Low-porosity Materials Research Articles

Assessment and modeling of mercury adsorption on carbon-based adsorbents prepared from Jacaranda mimosifolia and guava biomass via pyrolysis and hydrothermal carbonization

Abstract The mercury adsorption properties of carbon-based materials prepared from jacaranda (Jacaranda mimosifolia) and guava (Psidium guajava) seed wastes are reported and compared in this paper. These adsorbent samples were obtained via pyrolysis and hydrothermal carbonization. Mercury adsorption equilibrium was studied at pH 4 and 20–40 °C, and the adsorption enthalpy changes were calculated for all adsorbent samples. The results showed that jacaranda-based materials contained a higher amount of acidic functional groups than guava seed-based adsorbents, and consequently, their mercury adsorption properties were better. The surface area of these adsorbents was <10 m2/g thus being classified as low-porosity materials. Elemental analysis indicated that all adsorbents were mainly composed of oxygen (4–25%) and carbon (75–95%). The calculated adsorption capacities at saturation of the best adsorbent were 18.05–30.09 mg/g under the tested experimental conditions. Statistical physics calculations also indicated that the adsorption mechanism of HgCl2 species was multi-molecular and endothermic. Ligand exchange and van der Waals forces were involved in generating the mercury–adsorbent interface. These results highlight the importance of comparing and optimizing biomass thermochemical conversion routes to tailor the surface properties of adsorbents used for water purification.

Effect of ultrasound on mass transfer during vacuum impregnation and selected quality parameters of products: A case study of carrots

Many unit operations in the food industry are diffusional driven. These processes are usually very slow and difficult to handle for specific groups of raw materials. Vacuum impregnation (VI) is one example. Impregnating low-porous or densely-structured materials is problematic and often requires low pressure, which can negatively affect product quality and be expensive in energy consumption. This research aimed to evaluate ultrasound (US) as a factor in intensifying mass transfer and enhancing its effectiveness in the VI process. Experiments on impregnation enhanced with ultrasound applied at different stages of the process were carried out. Carrot, a difficult-to-process raw material, was impregnated with ascorbic acid as a mass transfer marker. The process’s effectiveness and selected quality parameters were then analyzed. Ultrasound was found to have a positive influence on mass transfer during VI. The effects of ultrasound enhancement were different for particular processes, and depended on the stage of the application and duration of US exposure. The greatest increase in the tissue’s ascorbic acid content (60% compared to the non-ultrasound-assisted process) was observed when ultrasound was applied continuously throughout the process. Applying ultrasound only during the relaxation (at atmospheric pressure) or aeration periods resulted in a similar effect – c.a. 20% increase in the marker’s content. The smallest increase (10%) was observed when ultrasound was applied only during the vacuum period. Applying US did not result in any unfavorable color change. In most cases, pH decreased, which is favorable for the semi-product’s stability. The carotenoid and phenolic compounds’ content did not decrease. The results unequivocally indicate that ultrasound has great potential for use as a mass transfer accelerator in the VI process for low porosity materials. The effectiveness of the US is influenced not only by pressure but also by exposure duration. The synergistic effect observed using ultrasound-enhanced impregnation throughout the process confirmed this hypothesis.

Estimation of the drying process in porous media using the parallel and series moisture transfer model

Moisture transfer is a very common phenomenon in a wide range of engineering fields, such as civil engineering (cement-based constructions), food processing, mining and soil penetration, drying and imbibition of porous media (including phase change materials), etc. Based on the diffusion assumptions, the classical adopted model (especially for drying) is completed by the liquid permeation. However, it is still inadequate to compromise the complexity of the porous structures. In this work, we propose a “parallel -series assumption” of moisture transferring pattern, comprising different forms of moisture presence and the coupling styles, achieved by an interpolation factor to cover all the possible contribution ratios of the two patterns. Experimentally, we perform the drying of low porosity material under two ambient conditions over 160 days on both local and global parameters, ie., relative humidity (RH) and mass loss (ML). In the simulation part, a nonlinear diffusion-drying model containing liquid permeation and vapor diffusion in the transfer mechanism is applied to estimate the drying process, and compared with the experiment data. Results show different tendency for the two cases of either the permeation dominating case or the no-dominating case. This approach also clarifies the transition from evaporation of weak permeability for vapor diffusivity (square root behavior) towards the linear and faster behavior, which is observed in more porous and permeable materials for the vapor diffusion.

