The dynamics of local mobility in compatible poly(methyl methacrylate)-poly(vinylidene fluoride) blends

The influence of the local environment of segments on the density of vibrational states of compatible PMMA-PVDF blends was revealed from data on the specific heat capacity measured within 2-60 K. The excess heat capacity (boson peak) for PMMA-PVDF blends at Tb = 4-5 K is chiefly due to additional vibrations localized in regions with a characteristic size of 2-8 nm. Transition to the fracton excitation mode over a wide temperature range above Tb was associated with the three-dimensional scale of self-similarity in the interval from 0.3-0.5 nm (which corresponds to the length of several main-chain bonds) to 1.5-2.0 nm (of the order of the length of the statistical chain segment).