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The long‐acting sustained‐release of active molecules is of great importance in chemical production, food preservative, drug delivery in vivo, and so on. However, the problems of initial‐burst release and short release time (dominated by Fick's lows) commonly exist in sustained‐release materials. Herein, we designed and fabricated two types of film materials to achieve slow, continuous, and long‐term release of small molecules using methyl orange (MO) as a target release substance. B‐MO@polymer films were obtained by embedding MO into polylactic acid/polyethylene glycol (PLA/PEG) substrate and then assembling a layered double hydroxide (LDH)/carboxymethyl chitosan (CMC) barrier layer on the substrate surface. Another type of film (LDH&MO@polymer) was prepared by blending LDH and MO into the PLA/PEG polymer matrix. These films show high loading capacities of ~500 μg/cm2 for MO and display long‐acting sustained‐release property arising from the barrier effect of LDH nano‐brick. Specifically, for the B‐MO@polymer film, the release time of 50% MO is 10 days and the release time of 80% MO can be extended to 30 days. Ultimately, the time for complete release (>96%) reaches over 60 days. By using LDH‐embedded polymer as carriers for active molecules, the zero‐order release of MO was realized for LDH&MO@polymer films, achieving sustained release within as long as 145 days. This work provides a new paradigm to achieve the long‐acting sustained‐release of active molecules through the barrier effect of 2D nano‐bricks. Highlight: Two types of films were obtained to achieve long‐term release of small molecules.The films show high loading capacities for active molecules.The long‐acting property is derived from the barrier effect of 2D nano‐brick.The films can be produced in a large scale and have good application prospects. [ABSTRACT FROM AUTHOR]

The use of two‐dimensional materials shows great promise for the development of next‐generation membrane materials, thanks to their atomic thinness and the ease with which precise nanochannels can be constructed. Among these materials, layered double hydroxides (LDHs) stand out as an important class, possessing many features that make them ideal for constructing high‐performance membranes. LDHs offer many advantages, such as their abundant and tunable interlayer anions, which enable the preparation of membranes with adjustable sub‐nanometer pore sizes. Additionally, their hydrophilicity and positive charge characteristics afford them unique benefits. LDHs have been found to be effective in gas separation, ion sieving, and nanofiltration. This review provides a summary of the latest progress in using LDHs for membrane separation. It begins by introducing the basic properties of LDHs, followed by the assembly strategy for LDH membranes. Furthermore, the review presents the research status of LDHs membranes in various fields in a systematic manner. Lastly, the paper highlights some challenges and future prospects for preparing and applying LDHs membranes. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) membranes have demonstrated potential for molecular separation; however, their applicability for Li/Mg ion separation has been restricted by their negatively‐charged and easily‐swellable properties in water. Moreover, their practical application has been hindered by the challenge of producing significant quantities of single‐layer nanosheets. To overcome these challenges, we have developed a scalable method for synthesizing micro‐sized nitrate ZnAl layered double hydroxide (LDH) and subsequent exfoliating to yield monolayer nanosheets for the construction of 2D membranes. The sub‐nanometer channels of the LDH membrane is positively charged, which prevents the passage of magnesium ions. These channels also impede the flow of magnesium ions that are more difficult to dehydrate. As a result, the LDH membranes exhibit robust lithium–magnesium separation ability, with a separation ratio of 6 (Li/Mg). This work provides a method for producing high‐quality LDH nanosheets and validates the enormous potential of LDH membranes in the field of lithium–magnesium separation. [ABSTRACT FROM AUTHOR]

Membranes with precise molecular sieving channels that break the permeability‐selectivity trade‐off are desirable for energy‐efficient gas separation. Two‐dimensional (2D) membranes sieve gas through their special interlayer channels between neighboring nanosheets. However, the regulation and precise control of the nanochannels that match well with the size of the gas molecules remains a big challenge. Herein, accurate tuning of the interlayer spacing of layered double hydroxide (LDH) membranes at sub‐nanometer level was achieved by intercalation of Cl−, Br−, I−, and NO3− ions. Such high‐precision control allows customizable gas separation by selecting specific LDH membranes with appropriate channels according to the size of the gas molecules. Two membranes were used for demonstration: Cl‐LDH membrane shows high H2 permeance of ∼1870 GPU and desirable selectivities for H2/CO2(81), H2/N2(197), H2/CH4(320), and H2/C3H8(603); while I‐LDH membrane displays CO2 permeance of ∼1780 GPU and CO2/N2, CO2/CH4 selectivities of 182 and 297, respectively. The simultaneously high permeabilities and selectivities surpass the 2008 Robeson upper bounds. Molecular dynamics simulations quantitatively support the experiment results, further confirming the significant role of interlayer anions in the regulation of gas‐sieving channels. Given the rich variability of layered spacing and interlayer microenvironment for LDH materials, this work provides a platform membrane for various molecular sieving, including gas separation, solvent purification, seawater desalination, and so on. [ABSTRACT FROM AUTHOR]

Tailored design of high‐performance nanofiltration membranes that can be used in a variety of applications such as water desalination, resource recovery, and sewage treatment is desirable. Herein, we describe the use of layered double hydroxides (LDH) intermediate layer to control the interfacial polymerization between trimesoyl chloride (TMC) and piperazine (PIP) for the preparation of polyamide (PA) membrane. The dense surface of LDH layer and its unique mass transfer behavior influence the diffusion of PIP, and the supporting role of the LDH layer allows the formation of ultrathin PA membranes. By only changing the concentration of PIP, a series of membranes with controllable thickness from 10 to 50 nm and tunable crosslinking‐degree can be prepared. The membrane prepared with a higher concentration of PIP shows excellent performance for divalent salt retention with water permeance of 28 Lm−2 h−1 bar−1, high rejection of 95.1 % for MgCl2 and 97.1 % for Na2SO4. While the membrane obtained with a lower concentration of PIP can sieve dye molecules of different sizes with a flux of up to 70 Lm−2 h−1 bar−1. This work demonstrates a novel strategy for the controllable preparation of high‐performance nanofiltration membranes and provides new insights into how the intermediate layer affects the IP reaction and the final separation performance. [ABSTRACT FROM AUTHOR]