Fig. 4

Influence of interparticle adhesion on eigenfrequencies and thermal transitions. Brillouin light scattering (BLS) spectra of PS_A-141 particles at different temperatures in two presentations: frequency f vs. a intensity, I and b I · f² (power spectra). Blue lines in (a) refer to Lorentzian lines of (s,1,2) mode. c Temperature dependence of the frequency, f(s,1,1) of the interaction-induced mode (low panel, opened circle) obtained at the maximum intensity and the scaled frequencies (f  · d) of the split fundamental (s,1,2) mode (upper panel, black and red filled circles) of PS_A-141 nanoparticles. Two crossed open circles in the low panel indicate two Lorentzian curve fit of a f(s,1,1). The longitudinal sound velocity (c_l) recorded at q = 0.0146 nm⁻¹ for the contiguous PS film, obtained from the PS_A-141 particles annealed at 393 K, is also shown at right-hand side of y-axis (upper panel, blue solid square). For PS film measurement, the annealed PS film is heated from room temperature (296 K) to 393 K. The hatched and filled areas indicate the softening T_s and glass-transition T_g temperatures, respectively