Copolymerization of Phase Change Materials with Water Resistance Poly(Acrylamide‐Co‐Polyacrylic Acid) Copolymer Encapsulation: Photothermal Conversion and Storage Performance Under Solar Conditions

Currently, the majority of composite phase change materials (PCM) are only available in solid‐phase environments. Therefore, it is important to prepare composite PCM with photothermal conversion capacity, high thermal conductivity, and stability in both solid and aqueous phase conditions. Herein, a composite PCM with high photothermal conversion storage efficiency (92.6%), high energy storage density (147.6 J g −1 ), and high thermal conductivity (1.19 W m −1 K) is prepared using poly(acrylamide ‐co ‐polyacrylic acid) copolymer (PAAAM) as the supporting material, boron nitride as the high thermal conductivity filler, and carboxyl‐rich carbon as the photothermal conversion agent and key bridge. With the help of the characteristics of PAAAM, although the PAAAM chain is swollen not broken, it still maintains cross interconnection with PCM in the water‐phase environment, which has excellent encapsulation performance in both the water/solid phase environment. This provides another option for broadening the application of PCM in aqueous solvent conditions.