Aaltodoc Repository :: Browsing by Author "Haataja, Johannes S."

Browsing by Author "Haataja, Johannes S."

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Brilliant whiteness in shrimp from ultra-thin layers of birefringent nanospheres
(Nature Publishing Group, 2023-06) Lemcoff, Tali; Alus, Lotem; Haataja, Johannes S.; Wagner, Avital; Zhang, Gan; Pavan, Mariela J.; Yallapragada, Venkata Jayasurya; Vignolini, Silvia; Oron, Dan; Schertel, Lukas; Palmer, Benjamin A.; Department of Applied Physics; Active Matter; Ben-Gurion University of the Negev; Weizmann Institute of Science; Indian Institute of Technology Kanpur; University of Cambridge
A fundamental question regarding light scattering is how whiteness, generated from multiple scattering, can be obtained from thin layers of materials. This challenge arises from the phenomenon of optical crowding, whereby, for scatterers packed with filling fractions higher than ~30%, reflectance is drastically reduced due to near-field coupling between the scatterers. Here we show that the extreme birefringence of isoxanthopterin nanospheres overcomes optical crowding effects, enabling multiple scattering and brilliant whiteness from ultra-thin chromatophore cells in shrimp. Strikingly, numerical simulations reveal that birefringence, originating from the spherulitic arrangement of isoxanthopterin molecules, enables intense broadband scattering almost up to the maximal packing for random spheres. This reduces the thickness of material required to produce brilliant whiteness, resulting in a photonic system that is more efficient than other biogenic or biomimetic white materials which operate in the lower refractive index medium of air. These results highlight the importance of birefringence as a structural variable to enhance the performance of such materials and could contribute to the design of biologically inspired replacements for artificial scatterers like titanium dioxide.
Chiral Plasmonics Using Twisting along Cellulose Nanocrystals as a Template for Gold Nanoparticles
(2016-07-13) Majoinen, Johanna; Hassinen, Jukka; Haataja, Johannes S.; Rekola, Heikki T.; Kontturi, Eero; Kostiainen, Mauri A.; Ras, Robin H A; Törmä, Päivi; Ikkala, Olli; Department of Applied Physics; Department of Forest Products Technology; Department of Biotechnology and Chemical Technology; Department of Bioproducts and Biosystems; Department of Chemical and Metallurgical Engineering; Molecular Materials; Quantum Dynamics; Soft Matter and Wetting
The right-handed twist along aqueous dispersed cellulose nanocrystals allows right-handed chiral plasmonics upon electrostatic binding of gold nanoparticles in dilute environment, upon tuning the particle sizes and concentrations. Simulations using nanoparticle coordinates from cryo-electron tomography confirm the experimental results. The finding suggests generalization for other chiral and helical colloidal templates for nanoscale chiral plasmonics.
Investigations of Complex Self-Assemblies
(Aalto University, 2018) Haataja, Johannes S.; Houbenov, Nikolay, Dr., Aalto University, Department of Applied Physics, Finland; Teknillisen fysiikan laitos; Department of Applied Physics; Molecular Materials; Perustieteiden korkeakoulu; School of Science; Ikkala, Olli, Prof., Aalto University, Department of Applied Physics, Finland
The demand for ever more complex nanostructures calls not only for new design concepts and synthetic protocols, but also incorporation of more advanced characterization methods and more refined data analysis tools. In this thesis, challenges to characterize complex molecular and colloidal self-assemblies are explored using model systems. In Publication I we study the molecular self-assembly of polyelectrolyte complexes into multicompartment micelles with intricate ''turbine-like'' surface morphologies. We demonstrate how conventional 2D transmission electron microscopy (TEM) is not sufficient to resolve such morphologies and thus 3D reconstruction based on electron tomography (ET) is needed. In Publication II we show how ET allows resolving chiral templated ionic self-assemblies of gold nanoparticles on cellulose nanocrystals. In Publication III, ET allows resolving capsid-like hollow superstructures of cobalt nanoparticles driven by hydrogen bonding between the nanoparticle ligands. In Publications III and IV we also investigate how molecular simulations can aid the interpretation of the experimental findings. Publication IV discusses structural characterization of pentablock quintopolymeric vesicular superstructures in solvent media. In simpler block copolymers, various staining methods allow the identification of the self-assembled domains. In self-assemblies involving 5 different microdomains resolving the microdomains and their structures was a real challenge. We implemented advanced inversion methods such as total variation in ET to differentiate between the different blocks of the self-assemblies. We discuss in detail the nature and mathematics of forward and inverse problems, including the specific cases ET and dynamic light scattering (DLS). We also show how the use of conventional spectroscopic methods, such as DLS and its data analysis routines, can result in fallacious conclusions when applied to complex self-assemblies, thus demonstrating the need for more diverse data collection in combination with Bayesian analysis for reliable inference. The investigations of this thesis pave way towards more advanced characterization methods and data analysis in electron microscopy and light scattering, which we foresee to be increasingly required for understanding the future complex self-assemblies.
