Browsing by Author "Lu, Yi"
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Item All-Aqueous Bicontinuous Structured Liquid Crystal Emulsion through Intraphase Trapping of Cellulose Nanoparticles(AMERICAN CHEMICAL SOCIETY, 2023-01-09) Guo, Shasha; Tao, Han; Gao, Guang; Mhatre, Sameer; Lu, Yi; Takagi, Ayako; Li, Jun; Mo, Lihuan; Rojas, Orlando J.; Chu, Guang; Department of Bioproducts and Biosystems; Materials Chemistry of Cellulose; Bio-based Colloids and Materials; University of British Columbia; South China University of TechnologyHere, we describe the all-aqueous bicontinuous emulsions with cholesteric liquid crystal domains through hierarchical colloidal self-assembly of nanoparticles. This is achieved by homogenization of a rod-like cellulose nanocrystal (CNC) with two immiscible, phase separating polyethylene glycol (PEG) and dextran polymer solutions. The dispersed CNCs exhibit unequal affinity for the binary polymer mixtures that depends on the balance of osmotic and chemical potential between the two phases. Once at the critical concentration, CNC particles are constrained within one component of the polymer phases and self-assemble into a cholesteric organization. The obtained liquid crystal emulsion demonstrates a confined three-dimensional percolating bicontinuous network with cholesteric self-assembly of CNC within the PEG phase; meanwhile, the nanoparticles in the dextran phase remain isotropic instead. Our results provide an alternative way to arrest bicontinuous structures through intraphase trapping and assembling of nanoparticles, which is a viable and flexible route to extend for a wide range of colloidal systems.Item Composite membranes of polyacrylonitrile cross-linked with cellulose nanocrystals for emulsion separation and regeneration(Elsevier Ltd, 2023-01) Wang, Dong; Yang, Haiying; Wang, Qingxiang; Lu, Yi; Yan, Jie; Cheng, Wanli; Rojas, Orlando J.; Han, Guangping; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Northeast Forestry University; University of British ColumbiaAs a result of fatigue and damage, the durability of separation membranes remains a major challenge for long-term use in the separation of multiphase systems, such as oily water and emulsions. Here, we synthesize electrospun membranes based on hydrolyzed polyacrylonitrile reinforced with cellulose nanocrystals (CNC). The nanofibers form highly porous systems that are held together by crosslinking, allowing fast mass transport while achieving high tensile strength and elongation at break. The membranes exhibit shape retention upon immersion in complex fluids. An underwater oil contact angle of 141° enables efficient emulsion separation (98.2 % separation at a flux as high as 1293 L·m−2·h−1 for hexane-in-water emulsions) and reliable operation for at least 20 filtration cycles. A similar performance is achieved in the separation of emulsions based on toluene, petroleum ether, diesel, and vegetable oils. Overall, the designed composite membranes endow stable three-dimensional structures, excellent durability, and separation performance.Item Monolithic nanocellulose films patterned with flower-shaped and other microstructures: A facile route to modulate topographical, wetting and optical properties(Elsevier, 2023-12) Banvillet, Gabriel; Pritchard, Samantha; Kaschuk, Joice J.; Shi, Xuetong; Imani, Monireh; Lu, Yi; Takagi, Ayako; Kamkar, Milad; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Biopolymer Chemistry and Engineering; University of British ColumbiaSurface microstructures are found in nature as a mean to control wettability and adhesion. Efforts to reproduce related architectures in designing functional materials, however, require the use of tedious procedures, such as micro- and nanolithography. Herein, we introduce a facile and scalable method to create highly ordered surface microstructures or patterns supported on films made from the same material, cellulose nanofibrils (CNF). The micropatterning is based on fluid flow through solid grids that transfer three-dimensional designs on the surface of the formed films, with precise control on their spatial distribution. The obtained patterned films can be modulated as far as their wettability, optical and haptic features. The viscosity of the CNF aqueous suspension and strength properties of the produced films are shown to define the architecture of the surface patterns. In particular, multi-scale flower-shaped structures generate new properties, going from super-absorbency through capillary action in unmodified films to superhydrophobic materials after mild hydrophobization treatment.Item Multiphase Under-Liquid Biofabrication With Living Soft Matter: A Route to Customize