Multifunctional PEEK-TiO₂ fibers: correlating mechanical deformation with optical anisotropy and antimicrobial efficacy

This study investigates the opto-mechanical properties and antimicrobial efficacy of PEEK fibers surface-modified with TiO₂ nanoparticles through cold-drawing processes. Michelson interferometry with Hilbert transform phase demodulation quantified spatially resolved refractive index distributions and birefringence evolution during mechanical deformation. TiO₂ grafting enhanced the extraordinary refractive index from 1.923 to 1.931 and increased birefringence from 0.31 to 0.312 in undrawn fibers, indicating nanoparticle-induced molecular alignment. TiO₂-grafted fibers demonstrated remarkable mechanical enhancement, achieving maximum draw ratios of 3.0 versus 2.0 for pristine PEEK. At maximum deformation, extraordinary refractive indices reached 1.992 with birefringence values of 0.458, representing 37% enhancement over unmodified fibers. This superior performance resulted from nanoparticle-mediated stress distribution promoting homogeneous deformation. Antimicrobial testing against four pathogenic strains showed 54.9–69.4% inhibition for undrawn fibers, enhanced to a 91.5% maximum through cold-drawing at optimal ratios of 2.4–2.6. The multifunctional TiO₂-PEEK fibers demonstrate promising biomedical potential, combining superior mechanical and antimicrobial properties. The synergistic combination of enhanced mechanical properties, tunable optical anisotropy, and potent antimicrobial activity positions TiO₂-grafted PEEK fibers as promising multifunctional materials for biomedical applications.