Effects of coating solvent and thermal treatment on transport and morphological characteristics of PDMS/Torlon composite hollow fiber membrane

Abstract

ABSTRACTA new approach for formation of the polydimethylsiloxane (PDMS) layer on Torlon polyamide‐imide hollow fiber (PAI‐HF) support has been developed by directly after fiber spinning without the need to undergo the final conventional solvent exchange and drying step, thereby saving postspinning processing steps. The produced PDMS/PAI‐HF composite membranes were found to have high CO2 permeance (i.e., 1100 GPU) and exhibited good CO2/N2 selectivities of 8–10 which is close to 90% of that of a PDMS dense film. The effects of coating solution, rewetting and crosslinking temperature on the PAI‐HF morphological features, that is, gas transport, skin thickness, skin integrity, and substructure resistance are investigated. The rewetting and thermal treatment of the PAI‐HF caused the densification of the skin layer and reduced the pore sizes on the top layer. In addition, the potential use of the PAI‐HF support with polymers that are insoluble in hexane is also considered. Effects of water, methanol, and hexane exposure of PAI‐HF to these solvents are considered. This evaluation calls attention to issues that must be addressed in any eventual use of the PAI‐HF with water‐soluble or methanol‐soluble selective layer polymers, rather than simple hexane‐soluble polymers such as PDMS. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45418.