Highly permeable and selective membranes are desirable for energy-efficient gas and liquid separations.Microporous organic polymers have attracted significant attention in this respect owing to their high porosity, permeability, and molecular selectivity. However, it remains challenging to fabricate selective polymer membranes with controlled microporosity which are stable in solvents. Here we report a new approach to designing crosslinked, rigid polymer nanofilms with enhanced microporosity by manipulating the molecular structure. Ultra-thin polyarylate nanofilms with thickness down to 20 nm were formed in-situ by interfacial polymerisation. Enhanced microporosity and higher interconnectivity of intermolecular network voids, as rationalised by molecular simulations, are achieved by utilising contorted monomers for the interfacial polymerisation. Composite membranes comprising polyarylate nanofilms with enhanced microporosity fabricated in-situ on crosslinked polyimide ultrafiltration membranes show outstanding separation performance in organic solvents, with up to two orders of magnitude higher solvent permeance than membranes fabricated with nanofilms made from noncontorted planar monomers.Conventional gas and liquid separation processes such as evaporation and distillation are widely used in the oil and gas, energy, chemical, and pharmaceutical industries, but are energy-intensive. An alternative to these processes is membrane separation technology, which typically consumes an order of magnitude less energy. To enable wider deployment of membrane technology, highly permeable membranes are required to process large volumes of gas or solvent using a viable membrane area over a feasible timeframe 1-2 . There are two main strategies being followed to this end. One is to design the polymer structure at the molecular level so as to provide greater interconnected microporosity 3-10 , whilst a second approach is to reduce the thickness of the separating layer to nanometre scale [11][12][13][14][15][16] .Microporous organic materials with well-defined pore structure are excellent candidates for highly permeable and selective membranes 1 , such as metal-organic frameworks (MOFs) and porous coordination polymers (PCPs) [17][18] , covalent organic frameworks (COFs) [19][20] , and porous organic cages 2 (POCs) [21][22][23] . However, the fabrication of these crystalline solids to form defect-free membranes is technically challenging. Recent significant progress includes fabrication of MOFs to form selective membranes by secondary crystal growth 24 , assembly of MOF nanosheets 15 , interfacial synthesis 25 , or mixed matrix membranes 10,26 . By contrast, industrial membranes are dominated by solution processing of polymers and interfacial polymerisation, for example in producing polyamide desalination membranes. Notable examples of microporous polymers are polymers of intrinsic microporosity (PIMs) [6][7][27][28][29][30][31] . Owing to the shape and rigidity of the component monomers, the polymer chains have contorted, ri...

As synthesised ZIF-8 nanoparticles (size $ 60 nm and specific surface area $ 1300-1600 m 2 g À1 ) were directly incorporated into a model polymer matrix (MatrimidÒ 5218) by solution mixing. This produces flexible transparent membranes with excellent dispersion of nanoparticles (up to loadings of 30 wt%) with good adhesion within the polymer matrix, as confirmed by scanning electron microscopy, dynamic mechanical thermal analysis and gas sorption studies. Pure gas (H 2 , CO 2 , O 2 , N 2 and CH 4 ) permeation tests showed enhanced permeability of the mixed matrix membrane with negligible losses in selectivity. Positron annihilation lifetime spectroscopy (PALS) indicated that an increase in the free volume of the polymer with ZIF-8 loading together with the free diffusion of gas through the cages of ZIF-8 contributed to an increase in gas permeability of the composite membrane. The gas transport properties of the composite membranes were well predicted by a Maxwell model whilst the processing strategy reported can be extended to fabricate other polymer nanocomposite membranes intended for a wide range of emerging energy applications.

