Morphology and polymorph study of a polyvinylidene fluoride (PVDF) membrane for protein binding: Effect of the dissolving temperature

Abstract

A microporous polyvinylidene fluoride (PVDF) membrane was prepared from a PVDF/N-methyl-2-pyrrolidone (NMP) solution using liquid-induced phase separation with 2-propanol as the soft coagulant. In this paper, the effect of the dissolving temperature on the morphology and crystalline structure of PVDF membrane and subsequently on protein binding was studied. Field emission scanning electron microscopy (FESEM) was performed to observe the membrane morphology, and Differential Scanning Calorimeter (DSC) along with Fourier transform infrared (FTIR) spectroscopy was used to investigate the crystallinity and crystalline structure of the membrane respectively. The FESEM and FTIR results show that membrane morphologies and crystalline changed significantly as a result of the dissolving temperature, while no obvious change observed on the crystallinity of the membrane, based on the DSC results. It was found that a critical temperature of 40 °C existed. At lower temperatures, the protein binding ability was governed by the crystalline structure of the membrane, whereas at temperatures greater than 40 °C, the protein binding was primarily governed by the membrane porosity.