Journal Article

Fabrication of Zwitterionized Nanocellulose/Polyvinyl Alcohol Composite Hydrogels Derived from Camellia Oleifera Shells for High-Performance Flexible Sensing

Lei, Zhendong, Jian, Jialin, Li, Jingnan, Wu, Yuming, Han, Shuaiyuan, Cong, Jie, Peng, Weikang, Su, Jiaqi, Zhao, Chenyang

2025

Overview

To address the growing demand for environmentally friendly flexible sensors, here, a composite hydrogel of nanocellulose (NC) and polyvinyl alcohol (PVA) was designed and fabricated using Camellia oleifera shells as a sustainable alternative to petroleum-based raw materials. Firstly, NC was extracted from Camellia oleifera shells and modified with 2-chloropropyl chloride to obtain a nanocellulose-based initiator (Init-NC) for atomic transfer radical polymerization (ATRP). Subsequently, sulfonyl betaine methacrylate (SBMA) was polymerized by Init-NC initiating to yield zwitterion-functionalized nanocellulose (NC-PSBMA). Finally, the NC-PSBMA/PVA hydrogel was fabricated by blending NC-PSBMA with PVA. A Fourier transform infrared spectrometer (FT-IR), proton nuclear magnetic resonance spectrometer (1H-NMR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), universal mechanical testing machine, and digital source-meter were used to characterize the chemical structure, surface microstructure, and sensing performance. The results indicated that: (1) FT-IR and 1H NMR confirmed the successful synthesis of NC-PSBMA; (2) SEM, TEM, and alternating current (AC) impedance spectroscopy verified that the NC-PSBMA/PVA hydrogel exhibits a uniform porous structure (pore diameter was 1.1737 μm), resulting in significantly better porosity (15.75%) and ionic conductivity (2.652 S·m−1) compared to the pure PVA hydrogel; and (3) mechanical testing combined with source meter testing showed that the tensile strength of the composite hydrogel increased by 6.4 times compared to the pure PVA hydrogel; meanwhile, it showed a high sensitivity (GF = 1.40, strain range 0–5%; GF = 1.67, strain range 5–20%) and rapid response time (<0.05 s). This study presents a novel approach to developing bio-based, flexible sensing materials.

• Publisher: MDPI AG,MDPI
• Subject: Alcohol industry / Alternating current / Ammonia / Caustic soda / Cellulose / Electric properties / Electrocardiography / Flexible components / Fourier transforms / FTIR spectrometers / Hydrogels / Infrared spectrometers / Infrared spectroscopy / Ion currents / Mechanical properties / Mechanical tests / Nanoparticles / Nanowires / Nitrogen / NMR / Nuclear magnetic resonance / Polymerization / Polyvinyl alcohol / Raw materials / Scanning electron microscopy / Sensors / Sodium / Solvents / Tensile strength / Transmission electron microscopes