Guivier Manon, Chevigny Chloé, Domenek Sandra, Casalinho Joel, Perré Patrick, Almeida Giana
Université Paris-Saclay, INRAE, AgroParisTech, UMR SayFood, 91120, 22 Place de l'Agronomie, Palaiseau, France.
CentraleSupélec, Laboratoire de Génie des Procédés et Matériaux, Université Paris-Saclay, 91190, Gif-Sur-Yvette, France.
Sci Rep. 2024 Jan 2;14(1):50. doi: 10.1038/s41598-023-50298-8.
To enhance PLA gas barrier properties, multilayer designs with highly polar barrier layers, such as nanocelluloses, have shown promising results. However, the properties of these polar layers change with humidity. As a result, we investigated water transport phenomena in PLA films coated with nanometric layers of chitosan and nanocelluloses, utilizing a combination of techniques including dynamic vapor sorption (DVS) and long-term water vapor adsorption-diffusion experiments (back-face measurements) to understand the influence of each layer on the behavior of multilayer films. Surprisingly, nanometric coatings impacted PLA water vapor transport. Chitosan/nanocelluloses layers, representing less than 1 wt.% of the multilayer film, increased the water vapor uptake of the film by 14.6%. The nanometric chitosan coating appeared to have localized effects on PLA structure. Moreover, nanocelluloses coatings displayed varying impacts on sample properties depending on their interactions (hydrogen, ionic bonds) with chitosan. The negatively charged CNF TEMPO coating formed a dense network that demonstrated higher resistance to water sorption and diffusion compared to CNF and CNC coatings. This work also highlights the limitations of conventional water vapor permeability measurements, especially when dealing with materials containing ultrathin nanocelluloses layers. It shows the necessity of considering the synergistic effects between layers to accurately evaluate the transport properties.
为提高聚乳酸（PLA）的气体阻隔性能，采用具有高极性阻隔层（如纳米纤维素）的多层设计已显示出有前景的结果。然而，这些极性层的性能会随湿度变化。因此，我们研究了涂有壳聚糖纳米层和纳米纤维素的PLA薄膜中的水传输现象，利用包括动态蒸汽吸附（DVS）和长期水蒸气吸附 - 扩散实验（背面测量）等技术组合，以了解各层对多层薄膜行为的影响。令人惊讶的是，纳米涂层影响了PLA的水蒸气传输。壳聚糖/纳米纤维素层占多层薄膜不到1 wt.%，却使薄膜的水蒸气吸收增加了14.6%。纳米壳聚糖涂层似乎对PLA结构有局部影响。此外，纳米纤维素涂层根据其与壳聚糖的相互作用（氢键、离子键）对样品性能表现出不同影响。带负电荷的羧甲基纤维素纳米纤维（CNF TEMPO）涂层形成了一个致密网络，与CNF和纤维素纳米晶（CNC）涂层相比，对水吸附和扩散表现出更高的抗性。这项工作还突出了传统水蒸气透过率测量的局限性，特别是在处理含有超薄纳米纤维素层的材料时。它表明考虑层间协同效应以准确评估传输性能的必要性。