Mesoporous carbon soft-templated from lignin nanofiber networks: Microphase separation boosts supercapacitance in conductive electrodes
(2016) Ago, Mariko; Borghei, Maryam; Haataja, Johannes S.; Rojas Gaona, Orlando; Department of Forest Products Technology; Department of Applied Physics; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials
Flexible electrodes with supercapacitance were developed from highly mesoporous carbon fibers synthesized from lignin. Polyvinyl alcohol (PVA) facilitated the electrospinning of aqueous solutions of lignin and was used as a sacrificial polymer. Most importantly, PVA produced phase-separated domains for extreme surface area (>2000 m2 g-1) and mesoporous volume (0.7 cm3 g-1). An optimized sequential thermal treatment that initially included stabilization at 250 °C, allowed the formation of flexible, freestanding carbon networks upon PVA evolution to the gas phase and carbonization of the as-spun lignin-based fibers. Their main morphological and chemical characteristics were assessed by field emission scanning microscopy, transmission electron tomography reconstructions and Raman spectroscopy. The carbon fiber networks were used directly as electrodes with electrochemical double layer capacitance as determined by cyclic voltammetry and galvanostatic charge/discharge methods. Excellent electrochemical performance was demonstrated from the measured high rate capability and long-term cycling stability. The determined specific capacitance (∼205 F g-1 in 0.5 M Na2SO4 electrolyte) is one of the highest recorded for electrodes obtained from biopolymer precursors. Moreover, the electrical conductivity of the carbon fiber network (386 S m-1) was significantly higher, by two-orders of magnitude, than that obtained from the precursor (non-fibrous, powder) sample (2.47 S m-1). The remarkable performance of the synthesized electrodes is ascribed to the robust network morphology and mesoporosity obtained by soft-templating from the phase-separated sacrificial polymer. This is a demonstration of lignin valorization for novel application in advanced materials.
Randomizing the growth of silica nanofibers for whiteness
(Elsevier, 2024-06-19) Lin, Zhen; Haataja, Johannes S.; Hu, Xichen; Hong, Xiaodan; Ikkala, Olli; Peng, Bo; Department of Applied Physics; Molecular Materials; Active Matter; Center of Excellence in Life-Inspired Hybrid Materials, LIBER
In colloids, the shape influences the function. In silica, straight nanorods have already been synthesized from water-in-oil emulsions. By contrast, curly silica nanofibers have been less reported because the underlying growth mechanism remains unexplored, hindering further morphology control for applications. Herein, we describe the synthetic protocol for silica nanofibers with a tunable curliness based on the control of the water-in-oil emulsion droplets. Systematically decreasing the droplet size and increasing their contact angle, the Brownian motion of the droplets intensifies during the silica growth, thus increasing the random curliness of the nanofibers. This finding is supported by simplistic theoretical arguments and experimentally verified by varying the temperature to finely tune the curliness. Assembling these nanofibers toward porous disordered films enhances multiple scattering in the visible range, resulting in increased whiteness in contrast to films constructed by spherical and rod-like building units, which can be useful for, e.g., coatings and pigments.
Rational design of ABC triblock terpolymer solution nanostructures with controlled patch morphology
(2016-06-29) Löbling, Tina I.; Borisov, Oleg; Haataja, Johannes S.; Ikkala, Olli; Gröschel, André H.; Müller, Axel H E; Department of Applied Physics; Molecular Materials; Peter the Great St. Petersburg Polytechnic University; Johannes Gutenberg University Mainz; University of Duisburg-Essen
Block copolymers self-assemble into a variety of nanostructures that are relevant for science and technology. While the assembly of diblock copolymers is largely understood, predicting the solution assembly of triblock terpolymers remains challenging due to complex interplay of block/block and block/solvent interactions. Here we provide guidelines for the self-assembly of linear ABC triblock terpolymers into a large variety of multicompartment nanostructures with C corona and A/B cores. The ratio of block lengths NC/NA thereby controls micelle geometry to spheres, cylinders, bilayer sheets and vesicles. The insoluble blocks then microphase separate to core A and surface patch B, where N B controls the patch morphology to spherical, cylindrical, bicontinuous and lamellar. The independent control over both parameters allows constructing combinatorial libraries of unprecedented solution nanostructures, including spheres-on-cylinders/sheets/vesicles, cylinders-on-sheets/vesicles, and sheets/vesicles with bicontinuous or lamellar membrane morphology (patchy polymersomes). The derived parameters provide a logical toolbox towards complex self-assemblies for soft matter nanotechnologies.
