Zhi Li

• PhD
• Professor (Associate) at Central South University

Silica aerogels (SAs) present great application prospects especially on thermal insulation, but their flammability is usually ignored. A combined study on the combustion behaviors and oxidation kinetics of hydrophobic silica aerogels prepared by ambient pressure drying (SA-apd) and supercritical drying (SA-sd) was performed by employing cone calori...

To meet the flexibility of some practical applications, aramid fiber reinforced silica aerogel composites (AF/aerogels) were successfully prepared, which possessed low density, remarkable flexibility and excellent thermal insulation properties. The microstructure of the AF/aerogels showed that the aramid fibers were inlaid in the aerogel matrix act...

Using tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) as co-precursors, hybrid silica aerogels were prepared via ambient pressure drying (APD) without further surface modification. Due to various precursors presenting different condensation rates, the effect of NH4OH used as catalyst was explored in detail to balance the condensation rat...

Lightweight, biodegradable multifunctional cellulose nanofiber (CNF) aerogel shows great potential in the fields of thermal insulation, electronic equipment and oil contaminant removal. However, its high fire risk and poor mechanical performance severely limit its extensive application. In this work, CNF aerogel with improved flame retardant and me...

This research enhances the thermal safety of hydrophobic silica aerogel (HSA) by integrating layered double oxides (LDOs). XRD and FTIR confirm that the introduction of LDOs does not affect the formation of SA. The LDO/SA composites demonstrate a low density (0.14–0.16 g/cm3), low thermal conductivity (23.28–28.72 mW/(m·K)), high porosity (93.4–96....

The thermal safety of hydrophobic silica aerogels (SAs) is essential to thermal insulation applications. Herein, trimethylchlorosilane (TMCS), dimethyldichlorosilane (DMDCS), and methyltrichlorosilane (MTCS) were employed as surface modifiers to prepare three different methylsilyl-modified SAs (i.e., TSA, DSA, and MSA) and their combustion characte...

Compared with nanoscale aerogels, the thermal conductivity of MTMS silica aerogel (MSA) is relatively large due to its micron-sized pore size, which hinders its popularization in the field of thermal insulation. In this study, the MSA samples with relatively low thermal conductivity (33.7 mW/m/K) and density (0.071 g/cm³) were prepared. Then, the t...

To enhance the thermal safety and preserve the excellent thermal insulation of hydrophobic silica aerogels (SA), sodium dodecyl sulfate (SDS) intercalated layered double hydroxides (LDH) was incorporated into SA by in situ doping to form SDS-LDH/SA composites. The intercalation modification by SDS extends the layer spacing of LDH and improves the d...

A R T I C L E I N F O Keywords: Clay-based aerogel Binary-network structure Mechanical properties Wettability behavior Thermal insulation A B S T R A C T Developing clay-based aerogel composites with integrated high strength, low thermal conductivity, and hy-drophobicity remains a great challenge. Here, binary-network structured montmorillonite/sil...

The propensity of foamed concrete to absorb water results in a consequential degradation of its performance attributes. Addressing this issue, the integration of aerogels presents a viable solution; however, their direct incorporation has been observed to compromise mechanical properties, attributable to the effects of the interface transition zone...

A R T I C L E I N F O Keywords: Clay-based aerogel Binary-network structure Mechanical properties Wettability behavior Thermal insulation A B S T R A C T Developing clay-based aerogel composites with integrated high strength, low thermal conductivity, and hy-drophobicity remains a great challenge. Here, binary-network structured montmorillonite/sil...

To improve the thermal safety of hydrophobic silica aerogels (SAs), montmorillonite (MMT) was used as a dopant to prepare MMT/silica aerogel composites (MMT/SAs) and their basic physicochemical properties and thermal safety were investigated in detail. It finds that a physical combination is formed between MMT and SAs, and the introduction of MMT d...

In this work, we prepared heat-treated aramid pulp/silica aerogel composites (AP/aerogels) and investigated in detail the feasibility of improving thermal stability and thermal insulation via tailored heat treatment. The microstructure and FTIR spectra reveal that AP/aerogels are formed by a physical combination of the silica aerogel matrix and ara...

In this study, the surface chemistry, skeleton structure and thermal safety of three different methylsilyl modified silica aerogels (SAs) have been explored under heat treatment in an argon atmosphere. With the heat treatment temperature increasing to 700°C, the secondary particles aggregate, the silica skeletons get denser and the pore volumes dim...

The composite of paraffin with reduced graphene oxide (paraffin/rGO) was obtained at 70 • C by the mechanical mixing of the components followed by ultrasonic dispersion. The introduction of only 0.3 wt.% rGO stained the paraffin black. It has been shown that thermal batteries made from 160 grams of pure paraffin and 160 grams of the composite are e...