17Mixed Matrix Membranes (MMMs) for gas separation applications, have enhanced selectivity when 18 compared with the pure polymer matrix, but are commonly reported with low intrinsic permeability, 30The current default technology for large scale CO 2 capture and storage (CCS) is based on liquid 31 phase absorption towers; whilst many projects of this sort are proposed, few reach completion as 32 costs become prohibitive 3 . Therefore, it is imperative to offer more cost-effective technological 33 solutions. Membrane separation is often considered; however, current commercial membrane 34 technologies are virtually as expensive as adsorption technologies. This is because gas fluxes 35 through selective membranes are so low that hundreds of millions of m 2 of commercial membranes 36 are required even for a single 1000MW power station 5 . When combined with membrane costs of 37 ~$50/m 2 , the capital cost for commercial membrane based solutions to CCS is not that different 38 from the unpalatably high costs of adsorption towers for CCS. The key to a future membrane based 39 2 CCS solution lies in significantly reducing the total membrane areas required, which in turn 40 requires cheap, higher permeability membrane materials that retain a high selectivity. New research 41 is aimed at developing better performance polymers (in selectivity and permeability); however the 42 timelines for reducing costs of such polymers may not be compatible with needs to find immediate 43 candidate materials for large scale membrane based CCS solutions. 44Typically, commercial membrane materials have low permeability of a few tens of Barrers 45(1 Barrer = 10 10 cm 3 (STP) cm cm 2 s 1 cmHg 1 ), but have acceptable selectivity for CO 2 removal 46 from flue-stack or natural gas sources. Merkel and co-workers 5 have shown it is imperative to 47 generate materials with orders-of-magnitude enhanced permeability whilst maintaining such 48 selectivity, to cost-effectively process the massive volumes of flue gas in power plants. 49 Microporous materials used for membrane technology potentially include inorganic and organic 50 frameworks, such as zeolites 7 , metal-organic frameworks (MOFs) 8 and covalent organic 51 frameworks 9 . However, commercial membranes units contain thin films of the selective material 52 where practical processability and physical durability requirements tend to favor the use of tough 53 polymeric thin films. Gas transport in most polymers can be explained with the solution diffusion 54 model, where the permeability coefficient (P) is a product of solubility (S) and diffusion coefficient 5510 . Polymers of Intrinsic Microporosity (PIMs) 11,12 , are a sub-class of microporous polymers 56 with a rigid, contorted backbone structure (for example, PIM-1 in Figure 1) and high intrinsic 57 permeabilities (e.g. P CO2 ~ 3000 Barrer), but with low selectivity compared to commercial polymers 58 (30-50 for CO 2 /N 2 separations) 13 . Thermal and other post-processing of PIM-1 and other polymers 59 such as TR-polymers 14 leads ...

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Organic open frameworks with well-defined micropore (pore dimensions below 2 nm) structure are attractive next-generation materials for gas sorption, storage, catalysis and molecular level separations. Polymers of intrinsic microporosity (PIMs) represent a paradigm shift in conceptualizing molecular sieves from conventional ordered frameworks to disordered frameworks with heterogeneous distributions of microporosity. PIMs contain interconnected regions of micropores with high gas permeability but with a level of heterogeneity that compromises their molecular selectivity. Here we report controllable thermal oxidative crosslinking of PIMs by heat treatment in the presence of trace amounts of oxygen. The resulting covalently crosslinked networks are thermally and chemically stable, mechanically flexible and have remarkable selectivity at permeability that is three orders of magnitude higher than commercial polymeric membranes. This study demonstrates that controlled thermochemical reactions can delicately tune the topological structure of channels and pores within microporous polymers and their molecular sieving properties.

