Ultra-strong and solvent-free castor oil-based polyurethane thermally conductive structural adhesives for heat management

Thermally conductive structural adhesives (TCSAs) are rendered high requirements with the rapid development of electronic devices towards miniaturization, light-weight and electrically insulating performance. Improving heat dissipation capacity and mechanical properties are both critical for the application of TCSAs as the interconnected materials between chips and metal substrates. Herein, we prepared environment-friendly TCSAs with different hard segments (HS) contents by using castor oil-based polyurethane (PU) as matrix and alumina (Al2O3) as thermal conductive filler through an extremely facile mechanical-mixing process. Impressively, the TCSA with 49.3% HS content exhibited an intense notable tensile stress of 8.6 MPa, a high elongation at break of 21%, and an excellent lap shear strength to different substrates, including organic glass (7.7 MPa), steel (9.5 MPa), cooper (10.3 MPa) and aluminum (14.2 MPa). Furthermore, the thermal conductive pathways in composites with 75 wt% Al2O3 fillers endow its good thermal conductivity with thermal conductivity k of 1.23 W/(m·K), 4.7 times higher than that of pure PU (k = 0.26 W/m·K). Overall, our fabricated TCSAs not only possessed superior mechanical performances but also high thermal conductivity, as well as showed great potential in thermal management application fields due to its simple and environmental fabricating method.