Doctoral theses of the School of Chemical Engineering are available in the open access repository maintained by Aalto, Aaltodoc.
Public defence in Bioproduct Technology, M.Sc. Han Tao
This thesis advances the understanding and control of self-assembly of biocolloids for complex soft matter and chiral metamaterials.
Public defence from the Aalto University School of Chemical Engineering, Department of Bioproducts and Biosystems
Public defence from the Aalto University School of Chemical Engineering, Department of Bioproducts and Biosystems
Title of the thesis: Controlling self-assembly of cellulose nanocrystals for multiphase colloids and chiral photonics
Thesis defender: Han Tao
Opponent: Prof. Bruno Frka-Petešić, University of Cambridge, UK
Custos: Prof. Eero Kontturi, Aalto University School of Chemical Engineering
The assembly of complex superstructures using biosourced nanoscale building blocks has broad implications in sustainable material development with property enhancement and structural synergy. However, achieving controlled self-assembly in bio-based nanoparticle systems remains challenging in terms of coordinating composition, interfacial organization, and morphology across multiple length scales. This thesis mitigates these challenges using cellulose nanoparticle as a model system, establishing generalizable strategies to program their self-assembly across different material states and hierarchical levels.
This thesis introduces the aqueous two-phase system as a powerful medium for programming the self-assembly of cellulose nanocrystals (CNCs). Such water-water interface confinement reveals how polymer partitioning, depletion forces, and interfacial permeability collectively govern cholesteric ordering, offering new physical insight into liquid-liquid templating of anisotropic nanoparticles. Beyond CNCs, this framework can be extended to other rod-like colloids, suggesting a universal route to control phase behaviour and structural organization in multicomponent soft-matter systems. The findings also emphasize the broader significance of colloid-polymer interactions in constructing dynamic, bioinspired architectures that may bridge synthetic control with biological complexity.
Moreover, this thesis lies the advent of using the intrinsic birefringence of natural, plant-based structures in the design of chiroptical materials. This approach delivers a sustainable, scalable route to create hierarchical photonic materials, paving the way for multifunctional optical platforms that unite sustainability, biocompatibility, and advanced photonic performance.
Key words: Nanocellulose, Cholesteric liquid crystal, Multiphase colloids, Chiral plasmonic metasurface
Thesis available for public display 7 days prior to the defence at .
Doctoral theses of the School of Chemical Engineering
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