Synergistic effects of guanidine-grafted CMC on enhancing antimicrobial activity and dry strength of paper

• Carboxymethyl cellulose (CMC) was oxidized to form dialdehyde CMC (DCMC).
• Guanidine hydrochloride (GH) was grafted onto the DCMC to obtain DCMC-GH.
• The coating of DCMC-GH onto paper resulted in the improvement of paper strength.
• The DCMC-GH-coated paper exhibited excellent antimicrobial activities.

In order to improve the strength property and antimicrobial activity of paper simultaneously, we prepared a novel multifunctional agent based on carboxymethyl cellulose (CMC) by a simple two-stage method. The first stage was the oxidation of CMC to obtain the dialdehyde CMC (DCMC), and the second stage was the graft of guanidine hydrochloride (GH) onto DCMC to obtain DCMC-GH polymer. The strength property and antimicrobial activity of DCMC-GH-coated copy paper have been studied by the tensile test and inhibition zone method, respectively. The results showed that the dry strength index could increase about 20% after the paper was coated with DCMC-GH. The coating of DCMC-GH on paper also resulted in excellent antimicrobial activities against Escherichia coli and Staphylococcus aureus, and the inhibition zone became larger as the GH content grafted on DCMC increased. The novel DCMC-GH polymer would be a multifunctional coating agent for food packaging paper.