Preparation method of composite films based on cellulose nanocrystals, cellulose nanofibers and reduced graphene oxide

A method for preparing a composite film based on reduced graphene oxide, cellulose nanocrystals, and cellulose nanofibers, comprising:

• in step (1), mixing graphite, potassium nitrate, potassium permanganate, and sulfuric acid in an ice water bath and stirring evenly to obtain a mixture, and transferring the mixture to a warm water bath perform a reaction;
• subsequently, adding deionized water to a reaction system including the mixture, increasing a temperature of the water bath, and stirring;
• finally, lowering the temperature of the water bath, adding hardwood microcrystalline cellulose, and stirring;
• adding hydrogen peroxide solution after stirring to terminate the reaction to obtain a suspension mixed with graphite oxide and cellulose;
• in step (2), centrifuging the suspension obtained in the step (1) and washing a sediment after centrifuging with deionized water to obtain a solution, homogenizing the solution in a high-pressure homogenizer to obtain a suspension mixed with graphene oxide, cellulose nanocrystals, and cellulose nanofibers;
• in step (3), drying the suspension mixed with graphene oxide, cellulose nanocrystals, and cellulose nanofibers in a petri dish to obtain a dried film, and soaking the dried film in a hydroiodic acid solution to obtain reduced graphene oxide, cellulose nanocrystals, and cellulose nanofibers to obtain a soaked film;
• and
• washing the soaked film with deionized water to obtain the composite film based on the reduced graphene oxide, the cellulose nanocrystals, and the cellulose nanofibers, wherein a mass ratio of the reduced graphene oxide, the cellulose nanocrystals, and the cellulose nanofibers in the composite film in the step (3) is 1:0.1-1:0.1-2.