CN-121975171-A - Ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly and preparation method and application thereof

CN121975171ACN 121975171 ACN121975171 ACN 121975171ACN-121975171-A

Abstract

The invention relates to a fluorine-fluorine self-assembled ultralow dielectric and high thermal conductivity composite material and a preparation method and application thereof, and belongs to the technical field of high polymer materials. The preparation method comprises the steps of carrying out directional freezing casting by using a perfluorinated solvent, combining a supercritical carbon dioxide drying technology, constructing a pure anhydrous 3D-FG bidirectional orientation framework in situ, preparing a fluorocarbonic acid ester resin impregnating solution at the same time, inducing the fluorocarbons to be perfectly wetted on the surface of the highly inert FG framework by using a vacuum-pressure alternating process, and carrying out solvent-free in situ heat curing to prepare the perfluorinated interpenetrating network structure composite material. The invention overcomes the pain points of the traditional material, such as high-frequency polarization, easy debonding of interface and water absorption and blindness in a high-humidity environment, has the Z-axis thermal conductivity of 1.85-5.80W/(m.K), the dielectric loss of less than or equal to 0.0022 under 77GHz, has extremely low water absorption and strong surface hydrophobicity, and is particularly suitable for the fields of automatic driving 77GHz millimeter wave radar, high-orbit satellite communication and wave-transparent thermal management in a marine high-humidity environment.

Inventors

NIU BO
WANG YOUYI
LONG DONGHUI
YAN CHANGSHENG
GAO JINGWEN
Shao Aijia
ZHANG FENGCHENG
LI YUZHU
CAO YU

Assignees

华东理工大学

Dates

Publication Date: 20260505
Application Date: 20260409

Claims (10)

1. The preparation method of the ultralow dielectric and high heat conduction composite material based on fluorine-fluorine self-assembly is characterized by comprising the following steps: S1, dispersing fluorinated graphene nano sheets in a perfluorinated solvent to form slurry, placing the slurry in a bidirectional temperature gradient die for directional freezing, taking out, and drying by supercritical CO 2 to obtain a 3D-FG sponge skeleton; s2, selecting a fluorine-containing bisphenol A type cyanate monomer as matrix resin, adding an organic metal salt catalyst, and dissolving in an organic solvent to prepare a homogeneous fluorine-containing impregnating solution; S3, injecting the fluorine-containing impregnating solution into the 3D-FG sponge skeleton by adopting a vacuum-pressure alternating impregnation process; and S4, removing the solvent from the 3D-FG sponge skeleton impregnated and saturated in the step S3, and heating for curing to obtain the fluorine-fluorine self-assembled ultralow dielectric and high heat conduction composite material.
2. The preparation method of the ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly, which is disclosed in claim 1, is characterized in that in step S1, the perfluorinated solvent is one or more of hydrofluoroether and perfluorohexane, and the mass fraction of the fluorinated graphene nano-sheets in the slurry is 5-20 wt.%.
3. The preparation method of the ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly according to claim 1, wherein in the step S1, the supercritical CO 2 is dried under the process conditions that the liquid CO 2 is replaced for 12-24 hours, the temperature in a supercritical state is 40-50 ℃, the pressure is 10-15 MPa, and the retention time is 2-6 hours.
4. The preparation method of the ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly according to claim 1, wherein in the step S2, the fluorine-containing bisphenol A type cyanate monomer is one or more of hexafluorobisphenol A type cyanate and octafluorobiphenyl dicyanate, the organic metal salt catalyst is one or more of zinc octoate and zinc naphthenate, and the organic solvent is trifluoromethylbenzene.
5. The method for preparing a fluorine-fluorine self-assembled ultralow dielectric and high thermal conductivity composite material according to claim 1, wherein in the step S2, the solid content of the fluorine-containing impregnating solution is 40-70 wt.%.
6. The preparation method of the ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly according to claim 1, wherein in the step S3, the vacuum-pressure alternating impregnation process is that the 3D-FG sponge skeleton is vacuumized to absolute pressure of less than or equal to 50 mbar and kept for 20-40 min, and after the fluorine-containing impregnation liquid is injected, positive pressure of 0.2-0.6 MPa is applied and kept for 20-40 min.
7. The preparation method of the ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly according to claim 1, wherein in the step S4, the solvent removing method is that the solvent is dried for 4-6 hours under the condition of 60-80 ℃.
8. The preparation method of the ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly according to claim 1 is characterized in that in the step S4, the temperature rising and curing method is that the temperature is sequentially raised to 140-160 ℃ at a rate of 2-5 ℃ per minute, the temperature is kept for 1-3 hours at 190-210 ℃, and the temperature is kept for 1-4 hours at 240-260 ℃.
9. The ultralow dielectric and high heat conduction composite material based on fluorine-fluorine self-assembly is characterized by being prepared by the preparation method of the ultralow dielectric and high heat conduction composite material based on fluorine-fluorine self-assembly according to any one of claims 1-8, wherein the composite material has a perfluorinated interpenetrating network structure of a supercritical anhydrous and dried bidirectional 3D-FG skeleton/triazine ring crosslinked fluorocyanic acid ester resin, the Z-axis thermal conductivity of the composite material is 1.85-5.80W/(m.K), the dielectric constant Dk is 2.38-2.58 at 77 GHz frequency, the dielectric loss Df is less than or equal to 0.0022, the water absorption rate is less than or equal to 0.05%, and the surface static water drop contact angle is more than or equal to 112 degrees.
10. The application of the ultralow dielectric and high heat conduction composite material based on fluorine-fluorine self-assembly is characterized in that the composite material according to claim 9 is applied to the fields of automatic driving 77 GHz millimeter wave radar, high orbit satellite communication and severe ocean high humidity environment.

