The global antimicrobial coatings industry was $1.6 billion in 2012, and increasing demand will drive it to $3.3 billion in 2018.1 Current antimicrobial coatings have significant shortfalls. First, none are truly broad-spectrum and able to kill bacteria, fungi, viruses and spores. This is important in the case of high-risk, high-touch surfaces that can have many different types of microorganisms living on them at different times. In some cases the antimicrobial activity against a single class of microorganisms is inadequate. Further, many of the currently used active ingredients in antimicrobial paints suffer from established microbial resistance. In addition, some active ingredients, including triclosan, quaternary ammonium compounds and silver, can drive antibiotic resistance. Last, the antimicrobial functions of current paints cannot be easily monitored, and once the paints are applied, the antimicrobial duration cannot be further extended if it is lost due to prolonged use, heavy soil, flooding, etc.
For these reasons, a novel latex polymer was developed in our lab by Drs. Yuyu Sun and Zhengbing Cao. This emulsion is intended to be used as a paint additive. The antimicrobial activity comes from N-halamine functional groups anchored to a polymer backbone. (An N-halamine is a compound containing one or more nitrogen-halogen covalent bonds that is formed by the chlorination of imide, amide or amine groups.) There are several advantages to this new additive. First, it has a broad spectrum and is effective against both gram-positive and gram-negative bacteria, viruses and fungi. Second, the antimicrobial function can be tested using potassium iodide. In addition, if the antimicrobial function is lost, it can be recharged using a dilute bleach solution.