Hybrid Organic–Inorganic–Organic Isoporous Membranes with Tunable Pore Sizes and Functionalities for Molecular Separation

Abstract

Accomplishing on‐demand molecular separation with a high selectivity and good permeability is very desirable for pollutant removal and chemical and pharmaceutical processing. The major challenge for sub‐10 nm filtration of particles and molecules is the fabrication of high‐performance membranes with tunable pore size and designed functionality. Here, a versatile top‐down approach is demonstrated to produce such a membrane using isoporous block copolymer membranes with well‐defined pore sizes combined with growth of metal oxide using sequential infiltration synthesis and atomic layer deposition (SIS and ALD). The pore size of the membranes is tuned by controlled metal oxide growth within and onto the polymer channels, enabling up to twofold pore diameter reduction. Following the growth, the distinct functionalities are readily incorporated along the membrane nanochannels with either hydrophobic, cationic, or anionic groups via straightforward and scalable gas/liquid–solid interface reactions. The hydrophilicity/hydrophobicity of the membrane nanochannel is significantly changed by the introduction of hydrophilic metal oxide and hydrophobic fluorinated groups. The functionalized membranes exhibit a superior selectivity and permeability in separating 1–2 nm organic molecules and fractionating similar‐sized proteins based on size, charge, and hydrophobicity. This demonstrates the great potential of organic–inorganic–organic isoporous membranes for high‐performance molecular separation in numerous applications.

Sub‐Nanoporous Engineered Fibrous Aerogel Molecular Sieves with Nanogating Channels for Reversible Molecular Separation

“…[ 1 ] Particularly, conventional MST toward the binary molecular mixtures with intrinsically similar molecular size and boiling points is a critical ongoing challenge. [ 2 ] The current separation technique mainly relies on the energy‐intense method involving repeated cryogenic distillation and extraction cycles, while the associated energy penalty urgently promotes interest in alternative energy‐saving separation methods. [ 3 ] Adsorption separation using the nanoporous molecular sieves is considered to be an appealing alternative due to the integrated advantages of mild energy consumption, ease of operation, and tiny carbon footprints.…”

“…[1] Particularly, conventional MST toward the binary molecular mixtures with intrinsically similar molecular size and boiling points is a critical ongoing challenge. [2] The current separation technique scales from 20 to 150 nm rather than sub-1nm scale (<1 nm), which result in catastrophic sieving performance toward subnanoscale molecule guests. [9] Moreover, restricted by the nonreversible pore-surface polarity, nanofibers are confronted with rigorously obstacles in gating molecular separation.…”

Al2O3 Dot and Antidot Array Synthesis in Hexagonally Packed Poly(styrene-block-methyl methacrylate) Nanometer-Thick Films for Nanostructure Fabrication

“… 8 − 11 The understanding of the basic mechanisms governing the process allowed expanding the list of materials that can be grown using this technique. In particular, the growth of several oxides, like Al 2 O 3 , TiO 2 , 12 ZnO, 12 − 15 WO x , 16 VO x , 12 In 2 O 3 , 17 , 18 Ga 2 O 3 , 18 and SnO 2 , 19 has been already reported in the literature for different applications, such as high-resolution hard masks, 20 − 25 nanoparticle coatings and decoration, 8 , 26 , 27 superhydrophobic coatings, 28 optical materials and antireflection coatings, 29 , 30 enhancer of the contrast and scattering of nanostructures, 24 , 31 , 32 3D superlattices, 33 oil sorbents, 34 UV and thermal protection, 14 tuning of mechanical propertries, 35 sensing applications, 15 membranes, 36 − 38 elastic energy-storage structures, 39 electrical devices, 13 , 17 , 40 , 41 and resistive switching devices. 42 In addition, SIS can be also exploited as a postlithography technique to improve the extreme ultraviolet patterning process.…”

Asymmetric Solvent‐Annealed Triblock Terpolymer Thick Films Topped by a Hexagonal Perforated Lamellar Nanostructure

“…7,8 Over the last decade, many efforts have been deployed to fabricate asymmetric and nanostructured BCP membranes devised with smart nanopores that can be potentially used to prevent the common problem of fouling. For instance, different external-stimuli responsive BCP membranes capable to adjust both the size and hydrophilic/hydrophobic character of their nanopores under changing environmental conditions (e.g., pH and temperature) have been manufactured by self-assembly and non-solvent induced phase separation (SNIPS), [8][9][10][11][12][13][14] which should allow facilitating the removal of foulants. 15 To extend this concept, the nanodesign of smart BCP membranes having double-stimuli responsive pores has also been demonstrated.…”