To address the leakage issue of paraffin phase-change materials in thermal management, a monolithic MTMS-based silica aerogel (MSA) is employed to encapsulate paraffin through a facile impregnation process. We find that the paraffin and MSA form a physical combination, with little interaction occurring between them. The prepared no-leakage paraffin...

Aiming at the problem of low efficiency of capturing respirable and hydrophobic dust in water mist dust removal technology, a chemical dust suppression method is adopted. Based on the research idea of improving the wetting efficiency of water mist, prolonging the droplet retention time, and improving the contact opportunity with dust, the experimen...

Ever-increasing application domains of Methylsilsesquioxane aerogels place a higher demand on the diverse wettability. This work prepares hydrophilic Methylsilsesquioxane aerogels under ambient pressure (APD) using 25 ml water and ethanol (EtOH) as co-solvents (12–36 vol% ethanol) and CTAB as a surfactant. We also find that the unique Methylsilsesq...

Polytetrafluoroethylene/cellulose composite aerogels containing PTFE from 0 to 40 wt.% were obtained by drying the corresponding suspension mixtures at a temperature of 50°C. Cellulose isolated from the stem of Sosnowski hogweed was used as the main component of the aerogels. In present work, the composite aerogels were heated in an inert atmospher...

In this work, we reported that aramid pulps (AP) reinforced clay aerogel composites with improved mechanical strength, good thermal insulation and fire resistance based on the combination of AP, Poly(vinyl alcohol) (PVA) and sodium montmorillonite (MMT), which present a promising prospect in the thermal insulation application. The PVA-MMT-APx (x: d...

To adjust the thermal safety of hydrophobic silica aerogel, layered double hydroxide (LDH)/silica aerogel (SA) composites were prepared by an in-situ sol-gel process at ambient pressure. This study found the physical combination of SA and MgAl-LDH based on the FTIR spectra and phase composition of LDH/SA. The N2 sorption analysis confirms that the...

In this paper, a nano-composite dust suppressant has been proposed to make up for the deficiency in wettability and moisturizing performance of a nanofluid dust suppressant. The nanometer material Al2O3, super absorbent polymer, carboxyl methyl starch sodium, and polyacrylamide were selected as effective components of it. The surface tension of the...

The thermal safety of hydrophobic silica aerogels (SA) attracts much concern in the field of heat insulation. It is urgent to develop SA composites with excellent thermal insulation properties to meet the current demands for efficient thermal insulation materials. In this work, alumina hydroxide (AH) doping SA (SA/AH) composites were prepared to en...

In this study, the interaction of two parallel line fires with a length-width ratio of greater than 50 was investigated and compared to a single line fire. Considering different length–width ratios and spacings between the fire sources, experiments were carried out to analyze the fire characteristics, such as the burning rate, the flame-merging sta...

This work presents a facile synthesis approach of methyltriethoxysilane (MTES) based aerogels using pure water as the only solvent, and the effects of precursor concentration on the physicochemical properties are investigated in detail. Therein, the precursor concentration has no effect on the chemical composition but causes the denser and slendere...

To overcome the poor mechanical performance of methyltrimethoxysilane (MTMS) aerogels and the low thermal stability of polyvinyl alcohol (PVA), the PVA/MTMS aerogel composites (PMAC) were successfully prepared through a facile impregnation process. It finds that the PVA concentration has a great influence on the physicochemical properties of the PM...

A facile post-doping of magnesium hydroxide (MH) is proposed to improve the flame retardancy of hydrophobic silica aerogels (SA). The lower tap density (0.12 g/cm³) and thermal conductivity (26 mW/m/K) are still maintained at the largest MH content of 20%. Meanwhile, the gross calorific value of the SA/MH is reduced by 15% and the thermal stability...

Silica aerogel (SA) is a nanoporous material and has attracted increasing attention in the field of thermal insulation in recent years. In this work, the thermal stability and pyrolysis characteristics of the methyltrimethoxysilane (MTMS) silica aerogel (MSA) prepared in pure water were investigated experimentally. The MSA shows a high thermal stab...

In this work, monolithic silica aerogels were prepared in pure water within 4 h by using MTMS as the precursor under ambient pressure drying (APD). The effects of the volume ratio of H2O/MTMS, CTAB content and NH3·H2O concentration on the properties of MTMS-based aerogels (MSA) were investigated experimentally. The realization of the rapid synthesi...

Considering the low thermal stability and high flammability of polyurethane sponge (PUS) and the poor mechanical performance of methyltrimethoxysilane (MTMS) aerogels, their combination for improvement of characteristics was investigated. The density of prepared polyurethane sponge/MTMS aerogel (PUSMA) composites increased exponentially between 0.0...

Silica aerogels are highly porous (~95%), predominantly mesoporous (20–50 nm) materials with very high surface area (~800 m²/g), but applications that valorize the chemical properties linked to the high surface area lag behind those that valorize the pore structure (thermal insulation). Here, we present widely applicable protocols to synthesize and...

