Waterborne polyurethanes (WBPUs) have attracted increasing attention in a wide range of industrial applications because of their versatile properties as well as ecofriendly nature. Although extensive research has been carried out on WBPU synthesis, the roles of some of the key synthesis components remain unclear. In this study, through systematically controlling and fine tuning the precursor compositions and reaction conditions, over 300 WBPUs are synthesized. This research enables the roles of several key components that govern WBPU physicochemical properties and ultimately the potential WBPU applications to be identified. Using hair styling as an example, it is demonstrated that only the WBPUs with an optimal range of properties (e.g., Young's modulus >150 MPa, elongation at break: 15-300%, moisture uptake <10%) can achieve strong styling performance. To further improve the natural-feel sensory benefits in the final styling products, a number of fatty acids with different carbon chain lengths or unsaturation levels are incorporated into WBPUs. Among the ten fatty acids studied, linoleic acid is identified as the most preferred additive. Both in vitro and in vivo testing demonstrate that WBPUs with optimal properties are promising materials for developing strong, long-lasting styling products with natural feel.

A large-scale MoS2 thin film with a holey structure enhances the in-plane Seebeck thermopower, resulting in an enhancement of the Seebeck thermopower anisotropy.

We experimentally investigate the cross-plane figure of merit (ZT) for an Al2O3/ZnO (AO/ZnO) superlattice film by measuring cross-plane electrical and thermal conductivity and Seebeck coefficient using the 3-ω method and an in-house Seebeck coefficient measurement system recently developed for 300–500 K and examine how ZT factors depend on the AO layer inside the AO/ZnO superlattice film using measured thermoelectric properties. The AO/ZnO superlattice film exhibited maximum power factor of ∼276.2 μW/m K2 with low thermal conductivity (∼0.31 W/m K), producing ZT ≥ 0.45 at 500 K, which is approximately 2,650% improvement compared with an undoped ZnO film (∼0.017). The enhanced ZT performance of the AO/ZnO superlattice film can be explained by enhanced phonon scattering at the interface and minority carrier blocking at the interfacial barrier due to the AO layer, suggesting that the interfacial AO layer is important to enhance ZT in oxide-based films. These results open new applications for micro- or nanoscale thin film-based thermoelectric devices.

We report on the electrical properties of natural p-type GeSe nanoflakes, which were mechanically exfoliated from GeSe single crystals by the polydimethylsiloxane (PDMS) stamp method, using a back-gate field effect transistor (FET) measured in a vacuum probe station at room temperature. In this study, we used two contact metals, including Au and Cr metals, as the Ohmic contacts to the GeSe nanoflake FETs, resulting in an Ohmic behavior with the Au contacts, with a total resistance of 5.5 × 106 Ω. We also found that the 40-nm-thick GeSe nanoflake FET exhibits clear p-type semiconductor behavior with a field-effect mobility of ∼1.0 × 10–3 cm2/(V · s) and a current on/off ratio of ∼104 at room temperature.