Synthesis and evaluation of N,O‐doped hypercrosslinked polymers and their performance in CO2 capture

A series of N, O‐doped hypercrosslinked microporous polymers (HCPs) with high surface area and rich microporosity were constructed via facile Friedel‐Crafts alkylation promoted by anhydrous ferric chloride (FeCl₃), which used benzyl alcohol (BA) and 2‐phenylimidazole (PID) as the basic building blocks. The effects of structural composition on the pore properties and gas adsorption properties of prepared HCPs were systematically investigated. The results show that by adjusting the ratio of PID to BA, the Brunauer–Emmett–Teller (BET) specific surface area and pore volume of the prepared HCPs can be controlled, and the BET specific surface area of the polymers range from 732–992 m²/g. Gas uptake experiments indicate that the obtained HCPs exhibit very high CO₂ adsorption capacity up to 3.55 mmol/g at 273 K/1.0 bar. Simultaneously, these N, O‐doped HCPs also show quite high isosteric heat of CO₂ sorption at the low coverage (up to 33 kJ/mol). In addition, the prepared HCPs have excellent selective adsorption performance, and the optimal selective adsorption of CO₂/N₂ is 62. These results demonstrate that these prepared HCPs are potential candidates for applications in CO₂ capture.     

Comparison of Gas Sorption Properties of Neutral and Anionic Metal–Organic Frameworks Prepared from the Same Building Blocks but in Different Solvent Systems

Two different 3D porous metal–organic frameworks, [Zn₄O(NTN)₂]?10 DMA?7 H₂O ( SNU‐150 ) and [Zn₅(NTN)₄(DEF)₂][NH₂(C₂H₅)₂]₂?8 DEF?6 H₂O ( SNU‐151 ), are synthesized from the same metal and organic building blocks but in different solvent systems, specifically, in the absence and the presence of a small amount of acid. SNU‐150 is a doubly interpenetrated neutral framework, whereas SNU‐151 is a non‐interpenetrated anionic framework containing diethylammonium cations in the pores. Comparisons of the N₂, H₂, CO₂, and CH₄ gas adsorption capacities as well as the CO₂ adsorption selectivity over N₂ and CH₄ in desolvated SNU‐150′ (BET: 1852 m² g^?1) and SNU‐151′ (BET: 1563 m² g^?1) samples demonstrate that the charged framework is superior to the neutral framework for gas storage and gas separation, despite its smaller surface area and different framework structure.     

Assembly of NaTaO3 porous microspheres via imperfect oriented attachment mechanism

Spongy-like NaTaO₃ mesoporous microspheres are assembled from nanoparticles via imperfect oriented attachment. Study shows that the NaTaO₃ spongy microspheres with the diameters of ～1 μm are composed of the fundamental building blocks of ～50 nm NaTaO₃ nanospheres. The high-resolution transmission electron microscopy further reveals that these fundamental building blocks are assembled from primary building blocks of ～10 nm NaTaO₃ nanocrystals. The pore diameters of these spongy microspheres are ca. 30 nm and the Brunauer–Emmett–Teller (BET) surface area is calculated to be 57.8 m² g^?1. This interesting ternary alkali metal composite oxide of NaTaO₃ spongy microspheres with high specific surface area and strong stability will be favorable for their practical application in photocatalysis. This synthesis route may throw light on the fabrication of the binary or ternary porous metal oxides by geometrical stacking of the nanobuilding blocks via imperfect oriented attachment.     

Tailor‐Made Metal–Organic Frameworks from Functionalized Molecular Building Blocks and Length‐Adjustable Organic Linkers by Stepwise Synthesis

In this work, we have demonstrated a family of diamondoid metal–organic frameworks (MOFs) based on functionalized molecular building blocks and length‐adjustable organic linkers by using a stepwise synthesis strategy. We have successfully achieved not only “design” and “control” to synthesize MOFs, but also the functionalization of both secondary building units (SBUs) and organic linkers in the same MOF for the first time. Furthermore, the results of N₂ and H₂ adsorption show that their surface areas and hydrogen uptake capacities are determined by the most optimal combination of functional groups from SBUs and organic linkers, interpenetration, and free volume in this system. A member of this series, DMOF‐6 exhibits the highest surface area and H₂ adsorption capacity among this family of MOFs.     