Reversible Supracolloidal Self-Assembly of Cobalt Nanoparticles to Hollow Capsids and Their Superstructures
(2017) Nonappa, Nonappa; Haataja, Johannes S.; Timonen, Jaakko V.I.; Malola, Sami; Engelhardt, Peter; Houbenov, Nikolay; Lahtinen, Manu; Häkkinen, Hannu; Ikkala, Olli; Department of Applied Physics; Molecular Materials; University of Jyväskylä; University of Helsinki
The synthesis and spontaneous, reversible supracolloidal hydrogen bond-driven self-assembly of cobalt nanoparticles (CoNPs) into hollow shell-like capsids and their directed assembly to higher order superstructures is presented. CoNPs and capsids form in one step upon mixing dicobalt octacarbonyl (Co2CO8) and p-aminobenzoic acid (pABA) in 1,2-dichlorobenzene using heating-up synthesis without additional catalysts or stabilizers. This leads to pABA capped CoNPs (core ca. 5nm) with a narrow size distribution. They spontaneously assemble into tunable spherical capsids (d≈50-200nm) with a few-layered shells, as driven by inter-nanoparticle hydrogen bonds thus warranting supracolloidal self-assembly. The capsids can be reversibly disassembled and reassembled by controlling the hydrogen bonds upon heating or solvent exchanges. The superparamagnetic nature of CoNPs allows magnetic-field-directed self-assembly of capsids to capsid chains due to an interplay of induced dipoles and inter-capsid hydrogen bonds. Finally, self-assembly on air-water interface furnishes lightweight colloidal framework films.
Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals : Self-Assembly, Optics, and Applications
(American Chemical Society, 2023-12-13) Frka-Petesic, Bruno; Parton, Thomas G.; Honorato-Rios, Camila; Narkevicius, Aurimas; Ballu, Kevin; Shen, Qingchen; Lu, Zihao; Ogawa, Yu; Haataja, Johannes S.; Droguet, Benjamin E.; Parker, Richard M.; Vignolini, Silvia; Department of Applied Physics; Active Matter; University of Cambridge; Max Planck Institute of Colloids and Interfaces; Technische Universität Dresden; Centre de Recherches sur les Macromolécules Végétales
Widespread concerns over the impact of human activity on the environment have resulted in a desire to replace artificial functional materials with naturally derived alternatives. As such, polysaccharides are drawing increasing attention due to offering a renewable, biodegradable, and biocompatible feedstock for functional nanomaterials. In particular, nanocrystals of cellulose and chitin have emerged as versatile and sustainable building blocks for diverse applications, ranging from mechanical reinforcement to structural coloration. Much of this interest arises from the tendency of these colloidally stable nanoparticles to self-organize in water into a lyotropic cholesteric liquid crystal, which can be readily manipulated in terms of its periodicity, structure, and geometry. Importantly, this helicoidal ordering can be retained into the solid-state, offering an accessible route to complex nanostructured films, coatings, and particles. In this review, the process of forming iridescent, structurally colored films from suspensions of cellulose nanocrystals (CNCs) is summarized and the mechanisms underlying the chemical and physical phenomena at each stage in the process explored. Analogy is then drawn with chitin nanocrystals (ChNCs), allowing for key differences to be critically assessed and strategies toward structural coloration to be presented. Importantly, the progress toward translating this technology from academia to industry is summarized, with unresolved scientific and technical questions put forward as challenges to the community.
Supramolecular amplification of amyloid self-assembly by iodination
(2015) Bertolani, Arianna; Pirrie, Lisa; Stefan, Loic; Houbenov, Nikolay; Haataja, Johannes S.; Catalano, Luca; Terraneo, Giancarlo; Giancane, Gabriele; Valli, Ludovico; Milani, Roberto; Ikkala, Olli; Resnati, Giuseppe; Metrangolo, Pierangelo; Department of Applied Physics; Molecular Materials
Amyloid supramolecular assemblies have found widespread exploitation as ordered nanomaterials in a range of applications from materials science to biotechnology. New strategies are, however, required for understanding and promoting mature fibril formation from simple monomer motifs through easy and scalable processes. Noncovalent interactions are key to forming and holding the amyloid structure together. On the other hand, the halogen bond has never been used purposefully to achieve control over amyloid self-assembly. Here we show that single atom replacement of hydrogen with iodine, a halogen-bond donor, in the human calcitonin-derived amyloidogenic fragment DFNKF results in a super-gelator peptide, which forms a strong and shape-persistent hydrogel at 30-fold lower concentration than the wild-type pentapeptide. This is remarkable for such a modest perturbation in structure. Iodination of aromatic amino acids may thus develop as a general strategy for the design of new hydrogels from unprotected peptides and without using organic solvents.
Topological invariance in whiteness optimisation
(Nature Publishing Group, 2023-12) Haataja, Johannes S.; Jacucci, Gianni; Parton, Thomas G.; Schertel, Lukas; Vignolini, Silvia; Department of Applied Physics; Active Matter; University of Cambridge
Maximizing the scattering of visible light within disordered nano-structured materials is essential for commercial applications such as brighteners, while also testing our fundamental understanding of light-matter interactions. The progress in the research field has been hindered by the lack of understanding how different structural features contribute to the scattering properties. Here we undertake a systematic investigation of light scattering in correlated disordered structures. We demonstrate that the scattering efficiency of disordered systems is mainly determined by topologically invariant features, such as the filling fraction and correlation length, and residual variations are largely accounted by the surface-averaged mean curvature of the systems. Optimal scattering efficiency can thus be obtained from a broad range of disordered structures, especially when structural anisotropy is included as a parameter. These results suggest that any disordered system can be optimised for whiteness and give comparable performance, which has far-reaching consequences for the industrial use of low-index materials for optical scattering.

Browsing by Author "Haataja, Johannes S."

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