Preventing the collapse of 3D bacterial cellulose network via citric acid

Bacterial cellulose (BC) is a three-dimensional interconnected network of biosynthesized nanofibers. Its rehydration potential would be reduced significantly after its first drying, as a result of entanglement and jamming of cellulose polymer chains. Consequently, its versatility would be also reduced to some limited applications in which repeated water absorbance potential is not of great importance. This study aims to prevent the drawback of carboxylic bridging/cross-linking between cellulose polymer chains. Ten-day-cultured BC pellicles were immersed in various citric acid solutions (as bridging agent) and cured at 160 °C for 5 min. The formation of bridges was confirmed using attenuated total reflection–fourier transform infrared spectroscopy. Scanning electron microscope images showed that there is a different porosity bridged/cross-linked BC specimens (XBC). According to Brunauer–Emmett–Teller analysis, the surface area of XBC (20 w/v % with catalyst) got 87.5 times larger than that of the unbridged/pristine BC (PBC). X-ray diffraction patterns showed no change of crystallinity of XBC in comparison with PBS. The thickness and wettability of XBC samples were 137 and 3.27 times more than PBC samples orderly. Furthermore, the water swelling rate increased significantly for XBC in comparison with PBC. Meanwhile, treated samples had lower elongation and strength than normal BC. The conclusion is that XBC could conserve its repeated absorbency potential after the presented process.