Nonlinear imaging and vibrational spectroscopic
analysis of cellulosic fibres treated with COEX®
flame-retardant for tapestry preservation

Year: 2022

Authors: Dal Fovo A., Striova J., Quintero Balbas D., Mattana S., Tacconi N., Cicchi R., Fontana R.

Autors Affiliation: Consiglio Nazionale delle Ricerche – Istituto Nazionale di Ottica (CNR-INO), Largo
Enrico Fermi 6, 50125 Firenze, Italy.

Università degli Studi di Firenze, Viale delle Idee 24, 50019 Sesto Fiorentino, Italy

Abstract: Cellulose-based fabrics are widely used in the preservation and storage of historic tapestries. Their ease of
flammability is a serious concern that greatly limits their applications and requires the development of
effective and safe flame-retardant treatments. In this work, we analysed linen and cotton textile samples
before and after COEX® treatment, a patented green technology imparting anti-flame properties by
functionalizing the cellulose molecules with phosphorus and sulphur groups. Some of the samples were
also exposed to photo-induced ageing after the treatment. The resulting structural and chemical
changes in both fibres were characterized by nonlinear optical imaging modalities, namely Second
Harmonic Generation (SHG) and Two-Photon Excited Fluorescence microscopies (TPEF), and Raman
and Attenuated Total Reflection – Fourier Transform Infrared (ATR-FTIR) spectroscopies.
Complementary results evidenced a reduction in microfibril crystallinity, attributed mainly to the
reduction of hydrogen bonding among cellulose macromolecules, with a concomitant increase in
fluorescence possibly due to the introduction of ester groups into cellulose chains and to
decomposition of lignin into fluorescent by-products.

Journal/Review: RSC ADVANCES

Volume: 12      Pages from: 26744  to: 26752

KeyWords: cellulose; textiles; preservation; flame-retardant; SHG; TPEF; Raman spectroscopy
DOI: 10.1039/d2ra02384a

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