Sulphur-containing phenylethynyl terminated polyimide via chemical crosslinking method for excellent thermal properties and antibacterial performance

Thermal stability and antibacterial property of polyimide have emerged as two significant property parameters when used in the aerospace field. In this work, sulphur-containing linkage is introduced into the polyimide by using phenylethynyl terminated imide oligomers (PETI) and sulphur agent. The curing properties of this new type of thermosetting polyimide were studied by Fourier transform infrared (FTIR) and Raman spectra, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). The sulphur-containing polyimide shows a unique thermoplastic-like glass transition behavior rather than typical thermoset behavior. Its film material shows the tensile strength and modulus of 59.46 MPa and 1767 MPa respectively, which have increased to 187.68% and 155.16% when compared with the control sample cured at 381 °C. And the mechanical retention rates of tensile strength and modulus reach 96.8% and 82.1% respectively after 371 °C/100 h aging. In addition, it shows potential value in the fabrication of carbon fiber reinforced composite and antibacterial materials. Though the curing temperature of PETI oligomer decreases from 381 °C to 300 °C, the prepared PI/CF composite shows excellent mechanical performance, and the interlaminar shear strength, the flexural strength, and the flexural modulus reach 104.53 MPa, 1846.71 MPa and 129.24 GPa, respectively. Also, the novel polyimide shows excellent antibacterial performance, with antibacterial retention rate to negative E. coli and positive S. aureus of 90.4% and 89.1%, respectively.