This Small Business Innovation Research Phase I project seeks to develop the technique of Nanothermal Dynamic Mechanical Analysis (Nanothermal DMA). Dynamic Mechanical Analysis (DMA) is an essential tool for characterizing bulk specialty polymers, but this type of measurement requires hours to extract the viscoelastic response of bulk samples, with no nanoscale spatial resolution. The Nanothermal DMA system will dramatically increase the sensitivity of current nanoscale thermal analysis techniques and add the ability to rapidly measure and map the temperature-dependent elasticity and viscoelastic response of polymers on the nanoscale. The instrument will be able to conduct force modulation frequency and temperature sweeps in times as short as milliseconds. These innovations will increase the spatial resolution and measurement rate by many orders of magnitude over currently available techniques. This would provide a novel nanoscale characterization technology that will allow high sensitivity mapping of the temperature dependent dynamic mechanical properties of materials at the nanoscale. Understanding materials' structure-property correlations at the nanoscale is crucial to achieving the desired material properties for ensuring sufficient strength, flexibility, toughness and thermal stability in high-value applications.
The broader impact/commercial potential of this project is to allow increased reliability and improved performance across multiple industries where polymeric materials, such as highly crosslinked and filled systems, are critical. A few of the high-value segments to be impacted are the multi-billion dollar industries of semiconductor packaging, photonic devices, medical devices and defense/aerospace. The market for epoxy materials alone is $15 billion, spread across numerous industries. In a number of these fields the volume of epoxy used per device is rapidly shrinking, which creates challenges for reliably curing the epoxy but also poses serious problems in the analysis of the epoxy. Since our nanothermal DMA tool is a non-destructive technique that can be used on actual devices, it can be used both for basic materials R&D and also for packaged device process control on very small volumes of material. It will also be useful for process control and troubleshooting of the portion of the $100 billion medical device industry where these adhesives are a key aspect of device reliability. In all of these industries, large investments are being made in nanoscale materials and new characterization tools are needed to address the critical lack of thermomechanical data at this length scale.
This NSF SBIR Phase I project has focused on developing new technology and instrumentation for characterization of the mechanical and thermal properties at the nanoscale. Large and growing classes of materials use nanostructured materials to achieve specific performance targets. An example most people will be personal experience with is polymer blends that are used in consumer products. To increase the likelihood that a device like a smart phone will survive after being dropped, material scientists have developed polymer materials that combine different polymers, for example rigid plastic for strength and rubbery polymers for shock absorption. To achieve best performance, many of these materials are being created with individual polymer regions on micro or nano-sized length scales. Many other examples exist, including materials with micro or nanosized filler particles that are intended to incease the strength, flame resistance, temperature stability, electrical conductivity or other properties. A major issue, however, has been the lack of characterization instruments that can measure and visualize critical material properties on the scale they are being engineered. Instead material scientists have largely been constrained to measuring bulk performance, being essentially blind to the details of material properties at the nanoscale. The goal of this project has been to create new techniques and instruments to fill this critical gap in material characterization. We demonstrated the feasibility of performing nanoscale measurements of the thermal properties of several classes of widely used materials that previously could not be readily measured, including materials widely used in semiconductor and consumer products industries. Additionally, we developed the ability to measure the thermal transitions of highly filled materials which are an important material class for several high value applications such as materials developed to handle harsh environments that involve significant shock and vibration (consider parts used in automotive, military and aerospace applications). In this Phase I project we developed techniques to allow material scientists the ability to perform nanoscale measurements of thermo-mechanical measurements with roughly 1000X faster measurement times that has been available with conventional instruments.
