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Preparation of Polymeric Membranes and Microcapsules Using an Ionic Liquid as Morphology Control Additive
Author(s) -
Lakshmi D. Shanthana,
Cundari Teresa,
Furia Emilia,
Tagarelli Antonio,
Fiorani Giulia,
Carraro Mauro,
Figoli Alberto
Publication year - 2015
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.201400214
Subject(s) - ionic liquid , membrane , phase inversion , solvent , hexafluorophosphate , fourier transform infrared spectroscopy , chemical engineering , materials science , morphology (biology) , porosity , phase (matter) , raman spectroscopy , casting , polymer chemistry , chemistry , organic chemistry , composite material , catalysis , genetics , biochemistry , physics , optics , biology , engineering
Summary Hydrophilic porous polyethersulfone (PES) membranes and microcapsules were prepared via Non‐Solvent Induced Phase Separation (NIPS) with the ionic liquid (IL) 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([BMIM][PF 6 ]) as structure control agent, added to the conventionally employed PVPK17 pore former. The introduction of [BMIM][PF 6 ] affects the phase inversion mechanism, resulting in different morphologies of the materials. Optimal conditions for the preparation of membranes (ILMs) were: 10–15 wt.% PES, 0–4 wt.% PVPK17, 5–25 wt.% [BMIM][PF 6 ], while slightly different conditions were applied for the preparation of microcapsules (ILMCs): 10% wt.% PES, 0–4% wt.% PVPK17, and 5–15 wt.% [BMIM][PF 6 ]. Thus, the produced porous spongy microcapsules (average diameter ∼800 μm) and flat sheet ionic liquid membranes (ILMs) were characterized by electronic microscopy (SEM), FTIR and Raman spectroscopy and thermal analysis. [BMIM][PF 6 ] concentration is a key factor for controlling the internal membrane morphology. Indeed, higher concentrations of [BMIM][PF 6 ] additive increases the viscosity of casting solution and reduces solvent exchange speed, thereby altering the membrane morphology from a channelled structures (finger‐like) to a spongy type.