Poly(ether sulfone)/Polyaniline Nanocomposite Membranes: Effect of Nanofiber Size on Membrane Morphology and Properties

Conducting Polyaniline for Antifouling Ultrafiltration Membranes: Solutions and Challenges

Conjugated polyaniline can impact the field of water filtration membranes due to its hydrophilic and antibacterial nature, facile and inexpensive synthesis procedure, heat and acid tolerance, and unique doping/dedoping chemistry. However, the gelation effect, its rigid backbone, and the limited hydrophilicity of polyaniline severely restrict the adaptability to membranes and their antifouling performance. This Mini Review summarizes important works of polyaniline-related ultrafiltration membranes, highlighting solutions to conquer engineering obstacles in processing and challenges in enhancing surface hydrophilicity with an emphasis on chemistry. As a pH-responsive polymer convertible to a conductive salt, this classic material should continue to bring unconventional advances into the realm of water filtration membranes.

Direct grafting of tetraaniline via perfluorophenylazide photochemistry to create antifouling, low bio-adhesion surfaces

Conjugated polyaniline has shown anticorrosive, hydrophilic, antibacterial, pH-responsive, and pseudocapacitive properties making it of interest in many fields. However, in situ grafting of polyaniline without harsh chemical treatments is challenging. In this study, we report a simple, fast, and non-destructive surface modification method for grafting tetraaniline (TANI), the smallest conjugated repeat unit of polyaniline, onto several materials via perfluorophenylazide photochemistry. The new materials are characterized by nuclear magnetic resonance (NMR) and electrospray ionization (ESI) mass spectroscopy. TANI is shown to be covalently bonded to important carbon materials including graphite, carbon nanotubes (CNTs), and reduced graphene oxide (rGO), as confirmed by transmission electron microscopy (TEM). Furthermore, large area modifications on polyethylene terephthalate (PET) films through dip-coating or spray-coating demonstrate the potential applicability in biomedical applications where high transparency, patternability, and low bio-adhesion are needed. Another important application is preventing biofouling in membranes for water purification. Here we report the first oligoaniline grafted water filtration membranes by modifying commercially available polyethersulfone (PES) ultrafiltration (UF) membranes. The modified membranes are hydrophilic as demonstrated by captive bubble experiments and exhibit extraordinarily low bovine serum albumin (BSA) and Escherichia coli adhesions. Superior membrane performance in terms of flux, BSA rejection and flux recovery after biofouling are demonstrated using a cross-flow system and dead-end cells, showing excellent fouling resistance produced by the in situ modification.

Polyaniline Nanofibers: Their Amphiphilicity and Uses for Pickering Emulsions and On-Demand Emulsion Separation

The wetting property of nanomaterials is of great importance to both fundamental understanding and potential applications. However, the study on the intrinsic wetting property of nanomaterials is interfered by organic capping agents, which are often used to lower the surface energy of nanomaterials and avoid their irreversible agglomeration. In this work, the wetting property of the nanostructured polyaniline that requires no organic capping agents is investigated. Compared to hydrophilic granular particulates, polyaniline nanofibers are amphiphilic and have an excellent capability of creating Pickering emulsions at a wide range of pH. It is suggested that polyaniline nanofibers can be easily wetted by water and oil. Furthermore, the amphiphilic polyaniline nanofibers as building blocks can be used to construct filtration membranes with a small pore size. The wetting layer of the continuous phase of emulsions in the porous nanochannels efficiently prevents the permeation of the dispersed phase, realizing high-efficiency on-demand emulsion separation.

Preparation and characterization of a polyethersulfone/polyaniline nanocomposite membrane for ultrafiltration and as a substrate for a gas separation membrane

PES/PANI nanocomposite membrane displayed excellent flux and antifouling property for UF. Meanwhile, PES/PANI non-woven fabrics supported membrane performed as a suitable substrate for gas separation membrane with PVAm selective layer.

Criteria for the selection of a support material to fabricate coated membranes for a life support device

The innovative design of coated membranes opens up wider applications for a life support device improving quality of life.