Through this award, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, the PI develops a new characterization method for the nanoscience community. This new method is especially useful for research in ultra-thin membrane material and therefore might serve national interests in terms of health (understanding biological membranes) as well as by its usefulness for the nanoelectronics industry, which uses material (e.g. silicon and graphene) at extremely small nanometer size in both conventional as well as advanced devices. Currently, these devices are used in both national defense components as well as commercial devices such as next generation cell phones. The new technique is called "Local Atomic-Level Thermodynamic Probe" and it uses nuclear magnetic resonance, a technique which is similar in nature to the popular MRI medical instrument often used in hospitals to diagnose features within the human body, and combines it with nanocalorimetry, a rather novel technique that can measure materials properties such as melting temperatures of membrane layers that are only a few atoms thick. Most prominent among the Broader Impacts activities of this project is the aim to increase the Native American participation in education and research within the scientific community. To achieve this, outreach efforts focus on offering two-day sessions of a Summer Science Camp at the local community college in Browning, MT, the home of the Native American Blackfeet tribe. The theme of the camp uses hands-on experiments focusing on energy related projects. Activities will include (1) the use of voltmeter for electrical measurements; (2) assembly of Wind Turbine for LED lighting; (3) assembling kits that utilize solar energy; (4) hands-on calorimetry/solar/meter setup for heating water from solar energy. The camp will educate 60 high/middle school students. Another Broader Impact of this project is the enhancement of National Instrumentation Infrastructure with the invention of the nanocalorimetry technique which helps sustain the country's leadership role in the field of nanoscale thermal analysis by addressing a current gap in the breadth of advanced analytical techniques in the field of nanotechnology.
2. TECHNICAL SUMMARY Through this award, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, the PI develops a new characterization method for the Nanoscience Community. This tool is a local atomic-level thermodynamic probe and consists of combining NMR and nanocalorimetry with new modeling methods (phenomenological thermodynamic models, DFT, MD and Monte Carlo). The project requires the synthesis of a special set of AgSCn-X 2D membranes, which act as the base material system for the development of the new technique. Two-dimensional (2D) membrane materials exhibit extraordinary properties that are universal in nature. They occur in living cells as well as in nanoelectronics. For example, graphene has remarkably high electron mobility and zero band gap while biological membranes form the outer layer structures of all living cells. Extraordinary changes in physical properties occur as the thickness of the membrane approaches the critical nanometer size range, e.g. size has a huge effect on the melting of lipid membranes in biological cell systems. Even changes of few degrees in temperature are critical in human body where the survival temperatures span over a very narrow range. Measuring the thermodynamic melting properties of single-layer membranes (~2 nm) and obtaining values for their melting point and enthalpy were only recently accomplished with the use of new nanocalorimetry technology. The latest discovery focuses on ultra-thin membranes with less than 7 carbons in the alkyl chains. Here the Gibbs-Thompson size-dependent model breaks down at a critical chain length at the transition between bulk and discrete sizes. In this small size regime, the shortcomings of nanocalorimetry and thermoanalysis become apparent when the thickness of membranes approaches their ultimate limit. At this small chain length, the melting point soars by 50 K and the melting enthalpy increases by ~400%. Nanocalorimetry has no depth perception; it only yields average thermodynamic values. NMR, on the other hand, can distinguish one atom from another. NMR has the unique capability to measure the local chemical environment of individual (type) atoms by monitoring the chemical shift. Combining these two techniques produces a powerful tool for Nanoscience investigations.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
