Degradation and selective-oxidization of chitosan realize preparation of cotton textiles with prominent antibacterial and antiviral activity via one-step esterification

As a ubiquitous daily necessity, cotton textiles (CTs) provide favorable conditions for microbial growth under suitable temperatures and humidity. For endowing CTs with antibacterial and antiviral activity and durability in an environmentally friendly way, the chitosan-based antibacterial agent was introduced onto the CTs via one one-step esterification reaction. Specifically, the natural long-chain chitosan (CS) was degraded and selectively oxidized through an H 3 PO 4 /HNO 3 -NaNO 2 system to be short-chain oxidized chitosan (OCS) that can provide carboxyl groups reacting directly with hydroxyl on cotton cellulose. OCS with a molecular weight (MW) of 17000 Da and carboxyl content of 29.5 % was proved to be the most active antibacterial agent and endowed the OCS conditioned CTs (OCS-CTs) with excellent antibacterial and antiviral activity ( S. aureus : 100 %, E. coli : 100 %, MS2: 99 %). Besides, benefitting from the stable ester bond, the OCS-CTs showed durable antibacterial properties. More importantly, the modification also makes the OCS-CTs show comparable tensile strength and improved slipperiness, drapeability, and air permeability. This work provides a facile method to prepare an effective chitosan-based antibacterial-antiviral agent with active C O groups, endowing the condition of CTs in one step, which is significant for textile functionalization.