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@PHDTHESIS{Schweizerhof:792661,
author = {Schweizerhof, Sjören},
othercontributors = {Möller, Martin and Richtering, Walter},
title = {{S}elective surface modification of gold nanorods with
functional polymers for tunable self-assembly and optical
properties},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
reportid = {RWTH-2020-06286},
pages = {1 Online-Ressource (XV, 236 Seiten) : Illustrationen,
Diagramme},
year = {2020},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2020},
abstract = {The beautiful optical appearance of colloidal gold inspired
not only alchemists and glass makers centuries ago to design
unique decorative art, but particularly impelled renowned
scientists to extensively explore and reveal the
physicochemical nature of these imposing materials. The
progressively gained knowledge and the potential and
diversity of colloidal gold lead to a remarkably
fast-growing and multidisciplinary research field that is
basically built on these plasmonic nanoparticles - better
known as ‘Nanotechnology’. The precise control over the
gold nanoparticles (AuNPs) size, shape, composition and the
relative orientation of adjacent AuNPs decisively determines
their opto-thermal properties, which display the key
attributes that are utilized within this research area.
Recent advances allowed for developing sophisticated
AuNPs-based systems that already find application in eminent
fields like (bio)medicine and cancer therapy, as well as for
building smart optothermally-driven devices and plasmonic
sensors.In this work, I will present how anisometric AuNPs,
i.e. gold nanorods (AuNRs), are reversibly guided into
ordered aggregates, either by light or heat, for
substantially tuning their opto-thermal properties in
dispersion. The approach to enable such a thermoreversible
association behavior is to combine AuNRs with
thermosensitive polymeric ligands based on
poly(N-isopropylacrylamide) (PNIPAm) which respond to minor
local temperature changes. The temperature-dependent phase
transition of the anchored PNIPAm is supposed to control the
interparticle distance in aqueous medium by switching
between hydrophobic attraction at high temperatures and
steric stabilization at low temperatures. Therefore, the
main focus of my work comprises the selective surface
modification of AuNRs with PNIPAm to realize their
(photo)thermally and reversible self-assembly into
predictable plasmonic structures. The assembly modes are
programmable either by tethering the PNIPAm (1) uniformly to
the AuNR surface or (2) selectively at the AuNR tips or (3)
at the AuNR side. I will particularly focus on the first two
concepts and additionally investigate the profound impact of
the dispersion composition and how the herein used PNIPAm
types affect the AuNR aggregation behavior. In this
context, I am going to highlight the accompanied and
pronounced spectral shifts of the absorption maximum of the
aggregated AuNRs with respect to their single plasmon
resonance maximum. Especially the aggregation-induced
spectral changes during photothermal treatment were observed
to have a self-limiting effect on the heat generation of the
dispersion. This phenomenon depicts an important step
towards the realization of an opto-thermal feedback
mechanism that might facilitate the fabrication of
light-driven and self-sustaining mesoscopic oscillators.
Beyond the main focus of this work, I will investigate how
AuNRs can be precisely and covalently linked into plasmonic
structures and how this affects their optical properties.
For this purpose, novel photoactivatable ligands are
synthesized, combined with AuNRs, and their reversibly
adjustable end-to-end assembly is demonstrated. The herein
synthesized photoactivatable ligands can contribute to new
reaction pathways for the design of functional AuNRs, which
might find application in diverse nanoscopic systems. Among
the investigations of reversible AuNR self-assembly, a
straightforward method for producing near infrared active
polysulfone (PSU) plastics is demonstrated. Inspired by the
famous Lycurgus Cup, commercial PSU was equipped with
various synthesized plasmonic nanoparticles. It is shown
that the obtained composite materials have exceptional but
easy to verify overt (coloring) and covert (photothermal)
features. In particular, the herein developed dichroic
PSU-AuNP composite is rather unique and the optical effect
hardly imitable. Hence, such composites might in the future
enable advanced forgery-proof strategies for the
safety-encoding of bank notes, plastics and consumer goods.},
cin = {156310 / 150000},
ddc = {540},
cid = {$I:(DE-82)156310_20190915$ / $I:(DE-82)150000_20140620$},
pnm = {DFG project 191948804 - SFB 985: Funktionelle Mikrogele und
Mikrogelsysteme (191948804) / Jellyclock - Light Actuated
Self-Pulsing Mircogels (695716)},
pid = {G:(GEPRIS)191948804 / G:(EU-Grant)695716},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2020-06286},
url = {https://publications.rwth-aachen.de/record/792661},
}
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