Towards antimicrobial polymer materials: A new niche for clay/polymer nanocomposites pp.567-592
Authors: (Rinat Nigmatullin, Fengge Gao, Viktoria Konovalova, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK, and others)
Abstract: Currently antimicrobial polymer materials are produced by either polymer compounding with inorganic or organic biocides or by coating polymer surfaces with biocidal molecules including chemical binding. The general problems with the additive approach are poor compatibility between many biocides and majority polymers, decreasing in mechanical and other major physical and engineering properties, biocide leaching, loss of the ntimicrobial activity and environmental and health risks due to leaching biocides. Coating especially via chemical binding can overcome many of these problems. However, it requires an additional materials treatment, which can result in nonuniform coatings, especially for articles of complex shapes. Therefore, in many applications it would be beneficial to make antimicrobial materials and commodities during the fabrication process. In this chapter, a robust processing of polymers into antimicrobial materials is introduced using polymer/clay nanotechnology. So far, the antimicrobial activity of commercially available organoclays modified with cationic surfactants has been overlooked. We have proven that commercially available organoclays modified with cationic surfactants are efficient against gram-negative E. coli and gram-positive S. aureus bacteria. Despite the leaching biocidal surfactants, cell interactions with organoclays surface have been identified to be responsible for antimicrobial activity of organoclays. Distribution of clay platelets within polymer matrix by melt extrusion process resulted in polymer/clay nanocomposites active against both gram-positeve and gram-negative bacteria by contact. Thus, organoclays modified with cationic surfactants are able to render polymer nanocomposites biocidal. However, the cationic surfactants used in the organoclay production migrate from the clays and nanocomposites.