Advances in technology introduce new materials challenges that cannot be solved by using conventional materials. Combination of different materials (i.e. organic and inorganic) at nano scales creates hybrid materials with synergetic properties superior to original materials. One of the recent techniques to develop these materials utilizes infiltration of vapor phase reactive organometallic precursors into bulk polymer to react with the polymer functional groups. In this work organic-inorganic hybrid materials are formed within poly(ethylene terephthalate) (PET) by infiltration of trimethylaluminum (TMA) vapors and their optical properties are investigated. PET naturally doesn't absorb visible spectrum and exhibits photoluminescence by absorption of UV light through excitation of the p electrons on aromatic groups of the polymer. Upon TMA infiltration reactions taking place between C=O groups and TMA, create a PET-Alumina hybrid material which shows significant absorption of visible light in the blue spectrum. Furthermore, photoluminescence (PL) spectroscopy at 355 nm demonstrates that hybrid materials show an order of magnitude increase in the intensity of luminescence in addition to a red shift compared to the untreated PET.  Photoluminescence excitation (PLE) is conducted to investigate the bands as well as the mechanism of the excitation and emission within hybrid materials is varied as a result of the TMA exposure temperature. Measurement of the absorption and internal quantum efficiency (IQE) at some excitation wavelengths show absorptions reaching ~97% and 4-fold increase in IQE (up to 36%), providing evidence of electron-hole pairs in the hybrid material and that a portion of these excitons are remain with lifetimes longer than recombination. Fiber cross sections are analyzed by TEM to correlate optical properties with the formation of the hybrid materials within PET. As a demonstration of the technology, patterning of the hybrid material is conducted to show a 'hidden marker' in the fabric, only visible under UV illumination.

Optical tuning of poly(ethylene terephthalate) by organometallic vapor infiltration

248th National Meeting (2014)

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