Fabricating enduring fluorescence cotton fabric with the energy transfer effect of Eu-containing polyoxometalate

Abstract

The development of cotton fabrics with exceptional and durable fluorescent properties has garnered significant attention. In this study, an enduring fluorescence cotton fabric was fabricated by a convenient and efficient approach. Interestingly, carboxyl reactive groups were employed as bridging agents to covalently link the raw fabric with Europium (Eu)-based polyoxometalate, thus guaranteeing the tight bonds between the polyoxometalates and the fabric matrix. The morphology and microstructures of composite fabrics were characterized and compared, demonstrating the successful integration of polyoxometalates into the fabric featuring covalent bonding interactions. Additionally, the fluorescence emissions of composite fabrics were investigated (λ_ex = 243 nm). The emission spectrum exhibits typical emission peaks of Eu³⁺ and polyoxometalate, corresponding to the ⁵D₀ → ⁷F_0–4 transitions in the range of 550–750 nm and the O → W transition, which results in distinct red fluorescence. Moreover, the lifetime-decay behavior, monitored at an excitation wavelength of 243 nm, follows a single-exponential function, yielding a lifetime (τ) of 0.4 ms. More importantly, owing to the robust interaction between the components, the composite fabric demonstrates exceptional fastness properties, including resistance to washing (50 times washing), abrasion (under both dry and wet conditions), and sunlight (9 days). In particular, three kinds of shaped masks were used, highlighting its potential as a reusable anti-counterfeiting material. The plausible mechanisms of the system is attributed to the efficient electron transition and energy transfer processes within the composite structure. Besides, mechanical property reveal PW₁₁Eu@CF almost inherits the original fabric’s mechanical property. This work provides a novel strategy for the controlled design and fabrication of polyoxometalate-based anti-counterfeit material.