Phase Transitions in Poly(vinylidene fluoride)/Polymethylene-Based Diblock Copolymers and Blends

Area of Science:

• Polymer science
• Materials science
• Crystallography

Background:

• Linear diblock copolymers offer unique phase behavior compared to polymer blends.
• Poly(vinylidene fluoride) (PVDF) exhibits diverse polymorphic structures influencing its properties.
• Understanding copolymer morphology is crucial for designing advanced materials.

Purpose of the Study:

• To investigate the crystallization and morphology of polymethylene-block-poly(vinylidene fluoride) (PM-b-PVDF) diblock copolymers.
• To compare the behavior of these copolymers with immiscible blends of their neat components.
• To explore the influence of copolymer structure and processing on PVDF polymorphism and ferroelectric properties.

Main Methods:

• Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS) for structural analysis.
• Polarized Light Optical Microscopy (PLOM) and Transmission Electron Microscopy (TEM) for morphology.
• Differential Scanning Calorimetry (DSC), Broadband Dielectric Spectroscopy (BDS), and Fourier Transform Infrared Spectroscopy (FTIR) for thermal and dielectric properties.

Main Results:

• PM-b-PVDF diblock copolymers exhibited miscibility in the melt, contrasting with immiscible blends.
• PVDF crystallization and its polymorphic structure were highly dependent on the material's environment (copolymer vs. blend).
• Specific preparation conditions allowed for the selective formation of ferroelectric PVDF phases.

Conclusions:

• Copolymerization significantly alters phase behavior and PVDF crystallization compared to blends.
• Tailoring processing conditions provides a route to control PVDF polymorphism and achieve desired ferroelectric properties.
• These findings are valuable for the development of functional PVDF-based materials.