Polyvinylidene Fluoride Aerogels with Tailorable Crystalline Phase Composition

In this work, polyvinylidene fluoride (PVDF) aerogels with a tailorable phase composition were prepared by following the crystallization-induced gelation principle. A series of PVDF wet gels (5 to 12 wt.%) were prepared from either PVDF-DMF solutions or a mixture of DMF and ethanol as non-solvent. The effects of the non-solvent concentration on the crystalline composition of the PVDF aerogels were thoroughly investigated. It was found that the nucleating role of ethanol can be adjusted to produce low-density PVDF aerogels, whereas the changes in composition by the addition of small amounts of water to the solution promote the stabilization of the valuable beta and gamma phases. These phases of the aerogels were monitored by FTIR and Raman spectroscopies. Furthermore, the crystallization process was followed by in-time and in situ ATR-FTIR spectroscopy. The obtained aerogels displayed specific surface areas > 150 m(2) g(-1), with variable particle morphologies that are dependent on the non-solvent composition, as observed by using SEM and Synchrotron Radiation Computed micro-Tomography (SR-mu CT).