ m 2 . [ 2 ] Improving integrated circuit technology will require that these dimensions decrease over time. However, at present a large fraction of the patterning and materials requirements that we expect to need for the construction of new integrated circuit technologies have no known solution. [ 2 ] Promising ingredients for advances in integrated circuit technology are nanowires, [ 3 ] molecular electronics [ 4 ] and defecttolerant architectures, [ 5 ] as demonstrated by reports of single devices [ 6–8 ] and small circuits. [ 9 , 10 ] Methods of extending these approaches to large-scale, high-density circuitry are largely undeveloped. The need for very high bit density (the number of memory elements per square centimeter) has pushed the research towards the study of new advanced materials that can overcome these limiting scaling diffi culties and of alternative methods for building memory devices from the bottom up using individual molecules. [ 1 ] These methods start with atoms and molecules and climb up to nanostructures through assembly by various mechanisms of molecular recognition. Self-assembly is emerging as an elegant bottom-up method for fabricating nanostructured materials. [ 11–15 ] Particularly attractive is the self-assembly of organic molecules that, when combined with

Proton Conductivity and Methanol Permeability of Sulfonated Syndiotactic Polystyrene Membranes

Proton conductivity of innovative ionomeric membranes based on partially sulfonated syndiotactic polystyrene (SsPS) was investigated. The membranes were prepared with various levels of sulfonation by chlorosulfonic reaction on sPS films, in its clathrate form, obtained by solution-casting. The actual sulfonation degree of sPS membranes was evaluated by elemental analysis and their proton conductivity was measured using a galvanostatic four-points-probe electrochemical impedance spectroscopy technique. The dependence of conductivity on the level of sulfonation, hydration condition, and temperature was studied. At higher sulfonation degrees, SsPS membranes showed the best performance in vapor phase at 100% RH. In particular, the best SsPS membrane with sulfonation degree about 26 mol% exhibited conductivity equal to 8.8 × 10−2 Ω−1 cm−1 at 31.5 °C. This property is stable during time and increases with temperature. For the membranes with the highest degree of sulfonation, we measured a methanol permeability very close to that of Nafion.