Coassembly of Nanorods and Nanospheres in Suspensions and in Stratified Films

Abstract

The entropically driven coassembly of nanorods (cellulose nanocrystals, CNCs) and nanospheres (dye-labeled spherical latex nanoparticles, NPs) was studied in aqueous suspensions and in solid films. In mixed CNC-latex suspensions, phase separation into an isotropic latex-NP-rich and a chiral nematic CNC-rich phase took place; the latter contained a significant amount of latex NPs. Drying the mixed suspension resulted in CNC-latex films with planar disordered layers of latex NPs, which alternated with chiral nematic CNC-rich regions. In addition, fluorescent latex NPs were embedded in the chiral nematic domains. The stratified morphology of the films, together with a random distribution of latex NPs in the anisotropic phase, led to the films having close-to-uniform fluorescence, birefringence, and circular dichroism properties.

Current characterization methods for cellulose nanomaterials

“…278,390,391 Physisorbed fluorophores can be used to produce fluorescent cellulose films that preserve the nematic structure of cellulose. A wide variety of fluorophores have been used, including quantum dots, 392,393 latex nanoparticles, 394,395 noble metal nanoparticles, 396,397 and optical brighteners. 363,398 The key point is to check if the physisorption is not reversible and monitor the quantity of fluorophores used.…”

Liquid Crystalline Tactoidal Microphases in Ferrofluids: Spatial Positioning and Orientation by Magnetic Field Gradients

“…Key to our approach is the discovery that isotropic phases can be endowed with significantly higher volume magnetic susceptibility (c m ) than liquid crystalline tactoids on the basis of the exclusion effects of tactoids on superparamagnetic magnetite doping nanoparticles (MNPs) (Figure 2A), 28 which is a result of the entropically driven microscopic phase separation of binary mixtures of rods and spheres. 29,30 When applying an external gradient magnetic field, isotropic phases experience unidirectional acceleration (driven by magnetic body forces) along the magnetic field and move to higher-magnetic-field regions; meanwhile, because liquid crystalline tactoids are discrete microdroplets with much lower volume magnetic susceptibility, they will be accelerated by magnetic buoyancy forces from the surrounding continuous isotropic phases and move in the opposite direction to lower-magnetic-field regions. Simultaneously, the tactoids are oriented parallel to the magnetic field by torque forces ( Figure 2B).…”

Neue Mitglieder der Royal Society: C. Abell, E. Kumacheva, R. E. Morris / Präsident der Chemical Society of Japan: H. Yamamoto

“…Kumacheva und ihre Gruppe interessieren sich für weiche Materie, im Besonderen Polymermaterialien, Nanowissenschaften, Polymere in biologischen Systemen und Mikrofluidik. In der Angewandten Chemie hat sie über die Koaggregation von Nanostäbchen und Nanokugeln berichtet und in ChemSusChem über die mikrofluidische Trennung von Ethylen und Ethan . Kumacheva ist im Editorial Advisory Board von Particle & Particle Systems Characterization .…”