Recent Insights into Low-Surface-Area Catalysts for Hydrogen Production from Ammonia

A potential method of storing and transporting hydrogen safely in a cost-effective and practical way involves the utilization of molecules that contain hydrogen in their structure such as ammonia. Because of its high hydrogen content and carbon-free molecular structure, as well as the maturity of related technology (easy liquefaction), ammonia has gained attention as a “hydrogen carrier” for the generation of energy. Unfortunately, hydrogen production from ammonia requires an efficient catalyst to achieve high conversion at low reaction temperatures. Recently, very attractive results have been obtained with low-surface-area materials. This review paper is focused on summarizing and comparing recent advances in novel, economic and active catalysts for this reaction, paying particular attention to materials with low surface area such as silicon carbide (SiC) and perovskites (ABO3 structure). The effects of the supports, the active phase and the addition of promoters in such low-porosity materials have been analyzed in detail. Advances in adequate catalytic systems (including support and active metal) benefit the perspective of ammonia as a hydrogen carrier for the decarbonization of the energy sector and accelerate the “hydrogen economy”.

Buriti biomass as catalysts based on activated carbon/Fe3O4 for ciprofloxacin removal by heterogeneous photo-Fenton process

In this study, activated carbon (AC) from Buriti biomass decorated with magnetite (Fe3O4) nanoparticles was produced as a new material to be applied in ciprofloxacin (CIP) removal using photo-Fenton-based process. All materials (identified as AC1, AC3 e AC4) were initially carbonized with H2SO4 at 100 °C for 24 h in an activating agent/biomass ratio of 0.85. Subsequently, AC3 and AC4 materials suffered a new heat treatment at 300 °C (AC3) and 400 °C (AC4) respectively, resulting in materials of low porosity. The Fe3O4 nanoparticles were produced by co-precipitation method and the catalysts were identified as AC1/F, AC3/F and AC4/F. The materials were characterized by TGA-DSC, MEV-EDS, porosimeter, FT-IR and point of zero charge (pHPZC). To evaluate the catalytic performance of the ACs/F in the removal of CIP as an emerging pollutant, a study using heterogeneous photo-Fenton process at pH 2.0, 7.0 and 10 was performed. It was found that the AC4/F catalyst at pH 2.0 was the most efficient material, achieving 100 % of CIP removal, monitored by UV–Vis. The pathway mechanism observed seems to be highly dependent on the greater interaction capacity of H2O2 and less dependent on the CIP adsorption with the hybrid surface catalyst, i.e. AC and Fe3O4. The total organic carbon (TOC) study for the AC4/F catalyst at pH 2.0 showed 71.8 % of CIP mineralization and residual iron content below the levels set by the Brazilian Environmental Legislation (15 mg L−1).

Radar Derived Subglacial Properties and Landforms Beneath Rutford Ice Stream, West Antarctica

AbstractBasal properties beneath ice streams and glaciers are known to be a control for ice flow dynamics, hence knowledge of them is crucial for predicting sea level due to changes in glacial dynamics. Basal properties, processes and topography also drive the formation of subglacial landforms. Bed properties beneath Rutford Ice Stream (West Antarctica) have previously been described using seismic acoustic impedance measurements at a sparse spatial coverage. Here, we derive bed properties in a 15 × 17 km grid of surface radar data with coverage and sampling much higher than previous seismic studies. Bed reflection amplitudes in surface radar data were calibrated using sediment porosities (ranging from 0.4–0.5) derived from seismic acoustic impedance. We find the bed properties are spatially variable, consisting of low porosity material in some areas and soft sediment in other areas. Comparison of seismic and surface radar data imply the low porosity material to be a consolidated sediment or sedimentary rock. Mega‐scale glacial lineations (MSGLs) are ubiquitous on the bed and consist of soft, high porosity, probably deforming sediment, consistent with previous interpretations of MSGLs. We find some MSGLs have high reflectivity on their crest, interpreted as water bodies overlying high porosity sediment, whereas the trough around and the upstream end of some landforms consist of low porosity material. Integrating these different observations, we place constraints on possible explanations for the occurrence of water on the crest of landforms.

Sustainable Development of Hot-Pressed All-Lignocellulose Composites-Comparing Wood Fibers and Nanofibers.

