Pulsed light-induced molecular changes in carboxymethylcellulose films

Growing demand for sustainable materials has driven the use of biopolymers for films and coatings. Carboxymethylcellulose (CMC) is notable for its favorable properties and broad applicability. This study evaluated the effects of pulsed light (PL), a promising nonthermal technology for surface decontamination and macromolecule modulation, on the morphological, structural, and physicochemical properties of CMC films. Films were prepared by casting and exposed to 4, 8, 16, or 32 pulses (1.56 J/cm⁻² per pulse). Samples were then characterized for morphology, structure, and physicochemical properties. FTIR spectra showed minor changes in band intensity and definition with increasing pulses, especially in the 3000–3500 cm⁻¹ region associated with O–H stretching of hydroxyl groups involved in hydrogen bonding. Thermogravimetric analysis indicated a slight increase in thermal stability, reflected in higher end temperatures for the first and second degradation events (from 121.42 °C and 336.20 °C in the control to 140.41 °C and 346.97 °C after 32 pulses). X-ray diffractograms confirmed retention of the material’s amorphous character, with no evidence of crystallization or new structural phases even at higher pulse numbers. Physicochemical measurements revealed reduced moisture content (from 13.3% in the control to 12.6% after 32 pulses) and decreased water vapor permeability (WVP) from 3.15×10⁻¹⁰ to 2.83×10⁻¹⁰ g·m⁻¹·s⁻¹·Pa⁻¹. The results of the PL treatment applied to the biopolymer indicated that the evaluated properties didn´t show significant changes, with only slight variations observed, while structural integrity was maintained. Therefore, the integration of LP and CMC holds promising potential and technological relevance for the development and expansion of more sustainable food packaging and coatings.