A novel atomic force microscopy (AFM) method is used for nanometer-scale mapping of the frequency dependence of the storage modulus, loss modulus, and loss tangent (tan δ) in rubber specimens. Our method includes a modified AFM instrument, which has an additional piezoelectric actuator placed between the specimen and AFM scanner. The specimen and AFM cantilever are oscillated by this actuator with a frequency between 1 Hz and 20 kHz. On the basis of contact mechanics between the probe and the sample, the viscoelastic properties were determined from the amplitude and phase shift of the cantilever oscillation. The values of the storage and loss moduli using our method are similar to those using bulk dynamic mechanical analysis (DMA) measurements. Moreover, the peak frequency of tan δ corresponds to that of bulk DMA measurements.

In the context of pneumatic tires, high durability and fuel efficiency reside in a trade-off relationship. This problem may be solved by the introduction of hydrogen bonds into cured rubber, as hydrogen bonds exhibit a different strain dependence of their energy dissipation compared to conventional chemical bonds. Herein, we have synthesized a series of novel deuterated polybutadienes with urethane linkages as a source of hydrogen bonds in the polymer main chain (d-PBUs) by changing the feed ratios of the polybutadiene and olefin-containing polyurethanes. Then, d-PBUs were analyzed by atomic force microscope (AFM) and small-angle neutron scattering (SANS) in order to examine the effect of the hydrogen bonds on polymer structure. As a result, d-PBUs exhibits the formation of large-domains with the introduction of urethane linkages. Furthermore, the scattering profiles of d-PBUs were separated into two fluctuation components of hard segment (HS) and soft segment (SS). The multiple hydrogen bonds with increasing urethane linkages caused changing the structure of HS from about I(q) ~ q -4 (sphere) to q -2 (disk-like or thin cylinder) at q > 0.4 nm -1 .