Low-porosity materials based on hot-pressed wood fibers or nanocellulose fibrils (no polymer matrix) represent a new concept for eco-friendly materials with interesting mechanical properties. For the replacement of fossil-based materials, physical properties of wood fiber materials need to be improved. In addition, the carbon footprint and cumulative energy required to produce the material also needs to be reduced compared with fossil-based composites, e.g., glass fiber composites. Lignin-containing fibers and nanofibers are of high yield and special interest for development of more sustainable materials technologies. The present mini-review provides a short analysis of the potential. Different extraction routes of lignin-containing wood fibers are discussed, different processing methods, and the properties of resulting fiber materials. Comparisons are made with analogous lignin-containing nanofiber materials, where mechanical properties and eco-indicators are emphasized. Higher lignin content may promote eco-friendly attributes and improve interfiber or interfibril bonding in fiber materials, for improved mechanical performance.

Fretting Wear and Scratch Resistance of Cold-Sprayed Pure Cu and Ti

The paper analyses the fretting and wear behavior of pure copper and pure titanium coatings realized through cold spray. The coatings were designed and produced by employing processing conditions leading to minimum porosity and high hardness; these conditions were 700 °C and 40 bar for Ti powders and 400 °C and 30 bar for Cu ones. The low porosity and high strength materials led to high resistance to wear damaging through the optimal energy dissipation upon fretting. Due to the sprayed particles deformation mode, the sprayed materials show non-uniform hardening along the deposition distance. As a matter of fact, hardness varied in the range 3.7–4.2 GPa for Ti coatings and 1.5–2 GPa for the Cu ones depending on the distance from the substrate and on the coatings thickness. This influenced the materials properties and the response to the wear damaging. This was demonstrated by the scratch tests performed on coatings with different thicknesses. Those coatings sprayed in major thickness revealed the best wear resistance due to the deformation hardening. The harder coatings also revealed brittle fracture at the experienced highest loads.

Eco-Friendly High-Strength Composites Based on Hot-Pressed Lignocellulose Microfibrils or Fibers

Unbleached lignocellulosic wood fiber materials of low porosity are of great interest as eco-friendly load-bearing materials because their yield is much higher than that for “pure” wood cellulosics. The difference between comparable materials based on lignocellulose fibers or nanocellulose is investigated. The structure, surface area, mechanical properties, moisture sorption, and optical properties of films based on fibers or microfibrillated lignocellulose (MFLC) were characterized as a function of lignin content, and the environmental impact was compared. The modulus and tensile strength of comparable fiber and MFLC films (≈25% porosity) increased up to an optimum lignin content (11–17%) and then decreased at a very high lignin content. Hot-pressed MFLC films with little porosity showed excellent properties, 230–260 MPa strength, 17–20 GPa modulus, and 81 MPa wet strength. The mechanical property values of hot-pressed wood fibers with 25% porosity were also as high as 154 MPa strength and 13.2 GPa modulus, which are higher than those of comparable materials reported in the literature. Because hot-pressed lignocellulose fibers can be readily recycled and show low cumulative energy demand, they are candidates for semistructural engineering materials. MFLC is of great interest for coatings, films, adhesives, and as additives or in high-technology applications.

Effects of Energy Parameters on Dimensional Accuracy When Joining Stainless-Steel Powders with Heterogeneous Metal Substrates

This work presents some breakthroughs for obtaining high dimensional accuracy and reliable geometrical tolerance in the joining of stainless-steel powders with heterogeneous substrates. In the laser melting process, the interfacial energy fractions and forces acting at the solid–liquid surface of the melting powders can effectively vary their geometrical shapes and positions before they turn into the liquid phase. When the interfacial free energy is low, the melting powders are near molten, thus the successive volumetric changes can alter the layered geometry and positions. This assumption was validated by a powder-bedding additive manufacturing process to consolidate stainless-steel 316L powders (SLM 316L) on a thin heterogeneous stainless-steel substrate. Experiments were carried out to reveal the effects of the process parameters, such as laser power (100–200 W), exposure duration (50–100 µs) and point distance (35–70 µm) on the resulting material density and porosity and the corresponding dimensional variations. A fractional factorial design of experiment was proposed and the results of which were analyzed statistically using analysis of variances (ANOVA) to identify the influence of each operating factor. High energy densities are required to achieve materials of high density (7.71 g/cm3) or low porosity (3.15%), whereas low energy densities are preferable when the objective is dimensional accuracy (0.016 mm). Thermally induced deflections (~0.108 mm) in the heterogeneous metal substrate were analyzed using curvature plots. Thermally induced deformations can be attributed to volumetric energy density, scanning strategy, and the lay-up orientation. The parametric optimizations for increasing in dimensional accuracy (Z1: ~0.105 mm), or in material density (~7.71 g/cm3) were proven with high conversion rates of 88.2% and 96.4%, respectively, in validation runs.

