Improving the Metal Ion Release from Nanoparticles Embedded in a Polypropylene Matrix for Antimicrobial Applications

Novel antimicrobial materials can be produced by adding copper nanoparticles (CNPs) into a polymeric matrix. To improve the behavior of these systems, the effect of different variables on the dispersion of copper metal nanoparticles embedded in a polypropylene matrix by melt mixing and its ion release was analyzed. The variables studied were predispersion of particles in liquid solvents, polymer molecular weight, melt mixing conditions, addition of a compatibilizer agent, two-step melt mixing, and surface functionalization of the metal particles. Our results show that by modifying these variables, a significant improvement in the filler dispersion, as quantified by optical microscope, can be obtained. For instance, the original CNP agglomerates can be reduced from an average size of 70 mu m to a final average size of 30 mu m and a larger amount of nanometric agglomerates by using a compatibilizer or predispersed nanoparticles. Moreover, by using surface-functionalized CNPs, micrometric agglomerates were not observed. Noteworthy, there is a direct relationship between the filler dispersion and the release of biocide copper ions when improvements were larger than a certain threshold with increases as high as 40%. These findings can be used in the development of antimicrobial materials with tailored behavior. (C) 2014 Wiley Periodicals, Inc.