title: Stimuli-Responsive Cellulose Nanocrystals for Surfactant-Free Oil Harvesting.
abstract: Cellulose nanocrystals with grafted binary polymer brushes (CNC-BPB), poly(oligoethylene glycol) methacrylate (POEGMA) and poly(methacrylic acid) (PMAA), were prepared by cerium-mediated polymerization in aqueous solution. The physical properties of CNC-BPB can be controlled by external triggers, such as temperature and pH, which can be utilized to stabilize and destabilize oil-water emulsions. By virtue of the modifications, these bifunctionalized CNCs diffused to the oil-water interface and stabilized the oil droplets at high pHs. When the pH was lowered to 2, strong hydrogen bonding between POEGMA and PMAA chains grafted on the CNC induced the coalescence of the emulsion droplets, resulting in the phase separation of oil and water. For emulsions stabilized by CNC-POEGMA and free PMAA mixtures, instantaneous coalescence was not observed at low pHs. Successive stabilization-destabilization over 5 cycles was demonstrated by modulating the pH with the addition of acid or base without any loss in efficiency. This work demonstrates that functional sustainable nanomaterials can be used for small scale oil-water separations, particularly for oil droplet transportation and harvesting of lipophilic compounds.
authors.affiliation: Department of Chemical Engineering, Waterloo Institute for Nanotechnology, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Juntao
authors.initials: J
authors.lastname: Tang
authors.affiliation: CelluForce, Inc. , 625 President-Kennedy Avenue, Montreal, Quebec H3A 1K2, Canada.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Berry
authors.affiliation: Department of Chemical Engineering, Waterloo Institute for Nanotechnology, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
authors.forename: Kam C
authors.initials: KC
authors.lastname: Tam
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D004655:Emulsions; D008689:Methacrylates; D053758:Nanoparticles / Q000737:chemistry*; D009821:Oils / Q000737:chemistry / Q000302:isolation & purification*; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D004655:Emulsions; D008689:Methacrylates; D009821:Oils; D011108:Polymers; D013501:Surface-Active Agents; D014867:Water; C008384:methacrylic acid; D002482:Cellulose