Thermoplasmonic‐Activated Hydrogel Based Dynamic Light Attenuator
Abstract
This work describes the morphological, optical, and thermo‐optical properties of a temperature‐sensitive hydrogel poly(N‐isopropylacrylamide‐co‐N‐isopropylmethacrylamide) [P(NIPAm‐co‐NIPMAm]) film containing a specific amount of gold nanorods (GNRs). The light‐induced thermoplasmonic heating of GNRs is used to control the optical scattering of an initially transparent hydrogel film. A hydrated P(NIPAm‐co‐NIPMAm) film is optically clear at room temperature. When heated to temperatures over 37 °C via light irradiation with a resonant source (λ = 810 nm) to the GNRs, a reversible phase transition from a swollen hydrated state to a shrunken dehydrated state occurs. This phenomenon causes a drastic and reversible change in the optical transparency from a clear to an opaque state. A significant red shift (≈30 nm) of the longitudinal band can also be seen due to an increased average refractive index surrounding the GNRs. This change is in agreement with an ad hoc theoretical model which uses a modified Gans theory for ellipsoidal nanoparticles. Morphological analysis of the composite film shows the presence of well‐isolated and randomly dispersed GNRs. Thermo‐optical experiments demonstrate an all‐optically controlled light attenuator (65% contrast ratio) which can be easily integrated in several modern optical applications such as smart windows and light‐responsive optical attenuators.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 21, 2020
- Source ID
- 10.1002/adom.202000324
Entities
People
- Alexa Guglielmelli
- Filippo Pierini
- Luciano De Sio
- Luigia Pezzi
- Massimiliano Lanzi
- Olga Urbanek
- Pawel Nakielski
- Robert Buda
- Tomasz A. Kowalewski
Organizations
- Air Force Office of Scientific Research
- Polish Academy of Sciences
- Sapienza University of Rome
- University of Bologna
- University of Calabria