Studies on the removal of phosphate in water through adsorption using a novel Zn-MOF and its derived materials

A novel zinc-based metal–organic framework, {[Zn₃(atz)₂(pda)₂]·2(H₂O)}_n (Zn-MOF; Hatz is 5-aminote-1H-terazole; H₂pda is malonic acid), was prepared using the solvothermal method. Carbonization of the prepared Zn-MOF was conducted under elevated temperatures to investigate its phosphate adsorption performance. Through pre-adsorption experiments, the optimal carbonization temperature of 500 °C was determined, yielding Zn-MOF-500. Besides, multiple characterization methods were used to analyze the properties of Zn-MOF and Zn-MOF-500 materials before and after the adsorption of phosphate ions. The results showed that the BET surface area of Zn-MOF-500 was 18.57 m²/g, which was 16.37 times larger than that of the BET surface area of Zn-MOF. At 25 °C, Zn-MOF and Zn-MOF-500 exhibited an adsorption capacity of 123.44 and 226.07 mg/g, respectively. Based on the adsorption isotherms and the adsorption kinetics, the adsorption of PO₄^3- occurs via monolayer. X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS) analysis showed that P was adsorbed on Zn-MOF and Zn-MOF-500 as the zinc hydrogen phosphate and zinc phosphate ions, respectively.     

Tuning of Microenvironment in Covalent Organic Framework via Fluorination Strategy promotes Selective CO2 Capture

Herein, we have designed and synthesized two heteroatom (N, O) rich covalent organic frameworks (COF), PD-COF and TF-COF , respectively, to demonstrate their relative effect on CO₂ adsorption capacity and also CO₂/N₂ selectivity. Compared to the non-fluorinated PD-COF (BET surface area 805 m² g⁻¹, total pore volume 0.3647 ccg⁻¹), a decrease in BET surface area and also pore volume have been observed for fluorinated TF-COF due to the incorporation of fluorine to the porous framework (BET surface area 451 m² g⁻¹, total pore volume 0.2978 ccg⁻¹). This fact leads to an enormous decrease in the CO₂ adsorption capacity and CO₂/N₂ selectivity of TF-COF , though it shows stronger affinity towards CO₂ with a Qst of 37.76 KJ/mol. The more CO₂ adsorption capacity by PD-COF can be attributed to the large specific surface area with considerable amount of micropore volume compared to the TF-COF . Further, PD-COF exhibited CO₂/N₂ selectivity of 16.8, higher than that of TF-COF (CO₂/N₂ selectivity 13.4).     

Metal Microporous Aromatic Polymers with Improved Performance for Small Gas Storage

A novel metal‐doping strategy was developed for the construction of iron‐decorated microporous aromatic polymers with high small‐gas‐uptake capacities. Cost‐effective ferrocene‐functionalized microporous aromatic polymers (FMAPs) were constructed by a one‐step Friedel–Crafts reaction of ferrocene and s‐triazine monomers. The introduction of ferrocene endows the microporous polymers with a regular and homogenous dispersion of iron, which avoids the slow reunion that is usually encountered in previously reported metal‐doping procedures, permitting a strong interaction between the porous solid and guest gases. Compared to ferrocene‐free analogues, FMAP‐1, which has a moderate BET surface area, shows good gas‐adsorption capabilities for H₂ (1.75 wt % at 77 K/1.0 bar), CH₄ (5.5 wt % at 298 K/25.0 bar), and CO₂ (16.9 wt % at 273 K/1.0 bar), as well as a remarkably high ideal adsorbed solution theory CO₂/N₂ selectivity (107 v/v at 273 K/(0–1.0) bar), and high isosteric heats of adsorption of H₂ (16.9 kJ mol^?1) and CO₂ (41.6 kJ mol^?1).     

