Current Research Topics
Green Chemistry and Sustainability
Smart and Sustainable Cellulosic Materials
In this context, a smart material comprises responsive and functional matter derived from renewable cellulose sources (e.g., wood, agricultural waste, or algae) that can adapt its properties—such as shape, elasticity, conductivity, permeability, or optical behavior—in response to external stimuli like temperature, pH, humidity, light, or mechanical stress. Our laboratory invented and patented a catalyst-free Green Chemistry process that uses dilute hydrogen peroxide to convert FSC-certified boreal forest biomass into carboxylated cellulose nanocrystals (cCNC). We explore applications of spray-drying as an implementation of active control to rescale the nanocrystals into nonequilibrium microbead assemblies. The scope of this approach is enormous because it allows us to create forms of matter whose properties lie outside the range of conventional nanoscale self-assembly. By active control of nanoparticle assembly, we have shown that cCNC microbeads can be used to remove synthetic dyes from water and to absorb oils. Nanodispersed cCNC undergoes molecule-by-molecule adsorption of synthetic and botanically-derived dyes from which vibrant pigments can be made by spray drying. Hybrid protein or synthetic polymer microbeads show unusual solid state phase transitions, whilst exhibiting tuneable mechanical properties and adjustable surface energy. In other cases, we rescale cCNC to make nano- and macro-porous structures with potential for tissue engineering. Our research is both interdisciplinary and multidisciplinary; to advance their research, students use the sophisticated instruments of our laboratory, and McGill's MC2 and FEMR facilities. Industrial collaborations introduce students to entrepreneurial strategies that foster incentives to elaborate fundamental research into purposeful outcomes. A recent example is the founding of McGill spin-off, Anomera Inc. The Andrews laboratory continues to develop cellulose nanocrystals for applications in medicine/pharmaceutics, health and beauty, bioplastics, printing, agriculture and many more.
Engineered Biological Systems for CO2 Capture and Energy Conversion
Gram negative bacteria naturally extrude nanoparticles known as outer-membrane vesicles (OMV). OMVs can be viewed as a type of nanofactory. Like their organism of origin, they contain the same outer membrane features - enzymes and periplasmic components. With the tools of molecular biology, we "instruct" photosynthetic organisms to produce OMVs to carry cargo (enzymes, redox moieties, chemical recognition elements, etc) to perform useful work. Our collaborations with the Mauzeroll group at McGill and internationally, lead us to explore OMVs as candidates for CO2 carbon capture, specialty and commodity chemical synthesis, catalysis, and electron transfer.
Field-Responsive Materials
Magnetorheological and Ferrofluids: Applications and Morphogenesis
Our interest in far-from-equilibrium phenomena leads us to explore stimuli-responsive “smart” materials like Magnetorheological Fluids (MRFs) and Ferrofluids. MRFs are suspensions of magnetic microparticles and Ferrofluids are suspensions of nanoparticles dispersed in a liquid phase. The rheological (flow) properties of MRFs can be rapidly and reversibly changed by applying a magnetic field. In partnership with academic, industrial and governmental institutions and agencies, we explore how MRF formulation and nanoscale interfacial chemistry can be modified to enhance applications of MRFs in the biomedical, robotic, automotive, and aerospace industries. Elsewhere, our studies of the field-responses of nano-magnetite (Fe3O4) ferrofluids lead us into the esoteric world of pattern formation and its relation to morphogenesis. Morphogenesis refers to the mechanisms by which cells, tissues, and organs are organized spatially - how they can form far-from-equlibrium patterns. Our studies of ferrofluids yield controllable, observable media where we use magnetic fields to create and trap complex patterns in metastable and far-from-equlibrium states. We combine machine learning and experiments to give insight into pattern formation and to understand how magnetic fluid "morphogenesis" maps onto patterns relevant to self-organization in living systems. Our view is that understanding pattern formation in ferrofluids might then lead us to new types of functional matter.
Photonic Materials and Processes
We "manage photons" for fundamental research into light-matter interactions, optical sensing, digital communications and to understand how Nature uses light to communicate and convert it to make oxygen and hydrocarbons from CO2. In biophotonics, we explore photosynthetic diatoms. These phytoplankton are major photosynthetic contributors to the global oxygen and carbon cycles. We study the optical properties of the ornate diatom nano-patterned periodic silica glass exoskeleton, called the frustule. Our examinations of the frustules of Nitzschia palea and N. filiformis provide insight into how they use nano-patterned glass as a complex optical system. The frustule coordinates the functions of many different photonic components into an optical circuit that ultimately converts CO2 into products crucial to planetary well-being. In other areas, we make and stabilize perovskite nanocrystals to understand their ultrafast photophysics and advance their laser applications. We investigate the materials chemistry of infrared glasses to enhance their performance for fiber optic communications. Our home-built integrated optics Raman spectrometer allows us to study chemical reactions in thin films and at interfaces. Nanoplasmonic waveguides give us insight into the spectroscopic optical near-field, enhancing our understanding of nanoscale chemical processes.