Browsing by Author "Xu, Peicheng"

Now showing 1 - 5 of 5

Magnetically controlled anisotropic light emission of DNA-functionalized supraparticles
(SPRINGER, 2022) Erdem, Talha; Zupkauskas, Mykolas; O’Neill, Thomas; Cassiagli, Alessio; Xu, Peicheng; Altintas, Yemliha; Mutlugun, Evren; Eiser, Erika; 0000-0003-3905-376X; 0000-0003-3715-5594; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Talha, Erdem; Altintas, Yemliha; Mutlugun, Evren
In this article, we show the DNA-functionalization of supraparticles, form their network, and manipulate the optical features of these networks by applying a magnetic field. We start with preparing the supraparticles (SPs) of semiconducting InP/ZnSeS/ZnS quantum dots (QDs), plasmonic silver nanoparticles, and superparamagnetic iron oxide nanoparticles. These SPs are prepared by employing azide-functionalized amphiphilic diblock or triblock copolymers as well as by using their combinations. Subsequently, we attached single-stranded DNAs to these SPs by employing copper-free click chemistry. Next, we hybridized DNA-coated QD SPs with the iron oxide SPs and formed a network. By applying a magnetic field, we restructured this network such that the iron oxide SPs are aligned. This led to an anisotropic emission from the QD SPs with a polarization ratio of 1.9. This study presents a proof-of-concept scheme to control the optical features of a self-assembled supraparticle system using an external interaction. We believe that our work will further contribute to the utilization of smart self-assembly techniques in optics and photonics.
Osmotic-Pressure-Induced Nematic Ordering in Suspensions of Laponite and Carboxy Methyl Cellulose
(AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2020) Xu, Peicheng; Yazici, Ahmet F.; Erdem, Talha; Lekkerkerker, Henk N. W.; Mutlugun, Evren; Eiser, Erika; 0000-0003-2747-7856; 0000-0003-3905-376X; 0000-0003-2881-8157; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
Laponite is a synthetic clay that is known to form gels in aqueous suspensions at low concentrations (0.01 g/cm(3)) Although it is expected to form lyotropic liquid crystals, such phases usually do not form, as a consequence of laponite's tendency to form gels at concentrations below the threshold for liquid crystal formation. Here we show that macroscopic, birefringent phases of laponite can be prepared through osmotic compression of a laponite solution by an aqueous solution of carboxy methyl cellulose (CMC). We present polarization imaging studies showing how the initially dilute, isotropic laponite phase shrinks while developing typical birefringence colors between crossed polarizers. Using the MichelLevy interference charts, we were able to extract the refractive index and orientation of the laponite nanodisks in the compressed region. Our observations allow us to propose a tentative state diagram, indicating the concentration regions for which we obtain optically anisotropic gels.
A simple approach to prepare self-assembled, nacre-inspired clay/polymer nanocomposites
(ROYAL SOC CHEMISTRY, THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND, 2020) Xu, Peicheng; Eiser, Erika; Erdem, Talha; 0000-0003-3905-376X; 0000-0003-2881-8157; 0000-0002-3807-326X; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
Inspired by the relationship between the well-ordered architecture of aragonite crystals and biopolymers found in natural nacre, we present a facile strategy to construct large-scale organic/inorganic nacre-mimetics with hierarchical structureviaa water-evaporation driven self-assembly process. We connect LAPONITE (R)-nanoclay platelets with each other using carboxymethyl cellulose, a cellulose derivative, thus creating thin, flexible films with a local brick-and-mortar architecture. The dried films show a pronounced resistance against tensile forces allowing for stronger thin films than nacre. In terms of functionalities, we report excellent glass-like transparency along with exceptional shape-persistent flame shielding. We also demonstrate that through metal ion-coordination we can further strengthen the interactions between the polymers and the nanoclays, and thus enhanced mechanical, and thermal properties as well as resistance against swelling and dissolution in aqueous environments. We believe that our simple pathway to fabricate such versatile polymer/clay nanocomposites can open avenues for inexpensive production of environmentally friendly, biomimetic materials in aerospace, wearable electrical devices, and in the food packaging industry.
Transparent Colloidal Crystals With Structural Colours
(FRONTIERS MEDIA SAAVENUE DU TRIBUNAL FEDERAL 34, LAUSANNE CH-1015, SWITZERLAND, 2022) Erdem, Talha; O'Neill, Thomas; Zupkauskas, Mykolas; Caciagli, Alessio; Xu, Peicheng; Lan, Yang; Bosecke, Peter; Eiser, Erika; 0000-0002-6231-9717; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Erdem, Talha
Spatially ordered arrangements of spherical colloids are known to exhibit structural colours. The intensity and brilliance of these structural colours typically improve with colloidal monodispersity, low concentrations of point and line defects and with increasing refractive index contrast between the colloids and the embedding medium. Here we show that suspensions of charge stabilised, fluorinated latex particles with low refractive-index contrast to their aqueous background form Wigner crystals with FCC symmetry for volume fractions between 13 and 40%. In reflection they exhibit both strong, almost angle-independent structural colours and sharp, more brilliant Bragg peaks despite the particle polydispersity and bimodal distribution. Simultaneously, these suspensions appear transparent in transmission. Furthermore, binary AB, A(2)B and A(13)B type mixtures of these fluorinated and similarly sized polystyrene particles appeared predominantly white but with clear Bragg peaks indicating a CsCl-like BCC structure and more complex crystals. We characterised the suspensions using a combination of reflectivity measurements and small-angle x-ray scattering, complemented by reflectivity modelling. Keywords
Transparent Films Made of Highly Scattering Particles
(AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2020) Erdem, Talha; Yang, Lan; Xu, Peicheng; Altintas, Yemliha; O'Neil, Thomas; Caciagli, Alessio; Ducati, Caterina; Mutlugun, Evren; Scherman, Oren A.; Eiser, Erika; 0000-0003-3366-6442; 0000-0002-6231-9717; 0000-0003-2881-8157; 0000-0003-3905-376X; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
Today, colloids are widely employed in various products from creams and coatings to electronics. The ability to control their chemical, optical, or electronic features by controlling their size and shape explains why these materials are so widely preferred. Nevertheless, altering some of these properties may also lead to some undesired side effects, one of which is an increase in optical scattering upon concentration. Here, we address this strong scattering issue in films made of binary colloidal suspensions. In particular, we focus on raspberry-type polymeric particles made of a spherical polystyrene core decorated by small hemispherical domains of acrylate with an overall positive charge, which display an unusual stability against aggregation in aqueous solutions. Their solid films display a brilliant red color due to Bragg scattering but appear completely white on account of strong scattering otherwise. To suppress the scattering and induce transparency, we prepared films by hybridizing them with oppositely charged PS particles with a size similar to that of the bumps on the raspberries. We report that the smaller PS particles prevent raspberry particle aggregation in solid films and suppress scattering by decreasing the spatial variation of the refractive index inside the film. We believe that the results presented here provide a simple strategy to suppress strong scattering of larger particles to be used in optical coatings.