Department of Wood and Paper Science, Kyungpook National University, Daegu 41566, Republic of Korea.
Department of Wood and Paper Science, Kyungpook National University, Daegu 41566, Republic of Korea.
Carbohydr Polym. 2021 Dec 1;273:118550. doi: 10.1016/j.carbpol.2021.118550. Epub 2021 Aug 11.
This study developed pH-indicator films by combining esterified cellulose nanocrystals (e-CNCs) with activated bromocresol purple (a-BCP) via covalent bonding for pH-sensitive color-changing applications. The e-CNC/a-BCP particles were incorporated into cellulose acetate polymer to prepare pH-sensitive color changing films. Binding of a-BCP to e-CNCs was proven by attenuated total reflection infrared (ATR-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Colorimetric analysis showed that films containing 10% or 15% e-CNC/a-BCP particles had critical color changes either at pH 4-5, or pH 7-8. The films with 10% e-CNC/a-BCP particles also revealed excellent leaching resistance under acidic conditions. Color changes were reversible between pH 2 and 10. These pH-indicator films had visible color changes in response to pH variations, color reversibility, leaching resistance, and sufficient rigidity even though mechanical properties decreased as the e-CNC/a-BCP content increased from 0% to 15%.
本研究通过共价键将酯化纤维素纳米晶体（e-CNC）与活性溴甲酚紫（a-BCP）结合，制备了 pH 指示剂薄膜，用于 pH 敏感的变色应用。将 e-CNC/a-BCP 颗粒掺入醋酸纤维素聚合物中，制备 pH 敏感的变色薄膜。ATR-IR 和 XPS 光谱证明了 a-BCP 与 e-CNC 的结合。比色分析表明，含有 10%或 15%e-CNC/a-BCP 颗粒的薄膜在 pH 4-5 或 pH 7-8 时具有临界颜色变化。含有 10%e-CNC/a-BCP 颗粒的薄膜在酸性条件下也表现出优异的抗浸出性。颜色变化在 pH 2 到 10 之间是可逆的。这些 pH 指示剂薄膜在响应 pH 变化、颜色可逆性、抗浸出性和足够的刚性方面具有明显的颜色变化，尽管随着 e-CNC/a-BCP 含量从 0%增加到 15%，力学性能有所下降。