Effect of WC-Ni Powder Composition and Preparation on Cold Spray Performance

Toxic metal reduction is at the forefront of many design considerations today; additive manufacturing has the ability to combine materials in ways other traditional processes cannot and has the potential to offer unique solutions to reduce hazardous materials needed in manufacturing. Tungsten carbide (WC) has been used as a substitute in wear applications where toxic processes are traditionally utilized, but it can be difficult to deposit high-quality, hard and durable coatings. Additionally, there is a need to apply WC coatings on surfaces not feasible with the current processes. Cold spray, a solid-state directed powder deposition process, is effective at depositing carbides, though powders must be thoughtfully designed to achieve desired mechanical properties. In this study, WC was investigated as a hard chrome alternative for wear applications. Various blend ratios and preparation methods were evaluated as feedstock powder and then sprayed. Feedstock characteristics were compared to cold spray performance. Cold spray consolidations were evaluated for coating porosity and hardness. It was found that when powder make-up and composition were optimized, a high-hardness and low-porosity material was made that will contribute to the reduction in dependency of Cr in wear-facing components.

Quasi-brittle porous material: Simulated effect of stochastic air void structure on compressive strength

The effect of porosity comprised of spherical air voids on the compressive strength of quasi-brittle material was studied via simulations. The simulated porous structures were based on pore size distributions of two mortar samples measured by X-ray microtomography. While the simulation method set practical limits on the size of sample, the base of the statistics was established by simulating 128 small structures generated by sampling from pore structures of two mortars. By studying the application of the classical strength-porosity formulas to the simulated data, a new simple model was formed. A linear relationship was achieved between the cubic root of air void fraction (porosity) and the simulated compressive strength. The reasons for scattering of simulated strength around fitted trend remained unresolved in this study; no clear dependence on pore number or other distribution properties was observed. With the presented simulation approach, the dependence of compressive strength on porosity is achieved independently of disturbances that occur in experimental studies creating understanding of compressional behavior of low porosity materials.

Structural and chemical heterogeneity in ancient glass probed using gas overcondensation, X-ray tomography, and solid-state NMR

Rare ancient glasses have complex, multi-scale structures requiring more sophisticated and non-destructive pore characterisation techniques than usual. Homotattic patch models for nitrogen adsorption gave better fits to the isotherm data, more accurate void space descriptors, and also greater understanding of the underlying physical factors affecting adsorption, than standard BET. These homotattic patch models revealed the critical role of iron impurities in determining adsorption behaviour. Non-destructive sodium-23 NMR relaxometry validated the homotattic patch model for some natron glasses, and, in turn, was validated using multiple quantum magic-angle spinning (MQMAS) 23Na NMR. X-ray tomography images of the glasses showed the presence of large macroporous bubbles, while FEG-SEM revealed nanopores within the glass matrix. A newly-developed, gas overcondensation technique, suitable for small amounts of low porosity material, assessed the inter-relationship between the disparate levels in this hierarchical porosity. This technique demonstrated that the nanoporosity did not form a ‘corona’ around the bubbles, due to leaching from the glass, as initially supposed from tomography data, but was completely disconnected, and, thus, is probably associated with glass alkalinity. Gas overcondensation is demonstrated as a non-destructive alternative to mercury porosimetry for probing multi-scale porosity in rare artefacts.

