The supramolecular organization of PVDF lamellae formed in diphenyl ketone dilutions via thermally induced phase separation

The crystallization of poly(vinylidene fluoride) (PVDF) during thermally induced solid-liquid phase separation leads to supermolecular structures in PVDF/montmorillonite (MMT)/diphenyl ketone dilutions with various poly(methyl methacrylate) (PMMA) contents. The presence of MMT had a significant nucleation enhancement on the β-PVDF crystals along with the MMT surfaces, and subsequently the α-PVDF crystals formed between MMT layers. The mechanism of the PVDF crystallization in the dilution was studied by DSC, POM, FTIR, and SEM results. A small amount of PMMA incorporation (0.3 wt%) improved the dispersion of MMT in the mixture, leading to the highest nucleation effect on the PVDF crystals. This result proves that PMMA chains acted as a good interfacial agent for PVDF and MMT nanoparticles. A well-interconnected supermolecular morphology formed in the dilutions resulted in a higher tensile strength. When the PMMA content was over 1.5 wt% in the dilution, the excessive amorphous PMMA chains would hinder the crystallization of PVDF; subsequently, less interconnected PVDF lamellae structures lowered the tensile strength.