Superhydrophilic polyvinylidene fluoride membrane with hierarchical surface structures fabricated via nanoimprint and nanoparticle grafting

Combining Topography and Chemistry to Produce Antibiofouling Surfaces: A Review

Despite decades of research on the reduction of surface fouling from biomolecules or micro-organisms, the ultimate antibiofouling surface remains undiscovered. The recent covid-19 pandemic strengthened the crucial need for such treatments. Among the numerous approaches that are able to provide surfaces with antibiofouling properties, chemical, biological, and topographical strategies have been implemented for instance in the marine, medical, or food industries. However, many of these methods have a biocidal effect and, with antibioresistance and biocide resistance a growing threat on humanity, strategies based on reducing adsorption of biomolecules and micro-organism are necessary for long-term solutions. Bioinspired strategies, combining both surface chemistry and topography, are currently at the heart of the best innovative and sustainable solutions. The synergistic effect of micro/nanostructuration, together with engineered chemical or biological functionalization is believed to contribute to the development of antibiofouling surfaces. This review aims to present approaches combining hydrophobic or hydrophilic chemistries with a specific topography to avoid biofouling in various industrial environments and healthcare facilities.

Nanoporous membrane fabrication by nanoimprint lithography for nanoparticle sieving

An isoporous membrane with strictly controlled pore size, shape and distribution could provide an efficient, precise and mild sieving of particles in nanotechnology and biomedical applications. However there is a lack of highly porous polymeric membranes combining isoporosity and high permeance in the range below 500 nm. Track-etched membranes are practically the only commercial option. Membranes prepared by phase inversion typically have a broad pore size distribution. Most nanofabrication methods have limited the preparation of membranes with pores in the micrometer range. In this work, we present a nanotechnology-based fabrication methodology to manufacture a stable and flexible nanoporous polymeric membrane with 300 nm isopores using UV nanoimprint lithography. The highly porous membrane has a pore density of 4 × 109 pores per cm2 and stable permeance of 108 000 L m-2 h-1 bar-1. Uniform ZIF-8 nanoparticles were synthesized and the isoporous membrane successfully demonstrated as high as 100% rejection and size-based sieving performance of nanoparticles.

Effect of Nanopatterning on Concentration Polarization during Nanofiltration

Membranes used for desalination still face challenges during operation. One of these challenges is the buildup of salt ions at the membrane surface. This is known as concentration polarization, and it has a negative effect on membrane water permeance and salt rejection. In an attempt to decrease concentration polarization, a line-and-groove nanopattern was applied to a nanofiltration (NF) membrane. Aqueous sodium sulfate (Na2SO4) solutions were used to test the rejection and permeance of both pristine and patterned membranes. It was found that the nanopatterns did not reduce but increased the concentration polarization at the membrane surface. Based on these studies, different pattern shapes and sizes should be investigated to gain a fundamental understanding of the influence of pattern size and shape on concentration polarization.