Synergistic design of ceramizable and ablation-resistant shape memory oxide-filled phenolic composites for self-adaptive thermal deformation

Rapid advancement of deep-space exploration vehicles places increasing demands on smart thermal deformation materials for high efficiency, adaptability, and stability. To solve the shape instability in smart deformable materials at elevated temperatures, a shape memory ceramizable phenolic composite (SMCPC) is proposed by synergistically incorporating the inorganic fillers into a phenolic–boric acid copolymer network. Linear phenolic segments and boric acid serve as the reversible and fixed phases respectively, providing excellent shape memory behavior with a shape recovery rate of 93%. While inorganic functional fillers are employed to trigger high-temperature ceramization, enabling rapid transition from a polymeric system to a mechanically robust ceramic structure. The oxide-filled phenolic composite exhibits a high char yield of 71.7% at 1000 °C, leading to a relative 37.9% increase of the phenolic matrix. At elevated temperatures, the carbonized phenolic matrix promotes thermochemical reduction of oxides, forming a multiphase ceramic framework composed of metal carbides, residual oxides, and graphitized carbon that endows the composite with excellent ablation resistance. Finally, the composite containing 24 wt% HfO₂ exhibits the lowest mass ablation rate of 0.038 g/s, representing a 69.8% reduction compared with the phenolic matrix. Although the material systems show a relative brittleness, the established new strategy of “deformation–recovery–ceramization” enables the potential application of shape memory polymers in extreme environments.