Coupling magnetic and plasmonic anisotropy in hybrid nanorods for mechanochromic responses

Abstract

Mechanochromic response is of great importance in designing bionic robot systems and colorimetric devices. Unfortunately, compared to mimicking motions of natural creatures, fabricating mechanochromic systems with programmable colorimetric responses remains challenging. Herein, we report the development of unconventional mechanochromic films based on hybrid nanorods integrated with magnetic and plasmonic anisotropy. Magneticplasmonic hybrid nanorods have been synthesized through a unique space-confined seedmediated process, which represents an open platform for preparing next-generation complex nanostructures. By coupling magnetic and plasmonic anisotropy, the plasmonic excitation of the hybrid nanorods could be collectively regulated using magnetic fields. It facilitates convenient incorporation of the hybrid nanorods into polymer films with a well-controlled orientation and enables sensitive colorimetric changes in response to linear and angular motions. The combination of unique synthesis and convenient magnetic alignment provides an advanced approach for designing programmable mechanochromic devices with the desired precision, flexibility, and scalability.

Polarization‐Modulated Multidirectional Photothermal Actuators

“…Meanwhile, we observe a new peak at ≈550 nm, largely because of the surface concavity of Ag rods, which induces a new concave peak. [ 21 ] Our thermal treatment on the hybrid rods demonstrates the perfect thermostability of Ag rods (Figure S9, Supporting Information). The strong coordination between Ag and trapped NH 4 + in RF shell is one possible reason for this enhanced stability.…”

“…The hybrid or Janus nanorods were synthesized by modifying an unconventional templating approach reported previously. [ 2a,21 ] Briefly, magnetic nanorods (110 nm × 20 nm) are used as an initial template. [ 22 ] Au seeds (≈2 nm, denoted as Aus) were attached to their surface through electrostatic interactions (Figure S1, Supporting Information).…”

Plasmonic Nanostructures for Photothermal Conversion

“…Later, we have addressed this issue by developing a space‐confined seeded growth method to synthesize well‐defined magnetic‐plasmonic hybrid nanostructures. [ 98 ] Anisotropic seeded growth of Au was initiated in a rod‐shaped void space created in a polymer shell by coating a Fe 3 O 4 nanorod, producing a pair of parallelly aligned Au/Fe 3 O 4 nanorods wrapped in each shell, as shown in Figure 6c. The resulting hybrid nanorods exhibited high structural and colloidal stability, allowing convenient control of the longitudinal mode of the AuNRs using an external magnetic field even at a high particle concentration (Figure 6d).…”

Responsive Plasmonic Nanomaterials for Advanced Cancer Diagnostics

“…The LSPR intensity and the perceived color of Au nanorods in a colloidal solution can be quickly tuned by applying a magnetic field. A few advanced techniques enable direct colloidal synthesis of magnetic-plasmonic hybrid nanostructures, including Fe 3 O 4 @Au core/shell nanospheres (Figure 2A) (Li et al, 2020a), Fe 3 O 4 /Au nanorods ( Figure 2B) (Li et al, 2020b), Fe 3 O 4 /Ag nanorods (Li et al, 2020e), Au/Ni/Au ( Figure 2C) (Jung et al, 2018a), Au/Fe/Au multiblock nanorods (Jung et al, 2018b), and Au dimer on magnetic nanoplate hybrid structure ( Figure 2D) (Feng et al, 2019). One advantage of magnetic orientational control is the selective excitation of the two modes of Au nanorods.…”

“…Reproduced fromLi et al (2020a) with permission from American Chemical Society. (B) Fe 3 O 4 /Au@polymer nanorods, Reproduced fromLi et al (2020b) with permission from the authors. (C) Au-Ni-Au multi-segment nanorods.…”