Photo-thermal and temperature-regulated sodium alginate-g-mPEG/carbon nanotube hybrid fibers with improved tensile strength

Despite the remarkable potential of phase change fibers for energy storage, their practical deployment has been hindered by two crucial challenges: inadequate external thermal stimulation to induce phase transition and leakage of the phase-change material. In this study, we successfully incorporated carbon nanotubes (CNTs) into a solution of sodium alginate grafted polyethylene glycol monomethyl ether (SA-g-mPEG) and utilized wet spinning processing to fabricate CNTs/SA-g-mPEG hybrid fibers with enhanced photo-thermal conversion and robust solid-solid phase change capabilities. Upon exposure to sunlight for merely 60 s, the hybrid fibers achieved a remarkable peak temperature of 40 °C. Upon cessation of sunlight exposure, these fibers demonstrated a gradual release of thermal energy, thereby underlining their exceptional photothermal conversion and temperature regulation capabilities. Furthermore, DSC analysis revealed that, at an optimal grafting ratio of 36.6 %, the hybrid fibers exhibited ΔHc and ΔHm values of 48.23 J/g and 50.83 J/g, respectively. Notably, hybrid fibers with a grafting ratio of 20.2 % demonstrated substantial enhancements in tensile properties, achieving a maximum breaking strength of approximately 2.02 cN/dtex—an impressive 11.3 % increase compared to SA-g-mPEG composite fibers. Our findings suggest that CNTs/SA-g-mPEG hybrid fibers hold immense promise for applications in body heat storage, fabric temperature regulation, and related fields.