**2.2. Preparation of QCS/AE/PVA composites**

An amount of PVA, AE, and QCS was dissolved in deionized (DI) water with a final concen‐ tration of 5% (m:v). The mass ratios of PVA, AE, and QCS in the PVA/AE/QCS (PAQ) mixture were selected at three levels which were 6:3:1 (PAQ1), 7:2:1 (PAQ2), and 8:1:1 (PAQ3). The mixture was poured into a mold with a depth of 0.5 mm and kept at 4°C for 4 h. The cold mixture was then frozen at ‐20°C for 4 h following a defrozen operation at room temperature for 4 h. This freezing‐defreezing operation was repeated three times until a homogeneous gel was achieved. Next, the gel was lyophilized and cut into an identical size for next studies.
