Tang Juntao, Berry Richard M, Tam Kam C
Department of Chemical Engineering, Waterloo Institute for Nanotechnology, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
CelluForce, Inc. , 625 President-Kennedy Avenue, Montreal, Quebec H3A 1K2, Canada.
Biomacromolecules. 2016 May 9;17(5):1748-56. doi: 10.1021/acs.biomac.6b00144. Epub 2016 Apr 19.
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.
通过铈介导的水溶液聚合反应制备了接枝二元聚合物刷（CNC-BPB）、聚（低聚乙二醇）甲基丙烯酸酯（POEGMA）和聚（甲基丙烯酸）（PMAA）的纤维素纳米晶体。CNC-BPB的物理性质可通过温度和pH等外部触发因素进行控制，这些因素可用于稳定和破坏油水乳液。通过这些改性，这些双功能化的CNC扩散到油水界面，并在高pH值下稳定油滴。当pH值降至2时，接枝在CNC上的POEGMA和PMAA链之间的强氢键导致乳液滴聚结，从而导致油和水的相分离。对于由CNC-POEGMA和游离PMAA混合物稳定的乳液，在低pH值下未观察到瞬时聚结。通过添加酸或碱调节pH值，在不损失任何效率的情况下，证明了在5个循环中连续的稳定-去稳定过程。这项工作表明，功能性可持续纳米材料可用于小规模油水分离，特别是用于油滴运输和亲脂性化合物的收集。
