Title: Towards sensor applications of a polymer/Ag nanoparticle nanocomposite film
We have demonstrated the capability of a nanocomposite film made of a 2D array of Ag nanoparticles embedded into a poly(glycidyl methacrylate), PGMA, matrix to monitor the presence of organic vapors in the atmosphere. Specifically, changes in the extinction spectra of the submicron nanocomposite film are used to sense the vapors. The transformations of the spectra are fully reversible and reproducible upon multiple exposures. We associate this reversibility and reproducibility with the construction of the nanocomposite film where the cross-linked PGMA network is able to spatially restore its structure upon deswelling. The structure of the extinction spectrum of the film is governed by a collective surface plasmon mode excited in the Ag NPs array. It was found that spectral bands associated with normal and tangential components of the plasmon mode change their width and position when the nanocomposite is exposed to organic vapors. This is due to increasing the spacing between neighboring NPs and a decrease of the refractive index of the polymer caused by swelling of the PGMA matrix. Therefore, the level of spectral transformation is directly related to the level of polymer–solvent thermodynamic affinity where the higher affinity corresponds to the higher level of the swelling. Therefore, we expect that the nanocomposite films (when designed for a particular solvent) can be effectively used as a sensing element in a low-cost volatile organic compounds (VOC) sensor device operating in visual light. more »« less
Ag nanostructures exhibit extraordinary optical properties, which are important for photonic device integration. Herein, we deposited Ag–LiNbO 3 (LNO) nanocomposite thin films with Ag nanoparticles (NPs) embedded into the LNO matrix by the co-deposition of Ag and LNO using a pulsed laser deposition (PLD) method. The density and size of Ag NPs were tailored by varying the Ag composition. Low-density and high-density Ag–LNO nanocomposite thin films were deposited and their optical properties, such as transmittance spectra, ellipsometry measurement, as well as angle-dependent and polarization-resolved reflectivity spectra, were explored. The Ag–LNO films show surface plasmon resonance (SPR) in the visible range, tunable optical constants and optical anisotropy, which are critical for photonic device applications.
Maguire, Shawn M.; Demaree, John Derek; Boyle, Michael J.; Keller, Austin W.; Bilchak, Connor R.; Kagan, Cherie R.; Murray, Christopher B.; Ohno, Kohji; Composto, Russell J.
(, Macromolecules)
We show that the polymer-grafted nanoparticles (NPs) initially welldispersed in a polymer matrix segregate to the free surface of a film upon thermal annealing in the one-phase region of the phase diagram because the grafted polymer has a lower surface energy than the matrix polymer. Using a combination of atomic force microscopy, transmission electron microscopy, and Rutherford backscattering spectrometry, the evolution of the poly(methyl methacrylate)-grafted silica NP (PMMA NP) surface excess in 25/75 wt % PMMA NP/poly(styrene-ranacrylonitrile) films is observed as a function of annealing time at 150 °C (T < TLCST). The temporal growth of the surface excess is interpreted as a competition between entropic contributions, surface energy differences of the constituents, and the Flory−Huggins interaction parameter, χ. For the first time in a miscible polymer nanocomposite mixture, quantitative comparisons of NP surface segregation are made with the predictions of theory derived for analogous polymer blends. These studies provide insight for designing polymer nanocomposite films with advantageous surface properties such as wettability and hardness and motivate the need for developing rigorous models that capture complex polymer nanocomposite phase behaviors.
Zhang, Aria C; Ohno, Kohji; Composto, Russell J
(, The Journal of Physical Chemistry B)
This study investigates Marangoni effect-induced structural changes in spin-coated polymer nanocomposite (PNC) films composed of poly(methyl methacrylate)-grafted silica nanoparticles (NPs) and poly(styrene-ran-acrylonitrile). Films cast from methyl isobutyl ketone (MIBK) solvent exhibit distinct hexagonal honeycomb cells with thickness gradients driven by surface tension variations. Atomic force microscopy reveals protruded ridges and junctions at cell intersections, where NP concentration is the highest. Upon annealing at 155 degrees C, NPs segregate to the surface due to their lower surface energy, and the initially protruding features flatten and eventually form depressed channels while maintaining higher NP density than surrounding areas. Time-of-flight secondary ion mass spectrometry corroborated these findings, highlighting enhanced surface segregation of NPs in MIBK films. These defects can be eliminated using methyl isoamyl ketone (MIAK) as a solvent that produces homogeneous films of uniform thickness. This study highlights the impact of the Marangoni effect on the microstructure and surface properties of PNC films, providing insights for enhancing film quality and performance.
Instantaneous control over the orientation of anisotropically shaped plasmonic nanostructures allows for selective excitation of plasmon modes and enables dynamic tuning of the plasmonic properties. Herein we report the synthesis of rod-shaped magnetic/plasmonic core-shell nanocomposite particles and demonstrate the active tuning of their optical property by manipulating their orientation using an external magnetic field. We further design and construct an IR-photoelectric coupling system, which generates an output voltage depending on the extinction property of the measured nanocomposite sample. We employ the device to demonstrate that the nanocomposite particles can serve as units for information encryption when immobilized in a polymer film and additionally when dispersed in solution can be employed as a new type of magnetic-field-direction sensor.