Membranes with fast and selective ion transport are widely used for water purification and devices for energy conversion and storage including fuel cells, redox flow batteries, and electrochemical reactors.However, it remains challenging to design cost-effective, easily processed ion-conductive membranes with well-defined pore architectures. Here, we report a new approach to designing membranes with narrow molecular-sized channels and hydrophilic functionality that enable fast transport of salt ions and high sizeexclusion selectivity towards small organic molecules. These membranes, based on polymers of intrinsic microporosity (PIMs) containing Tröger's base or amidoxime groups, demonstrate that exquisite control over subnanometer pore structure, the introduction of hydrophilic functional groups, and thickness control all play important roles in achieving fast ion transport combined with high molecular selectivity. These membranes enable aqueous organic flow batteries with high energy efficiency and high capacity retention, suggesting their utility for a variety of energy-related devices and water purification processes.In addition to conventional membrane separation processes 1, 2 , there is a rapidly growing demand for iontransport membranes in applications related to energy 1-3 . With greater reliance on renewable but intermittent energy sources such as solar and wind power, energy conversion and storage technologies are required to integrate low-carbon energy into the power grid. These include electrochemical water splitting and electrolysis for H 2 production 4 , proton-exchange membrane (PEMs) and alkaline fuel cells for energy conversion 5 , electrochemical reduction of CO 2 and N 2 to fuel and chemicals 6 , and scalable redox flow batteries (RFBs) 3,7 . In all of these established and emerging electrochemical processes, ion-selective membranes transport ions whilst isolating the electrochemical reactions in separate cells. In the new generation of RFBs 8-14 , low-cost and high-performance membranes need to have precise selectivity between ions and organic redox-active molecules [15][16][17][18] .Whilst various new electrochemical processes have been developed, the use of expensive commercial ion-exchange membranes, such as the poly(perfluorosulfonic acid) (PFSA)-based Nafion Council through grant agreement number 758370 (ERC-StG-PE5-CoMMaD). Q.S. acknowledges the financial support by Imperial College Department of Chemical Engineering Start-up Fund, seed-funding grant from Institute of Molecular Science and Engineering (IMSE, Imperial College) and seed-funding from EPSRC centres CAM-IES and Energy SuperStore (UK Energy Storage Research Hub). R.T. acknowledges a full PhD scholarship funded by China Scholarship Council. A.W. acknowledges a full PhD scholarship funded by Department of Chemical Engineering at Imperial College. B.P.D. acknowledges the Statoil scholarship. K.E.J. acknowledge the Royal Society University Research Fellowship. A.I.C. and L.C. acknowledge the Leverhulme Trust for supporting the Lev...

Chemical-looping combustion of biomass was carried out in a 10 kW th reactor with iron oxide as an oxygen carrier. A total 30 h of test was achieved with the same batch of iron oxide oxygen carrier. The effect of the fuel reactor temperature on gas composition of the fuel reactor and the air reactor, the proportion of biomass carbon reacting in the fuel reactor, and the conversion of biomass carbon to CO 2 in the fuel reactor was experimentally investigated. The results showed that the CO production from biomass gasification with CO 2 was more temperature dependent than the CO oxidation with iron oxide in the fuel reactor, and an increase in the fuel reactor temperature produced a higher increase for the CO production from biomass gasification than for the oxidation of CO by iron oxide. Although the conversion of biomass carbon to CO 2 in the fuel reactor decreased with the increase of the fuel reactor temperature, there was a substantial increase in the proportion of biomass carbon reacting in the fuel reactor. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to characterize fresh and reacted oxygen carrier particles. The results showed that the transformation of Fe 2 O 3 to Fe 3 O 4 is the favored step in the process of iron oxide reduction with biomass syngas. The low reactivity of reacted oxygen carrier was mainly ascribed to the sintering grains on the particle surface. To restrain the surface sintering of oxygen carrier particles, an intensive oxidization of reduced oxygen carrier with air in the air reactor should be avoided in the process of oxygen carrier regeneration, and air staging should be adopted for the oxidization of reduced oxygen carrier with air in the air reactor.

In recent years, organometal halide perovskite materials have attracted significant research interest in the field of optoelectronics. Here, we introduce a simple and low-temperature route for the formation of self-assembled perovskite nanocrystals in a solid organic matrix. We demonstrate that the size and photoluminescence peak of the perovskite nanocrystals can be tuned by varying the concentration of perovskite in the matrix material. The physical origin of the blue shift of the perovskite nanocrystals’ emission compared to its bulk phase is also discussed.