Effect of remote Plasma assisted WPU/CNF multilayer coating assembly on PLA film properties

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 688; p. 133519
• Main Authors: Yang, Xin, Li, Ru, Liu, Naiyu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05-05-2024
• Subjects: Barrier properties; Hydrophilic properties; Layer-by-layer self-assembly; Polylactic acid films; Remote plasma; Barrier properties; Remote plasma; Polylactic acid films; Hydrophilic properties; Layer-by-layer self-assembly
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2024.133519

Disadvantages such as poor toughness, brittleness, and poor barrier properties of polylactic acid (PLA) films limit their application in packaging materials. To ameliorate this problem, in this paper, remote plasma was first employed to improve the hydrophilic properties of PLA films, followed by the layer-by-layer self-assembly (LBL) method to assemble alternate layers of cationic waterborne polyurethane (WPU) and carboxylated nanofibrillated cellulose (CNF) on the surface of the remotely plasma-modified PLA films. The results showed that the best hydrophilicity of PLA films was achieved at the modification time of 180 s, pressure of 25 Pa, RF power of 100 W, and axial distance of 10 cm. With the increase of the number of WPU/CNF assembled layers, the oxygen transmission rate （OTR） and the water vapor transmission rate (WVTR) of PLA film decreased; when assembled to 12 layers, the OTR of PLA film decreased from 695 cm3/(m2dbar) to 3.15 cm3/(m2dbar), and the WVTR decreased from 150.50 g/(m2.24 h) to 55.41 g/(m2.24 h), under these conditions the composite PLA film can be used for packaging meat and other foods sensitive to moisture and oxygen. At the same time, the thermal stability and elongation at the break of PLA films increased with the increase in the number of coated layers. When assembled to 12 layers, the residual rate at 600 °C increased from 2.78% to 10.4%, and the elongation at break increased from 2.04% (transverse) and 2.48% (longitudinal) to 3.449% (transverse) and 5.133% (longitudinal).
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