Investigation of nanocomposite PNIPAm‐g‐graphene with pre‐lower critical solution temperature rapid thermal response function for chip adaptive cooling: A molecular dynamics and computational fluid dynamics simulations

Abstract

Temperature‐sensitive hydrogels have been widely used for rapid adaptive cooling in electronic device thermal management with promising applications. However, existing temperature‐sensitive hydrogels can only regulate the flow in the chip cooling system after the ambient temperature reaches their lower critical solution temperature (LCST). Before reaching LCST, effective rapid heat dissipation for electronic chips is not achievable. This study aims to develop a temperature‐sensitive hydrogel that can provide assisted adaptive cooling for electronic chips before reaching its LCST. This requires the hydrogel to have a thermal conductivity far surpassing existing hydrogel materials. Using the temperature‐sensitive hydrogel PNIPAm and graphene molecules as base materials, this research utilized molecular dynamics simulations to graft graphene molecules onto PNIPAm molecules in different ways, resulting in the temperature‐sensitive hydrogel material PNIPAm‐g‐graphene. Non‐equilibrium molecular dynamics (NEMD) was employed to calculate the thermal conductivity of this material under different temperature conditions. The results indicate that the thermal conductivity of PNIPAm‐g‐graphene can reach up to 1.95474 W/m K (graphene grafted at CH3 functional group, temperature at 280 K). Compared to the thermal conductivity of PNIPAm under the same conditions (0.45 W/m K), the increase in thermal conductivity is significant, demonstrating excellent thermal conductivity compared to PNIPAm. Subsequently, this study analyzed the underlying mechanisms of different thermal conductivities in materials obtained by grafting graphene molecules at different points using the method of overlap in Phonon Density of States Curves (PDOS) from the perspective of interfacial thermal conduction. Finally, through computational fluid dynamics (CFD) simulations, this study investigates the chip's adaptive cooling performance with PNIPAm‐g‐graphene material. The results show that, compared to traditional temperature‐sensitive hydrogels, PNIPAm‐g‐graphene can achieve efficient adaptive cooling of chip hotspots before the cooling fluid temperature reaches its LCST value. This finding is significant for the field of chip cooling. The study proposes a new method for rapid, adaptive cooling of chip hotspots and explores its feasibility from the perspectives of molecular dynamics and CFD simulation. It holds importance in the thermal management of electronic devices and the rapid adaptive cooling of electronic chips.