Numerical simulation of transpiration cooling experiments in supersonic flow using OpenFOAM

Transpiration cooling applied to modern ceramic matrix composite materials is an interesting concept for thermal protection of future aerospace applications. Therefore, reliable and accurate numerical tools for the simulation of transpiration cooling processes in complex flow situations and for complex porous geometries are needed. In this study, we present a fully coupled OpenFOAM solver and discuss the choice of suitable interface conditions as well as the coupling of numerical domains at the transpired surface. Additionally, a modified turbulence boundary condition for transpiration through low-porosity materials is proposed. The numerical solver is then applied to validation test cases with a flat and a double-wedge porous sample under blowing ratios up to $$F_{\text{Air}} = 0.75\%$$. The corresponding experiments with Carbon/Carbon samples were performed at the ITLR Hot Gas Facility at supersonic steady-state conditions, i.e. $${\text{Ma}} = 2.5$$ and $$T_{t} = 500\;{\text{K}}$$. The simulation results are in good overall agreement with the experimental data for both test cases while capturing the influences of blowing ratio, as well as variations of the external flow field and in the heat flux distribution. Temperature predictions for the sample surface, within the porous wall, and in the downstream wake region show a good conformity to measurements, whereas deviations are observed in the direct wake. Based on the complementary insights provided by the numerical results, aspects such as the coolant through-flow behaviour as well as the sample’s internal temperature distribution and heat conduction are analysed.

New engineered stones: Development and characterization of mineral-glass composites

Engineered stones are high-end materials increasingly being used as kitchen countertops, floor and facade tiles, as well as in other architectural applications. These materials consist of approximately 70–95 wt% of mineral particles (usually quartz) dispersed in a matrix made of cement, ceramics or, much more often, polymer resins. Despite their very attractive aesthetic appeal, using polymer matrices is associated to low wear resistance, low chemical resistance and degradation by UV radiation or by contact with hot objects; therefore the use of a glass matrix can overcome some of these disadvantages. This paper addresses the development, optimization of compositions and thermal treatment of a novel type of composite - engineered stones - using recycled window glass and four distinct minerals. New glass-mineral composites were developed containing up to 70% weight of albite, alumina, petalite or quartz (the rest being window glass). The materials were characterized for their flexural strength, hardness, water absorption, thermal shock resistance and chemical durability. Except for the Quartz/glass composites, low-porosity materials (<10%) with competitive properties if compared to commercial products were obtained. For instance, an Alumina/glass composite showed a (4-point) flexural strength of approximately 115 MPa and a hardness of 9 GPa, whereas commercial products (polymer and ceramic matrix) showed average values of 10 MPa and 70 GPa, respectively. The Petalite/glass composite exhibited high thermal shock resistance (ΔTc ∼ 330 °C); whereas the Albite/glass composite showed very good chemical durability, with practically unchanged weight and visual aspect after coming into contact with both acidic and alkaline concentrated solutions. This new type of composite is thus very promising and warrants further study and development.

Numerical solution of Euler equations employing enthalpy-based equation of state for simulating shock wave propagation in porous materials

Shock wave propagation through porous materials is investigated using numerical simulations of one dimensional Euler equations of inviscid fluid flow, with the basic aim to demonstrate the application of the enthalpy-based equation of state. A one dimensional hydrodynamics solution method employing the flux-corrected transport algorithm, which does not make use of artificial viscosity, is used for all simulations. Benchmark results on the Sedov-von Neumann-Taylor blast wave problem are given thereby showing the capabilities of the algorithm for capturing strong shock profiles. Next, numerical results for plate impact problems are obtained for porous Cu, Al, Fe and W, and compared with experimental data available in the literature. It is shown that shock waves attenuate very fast even in materials of small size and low porosity. Excellent agreement is also found with experimental data on pressure versus particle velocity in the four target materials for different porosities. Thus the enthalpy-based approach, using a few experimental data of solids at normal conditions, is shown to be capable of quantitative prediction of shock wave parameters of porous materials. An accurate but simple approach for in-line calculation of the enthalpy parameters is discussed in the appendix together with numerical results.

Stress Concentration in Low-Porosity Periodic Tessellations With Generic Patterns of Elliptical Holes Under Biaxial Strain

Stress concentration in porous materials is one of the most crucial culprits of mechanical failure. This paper focuses on planar porous materials with porosity less than 5%. We present a stress-prediction model of an arbitrarily rotated elliptical hole in a rhombus shaped representative volume element (RVE) that can represent a class of generic planar tessellations, including rectangular, triangular, hexagonal, Kagome, and other patterns. The theoretical model allows the determination of peak stress and distribution of stress generated near the edge of elliptical holes for any arbitrary tiling under displacement loading and periodic boundary conditions. The results show that the alignment of the void with the principal directions minimizes stress concentration. Numerical simulations support the theoretical findings and suggest the observations remain valid for porosity as large as 5%. This work provides a fundamental understanding of stress concentration in low-porosity planar materials with insight that not only complements classical theories on the subject but also provides a practical reference for material design in mechanical, aerospace, and other industry.