Polymer nanocomposite (PNC) films are of interest for many applications including electronics, energy storage, and advanced coatings. In phase-separating PNCs, the interplay between thermodynamic and kinetic factors governs the assembly of polymer-grafted nanoparticles (NPs), which directly influences material properties. Understanding how processing parameters affect the structure-property relationship of PNCs is important for designing advanced materials. This thesis provides insight by investigating a model PNC system of poly(methyl methacrylate)-grafted nanoparticles (PMMA-NPs) embedded in a poly(styrene-ran-acrylonitrile) (SAN) matrix. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was developed to quantify the distribution of NPs within PMMA-NP/SAN films, enabling precise 3D reconstruction of PNC structures. Experimental parameters such as primary ion beam angle and charge compensation were optimized to enhance secondary ion signals and depth resolution. Upon annealing in the twophase region, PMMA-NP/SAN films exhibited phase separation and surface segregation, leading to morphological evolutions characterized by atomic force microscopy (AFM), ToF-SIMS, water contact angle measurements, and transmission electron microscopy. By systematically exploring the effects of film thickness on PNC structures, we found that film thickness-induced confinement reduces lateral phase separation and enhances NP dispersion at the surface. A dimensional crossover from three to two dimensions was observed around 240 nm, below which surface-directed spinodal decomposition is suppressed. As a result of phase separation and surface segregation, six distinct bulk morphologies were identified, allowing for the construction of a morphology map correlating film thickness and annealing time. Among these morphologies, percolated structures were found to improve mechanical properties such as hardness and reduced modulus, as measured using AFM nanoindentation. Notably, interconnected networks show the highest hardness and modulus at both low and high force loadings. Additionally, Marangoni-induced hexagonal honeycomb patterns were observed in spin-coated as-cast PMMA-NP/SAN films. By changing to a less volatile solvent, these defects were eliminated, demonstrating the importance of solvent selection in achieving uniform and high-quality thin films. These findings demonstrate the potential for precise control of surface-enriched and phase-separated microstructures in PNC films through tailoring processing conditions. This thesis advances the understanding of processing-structure-property relationships in PNCs, providing a foundation for designing highly functional materials with broad industrial applications.
Yeshchenko, O. A., Malynych, S. Z., Polomarev, S. O., Galabura, Yu., Chumanov, G., and Luzinov, I. Towards sensor applications of a polymer/Ag nanoparticle nanocomposite film. Retrieved from https://par.nsf.gov/biblio/10094029. RSC Advances 9.15 Web. doi:10.1039/c9ra00498j.
Yeshchenko, O. A., Malynych, S. Z., Polomarev, S. O., Galabura, Yu., Chumanov, G., & Luzinov, I. Towards sensor applications of a polymer/Ag nanoparticle nanocomposite film. RSC Advances, 9 (15). Retrieved from https://par.nsf.gov/biblio/10094029. https://doi.org/10.1039/c9ra00498j
Yeshchenko, O. A., Malynych, S. Z., Polomarev, S. O., Galabura, Yu., Chumanov, G., and Luzinov, I.
"Towards sensor applications of a polymer/Ag nanoparticle nanocomposite film". RSC Advances 9 (15). Country unknown/Code not available. https://doi.org/10.1039/c9ra00498j.https://par.nsf.gov/biblio/10094029.
@article{osti_10094029,
place = {Country unknown/Code not available},
title = {Towards sensor applications of a polymer/Ag nanoparticle nanocomposite film},
url = {https://par.nsf.gov/biblio/10094029},
DOI = {10.1039/c9ra00498j},
abstractNote = {We have demonstrated the capability of a nanocomposite film made of a 2D array of Ag nanoparticles embedded into a poly(glycidyl methacrylate), PGMA, matrix to monitor the presence of organic vapors in the atmosphere. Specifically, changes in the extinction spectra of the submicron nanocomposite film are used to sense the vapors. The transformations of the spectra are fully reversible and reproducible upon multiple exposures. We associate this reversibility and reproducibility with the construction of the nanocomposite film where the cross-linked PGMA network is able to spatially restore its structure upon deswelling. The structure of the extinction spectrum of the film is governed by a collective surface plasmon mode excited in the Ag NPs array. It was found that spectral bands associated with normal and tangential components of the plasmon mode change their width and position when the nanocomposite is exposed to organic vapors. This is due to increasing the spacing between neighboring NPs and a decrease of the refractive index of the polymer caused by swelling of the PGMA matrix. Therefore, the level of spectral transformation is directly related to the level of polymer–solvent thermodynamic affinity where the higher affinity corresponds to the higher level of the swelling. Therefore, we expect that the nanocomposite films (when designed for a particular solvent) can be effectively used as a sensing element in a low-cost volatile organic compounds (VOC) sensor device operating in visual light.},
journal = {RSC Advances},
volume = {9},
number = {15},
author = {Yeshchenko, O. A. and Malynych, S. Z. and Polomarev, S. O. and Galabura, Yu. and Chumanov, G. and Luzinov, I.},
}
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