Two-stage melting of the dilute gels of poly(γ-benzyl l-glutamate) in benzene has been studied by differential scanning calorimetry, wide-angle X-ray diffraction, and small-angle X-ray scattering using synchrotron radiation. Differential scanning calorimetry measurements show that the traces on heating exhibit two endothermic peaks at about 25 °C and at about 31 °C, thereby indicating the melting of two types of aggregates, while those on cooling exhibit no exotherm even at 0 °C, thereby indicating a large thermal hysteresis. Wide-angle X-ray diffraction measurements show that the profiles yield little of interest other than diffuse halos from the solvent except a diffuse small-angle scattering, thereby indicating that the aggregates do not contain a solid crystalline phase but a crystal−solvate phase. Small-angle X-ray scattering measurements show that the two-stage melting of the aggregates can be attributed to a melting first of the bundles of three rods and then of the bundles of two rods and that, above the two-stage melting temperature, the gels transform into the dilute and isotropic solutions, in which the poly(γ-benzyl l-glutamate) stiff chains are randomly dispersed and do not interact with each other. We suggest that the intermolecular interactions causing the bundles to aggregate are induced by the solvent.

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The authors utilized a SAW directional coupler which consists of two IDTs and two waveguides with a horn structure for focusing SAW at each end of the waveguides, as an electrostatic voltage sensor and a displacement sensor. In the electrostatic voltage sensor, electrostatic voltage is applied on the surface of the substrate between two parallel waveguides.An amplifier was connected between the two IDTs, and a SAW oscillator with the oscillation frequency 10 MHz was constructed. The senitivity of the sensor is 0.07 Hz/V for the waveguide distance 0.4 nun.The displacement sensor consists of two substrates, on each one of which an IDT and a waveguide with a horn structure were formed by A1 deposition. The two substrates are contacted on the surfaces with the waveguide, with each other, and one is movable OK slides to the other. Thus a dirctional coupler with a variable coupling distance was performed, and a SAW oscillator was constructed by connecting an amplifier.The oscillation frequency is changed by moving or sliding one substrate and fixing the other. The sensitivity of the sensor is 50 kHz/mm.