 FRET efficiency map revealing the interphase in epoxy/NFC composite (left image), and color composite image from donor (blue) and acceptor (green) fluorescence in epoxy/NFC composite (right image).Composites have percolated into a wide range of material applications, ranging from vehicle light weighting to construction materials. With an increase in demand comes the need for more sustainable sources of components for composites. Understanding the components' interactions at the interphase in composites will help target possible sources for both the reinforcing and matrix portion when designing a composite. F�rster Resonance Energy Transfer (FRET) imaging of a composite interphase was pioneered at the National Institute of Standards and Technology previously, through the dispersion of donor dye in a polymer matrix and covalent attachment of the acceptor dye to nanofibrillated cellulose (NFC). In this work, we examine the interphase of an epoxy/NFC composite using FRET. To this end, a donor fluorophore and acceptor fluorophore were covalently attached to the epoxy and NFC, respectively, (see Figure, right image) to prevent dye migration. The chemistry employed optimized spectral overlap, between the donor emission and acceptor absorbance, to maximize energy transfer efficiency at the interphase. Because the dyes are anchored to each phase, an increase in FRET signal is expected where the two phases are more intimately mixed (see Figure, left image). Here we investigated the FRET response to changes at the interphase caused by mechanical and thermal stresses.

Study of dynamics at a composite interphase as a result of applied stress using FRET

247th National Meeting (2014)

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