Preparation of nonwoven polyimide/silica hybrid nanofiberous fabricsby combining electrospinning and controlled in situ sol-gel techniques

摘要

A controlled in situ sol-gel synthesis combined with the electrospinning technique andpostspun imidization was applied in the fabrication of polyimide/silica hybrid nonwovennanofiberous fabrics with excellent thermal and mechanical performance. The nanofiber-ous fabrics were prepared by electrospinning of the solution of tetraethoxysilane (TEOS)and polyamic acid (PAA). The different silica contents in the fabrics were achieved by vary-ing the amount of TEOS while fitting the solid content of PAA. The final polyimide/silicafabrics was obtained after imidization of PAA and gelation of silica phase simultaneouslyaccomplished through a step-wise heating process. Some specific 1R techniques and othercharacterizations indicated the successful incorporation of the silicon dioxide (SiO_2) intothe P1 matrix and the relatively even distribution of the SiO_2 in the fabrics. An increaseof 133 °C in the decomposition temperature and 4-fold enhancement of the ultimate ten-sile strength were achieved for the hybrids with a 6.58 wt.% of SiO_2content, compared tothe pure PI fabric. The excellent performance could be attributed to the good compatibilitybetween the polyimide and silica, and good adhesion among the fibers, which resultedfrom the controlled TEOS hydrolysis and the simultaneous imidization and gelationprocess.