Aligned Bacterial Cellulose Arrays as "Green" Nanofibers for Composite Materials

Conventional bacterial cellulose (BC) membranes are formed by randomly aligned nanofibrils stacked in a reticulated fashion. While such membranes are used in many applications, full utilization of the mechanical properties of nanofibrils has not been achieved in composite materials because of their random alignment. In the present research, aligned BC, in the form of arrays, has been developed through an optimally designed polydimethylsiloxane grating substrate placed at the air-liquid interface of the culture medium. The substrate prepared with the help of a 3-D printed mold served as an alignment template providing bacteria a preferred direction for BC growth. Additional alignment in BC arrays was obtained by stretching the hydrogel at a controlled strain rate and strain ratio. The degree of orientation, Young's modulus, and tensile strength of aligned BC arrays increased by approximately 184, 409, and 256%, respectively, compared to the conventional BC pellicle. Such aligned BC arrays could open up future opportunities to design lightweight advanced "green" composites as alternatives to petroleum-based composites for a range of technical applications.