Hydrothermal synthesis and photocatalytic property of porous CuO hollow microspheres via PS latex as templates

Porous copper oxide (CuO) hollow microspheres have been fabricated through a simple hydrothermal method using PS latex as templates. The as-obtained samples were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). The influences of the mole ratio of Ethylenediamine (C₂H₈N₂) and copper acetate (Cu(Ac)₂·H₂O), hydrothermal temperature and time on the size and morphologies of the final products have been investigated. The possible formation mechanism of porous CuO hollow microspheres has been proposed and the specific surface area of the hollow microspheres with 81.71 m²/g is measured by BET method. The band gap value calculated from a UV–vis absorption spectrum of porous CuO hollow microspheres is 2.71 eV. The as-synthesized product exhibits high photocatalytic activity during the photodegradation of an organic dyestuff, rhodamine B (RhB), under UV-light illumination.     

Topotactic Synthesis of Phosphabenzene‐Functionalized Porous Organic Polymers: Efficient Ligands in CO2 Conversion

Progress toward the preparation of porous organic polymers (POPs) with task‐specific functionalities has been exceedingly slow—especially where polymers containing low‐oxidation phosphorus in the structure are concerned. A two‐step topotactic pathway for the preparation of phosphabenzene‐based POPs (Phos‐POPs) under metal‐free conditions is reported, without the use of unstable phosphorus‐based monomers. The synthetic route allows additional functionalities to be introduced into the porous polymer framework with ease. As an example, partially fluorinated Phos‐POPs (F‐Phos‐POPs) were obtained with a surface area of up to 591 m² g^?1. After coordination with Ru species, a Ru/F‐Phos‐POPs catalyst exhibited high catalytic efficiency in the formylation of amines (turnover frequency up to 204 h^?1) using a CO₂/H₂ mixture, in comparison with the non‐fluorinated analogue (43 h^?1) and a Au/TiO₂ heterogeneous catalysts reported previously (<44 h^?1). This work describes a practical method for synthesis of porous organic phosphorus‐based polymers with applications in transition‐metal‐based heterogeneous catalysis.     

Hypercrosslinking Polymers Fabricated from Divinyl Benzene via Friedel-Crafts Addition Polymerization

Microporous organic polymers with high surface area are widely used in many applications.Among them,hypercrosslinked polymers have been extensively concerned because of their simple processes and low-cost reagents.However,due to most state-of-the-art strategies for HCPs based on condensation reactions,the release of small molecules such as hydrochloric acid and methanol involved in such strategies brings about new hazards to environment.Herein,we propose a method of fabrication of hypercrosslinked polymers via self-addition polymerization of divinyl benzene and its crosslinking with polar aromatic molecules.The hypercrosslinked polyDVB-based products are demonstrated by FriedelCrafts addition reaction of double bonds on DVB that can connect adjacent phenyl rings of aromatic molecules to form the crosslinked networks.The HCPDVB-CB obtained in 1-chlorobutane as solvent has a high micropore content and displays high surface area up to 931 m²/g.Following this finding,DVB is used as a novel external crosslinker for knitting polar aromatic molecules.When L-phenylalanine and bisphenol A are used as the aromatic units,the obtained HCP(Phe-DVB)and HCP(BPA-DVB)could reach surface area of 612 and 471 m²/g,and have hydrogen uptake of0.62 wt%and 0.58 wt%at 77 K and 1.13 bar by comparison with HCPDVB-CB having hydrogen uptake of 0.30 wt%,respectively.     

Fine pore mouth structure of molecular sieve carbon with GCMC-assisted supercritical gas adsorption analysis

N₂ adsorption isotherms of molecular sieve carbon were measured at 77 K and 303 K. The Ar adsorption isotherms of molecular sieve carbon samples were also measured at 303 K. The grand canonical Monte Carlo (GCMC) simulation technique was applied to calculate the N₂ and Ar adsorption isotherms at 303 K using the ultramicropore volume determined by H₂O adsorption. The comparative method of experimental and simulated isotherms of supercritical N₂ and Ar at 303 K gave the width of the micropore mouth of the molecular sieve carbon, which can be applied to the ultramicropore width determination for other noncrystalline porous solids.     