In this study, tailored heat treatment was employed to lower the flammability of hydrophobic silica aerogels (HSA). The effects of heat treatment temperature, time, and heating rate on the pore structure and flammability of the treated SA were investigated in detail. It was revealed that the heat-treated HSA still maintained a mesoporous structure...

Reducing organic groups on hydrophobic silica aerogels (SA) is worth exploring for lowering their thermal hazard risk. In this work, we used dimethyldichlorosilane (DMDCS) to modify silica alcogels, investigated the effects of DMDCS concentration and focused on the thermal hazard assessment of the DMDCS modified SA (DSA). It was turned out that the...

Methylchlorosilanes (MSCs) of the type (CH3)nSiCl4−n (n = 1, 2, 3) are usually used for surface modification of silica aerogels (SAs), in which the quantity of Si–Cl and Si–CH3 groups deeply affects the properties of prepared SAs. In this work, methyltrichlorosilane (MTCS, n = 1), dimethyldichlorosilane (DMDCS, n = 2), and trimethylchlorosilane (TM...

Solar chimney has been frequently adopted in buildings to save energy by enhancing the natural ventilation. Although its optimization studies have been frequently taken previously, most of them have focused on the configuration of solar chimney but ignored the air inlet, even though its significant influence has already been confirmed. The interact...

In this work, we utilized Al(OH)3 (AH) and Mg(OH)2 (MH) as dopants to reduce the flammability of hydrophobic silica aerogels (SA) and the related thermal properties and flame retardance were investigated detailedly. The TG-DSC analyses showed the thermostability of SA in MH/SA reached 512.4 °C and that for AH/SA was just 426.1 °C, both of which wer...

To reduce the flammability, hydrophobic silica aerogels (SAs) were modified by replacing commonly used trimethylchlorosilane (TMCS) with methyltrichlorosilane (MTCS). It was observed that the MTCS modified SAs (MSA) showed similar physicochemical properties to those TMCS modified SAs (TSA), including the density, thermal conductivity, hydrophobicit...

In this paper, using methyltrimethoxysilane (MTMS) as precursor, silica aerogels (SA) with excellent performance were synthesized within 10 h via APD without further surface modification and solvent exchange. The investigation was concentrated on three primary factors, including base catalyst, surfactant, and co-solvent system. The results indicate...

Organic groups on silica aerogels (SAs) introduced by surface modification not only achieve the hydrophobicity but also constitute the primary combustible components. In this study, the flammability of the typical precursor, i.e., tetraethoxysilane (TEOS) and sodium silicate (SS), synthetic SAs was investigated separately by cone calorimeter. The r...

In this paper, we report the experimental results of the silica aerogel powders prepared by water glass and ambient pressure drying within 4 h. Water glass was hydrolyzed in water using HCl as the acid catalyst. In order to reduce the consumption of modifier and preparation period, the new technological process of mechanical crushing and filtration...

To avoid lengthy solvent exchange and surface modification processes and reduce the production cost, monolithic silica aerogels were prepared rapidly (reduced from regular three days to 5 hours) under ambient pressure using methyltrimethoxysilane (MTMS, precursor) and water (solvent). For preparing aerogels in aqueous phase, the phase separation ca...

Aerogels are the best thermal insulating materials ever known because of their extremely low thermal conductivity. However, their applications are limited because of their brittleness and low strength. For maintaining the integrity, we prepared glass fiber film reinforced silica aerogel composites have been prepared by the sol–gel method via ambien...

For maintaining the integrality and improving the mechanical strength of fiber/silica aerogel composites without compromising thermal insulation properties, aramid pulp reinforced silica aerogel composites were prepared under ambient pressure drying by adding aramid pulps into silica sol directly. The microstructures indicated the ample fibrillated...

In this paper, we have prepared methyltrimethoxysilane (MTMS)-based sponge-reinforced silica aerogel with low density through facile synthesis within 12 h. The sample’s mechanical property has been improved significantly compared with pure MTMS-based silica aerogel. The aerogels are hydrophobic and oleophilic. And its absorption capacity to the org...

Methyltrimethoxysilane (MTMS) and tetraethoxysilane (TEOS) are used as precursors to synthesize MTMS/TEOS co-precursor aerogels (cp-aerogels) via ambient pressure drying (APD). The effects of NH3·H2O concentration on thermal properties of the MTMS/TEOS cp-aerogels were explored in detail. As the NH3·H2O concentration increased, the density slightly...

In order to compare the various surface modification methods of ambient-pressure-dried aerogels, three different surface modification methods, namely co-precursor method, derivatization method and two-step method, were studied in this paper. The property differences of the aerogels caused by the three surface modification methods were discussed in...

In this study, we tried to synthesize ultralow density and super hydrophobic silica aerogel with extra high specific surface area, by using absolutely cost effective processing from sodium silicate. Hydrosol was obtained through ion exchange. To reduce the processing time, the gels were mechanically agitated to granules before solvent exchange. N,N...