Academic Journal
pH-responsive Pickering emulsions stabilized by silica nanoparticles in combination with a conventional zwitterionic surfactant
| العنوان: | pH-responsive Pickering emulsions stabilized by silica nanoparticles in combination with a conventional zwitterionic surfactant |
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| المؤلفون: | Binks, Bernard P., Cui, Zhenggang, Jiang, Jianzhong, Liu, Kaihong |
| بيانات النشر: | American Chemical Society |
| سنة النشر: | 2017 |
| المجموعة: | University of Hull: Repository@Hull |
| مصطلحات موضوعية: | Pickering emulsions, Silica nanoparticles, Zwitterionic surfactant |
| الوصف: | pH-responsive oil-in-water Pickering emulsions were prepared simply by using negatively charged silica nanoparticles in combination with a trace amount of a zwitterionic carboxyl betaine surfactant as stabilizer. Emulsions are stable to coalescence at pH 5 but phase separate completely at pH > 8.5. In acidic solution, the carboxyl betaine molecules become cationic allowing them to adsorb on silica nanoparticles via electrostatic interactions, thus hydrophobizing and flocculating them enhancing their surface activity. Upon increasing the pH, surfactant molecules are converted to witterionic form and significantly desorb from particles surfaces triggering de-hydrophobization and coalescence of oil droplets within the emulsion. The pH-responsive emulsion can be cycled between stable and unstable many times upon alternating the pH of the aqueous phase. The average droplet size in re-stabilized emulsions at low pH however increases gradually after four cycles due to the accumulation of NaCl. Experimental evidence including adsorption isotherms, zeta potentials, microscopy and three-phase contact angles is given to support the postulated mechanisms. |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | English |
| تدمد: | 0743-7463 |
| Relation: | https://hull-repository.worktribe.com/output/448509; Langmuir; Volume 33; Issue 9; Pagination 2296-2305; https://hull-repository.worktribe.com/file/448509/1/Supporting%20information |
| DOI: | 10.1021/acs.langmuir.6b04459 |
| الاتاحة: | https://hull-repository.worktribe.com/file/448509/1/Supporting%20information https://hull-repository.worktribe.com/output/448509 https://doi.org/10.1021/acs.langmuir.6b04459 |
| Rights: | openAccess |
| رقم الانضمام: | edsbas.9A403B1E |
| قاعدة البيانات: | BASE |
| تدمد: | 07437463 |
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| DOI: | 10.1021/acs.langmuir.6b04459 |