A Series of Mesoporous Metal-Organic Frameworks with Tunable Windows Sizes and Exceptionally High Ethane over Ethylene Adsorption Selectivity

The NIIC-20 (NIIC stands for Nikolaev Institute of Inorganic Chemistry) is a family of five isostructural metal-organic frameworks (MOFs) based on dodecanuclear wheel-shaped carboxylate building blocks {Zn₁₂(RCOO)₁₂(glycol)₆} (glycol is deprotonated diatomic alcohol: ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol or glycerol), quantitatively crystallized from readily available starting chemicals. The crystal structures contain large mesoporous cages of 25 Å connected through {Zn₁₂} rings, of which inner diameter and chemical nature depend solely on the chosen glycol. The NIIC-20 compounds feature high surface area and rarely observed inversed adsorption affinity for saturated hydrocarbon (ethane) over the unsaturated ones (ethylene, acetylene). The corresponding IAST (Ideal Adsorbed Solution Theory) adsorption selectivity factors reach as much as 15.4 for C₂H₆/C₂H₄ and 10.9 for C₂H₆/C₂H₂ gas mixtures at ambient conditions, exceeding those for any other porous MOF reported so far. The remarkable combination of high adsorption uptakes and high adsorption selectivities makes the NIIC-20 series a new benchmark of porous materials designed for ethylene separation applications.     

Control of Interpenetration and Gas‐Sorption Properties of Metal–Organic Frameworks by a Simple Change in Ligand Design

In metal–organic framework (MOF) chemistry, interpenetration greatly affects the gas‐sorption properties. However, there is a lack of a systematic study on how to control the interpenetration and whether the interpenetration enhances gas uptake capacities or not. Herein, we report an example of interpenetration that is simply controlled by the presence of a carbon–carbon double or single bond in identical organic building blocks, and provide a comparison of gas‐sorption properties for these similar frameworks, which differ only in their degree of interpenetration. Noninterpenetrated ( SNU‐70 ) and doubly interpenetrated ( SNU‐71 ) cubic nets were prepared by a solvothermal reaction of [Zn(NO₃)₂] ? 6 H₂O in N,N‐diethylformamide (DEF) with 4‐(2‐carboxyvinyl)benzoic acid and 4‐(2‐carboxyethyl)benzoic acid, respectively. They have almost‐identical structures, but the noninterpenetrated framework has a much bigger pore size (ca. 9.0×9.0 Å) than the interpenetrated framework (ca. 2.5×2.5 Å). Activation of the MOFs by using supercritical CO₂ gave SNU‐70′ and SNU‐71′ . The simulation of the PXRD pattern of SNU‐71′ indicates the rearrangement of the interpenetrated networks on guest removal, which increases pore size. SNU‐70′ has a Brunauer–Emmett–Teller (BET) surface area of 5290 m² g^?1, which is the highest value reported to date for a MOF with a cubic‐net structure, whereas SNU‐71′ has a BET surface area of 1770 m² g^?1. In general, noninterpenetrated SNU‐70′ exhibits much higher gas‐adsorption capacities than interpenetrated SNU‐71′ at high pressures, regardless of the temperature. However, at P<1 atm, the gas‐adsorption capacities for N₂ at 77 K and CO₂ at 195 K are higher for noninterpenetrated SNU‐70′ than for interpenetrated SNU‐71′ , but the capacities for H₂ and CH₄ are the opposite; SNU‐71′ has higher uptake capacities than SNU‐70′ due to the higher isosteric heat of gas adsorption that results from the smaller pores. In particular, SNU‐70′ has exceptionally high H₂ and CO₂ uptake capacities. By using a post‐synthetic method, the C?C double bond in SNU‐70 was quantitatively brominated at room temperature, and the MOF still showed very high porosity (BET surface area of 2285 m² g^?1).     

A Simple Ni-based Metal–organic Framework as Catalyst for Dye-sensitized Photocatalytic H2 Evolution from Water Reduction

Metal–organic frameworks (MOF) are recently developed coordination porous materials, and their unique structures are very conducive to catalytic reactions. In this paper, p-benzenedicarboxylic acid (PBA)-Ni²⁺ MOF materials (denoted as PBA-Ni-x, where x represents the initial ratio of PBA to Ni²⁺) were synthesized by a hydrothermal method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and N₂ gas adsorption. H₂ gas was produced using the synthesized MOF as a photocatalyst and Eosin Y as a photosensitizer. The dependence of the special surface area and thickness of the nanosheets of Ni-MOF on the initial ratio of PBA to Ni²⁺ (PBA/Ni²⁺) was investigated. The BET surface areas of PBA-Ni-1 PBA-Ni-2 and PBA-Ni-3 are 11.00, 24.61 and 13.04 m² g⁻¹, respectively. And the thicknesses of nanosheets are approximately 600–1000, 200–500 and 300–700 nm. Among the three materials, PBA-Ni-2 has the thinnest sheet-like structure and largest surface area. Thus, it displays the highest H₂ evolution rate of 20.0 μmol h⁻¹. The noble-metal-free hydrogen production system is valuable for the application of MOF materials in photocatalytic water splitting.     

