Water-induced modulus changes of bio-based uncured nanocomposite film based on natural rubber and bacterial cellulose nanocrystals

Bacterial cellulose whiskers (BCWs) were firstly incorporated into natural rubber (NR) by an evaporation method. The structure, morphology, dynamic mechanical properties, water uptake and water-responsive behavior of modulus for NR/BCWs nanocomposite films were investigated. It was found that the hydrophilic BCWs generated a significant reinforcement effect on the storage modulus of NR. In the presence of water, the nanocomposite films showed a pronounced response in storage modulus, especially for the nanocomposite filled with highest filler content. The storage modulus of films with 20 phr (parts per hundred rubber) BCWs decreased by 95.3% after equilibrium swelling in water. This modulus change behavior was attributed to the disentanglement of hydrophilic filler network via competitive hydrogen bonding with water. NR/BCWs nanocomposite film could be used as a new type of shape-memory material for biomedical applications.