Collagen-Assisted Fabrication of Polyacrylonitrile Porous Fibers: Structural Regulation and Thermal Insulation Performance

Polyacrylonitrile (PAN) fibers have promising applications in lightweight thermal insulation materials; however, constructing porous PAN fibers with uniform pore structures and good mechanical properties remains challenging. In strong coagulation systems such as water, PAN tends to undergo rapid nonsolvent-induced phase separation, leading to nonuniform structures with finger-like pores. Herein, a collagen-assisted strategy was proposed to regulate the PAN fiber-forming process and promote porous structure development. PAN/Col porous fibers were prepared by dry-wet spinning combined with glycerol/DMSO precoagulation and subsequent solvent exchange. The introduction of collagen reduced the viscosity of the spinning dope and promoted chain relaxation, providing a rheological basis for regulating fiber microstructure formation. An appropriate collagen content of approximately 10% favored the formation of a uniform and interconnected sponge-like porous structure, whereas excessive collagen caused pore coarsening and local framework collapse. FTIR, protein content, and thermogravimetric analyses suggested that most collagen was removed during coagulation, washing, and solvent exchange, and the final fibers were mainly composed of a PAN framework. Among the samples, PAN/Col-10% exhibited the best overall performance, with a specific surface area of 16.10 m2·g−1, a tensile strength of 23.31 MPa, and good structural integrity. The corresponding fabric showed a low density of 0.149 g·cm−3 and a low thermal conductivity of 0.030 W·m−1·K−1, confirming its thermal insulation potential. This study provides a collagen-assisted route for regulating PAN porous fiber formation and developing lightweight PAN-based thermal insulation fibers through coupled rheological, structural, and performance control.