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Shape-Tunable Biphasic Janus Particles as pH-Responsive Switchable Surfactants
Macromolecules ( IF 5.1 ) Pub Date : 2017-11-21 00:00:00 , DOI: 10.1021/acs.macromol.7b02365 Kang Hee Ku 1 , Young Jun Lee 1 , Gi-Ra Yi 2 , Se Gyu Jang 3 , Bernhard V. K. J. Schmidt 4 , Kin Liao 5 , Daniel Klinger 6 , Craig J. Hawker 7 , Bumjoon J. Kim 1
Macromolecules ( IF 5.1 ) Pub Date : 2017-11-21 00:00:00 , DOI: 10.1021/acs.macromol.7b02365 Kang Hee Ku 1 , Young Jun Lee 1 , Gi-Ra Yi 2 , Se Gyu Jang 3 , Bernhard V. K. J. Schmidt 4 , Kin Liao 5 , Daniel Klinger 6 , Craig J. Hawker 7 , Bumjoon J. Kim 1
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We report a simple and robust strategy to prepare pH-responsive biphasic Janus particles composed of polystyrene/poly(2-vinylpyridine) (PS/P2VP) homopolymers that are able to control the reversible formation, breakage, and switching of Pickering emulsions depending on their geometry- and pH-dependent hydrophilic–lipophilic balance. The chemical stability of these PS/P2VP Janus particles was tuned through the incorporation of cross-linkable benzophenone units along the backbone of the homopolymers. By employing these stabilized particles as emulsifiers for toluene and water, a facile transformation of emulsion types (i.e., from toluene-in-water to water-in-toluene emulsions) was achieved by adjusting the pH of the aqueous phase. More importantly, this pH-dependent switching behavior and associated stability of the emulsions could be actively controlled by adjusting the relative size ratio of PS to P2VP. When the PS volume fraction (ϕPS) was between 0.33 and 0.67, a wide range tuning of emulsion phase including rapid and reversible pH-triggered emulsion inversion was achieved by the Janus surfactants. Finally, incorporation of iron oxide nanoparticles facilitated magnetic separation of oil droplets from O/W emulsions and recovery of the Janus particles, which represents a considerable advantage for these systems.
中文翻译：
可调节形状的双相Janus颗粒作为pH敏感型可转换表面活性剂
我们报告了一个简单而强大的策略来制备由聚苯乙烯/聚（2-乙烯基吡啶）（PS / P2VP）均聚物组成的pH响应双相Janus颗粒，该均聚物能够控制Pickering乳液的可逆形成，破损和转换，具体取决于它们的Pickering乳液几何形状和pH依赖的亲水亲脂平衡。这些PS / P2VP Janus颗粒的化学稳定性可通过沿均聚物主链引入可交联的二苯甲酮单元来调节。通过将这些稳定化的颗粒用作甲苯和水的乳化剂，可以通过调节水相的pH值轻松实现乳液类型的转化（即，从水中的甲苯到甲苯中的水乳液）。更重要的是，可以通过调节PS与P2VP的相对尺寸比来主动控制与pH值相关的转换行为和乳液的相关稳定性。当PS体积分数（ϕPS）在0.33至0.67之间，通过Janus表面活性剂实现了乳液相的宽范围调节，包括快速和可逆的pH触发的乳液转化。最后，掺入氧化铁纳米粒子有助于从O / W乳液中磁分离油滴和回收Janus粒子，这代表了这些系统的显着优势。
更新日期：2017-11-21
中文翻译：
可调节形状的双相Janus颗粒作为pH敏感型可转换表面活性剂
我们报告了一个简单而强大的策略来制备由聚苯乙烯/聚（2-乙烯基吡啶）（PS / P2VP）均聚物组成的pH响应双相Janus颗粒，该均聚物能够控制Pickering乳液的可逆形成，破损和转换，具体取决于它们的Pickering乳液几何形状和pH依赖的亲水亲脂平衡。这些PS / P2VP Janus颗粒的化学稳定性可通过沿均聚物主链引入可交联的二苯甲酮单元来调节。通过将这些稳定化的颗粒用作甲苯和水的乳化剂，可以通过调节水相的pH值轻松实现乳液类型的转化（即，从水中的甲苯到甲苯中的水乳液）。更重要的是，可以通过调节PS与P2VP的相对尺寸比来主动控制与pH值相关的转换行为和乳液的相关稳定性。当PS体积分数（ϕPS）在0.33至0.67之间，通过Janus表面活性剂实现了乳液相的宽范围调节，包括快速和可逆的pH触发的乳液转化。最后，掺入氧化铁纳米粒子有助于从O / W乳液中磁分离油滴和回收Janus粒子，这代表了这些系统的显着优势。
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