Tuning segmental dynamics of PVDF in blends with linear precursors and single-chain nanoparticles: Insights from broadband dielectric spectroscopy

The dynamic behavior of poly(vinylidene fluoride) (PVDF) in blends with either a PMMA-based linear precursor copolymer or its single-chain nanoparticle (SCNP) counterpart was investigated using broadband dielectric spectroscopy (BDS) over 125-500 K. Structural and thermal characterization revealed that both the precursor and SCNP components remain glassy under these conditions, while PVDF exhibits active segmental mobility near its α-relaxation. In PVDF-rich blends, SCNPs induce phase separation, preserving the intrinsic α- and β-relaxations of PVDF, whereas the linear precursor promotes partial mixing, attenuating the α-relaxation and lowering the apparent glass transition temperature due to the surrounding glassy component. At intermediate and low PVDF contents, both blend types exhibit more complex relaxation spectra, reflecting enhanced interfacial interactions and confinement effects. Analysis of the characteristic relaxation times shows that the activation energy ( E a ) of the secondary relaxation increases with the fraction of precursor or SCNPs, indicating hindered local motions due to interfacial constraints or nanoconfinement. Overall, the precursor and SCNP components modulate PVDF dynamics via distinct mechanisms: partial miscibility and dynamic coupling for the precursor, and nanoscale confinement with phase separation for SCNPs, providing strategies to tune segmental dynamics in hybrid glassy polymer systems.