Nanorheological atomic force microscopy (AFM) is a measurement technique that maps dynamic viscoelasticity with nanoscale spatial resolution. The technique combines dynamic measurements with quasi-static force curve measurements, allowing quantification of the contact area using a theoretical model of contact elasticity and, therefore, the dynamic modulus. However, the nano-viscoelasticity measured by nanorheological AFM is not in perfect agreement with the macro-viscoelasticity measured by a rheometer. To improve the quantitative performance of the dynamic modulus, a variable was introduced to correct for the difference from the contact area of Johnson-Kendall-Roberts theory. The load dependence of the storage stiffness of polydimethylsiloxane (PDMS) and styrene-butadiene rubber (SBR) was investigated to determine variables for each measurement frequency. The novel analytical method gives results in better agreement with the macroscopic measurement method.

One possible choice for soft actuator is polymeric actuator composed of twisted fishing line. An actuator composed of twisted linear low-density polyethylene (LLDPE) exhibits reversible extension and shrinkage induced by changes in temperature. It has been assumed that the origin of this actuation is attributed to the tie molecules bridging crystalline lamellae. In this study, a combination of in situ X-ray and NMR measurements are adopted for evaluation of the role of tie molecules on stretching and shrinking of drawn LLDPE film. In situ small-angle X-ray scattering (SAXS) measurements indicate that crystalline lamellae stack perpendicular to the stretching direction for the stretched state; however, they tilt for the shrunk state. In situ pulse NMR measurements confirm that the intermediate components attributed to tie molecules bridging crystalline lamellae are mainly stretched and shrunk, reflecting the resultant stress response. Macroscopic strain change of the sample film agrees with microscopic tie-molecular stretching and shrinking, which dominates the actuating behavior of the drawn LLDPE film. Structural changes on heating correspond to those on shrinking, indicating that temperature actuation is also driven by stretching and shrinking of tie molecules. Such obtained results predict the mechanism of actuation of drawn LLDPE.

Silane coupling agents are type of silicon compound and have molecular structure that react with both inorganic and organic substances. These silanes react with inorganic substances through a two-step hydrolysis reaction and a dehydration-condensation reaction.

On the other hand, silica formulations are spreading because of low rolling resistance in the tire industry. These formulations include silane coupling agents to provide interaction between silica and rubber. The silane coupling agents react with silica during mixing and react with rubber during vulcanization. As a result, we can get a rubber stocks with high dispersibility and low energy loss.

Toward improvement in the reliability of polymeric materials, it is necessary to develop technologies that prevent and report fractures in materials caused by an external force. Among some strategies to dramatically improve the mechanical performances of unfilled polymer networks, an energy dissipation mechanism via rupture of weak bonds, so-called sacrificial bonds, is one of the promising approaches for realizing tough materials. Furthermore, the burgeoning of polymer mechanochemistry, based on mechano-responsive molecular units, i.e., mechanophores, enables detection, or sometimes utilization, of molecular scale force within a polymer. This review briefly summarizes the two research fields and points out their remaining issues. In the context of the current situation, our recent achievement on a toughened and self-reporting elastomer emerging from the fusion of the sacrificial bond principle and polymer mechanochemistry is discussed.