A Robust 3D Cage‐like Ultramicroporous Network Structure with High Gas‐Uptake Capacity

A three‐dimensional (3D) cage‐like organic network (3D‐CON) structure synthesized by the straightforward condensation of building blocks designed with gas adsorption properties is presented. The 3D‐CON can be prepared using an easy but powerful route, which is essential for commercial scale‐up. The resulting fused aromatic 3D‐CON exhibited a high Brunauer–Emmett–Teller (BET) specific surface area of up to 2247 m² g^?1. More importantly, the 3D‐CON displayed outstanding low pressure hydrogen (H₂, 2.64 wt %, 1.0 bar and 77 K), methane (CH₄, 2.4 wt %, 1.0 bar and 273 K), and carbon dioxide (CO₂, 26.7 wt %, 1.0 bar and 273 K) uptake with a high isosteric heat of adsorption (H₂, 8.10 kJ mol^?1; CH₄, 18.72 kJ mol^?1; CO₂, 31.87 kJ mol^?1). These values are among the best reported for organic networks with high thermal stability (ca. 600 °C).     

Synthesis of Porous,Hollow Metal MCO3 (M=Mn,Co, Ca) Microstructures and Adsorption Properties Thereof

Porous, hollow metal carbonate microstructures show many unique properties, and are attractive for various applications. Herein, we report the first demonstration of a general strategy to synthesize hollow metal carbonate structures, including porous MnCO₃ hollow cubics, porous CoCO₃ hollow rhombuses and porous CaCO₃ hollow capsules. For example, the porous, hollow MnCO₃ microcubes show larger Brunauer–Emmett–Teller (BET) surface areas of 359.5 m² g^?1, which is much larger than that of solid MnCO₃ microcubics (i.e., 12.03 m² g^?1). As a proof of concept, these porous MnCO₃ hollow microcubes were applied to water treatment and exhibited an excellent ability to remove organic pollutants in waste water owing to their hollow structure and large specific surface area.     

Metal ion-induced capacitance modulation in near-isostructural complexes-derived electrochromic coordination polymers

Coordination polymers and metal–organic frameworks have attracted immense attention across different fields of science as materials with numerous functional applications. Herein, we report the use of coordination polymers obtained from near-isostructural metal (Mn²⁺, Fe²⁺, and Co²⁺) bipyridine complexes as electrode materials in a symmetric supercapacitor test cell. The variation in the central metal ion (Mn²⁺ vs. Fe²⁺ vs. Co²⁺) in these nearly identical coordination complexes was found to dictate the capacitive performance of the coordination polymers obtained via Pd(II) cross-linking. The central metal ion not only influences the porosity, Brunauer–Emmett–Teller (BET) surface area (6.5 (Mn), 10.4 (Fe), and 29.7 (Co) m²/g), and the areal capacitance, but also the performance parameters such as the cycling stability and charge–discharge kinetics as well as the charge transfer mechanism. A 3:4:5 ratio for the areal capacitance values (9.1 (Mn), 12.2 (Fe), and 15.4 (Co) mF cm^?2 at a scan rate of 5 mV/s) corroborates the modulative effect of the metal center. The cycling stabilities of these coordination polymers also followed the same order. At higher current densities (>0.50 mA cm^?2), the supercapacitors fabricated from the Mn-coordination polymer were found to charge and discharge at faster rates, whereas those fabricated from Fe- or Co-coordination polymers continued to discharge at similar rates, indicating similar pore volumes for the latter as confirmed by BET surface area measurements. Although the materials used in this study resulted in modest capacitive performance, the possibilities to enhance their surface area and crystallinity is envisaged to result in the development of new, multifunctional non-carbon electrode materials with efficient electrochemical storage characteristics and tunable electro-optical properties.     

