Membrane preparation by sequential spray deposition of polymer PISA nanoparticles

Illuminating for purity: Photocatalytic and photothermal membranes for sustainable oil-water separation

The integration of photocatalytic and photothermal materials with oil-water separation membranes marks a significant advancement in sustainable separation technologies. These hybrid membranes exhibit exceptional functionalities, including resistance to oil fouling, self-cleaning, antibacterial properties, and reduced oil viscosity. Based on their reaction mechanisms, current photocatalytic and photothermal membranes are categorized into four types, i.e., photocatalytic membranes, photo-Fenton membranes, PMS-assisted photocatalytic membranes, and photothermal membranes. Under light irradiation, photocatalytically functionalized membranes generate reactive oxygen species (ROS) that degrade organic pollutants and inactivate bacteria on the membrane surfaces, enabling in-situ cleaning and regeneration. In addition to the above benefits, photothermal membranes achieve reduction of oil viscosity for higher membrane permeation and removal of light oil from membrane surfaces through light-induced heating. This review first explores the mechanisms underlying light-driven advanced oxidation processes (AOPs) and photothermal effects, followed by an in-depth discussion on the fabrication methods of these membranes. Additionally, the applications of photocatalytic and photothermal membranes in oil-water separation are examined, with an emphasis on how the photocatalytic and photothermal materials contribute to membrane functionality. Finally, this review presents the challenges currently faced by photocatalytic and photothermal membranes and outlines future research directions.

Preparation of polymer nanoparticle-based complex coacervate hydrogels using polymerisation-induced self-assembly derived nanogels

This paper reports a generic method to prepare polymer nanoparticle-based complex coacervate (PNCC) hydrogels by employing rationally designed nanogels synthesised by reversible addition-fragmentation chain-transfer (RAFT)-mediated polymerisation-induced self-assembly (PISA). Specifically, a poly(potassium 3-sulfopropyl methacrylate) (PKSPMA) macromolecular chain-transfer agent (macro-CTA) was synthesised via RAFT solution polymerisation followed by chain-extension with a statistical copolymer of benzyl methacrylate (BzMA) and methacrylic acid (MAA) at pH 2. Thus, pH-responsive nanoparticles (NPs) comprising a hydrophobic polyacid core-forming block and a sulfonate-functional stabiliser block were formed. With the introduction of methacrylic acid into the core of the NPs, they become swollen with increasing pH, as judged by dynamic light scattering (DLS), indicating nanogel-type behaviour. PNCC hydrogels were prepared by simply mixing the PISA-derived nanogels and cationic branched polyethyleneimine (bPEI) at 20% w/w. In the absence of MAA in the core of the NPs, gel formation was not observed. The mass ratio between the nanogels and bPEI affected resulting hydrogel strength and a mixture of bPEI and PKSPMA₆₈-P(BzMA_0.6-stat-MAA_0.4)₃₀₀ NPs with a mass ratio of 0.14 at pH ∼7 resulted in a hydrogel with a storage modulus of approximately 2000 Pa, as determined by oscillatory rheology. This PNCC hydrogel was shear-thinning and injectable, with recovery of gel strength occurring rapidly after the removal of shear.

Spraying of Ultrathin Isoporous Block Copolymer Membranes-A Story about Challenges and Limitations

Isoporous membranes can be prepared by a combination of self-assembly of amphiphilic block copolymers and the non-solvent induced phase separation process. As the general doctor-blade technique suffers from high consumption of expensive block copolymer, other methods to reduce its concentration in the casting solution are sought after. Decreasing the block copolymer concentration during membrane casting and applying the block copolymer solution on a support membrane to obtain ultrathin isoporous membrane layers with e.g., spraying techniques, can be an answer. In this work we focused on the question if upscaling of thin block copolymer membranes produced by spraying techniques is feasible. To upscale the spray coating process, three different approaches were pursued, namely air-brush, 1-fluid nozzles and 2-fluid nozzles as generally used in the coating industry. The different spraying systems were implemented successfully in a membrane casting machine. Thinking about future development of isoporous block copolymer membranes in application it was significant that a continuous preparation process can be realised combining spraying of thin layers and immersion of the thin block copolymer layers in water to ensure phase-separation. The system was tested using a solution of polystyrene-block-poly(4-vinylpyridine) diblock copolymer. A detailed examination of the spray pattern and its homogeneity was carried out. The limitations of this method are discussed.

Investigating the influence of solvent quality on RAFT-mediated PISA of sulfonate-functional diblock copolymer nanoparticles

Solvent quality has a marked impact on the assembly of sulfonate-functional diblock copolymer nanoparticles prepared by PISA.

Alcohol-based PISA in batch and flow: exploring the role of photoinitiators

Polymerization-induced self-assembly (PISA) via PhotoRAFT (photoinduced reversible addition–fragmentation radical transfer) was investigated in polar solvents via continuous flow reactors.

Recent advances in RAFT-mediated surfactant-free emulsion polymerization

We summarized the RAFT-mediated surfactant-free emulsion polymerization using various RAFT agents and the polymerization types for the preparation of organic/inorganic hybrid materials.