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CN-121974655-A - Low-temperature integrated MXene-based conductive flame-retardant flexible composite aerogel and preparation method thereof

CN121974655ACN 121974655 ACN121974655 ACN 121974655ACN-121974655-A

Abstract

The invention discloses a low-temperature integrated MXene-based conductive flame-retardant flexible composite aerogel and a preparation method thereof. The method comprises the steps of hydrolyzing TEOS to obtain acidic silica sol, mixing PDMS-OH, KH-550, APP and MXene dispersion liquid under ice water bath cooling, adding the silica sol and a tin catalyst to form homogeneous composite sol, and carrying out supercritical carbon dioxide drying after low-temperature gelation and solvent replacement. The invention combines full low temperature (less than or equal to 60 ℃) technology with supercritical drying, effectively protects MXene from oxidation, and realizes 'one-dose multi-effect' interface regulation and control by KH-550. The obtained aerogel has a three-dimensional intercommunication structure, APP and MXene are uniformly dispersed in a PDMS-SiO2 hybrid skeleton, and the aerogel has the characteristics of low density (50-150 mg/cm 3 ), high flexibility (compression rebound rate is more than or equal to 95%), good electrical conductivity (10 ‑3 -10 ‑1 S/m), high flame retardance (limiting oxygen index is more than or equal to 35%, UL-94 grade V-0) and low heat conduction, and is suitable for the fields of flexible electronic protection, electromagnetic shielding, fireproof heat insulation and the like.

Inventors

  • LI XUEZHI
  • YANG CHAOJIN
  • TIAN XINGXING
  • WU YAO
  • WU CHAOYAN
  • XIA BAIHUI
  • BAI QIJUN
  • SU YA
  • ZENG YUTING

Assignees

  • 贵州航天乌江机电设备有限责任公司

Dates

Publication Date
20260505
Application Date
20260224

Claims (8)

  1. 1. The preparation method of the low-temperature integrated MXene-based conductive flame-retardant flexible composite aerogel is characterized by comprising the following steps of: (1) Mixing tetraethoxysilane, alcohol, water and an acid catalyst, and hydrolyzing at room temperature to obtain acidic silica sol; (2) Primarily mixing hydroxyl-terminated polydimethylsiloxane, silane coupling agent aminopropyl triethoxy siloxane, ammonium polyphosphate powder dispersion liquid and MXene dispersion liquid, and adding a tin catalyst and the acidic silica sol obtained in the step (1) under the conditions of cooling and stirring to form homogeneous composite sol; (3) Gelling the homogeneous composite sol at 40-50 ℃ to obtain wet gel, and performing complete solvent replacement on the wet gel by using absolute ethyl alcohol; (4) And drying the wet gel subjected to solvent replacement by supercritical carbon dioxide to obtain the composite aerogel.
  2. 2. The method of claim 1, wherein the maximum temperature during the whole production process is not more than 60 ℃.
  3. 3. The method according to claim 1, wherein in the step (2), MXene in the MXene dispersion is 2-5 layers of Ti 3 C 2 T x nano-sheets with the concentration of 2-8 mg/mL, and the tin catalyst is dibutyl tin dilaurate, and the amount of the tin catalyst is 1% of the mass of the hydroxyl-terminated polydimethylsiloxane.
  4. 4. The method according to claim 1, wherein in the step (2), the cooling condition is ice water bath cooling, the temperature of the mixed system is maintained below 10 ℃, and the stirring is high-speed stirring, and the rotating speed is not lower than 8000 rpm.
  5. 5. The method according to claim 1, wherein in the step (3), the wet gel is subjected to the solvent replacement for 24 to 48 hours, during which the absolute ethanol is replaced 2 to 3 times.
  6. 6. The method according to claim 1, wherein in the step (4), the supercritical carbon dioxide is dried at a temperature of 35-40 ℃, a pressure of 8-12MPa, a drying time of 4-6 hours, a pressure release rate of 0.5-1.0 MPa/min and a carbon dioxide flow rate of 1500-2500kg/h.
  7. 7. The preparation method of the polyurethane foam as claimed in claim 1, wherein the raw materials comprise, by mass, 100 parts of hydroxyl-terminated polydimethylsiloxane, 80-160 parts of ethyl orthosilicate, 15-25 parts of silane coupling agent aminopropyl triethoxy siloxane, 30-50 parts of ammonium polyphosphate and 0.5-2 parts of MXene.
  8. 8. The low-temperature integrated MXene-based conductive flame-retardant flexible composite aerogel prepared by the preparation method of any one of claims 1 to 7 is characterized by being a block body with a three-dimensional intercommunicating porous structure and without macroscopic cracks, wherein ammonium polyphosphate particles and MXene nano sheets are uniformly dispersed and fixed in a hybrid skeleton formed by hydroxyl-terminated polydimethylsiloxane and silicon dioxide.