Ag Nanoparticles Supported on a Resorcinol‐Phenylenediamine‐Based Covalent Organic Framework for Chemical Fixation of CO2

Covalent organic frameworks are a new class of crystalline organic polymers possessing a high surface area and ordered pores. Judicious selection of building blocks leads to strategic heteroatom inclusion into the COF structure. Owing to their high surface area, exceptional stability and molecular tunability, COFs are adopted for various potential applications. The heteroatoms lining in the pores of COF favor synergistic host–guest interaction to enhance a targeted property. In this report, we have synthesized a resorcinol‐phenylenediamine‐based COF which selectively adsorbs CO₂ into its micropores (12 Å). The heat of adsorption value (32 kJ mol^?1) obtained from the virial model at zero‐loading of CO₂ indicates its favorable interaction with the framework. Furthermore, we have anchored small‐sized Ag nanoparticles (≈4–5 nm) on the COF and used the composite for chemical fixation of CO₂ to alkylidene cyclic carbonates by reacting with propargyl alcohols under ambient conditions. Ag@COF catalyzes the reaction selectively with an excellent yield of 90 %. Recyclability of the catalyst has been demonstrated up to five consecutive cycles. The post‐catalysis characterizations reveal the integrity of the catalyst even after five reaction cycles. This study emphasizes the ability of COF for simultaneous adsorption and chemical fixation of CO₂ into corresponding cyclic carbonates.     

Effects of phosphoric acid as additive in the preparation of activated carbon fibers from poly(p-phenylene benzobisoxazole) by carbon dioxide activation

Poly(p-phenylene benzobisoxazole) (PBO) was impregnated with small amounts of H₃PO₄, and the effects of this additive on the porosity and other characteristics of chars and activated carbon fibers (ACFs) derived from this polymer were investigated. To this end, PBO-AS impregnated with 5, 10 or 15 wt.% H₃PO₄ was pyrolyzed at 850 °C, and the resulting chars were physically activated with carbon dioxide at 800 °C to different burn-off (BO) degrees. Thermal analysis techniques only detected minor effects of H₃PO₄ on PBO pyrolysis. The char yield and char reactivity towards CO₂ increased following PBO-AS impregnation with H₃PO₄. Structural (X-ray diffraction), porous textural (CO₂ adsorption) and surface chemical (temperature-programmed desorption, X-ray photoelectron spectroscopy) characterizations of the pyrolysis chars indicated that the increase in char reactivity is probably associated with a higher content of oxygenated functionalities. Following CO₂ activation, the surface area and pore volume of the obtained ACFs chiefly depended on the BO degree, but impregnation with H₃PO₄ restricted the pore size to the micropore and narrow mesopore range, thus producing adsorbents with a slightly narrower pore size distribution than in the absence of H₃PO₄. The results are compared with those previously obtained under equivalent conditions with other high-crystallinity polymers as precursors for ACFs.     

The effect of molecular imprinting on the pore size distribution of polymers

Molecular imprinting techniques are becoming an increasingly important domain of porous polymers generally, to achieve molecule specific recognition through morphology or stereochemistry of cavities. Imprinting is sought to increase both selectivity and sensitivity where the polymer may be present as particulate, membrane or thin film forms. Here, we detail mechanisms involved in the formation, stability and adsorption of binding sites, through the influence of polymerisation conditions and templates on the porosity of highly crosslinked molecularly imprinted polymers (MIPs). Environmental control represents an important area for porous polymers, here we focus on two template fungicides, iprodione and pyrimethanil, for ethylene glycol dimethacrylate (EGDMA) based polymers. In general, control of the pre-polymerisation interactions were able to vary the surface areas of polymers from 40–60 m² g⁻¹ to 300–436 m² g⁻¹ while pore sizes fell into distributions (a) close to the micropore region at ∼3.8 nm, (b) in the 10 to 20 nm mesopore region and (c) in the 20 to 50 nm mesopore region. The importance of intermolecular interactions and aggregation in the pre-polymerisation solution to the Brunauer, Emmett, Teller (BET) surface areas and pore size distribution of final polymers has been demonstrated by systematic variation of chemical functionality. These effects confirm recent molecular dynamic simulation studies of MIP formation and cavity stability.