Shakeel Ahmad, Farooq Ujala, Chassagne Claire
Faculty of Civil Engineering and Geosciences, Department of Hydraulic Engineering, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands.
Faculty of Aerospace Engineering, Aerospace Manufacturing Technologies, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands.
Nanomaterials (Basel). 2020 Feb 18;10(2):356. doi: 10.3390/nano10020356.
Oil/water emulsions are usually stabilized either by interfacial modification using nanoparticles and surfactants (stated as pickering emulsion or bijels) or by bulk stabilization with the help of low-molecular-weight or polymeric gelators (known as bigels) in response to some external stimuli (e.g., pH, temperature). Both these approaches result in different systems that are quite useful for different applications, including catalysis, pharmaceutical and agrochemicals. However, these systems also possess some inherent drawbacks that need to be addressed, like difficulty in fabrication and ensuring the permanent binding of nanoparticles at the oil/water interface, in case of nanoparticles stabilized emulsions (i.e., interfacial stabilization). Similarly, the long-term stability of the oil/water systems produced by using (hydro/organo) gelators (i.e., bulk stabilization) is a major concern. Here, we show that the oil/water system with improved mechanical and structural properties can be prepared with the synergistic effect of interfacial and bulk stabilization. We achieve this by using nanoparticles to stabilize the oil/water interface and polymeric gelators to stabilize the bulk phases (oil and water). Furthermore, the proposed strategy is extremely adaptable, as the properties of the resultant system can be finely tuned by manipulating different parameters such as nanoparticles content and their surface functionalization, solvent type and its volume fraction, and type and amount of polymeric gelators.
油/水乳液通常通过使用纳米颗粒和表面活性剂进行界面改性（称为皮克林乳液或双连续乳液）或借助低分子量或聚合物凝胶剂（称为双凝胶）在某些外部刺激（例如pH值、温度）下进行本体稳定化来实现稳定。这两种方法都会产生不同的体系，这些体系在包括催化、制药和农用化学品在内的不同应用中非常有用。然而，这些体系也存在一些需要解决的固有缺点，比如在纳米颗粒稳定的乳液（即界面稳定化）中，制造困难且难以确保纳米颗粒在油/水界面的永久结合。同样，使用（水/有机）凝胶剂产生的油/水体系（即本体稳定化）的长期稳定性也是一个主要问题。在此，我们表明通过界面稳定化和本体稳定化的协同作用，可以制备出具有改善的机械和结构性能的油/水体系。我们通过使用纳米颗粒稳定油/水界面并使用聚合物凝胶剂稳定本体相（油和水）来实现这一点。此外，所提出的策略具有极强的适应性，因为通过操纵不同参数，如纳米颗粒含量及其表面功能化、溶剂类型及其体积分数以及聚合物凝胶剂的类型和用量，可以精细调节所得体系的性能。
