Plant-Derived Polyphenols as Potential Cross-Linking Agents for Methylcellulose-Chitosan Biocomposites

Abstract

Blending of two polymers can result in a number of new composite materials with enhanced properties and applications in several fields. Biopolymers need to be crosslinked in order to modulate their general properties. Chemical crosslinking is a highly versatile method and is generally carried out using aldehydic compounds. Although these are very good cross-linkers, they are not preferred owning to their physiological toxicity. Therefore, the search for natural crosslinking agents is of great interest. Possible candidates are polyphenols, which are widely distributed as minor but functionally important constituents of plant tissues. Thus, this work investigated the use of polyphenols as natural cross-linking agents to produce new materials, namely methylcellulose-chitosan (MC-CS) biocomposites. Two plant–derived polyphenols, i.e. gallic acid (GA) and ferulic acid (FA), were studied as cross-linking agents. FT-IR, DSC, and SEM techniques were used to investigate the formation of the biocomposites. The results showed that only FA can interact with methylcellulose and chitosan as it formed turbid appearance when the clear solutions of MC and plant–derived polyphenols were mixed. The particle size of MC-FA was in the range of 500-600 nm when using 0.5% of polymer and polyphenol compounds. The CS-FA composite possessed relatively large size (6-8 µm) compared to that of the MC one. SEM analysis showed the differences in surface morphology between the cross-linked MC-CS biocomposites and the polymers. The FT-IR and DSC results also indicated that new compounds were formed.