Department of Chemistry, Faculty of Sciences, University of Navarra, 31080 Pamplona, Spain.
Int J Mol Sci. 2021 Feb 24;22(5):2257. doi: 10.3390/ijms22052257.
Polymeric materials, such as polyvinyl alcohol (PVA) and ethylene-PVA copolymers (EVOH) are widely used in the food sector as packaging materials because of their excellent properties. TiO nanoparticles (NPs) show photocatalytic activity; when added to the aforementioned polymers, on the one hand, they are expected to provide bactericidal capacity, whereas on the other hand, they could favor nanocomposite degradation. These types of nanoparticles can be derivatized with cyclodextrin macromolecules (CDs), which can act as food preservative carriers, increasing the packaging food protective properties. In this work, films containing β-Cyclodextrin (βCD)-grafted TiO nanoparticles and PVA or EVOH were prepared. Regarding the photocatalytic activity of the nanoparticles and the possible environmental protection, accelerated aging tests for PVA, EVOH, and their composites with cyclodextrin-grafted TiO nanoparticle (NP) films were performed by two methods, namely, stability chamber experiments at different conditions of temperature and relative humidity and UV light irradiation at different intensities. After analyzing the systems color changes (CIELAB) and Fourier transform infrared spectroscopy (FTIR) spectra, it was observed that the film degradation became more evident when increasing the temperature (25-80 °C) and relative humidity percentage (28-80%). There was no significant influence of the presence of CDs during the degradation process. When irradiating the films with UV light, the largest color variation was observed in the nanocomposite films, as expected. Moreover, the color change was more relevant with increasing NP percentages (1-5%) due to the high photocatalytic activity of TiO. In addition, films were characterized by FTIR spectroscopy and variation in the signal intensities was observed, suggesting the increase of the material degradation in the presence of TiO NPs.
高分子材料，如聚乙烯醇（PVA）和乙烯-聚乙烯醇共聚物（EVOH），由于其优异的性能，被广泛应用于食品包装材料。TiO2 纳米粒子（NPs）具有光催化活性；当添加到上述聚合物中时，一方面，它们有望提供杀菌能力，另一方面，它们可能有利于纳米复合材料的降解。这些类型的纳米粒子可以与环糊精大分子（CDs）衍生化，CDs 可以作为食品防腐剂载体，增加包装食品的保护性能。在这项工作中，制备了含有β-环糊精（βCD）接枝 TiO2 纳米粒子的 PVA 或 EVOH 薄膜。关于纳米粒子的光催化活性和可能的环境保护，通过两种方法对 PVA、EVOH 及其与环糊精接枝 TiO2 纳米粒子（NP）薄膜的复合材料进行了加速老化试验，即不同温度和相对湿度条件下的稳定性室实验和不同强度的紫外光照射。分析系统的颜色变化（CIELAB）和傅里叶变换红外光谱（FTIR）谱后，观察到随着温度（25-80°C）和相对湿度百分比（28-80%）的升高，薄膜降解变得更加明显。在降解过程中，CD 的存在没有显著影响。用紫外光照射薄膜时，纳米复合材料薄膜观察到最大的颜色变化，这是预期的。此外，随着 NP 百分比（1-5%）的增加，颜色变化更为显著，这是由于 TiO2 的高光催化活性。此外，还对薄膜进行了傅里叶变换红外光谱（FTIR）表征，观察到信号强度的变化，表明在 TiO2 NPs 的存在下，材料的降解增加。
