Single‐Chain Inherent Elasticity Reveals γ‐Irradiation–Induced Backbone Reconstruction in Poly(Vinylidene Fluoride)

ABSTRACT

γ‐Irradiation significantly alters the mechanical properties and functions of poly(vinylidene fluoride) (PVDF), yet the molecular mechanism underlying its property evolution at high irradiation dose remains unclear. Because the single‐chain inherent elasticity of a polymer directly reflects its backbone structure, single‐molecule force spectroscopy (SMFS) was employed to examine PVDF under different γ‐irradiation doses. The results show a progressive increase in chain flexibility with increasing dose. Fourier‐transform infrared spectroscopy and X‐ray photoelectron spectroscopy reveal the formation of oxygen‐containing groups accompanied by C═C bonds. By quantitatively correlating SMFS measurements with theoretical elasticities derived from quantum mechanical calculations, we provide the first single‐molecule‐level evidence that prolonged high‐dose irradiation (2000 kGy) reconstructs the PVDF backbone into an alternating ether (C─O─C) and double‐bond (C═C) architecture. This work establishes a direct link among irradiation dose, backbone transformation, and mechanical response, offering molecular insight into the irradiation regulation of PVDF for applications in extreme radiation environments.