Fabrication of microfiltration membranes from polyisobutylene/polymethylpentene blends

An approach for fabrication of microfiltration membranes by solvent extraction of one of the immiscible components from a polymer blend was developed. Poly(4‐methyl‐1‐pentene) (PMP) was the membrane material, and poly(isobutylene) (PIB) was the extractable component. The PIB content varied in the wide range 0–45 wt%, and all blends could be melted and processed at a temperature of 240 °C. A rheological study demonstrated a pronounced non‐Newtonian behavior of PMP/PIB blends and their very low viscosity due to interlayer slip. With a PMP content of 55 and 60 wt%, it was possible to fabricate microfiltration membranes with a water permeability of 31 and 3.7 m3 m−2 h–1 bar–1, respectively. The microfiltration membranes based on both compositions demonstrated good rejection performance at the level of 93%–98% for submicron particles of phthalocyanine dye with a size of 240 nm. These results indicate that the PMP/PIB system can be utilized for fabrication of filtration membranes by means of 3D printing followed by solvent extraction.