Reduced graphene oxide and PEG-grafted TEMPO-oxidized cellulose nanocrystal reinforced poly-lactic acid nanocomposite film for biomedical application

In this work, both cellulose nanocrystals (CNC) and reduced graphene oxide (rGO) were reinforced into polylactic acid (PLA) to enhance the stiffness, strength and thermal stability of the pure polymer i.e. PLA. To enhance the uniform dispersion of CNC (which is a major concern with PLA) and rGO in the hydrophobic polymer, matrix, CNC's surface was first modified using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation method followed by surface grafting of TEMPO-oxidized CNC (TOCNC) performed with polyethylene glycol (PEG). The PEG-grafting on crystalline region of cellulose nanofibrils was achieved through ionic bonds by applying ionexchange method (simple and easy method). The obtained PEG-grafted-TOCNC indicated uniform dispersion at the nanoelement level in non-polar (organic) compound i.e. chloroform. Further, the PEG-grafted-TOCNC/chloroform with different blend ratios, PLA/chloroform and rGO/chloroform solution were mixed together and solvent casted onto a petri-dish to obtain PLA/PEG-TOCNC/rGO nanocomposite film. The tensile strength and thermal stability were remarkably improved for the film containing highest wt% of modified CNC. In addition to this, the film showed reduced water vapor barrier properties and antioxidant activity which enables it to be used as a packaging films. Moreover, the film displayed negligible toxicity and cytocompatibility to fibroblast cells C3H10T1/2. These attractive properties of PLA/PEG-TOCNC/rGO nanocomposite film render the application of film as a scaffold in tissue engineering field and in packaging application.