Description

Low-temperature integrated MXene-based conductive flame-retardant flexible composite aerogel and preparation method thereof Technical Field The invention belongs to the technical field of functional aerogel materials, and particularly relates to a composite aerogel with conductive, flexible, flame-retardant and heat-insulating properties and a preparation method thereof. In particular, the invention provides an MXene-based conductive flame-retardant flexible composite aerogel prepared by a full low-temperature integrated process, which is suitable for the fields of electromagnetic shielding, fire protection electronic devices, intelligent fireproof coatings, flexible wearable electronic equipment and the like. Background Along with the rapid development of the fields of flexible electronic, intelligent wearable equipment and special safety protection, the requirements for light-weight and multifunctional integrated protection materials are increasingly urgent. Aerogel is an ideal light-weight matrix material due to its ultra-low density, high porosity and low thermal conductivity. Two-dimensional transition metal carbo/nitrides (MXene, such as Ti 3C2Tx) have high conductivity similar to metals and are ideal materials for constructing conductive networks. However, MXene has poor chemical stability and is very susceptible to oxidation to very poorly conductive titanium dioxide in oxygen-containing, humid or high temperature environments, resulting in rapid decay of material function, which severely limits its application to devices requiring long-term stable operation. At present, when the MXene composite aerogel with flame retardance and electric conduction functions is prepared, two technical bottlenecks are faced, namely, firstly, the high-temperature solidification, heat treatment or normal-pressure drying (usually higher than 100 ℃) which are difficult to avoid in the traditional process can irreversibly damage the crystal structure of the MXene and aggravate oxidation and seriously damage electric conduction performance, and secondly, flame retardants such as ammonium polyphosphate (APP) and the like which are introduced to endow the material with flame retardance have poor compatibility with a common flexible polymer matrix (such as silicon rubber), migration and precipitation are easy to occur, so that the flame retardance durability is reduced, and a continuous electric conduction network constructed by the MXene nano-sheets is damaged, and the electric conductivity is reduced. In order to solve the problems, the prior art adopts a complex multi-step modification process to pretreat the MXene and the flame retardant, thereby increasing the cost and the complexity of the process, or sacrifices other properties (such as increased brittleness and lost flexibility) for pursuing one property (such as high flame retardance), and the synergistic unification of high elasticity, high conductivity, high flame retardance and high stability is difficult to realize under a simple and scalable process. Therefore, the integrated preparation method capable of realizing uniform dispersion of functional filler, firm combination of interfaces and nondestructive molding of the three-dimensional nano porous structure in one step under the condition of full low temperature is developed, and has important scientific significance and application value. Disclosure of Invention The invention aims to overcome the defects of easy oxidation, complex process and difficult performance coordination of MXene in the prior art, and provides a low-temperature integrated preparation method which is easy to obtain raw materials, simple and convenient to operate and suitable for amplification, and an MXene-based conductive flame-retardant flexible composite aerogel with excellent comprehensive performance prepared by the method. In order to achieve the technical purpose, the following technical scheme is adopted: in one aspect, the invention provides a preparation method of a low-temperature integrated MXene-based conductive flame-retardant flexible composite aerogel, which comprises the following steps: (1) Mixing Tetraethoxysilane (TEOS), alcohol and water with an acid catalyst, and hydrolyzing at room temperature to obtain acidic silica sol; (2) Primarily mixing hydroxyl-terminated polydimethylsiloxane (PDMS-OH), silane coupling agent aminopropyl triethoxy siloxane (KH-550), ammonium polyphosphate (APP) powder dispersion liquid and MXene dispersion liquid, and adding a tin catalyst and the acidic silica sol obtained in the step (1) under the conditions of cooling and stirring to form homogeneous composite sol; (3) Gelling the homogeneous composite sol at 40-50 ℃ to obtain wet gel, and performing complete solvent replacement on the wet gel by using absolute ethyl alcohol; (4) And drying the wet gel subjected to solvent replacement by supercritical carbon dioxide to obtain the composite aerogel. Preferably, the maximum temperature during