Leak-proof liquid metal/melamine insulating and thermally conductive film and preparation method thereof

A preparation method for a leak-proof liquid metal (LM)/melamine insulating and thermally conductive film, wherein the preparation method comprises the following steps:

• (1) sponge substrate selection:
• the selected substrate is a composite modified sponge;
• (2) LM selection:
• employing a gallium-indium alloy;
• (3) preparation of a LM/ethanol dispersion:
• mixing the LM and ethanol, then placing the mixture into an ultrasonic cell disruptor for disruption to obtain a LM/ethanol dispersion;
• the mass ratio of the LM to ethanol is 1:12 to 1:18, the ultrasonic power is 400 W, and the processing time is 2-6 minutes;
• (4) melamine sponge impregnation treatment:
• placing the composite modified sponge obtained in step (1) into the LM/ethanol dispersion obtained in step (3) according to a volume ratio of 1:5 for impregnation treatment, then taking it out to obtain an impregnated sample;
• (5) drying treatment:
• placing the impregnated sample obtained in step (4) into an air drying oven for drying treatment until the ethanol is completely evaporated;
• wherein the air speed inside the air drying oven is 0.5 m/s, the temperature is 50° C., and the time is 0.5 hours;
• (6) multiple impregnations:
• repeating steps (4) and (5) multiple times to obtain a multiple-impregnated composite material;
• (7) LM component pressing:
• mechanically pressing the multiple-impregnated composite material obtained in step (6) to obtain a film sample;
• the mechanical pressing step comprises:
• dividing the obtained multiple-impregnated composite material into four parts, placing them into a tablet press for automatic pressing, wherein the tablet press acts on one of the four parts each time, four times constitute one cycle, and a total of 10 to 12 cycles are performed;
• (8) Polydimethylsiloxane (PDMS)/ethyl acetate solution preparation:
• taking PDMS and a curing agent according to a mass ratio of 9:1 and mixing them uniformly to obtain a preliminary mixture, pouring the preliminary mixture into ethyl acetate according to a mass ratio of preliminary mixture to ethyl acetate of 1:9 into a centrifuge tube, centrifugally stirring for 5 minutes to prepare a 10% PDMS/ethyl acetate solution, and diluting the obtained solution 10 times to obtain a 1% PDMS/ethyl acetate solution;
• (9) molding:
• suspending the film sample obtained in step (7) on an aluminum mesh support, aspirating the 1% PDMS/ethyl acetate solution obtained in step (8) with a pipette, dripping it onto both sides of the film sample for uniform coverage, placing it in an air drying oven to evaporate the ethyl acetate, and finally obtaining the leak-proof LM/melamine insulating thermally conductive film;
• the air speed inside the air drying oven is 0.5 m/s, the temperature is 60° C., and the time is 2 hours;
• the preparation method of the composite modified sponge comprises the following steps:
• (1) repeatedly rinsing a melamine sponge with anhydrous ethanol and deionized water for 10 minutes each, then vacuum drying at a temperature of 55° C. for 2 hours to obtain a cleaned melamine sponge;
• (2) uniformly dispersing silver nanowires into deionized water to obtain a silver nanowire dispersion;
• the mass fraction of the silver nanowires in the silver nanowire dispersion is 10-13 wt %;
• (3) immersing the cleaned melamine sponge into the silver nanowire dispersion, applying a pressure of 0.5 MPa to the cleaned melamine sponge, holding the pressure for 10 seconds, then releasing the pressure, maintaining for 20 seconds, repeating this cycle 5 times, then taking it out, placing it in a vacuum drying oven, and vacuum drying at 55° C. for 4 hours to obtain a melamine sponge composite material;
• (4) adding dopamine hydrochloride to a Tris solution, stirring and mixing uniformly to obtain a treatment solution;
• adding the melamine sponge composite material to the treatment solution, performing ultrasonic dispersion for 10 minutes, adjusting the temperature to 65° C., maintaining a sealed impregnation for 15 hours, taking it out, and then vacuum drying at a temperature of 55° C. for 4 hours to obtain the composite modified sponge.