Linking Interfacial Bonding and Thermal Conductivity in Molecularly-Confined Polymer-Glass Nanocomposites with Ultra-High Interfacial Density.

Thermal transport in polymer nanocomposites becomes dependent on the interfacial thermal conductance due to the ultra-high density of the internal interfaces when the polymer and filler domains are intimately mixed at the nanoscale. However, there is a lack of experimental measurements that can link the thermal conductance across the interfaces to the chemistry and bonding between the polymer molecules and the glass surface. Characterizing the thermal properties of amorphous composites are a particular challenge as their low intrinsic thermal conductivity leads to poor measurement sensitivity of the interfacial thermal conductance.

Insights into the Mechanical Properties of Ultrathin Perfluoropolyether-Silane Coatings.

Ultrathin perfluoropolyether-silane (PFPE-silane) films offer excellent functionality as antifingerprint coatings for display touchscreens due to their oleophobic, hydrophobic, and good adhesion properties. During smartphone use, PFPE-silane coatings undergo many abrasion cycles which limit the coating lifetime, so a better understanding of how to optimize the film structure for improved mechanical durability is desired. However, the hydrophobic and ultrathin (1-10 nm) nature of PFPE-silane films renders them very difficult to experimentally characterize.

Tapered Polymer Whiskers to Enable Three-Dimensional Tactile Feature Extraction.

Many mammals use their vibrissae (whiskers) to tactually explore their surrounding environment. Vibrissae are thin tapered structures that transmit mechanical signals to a wealth of mechanical receptors (sensors) located in a follicle at each vibrissal base. A recent study has shown that-provided that the whisker is tapered-three mechanical signals at the base are sufficient to determine the three-dimensional location at which a whisker made contact with an object.

Temperature effects on the nanoindentation characterization of stiffness gradients in confined polymers.

The stiffening of polymers near inorganic fillers plays an important role in strengthening polymer nanocomposites, and recent advances in metrology have allowed us to sample such effects using local mechanical measurement techniques such as nanoindentation and atomic force microscopy. A general understanding of temperature and confinement effects on the measured stiffness gradient length-scale ξ is lacking however, which convolutes molecular interpretation of local property measurements. Using coarse-grained molecular dynamics and finite element nanoindentation simulations, we show that the measured ξ increases with temperature in highly confined polymer systems, a dependence which acts in the opposite direction in systems with low confinement.

Open-source micro-tensile testers via additive manufacturing for the mechanical characterization of thin films and papers.

The cost of specialized scientific equipment can be high and with limited funding resources, researchers and students are often unable to access or purchase the ideal equipment for their projects. In the fields of materials science and mechanical engineering, fundamental equipment such as tensile testing devices can cost tens to hundreds of thousands of dollars. While a research lab often has access to a large-scale testing machine suitable for conventional samples, loading devices for meso- and micro-scale samples for in-situ testing with the myriad of microscopy tools are often hard to source and cost prohibitive.