Cellulose: a study of drying method selection based on the structure and property changes

The structural and mechanical properties of cellulose and its derivatives are critically influenced by the drying method employed. This study provides a comprehensive evaluation of six drying methods—TBA freeze-drying (T), supercritical CO₂-drying (S), freeze-drying (F), vacuum-drying (V), oven-drying (O), and microwave-drying (M) for processing bacterial cellulose (BC) hydrogels. Multimodal characterization revealed that cold-assisted methods (T, S, F) effectively preserved the nanofibrillar network, porosity, and polymerization degree (DP) of BC. TBA freeze-drying yielded aerogels with the highest specific surface area (79.31 m²/g) and most uniform pore structure, while freeze-drying minimized DP degradation. In contrast, thermal-assisted methods (V, O, M) induced structural collapse, pore reduction, and severe cellulose chain scission, particularly under microwave drying. Regenerated cellulose fibers (RCFs) produced from TBA freeze-dried and freeze-dried BC exhibited superior mechanical performance. This work underscores the profound impact of drying protocols on BC’s properties and offers practical guidance for selecting appropriate drying strategies based on application-specific requirements.