Description

Ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly and preparation method and application thereof Technical Field The invention relates to the technical field of high polymer materials, in particular to a fluorine-fluorine self-assembled ultralow dielectric and high heat conduction composite material, and a preparation method and application thereof. Background With the evolution of an autopilot sensing system represented by 77GHz/79GHz millimeter wave radar, a high-orbit satellite Internet satellite-borne phased array antenna and a new-generation active phased array radar in a high-integration and high-power direction, the emission power density of a core radio frequency front end T/R component of the active phased array radar rapidly rises, and the problem of heat accumulation generated by the emission power density rapidly becomes a key bottleneck for restricting the reliability and the service life of devices. On the other hand, the working frequency range expands to extremely high frequency (such as millimeter wave or even terahertz wave), and extremely severe requirements are put on electromagnetic performance of wave-transparent components such as radomes, radar windows and the like, namely the material needs to have extremely low dielectric constant (Dk) and dielectric loss (Df) so as to ensure low delay and high-fidelity transmission of signals. At present, the conventional wave-transparent thermal material system has the following inherent defects that firstly, high-frequency resin matrixes represented by Polytetrafluoroethylene (PTFE) have excellent dielectric properties, but the heat conductivity coefficient is extremely low (usually lower than 0.3W/(m.K)), and the difficulty of melt processing is high, so that the direct application of the high-frequency resin matrixes in high-power scenes is limited. Secondly, when conventional ceramic fillers (such as alumina and boron nitride) are added into a resin matrix to improve the heat conducting property, the fillers are often subjected to surface polarization modification or an aqueous ice template molding process, and a large amount of free hydroxyl (-OH) is inevitably remained in the material due to the treatment. The strong hygroscopicity of hydroxyl groups can promote water molecules in the environment to infiltrate into the inside of the material in severe environments such as high temperature, high humidity, heavy rainfall or ocean salt fog. The polarization effect of water molecules causes severe attenuation and dispersion of high-frequency electromagnetic waves at an interface, and the radar signal can be interrupted when severe, namely, a blind phenomenon occurs. Finally, fluorinated Graphene (FG) is used as a two-dimensional material with both intrinsic high thermal conductivity and ultralow polarizability, and can solve the problems of heat conduction and dielectric loss synchronously in theory. However, since FG surface has extremely strong chemical inertness (presents 'hydrophobic and oleophobic' characteristics similar to Teflon), it is extremely difficult to uniformly disperse in conventional organic or aqueous solvents, and continuous three-dimensional phonon heat conduction frameworks cannot be effectively constructed, meanwhile, the interfacial bonding force between FG and a polymer matrix is extremely weak, and a large number of interfacial air gap defects are easily introduced into the composite material, and the interfacial defects not only exacerbate phonon scattering, but also worsen the comprehensive mechanical and dielectric properties of the material. Therefore, how to overcome the technical bottleneck, developing a novel composite material which can maintain ultra-low dielectric loss in an ultra-high frequency band (77 GHz and above), has high thermal conductivity in the Z-axis direction, and realizes near zero water absorption in an extreme damp-heat environment has become a key technical problem to be solved in the art. Disclosure of Invention In view of the above analysis, the present invention aims to provide an ultralow dielectric and high thermal conductivity composite material based on fluorine-fluorine self-assembly, and a preparation method and application thereof, so as to solve the technical problems of polarity defect and interface debonding of the existing electronic packaging composite material. In one aspect, the invention provides a preparation method of a fluorine-fluorine self-assembled ultralow dielectric and high thermal conductivity composite material, which comprises the following steps: s1, dispersing Fluorinated Graphene (FG) nanosheets in a perfluorinated solvent to form slurry, placing the slurry in a bidirectional temperature gradient die for directional freezing, taking out, and drying by supercritical CO 2 to obtain a 3D-FG sponge skeleton; s2, selecting a fluorine-containing bisphenol A type cyanate monomer as matrix resin, adding an o