Technical Problem and Solution
B. Thermal property measurements of ultra-thin polymeric films
The emerging area of thermal transport research into ultra-thin polymer films is ideal for nano-composite polymer research. The underlying subject area unifying this emerging field is the experimental measurement of thermo-physical properties and modeling of ultra-thin polymeric films which contain engineered nano-particles for enhancement or reduction of thermal transport. This study will allow tailoring of thermo-physical properties for ultra-thin nano-composite based functional requirements via nano-particle length scale and/or polymeric matrix. Unlike prior research programs where thermo-physical properties were measured for bulk or large media structures, this program will center on investigations in thermal transport of ultra-thin (~micron and submicron) polymeric films containing nano-constituents of different geometries and orientations. The interactions, dynamics, and structure between colloidal particles in polymer solution and melt media greatly affect thermal transport because the characteristic length scale for phonon collisions will be influenced and thus affect the means for transmission of thermal energy between nano-constituents and/or nano-constituents to polymer matrix. While the above mode of thermal transport will dominate in bulk nano-composite media, an additional scattering of phonons effect will be incurred with the presence of physical boundaries. These boundaries are due to reductions of the nano-composite matrix to ultra-thin film dimensions. Multi-scale modeling parameters include film thickness, phonon mean-free path, polymeric entanglement length, crystalline spacing (i.e., for semi-crystalline films), and nano-particle size. The proposed SPL instrument is the enabling platform that will allow the validation of the modeling effort through experimental measurements of the thermo-physical properties (e.g., thermal contact resistance at nano-scale dimensions). Moreover, thermal transport mechanisms are highly sensitive to length and time-scale dimensions; therefore, experimental measurements of the thermo-physical properties with the assistance of the SPL instrumentation will help validate these multi-scale models.
The majority of experimental and analytical research conducted in the past decade has dealt mainly with the measurement of thermophysical properties in inorganic and metallic thin filmsP19-22P. Recently, interest has been generated for thermal transport properties of nanoscale autonomic polymer films with thickness in the range of 20 to 500nm. Due to nanotechnology entering the data storage area, a new scanning-probe-based data storage concept called “millipede” has combined ultrahigh density, terabit capacity, with a small form factor to go beyond the well-known “super-paramagnetic limit”. Current magnetic storage technology will soon hit this limit, and fundamental changes must occur if further advances are to occur; the “millipede” concept will meet these ultrahigh density requirements. However, a nanoscale writable polymeric film of PMMA has been proposed as the medium by which nanoindentations via a Thermo-mechanical AFM device creates data storage. The time it takes to heat the bit volume of polymer material beyond the glass-transition temperature is a potentially rate-limiting step. Moreover, the thermal spreading resistance in the polymer and the thermal contact resistance are the most critical parameters which are presently unknown. The proposed system will be the enabling technology for the quantification of these parametersP23P, besides providing the technique to read and write data on ultra-thin polymer films.
