eprintid: 1469050 rev_number: 34 eprint_status: archive userid: 608 dir: disk0/01/46/90/50 datestamp: 2015-06-04 08:50:41 lastmod: 2021-09-20 22:22:16 status_changed: 2015-06-04 08:50:41 type: article metadata_visibility: show item_issues_count: 0 creators_name: Lee, K-Y creators_name: Blaker, JJ creators_name: Heng, JYY creators_name: Murakami, R creators_name: Bismarck, A title: pH-triggered phase inversion and separation of hydrophobised bacterial cellulose stabilised Pickering emulsions ispublished: pub divisions: UCL divisions: B04 divisions: C05 note: This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. abstract: The pH-triggered transitional phase behaviour of Pickering emulsions stabilised by hydrophobised bacterial cellulose (BC) is reported in this work. Neat BC was esterified with acetic (C2–), hexanoic (C6–) and dodecanoic (C12–) acids, respectively. We observed that C6– and C12–BC stabilised emulsions exhibited a pH-triggered reversible transitional phase separation. Water-in-toluene emulsions containing of 60 vol.% dispersed phase stabilised by C6– and C12–BC were produced at pH 5. Lowering the pH of the aqueous phase to 1 did not affect the emulsion type. Increasing the pH to 14, however, caused the emulsions to phase separate. This phase separation was caused by electrostatic repulsion between modified BC due to dissociable acidic surface groups at high pH, which lowered the surface coverage of the water droplets by modified BC. When the pH was re-adjusted to 1 again, w/o emulsions re-formed for C6– and C12–BC stabilised emulsions. C2–BC stabilised emulsions, on the other hand, underwent an irreversible pH-triggered transitional phase separation and inversion. This difference in phase behaviour between C2–BC and C6–/C12–BC was attributed to the hydrolysis of the ester bonds of C2–BC at high pH. This hypothesis is in good agreement with the measured degree of surface substitution (DSS) of modified BC after the pH-triggered experiments. The DSS of C2–BC decreased by 20% whilst the DSS remained constant for C6– and C12–BC. date: 2014-12 official_url: http://dx.doi.org/10.1016/j.reactfunctpolym.2014.09.016 vfaculties: VENG oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_source: crossref elements_id: 1036481 doi: 10.1016/j.reactfunctpolym.2014.09.016 lyricists_name: Lee, Koon lyricists_id: KYLEE17 full_text_status: public publication: Reactive and Functional Polymers volume: 85 pagerange: 208 - 213 issn: 1381-5148 citation: Lee, K-Y; Blaker, JJ; Heng, JYY; Murakami, R; Bismarck, A; (2014) pH-triggered phase inversion and separation of hydrophobised bacterial cellulose stabilised Pickering emulsions. Reactive and Functional Polymers , 85 208 - 213. 10.1016/j.reactfunctpolym.2014.09.016 <https://doi.org/10.1016/j.reactfunctpolym.2014.09.016>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/1469050/1/1-s2.0-S1381514814001953-main.pdf