Preparation and Thermal Conductivity Sensing Properties of Polyacrylamide/Carboxymethyl Chitosan/Hydroxylated Boron Nitride Composite Hydrogel

Hexagonal boron nitride (h-BN) is the most stable crystalline form of boron nitride (BN), which has excellent thermal conductivity, even better than graphite, and has good stability at high temperature without decomposition or transformation. Using acrylamide (AM) and carboxymethyl chitosan (CMCS) to build a double network structure, soaking in Ferric chloride hexahydrate (FeCl₃ · 6H₂O) solution, and adding hydroxylated boron nitride (OH-BNNS) as heat conduction application, PAM/CMCS-Fe³⁺/OH-BNNS composite hydrogel was prepared by two-step method. The structure of the hydrogel was characterized by scanning electron microscope and Fourier transform infrared spectrometer, and its mechanical properties and self-recovery properties were tested by electronic universal material testing machine. Finally, its thermal conductivity was tested by thermal conductivity tester and thermal infrared imager. Results show that the composite hydrogel has excellent flexibility, great thermal conductivity, water absorption, great mechanical strength and self-recovery performance. By simply changing the amount of OH-BNNS, the mechanical and thermal responses of the composite hydrogel are significantly enhanced, and its thermal conductivity could reach 0.514 W/(m·℃) at the maximum.