Abstract
Color change is a desirable response when designing user-friendly chemical sensors. However, when preparing colored nanocomposites sensors, it can be challenging to transfer the color from solution into films. This work demonstrates that films of various colors can be prepared by blending premade nanoparticles with poly(vinyl alcohol) (PVA); however, the color in solution differed from the color in film. While, this color discrepancy and the appearance of the films depended on how the optical properties of nanoparticles were tuned, UV-visible spectroscopy and Transmission Electron Microscopy (TEM) showed that changes in nanoparticleâs morphology was not the cause of the color discrepancy. Reflecting the polydispersity of nanoparticles in solution, more homogeneous colored films were obtained by controlling the size of nanoparticles rather than their shape. This work shows how to readily prepare silver-PVA nanocomposite films of various colors, which may facilitate the design of nanocomposites intended for chemical sensing based on the optical properties of silver nanoparticles.
Highlights
Films made of silver nanoparticles embedded in poly (PVA) are of interest because the transparency, solubility, and permeability of poly(vinyl alcohol) (PVA) makes this matrix attractive for sensors that use Localized Surface Plasmon Resonance (LSPR) [3,4,5] and Surface-Enhanced Raman Spectroscopy (SERS) [6,7]
Appearance of PVA Films Embedded with Silver Nanoparticles
The blue solution from shape-tuned nanoparticles produced a film with distinctive yellow, purple, and blue zones (Figure 2c). These results demonstrate that films of various colors, and not just yellow, can be prepared by blending premade nanoparticles in a PVA matrix
Summary
Polymeric films containing nanoparticles are nanocomposite materials with novel optical properties that can be controlled by modifying the composition of both polymer and metal nanoparticles [1,2]. Confining nanoparticles in films has gone beyond preventing the unwanted aggregation that nanoparticles experience in solution, and new nanocomposites have been engineered to control the interaction of nanoparticles [1]. Preserving the properties and controlling the distribution of nanoparticles in films can be challenging, in most cases requiring modifications of the nanoparticles to secure its compatibility with the polymer. Silver nanoparticles are advantageous to study such compatibility because their light extinction falls in the visible spectra and changes in color offer information about the interaction between nanoparticle and polymer. Films made of silver nanoparticles embedded in poly (vinylalcohol) (PVA) are of interest because the transparency, solubility, and permeability of PVA makes this matrix attractive for sensors that use Localized Surface Plasmon Resonance (LSPR) [3,4,5] and Surface-Enhanced Raman Spectroscopy (SERS) [6,7]
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