A Finite Element Model to Predict the Effect of Porosity on Elastic Modulus in Low-Porosity Materials

The effect of porosity on elastic modulus in low-porosity materials is investigated. First, several models used to predict the reduction in elastic modulus due to porosity are compared with a compilation of experimental data to determine their ranges of validity and accuracy. The overlapping solid spheres model is found to be most accurate with the experimental data and valid between 3 and 10 pct porosity. Next, a FEM is developed with the objective of demonstrating that a macroscale plate with a center hole can be used to model the effect of microscale porosity on elastic modulus. The FEM agrees best with the overlapping solid spheres model and shows higher accuracy with experimental data than the overlapping solid spheres model.

3D-printing porosity: A new approach to creating elevated porosity materials and structures

We introduce a new process that enables the ability to 3D-print high porosity materials and structures by combining the newly introduced 3D-Painting process with traditional salt-leaching. The synthesis and resulting properties of three 3D-printable inks comprised of varying volume ratios (25:75, 50:50, 70:30) of CuSO4 salt and polylactide-co-glycolide (PLGA), as well as their as-printed and salt-leached counterparts, are discussed. The resulting materials are comprised entirely of PLGA (F-PLGA), but exhibit porosities proportional to the original CuSO4 content. The three distinct F-PLGA materials exhibit average porosities of 66.6–94.4%, elastic moduli of 112.6-2.7 MPa, and absorbency of 195.7–742.2%. Studies with adult human mesenchymal stem cells (hMSCs) demonstrated that elevated porosity substantially promotes cell adhesion, viability, and proliferation. F-PLGA can also act as carriers for weak, naturally or synthetically-derived hydrogels. Finally, we show that this process can be extended to other materials including graphene, metals, and ceramics. Statement of SignificancePorosity plays an essential role in the performance and function of biomaterials, tissue engineering, and clinical medicine. For the same material chemistry, the level of porosity can dictate if it is cell, tissue, or organ friendly; with low porosity materials being far less favorable than high porosity materials. Despite its importance, it has been difficult to create three-dimensionally printed structures that are comprised of materials that have extremely high levels of internal porosity yet are surgically friendly (able to handle and utilize during surgical operations). In this work, we extend a new materials-centric approach to 3D-printing, 3D-Painting, to 3D-printing structures made almost entirely out of water-soluble salt. The structures are then washed in a specific way that not only extracts the salt but causes the structures to increase in size. With the salt removed, the resulting medical polymer structures are almost entirely porous and contain very little solid material, but the maintain their 3D-printed form and are highly compatible with adult human stem cells, are mechanically robust enough to use in surgical manipulations, and can be filled with and act as carriers for biologically active liquids and gels. We can also extend this process to three-dimensionally printing other porous materials, such as graphene, metals, and even ceramics.

Fast and efficient synthesis of microporous polymer nanomembranes via light-induced click reaction.

Conjugated microporous polymers (CMPs) are materials of low density and high intrinsic porosity. This is due to the use of rigid building blocks consisting only of lightweight elements. These materials are usually stable up to temperatures of 400 °C and are chemically inert, since the networks are highly crosslinked via strong covalent bonds, making them ideal candidates for demanding applications in hostile environments. However, the high stability and chemical inertness pose problems in the processing of the CMP materials and their integration in functional devices. Especially the application of these materials for membrane separation has been limited due to their insoluble nature when synthesized as bulk material. To make full use of the beneficial properties of CMPs for membrane applications, their synthesis and functionalization on surfaces become increasingly important. In this respect, we recently introduced the solid liquid interfacial layer-by-layer (LbL) synthesis of CMP-nanomembranes via Cu catalyzed azide–alkyne cycloaddition (CuAAC). However, this process featured very long reaction times and limited scalability. Herein we present the synthesis of surface grown CMP thin films and nanomembranes via light induced thiol–yne click reaction. Using this reaction, we could greatly enhance the CMP nanomembrane synthesis and further broaden the variability of the LbL approach.