Functional Architectures With Microbial Nanocellulose(Wiley-VCH Verlag, 2024-07-04) Lu, Yi; Chun, Yeedo; Shi, Xuetong; Wang, Dong; Ahmadijokani, Farhad; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; University of British ColumbiaThe growth of aerobic microbes at air–water interfaces typically leads to biofilm formation. Herein, a fermentative alternative that relies on oil–water interfaces to support bacterial activity and aerotaxis is introduced. The process uses under-liquid biofabrication by structuring bacterial nanocellulose (BNC) to achieve tailorable architectures. Cellulose productivity in static conditions is first evaluated using sets of oil homologues, classified in order of polarity. The oils are shown for their ability to sustain bacterial growth and BNC production according to air transfer and solubilization, both of which impact the physiochemical properties of the produced biofilms. The latter are investigated in terms of their morphological (fibril size and network density), structural (crystallinity) and physical–mechanical (surface area and strength) features. The introduced under-liquid biofabrication is demonstrated for the generation of BNC-based macroscale architectures and compartmentalized soft matter. This can be accomplished following three different routes, namely, 3D under-liquid networking (multi-layer hydrogels/composites), emulsion templating (capsules, emulgels, porous materials), and anisotropic layering (Janus membranes). Overall, the proposed platform combines living matter and multi-phase systems as a robust option for material development with relevance in biomedicine, soft robotics, and bioremediation, among others.Item Structured Ultra-Flyweight Aerogels by Interfacial Complexation: Self-Assembly Enabling Multiscale Designs(WILEY-V C H VERLAG GMBH, 2022-05-19) Kamkar, Milad; Ghaffarkhah, Ahmadreza; Ajdary, Rubina; Lu, Yi; Ahmadijokani, Farhad; Mhatre, Sameer E.; Erfanian, Elnaz; Sundararaj, Uttandaraman; Arjmand, Mohammad; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; University of British Columbia; University of CalgaryThe rapid co-assembly of graphene oxide (GO) nanosheets and a surfactant at the oil/water (O/W) interface is harnessed to develop a new class of soft materials comprising continuous, multilayer, interpenetrated, and tubular structures. The process uses a microfluidic approach that enables interfacial complexation of two-phase systems, herein, termed as “liquid streaming” (LS). LS is demonstrated as a general method to design multifunctional soft materials of specific hierarchical order and morphology, conveniently controlled by the nature of the oil phase and extrusion's injection pressure, print-head speed, and nozzle diameter. The as-obtained LS systems can be readily converted into ultra-flyweight aerogels displaying worm-like morphologies with multiscale porosities (micro- and macro-scaled). The presence of reduced GO nanosheets in such large surface area systems renders materials with outstanding mechanical compressibility and tailorable electrical activity. This platform for engineering soft materials and solid constructs opens up new horizons toward advanced functionality and tunability, as demonstrated here for ultralight printed conductive circuits and electromagnetic interference shields.Item Super-Macroporous Lightweight Materials Templated from Bicontinuous Intra-Phase Jammed Emulsion Gels Based on Nanochitin(WILEY-VCH VERLAG, 2023-09-27) Lu, Yi; Kamkar, Milad; Guo, Shasha; Niu, Xun; Wan, Zhangmin; Xu, Junhua; Su, Xiaoya; Fan, Yimin; Bai, Long; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; University of British Columbia; Nanjing Forestry University; Northeast Forestry UniversityNon-equilibrium multiphase systems are formed by mixing two immiscible nanoparticle dispersions, leading to bicontinuous emulsions that template cryogels with interconnected, tortuous channels. Herein, a renewable, rod-like biocolloid (chitin nanocrystals, ChNC) is used to kinetically arrest bicontinuous morphologies. Specifically, it is found that ChNC stabilizes intra-phase jammed bicontinuous systems at an ultra-low particle concentration (as low as 0.6 wt.%), leading to tailorable morphologies. The synergistic effects of ChNC high aspect ratio, intrinsic stiffness, and interparticle interactions produce hydrogelation and, upon drying, lead to open channels bearing dual characteristic sizes, suitably integrated into robust bicontinuous ultra-lightweight solids. Overall, it demonstrates the successful formation of ChNC-jammed bicontinuous emulsions and a facile emulsion templating route to synthesize chitin cryogels that form unique super-macroporous networks.
