The environmental release of model nanofillers (semiconductor nanocrystals) from free-standing polymer nanocomposite films

T.V. Duncan, K.V. Pillai, P. Gray, C-C Tien, R. Bleher, L-P Sung
U.S. Food and Drug Administration,
United States

Summary:

The development of polymer nanocomposite (PNC) technologies across numerous industries is accompanied by uncertainty with which engineered nanoparticles embedded within these materials may be released into the external environment, particularly liquid media. Recently, migration of nanoscale fillers from PNCs has been evaluated. Unfortunately, many studies investigating nanoscale filler migration rely on uncharacterized or proprietary materials and therefore making general conclusions about impact of factors, such as particle size, on release phenomena is difficult. We use a strategy that relies on quantum dots (QDs) as model nanoscale fillers to quantify potential release into liquid media under specific environmental conditions. We incorporated well-characterized QDs of various sizes and compositions into low-density polyethylene by melt compounding and extruded the mixtures as free-standing fluorescent films. These films were subjected to tests under conditions intended to simulate a “worst case scenario” for environmental release. Using a variety of chemical and materials analysis techniques, we were able to provide a unique look at the effect of the external medium chemistry, exposure time, and particle size/composition on release kinetics, as well as draw fundamental conclusions about the primary mechanism for release. Collectively, this work refines our general understanding of the potential migration of nanoparticles from PNCs in consumer products.