Phase Behavior of Medium and High Internal Phase Water-in-Oil Emulsions Stabilized Solely by Hydrophobized Bacterial Cellulose Nanofibrils
Phase Behavior of Medium and High Internal Phase Water-in-Oil Emulsions Stabilized Solely by Hydrophobized Bacterial Cellulose Nanofibrils
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DOI：
10.1021/la4032514
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发表时间：
2014-01-21
期刊：
影响因子：
3.9
通讯作者：
Bismarck, Alexander
中科院分区：
文献类型：
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作者：
Lee, Koon-Yang;Blaker, Jonny J.;Bismarck, Alexander
通过与不同链长有机酸（乙酸C-2-、己酸C-6-、十二酸C-12-）的酯化反应，制备了完全由细菌纤维素纳米纤维（BCNs）稳定的油包水乳状液，并对其进行了表征。冻干的C-6-BCN和C-12-BCN只能稳定60%的最大水体积分数（phi(w)），而C-2-BCN则不能得到乳液。而C-2-BCN、C-6-BCN和C-12-BCN的最大phi(w)在初始乳化后150 h分别增加到71%、81%和77%，从而形成高内相的甲苯水乳状液。观察到这些乳液的时间依赖性行为与冻干改性BCN束随时间解缠和分散成单个纳米纤维一致。当phi(w)增加时，这些乳剂表现出灾难性的相分离，而其他皮克林乳剂则表现出灾难性的相反转。
Water-in-oil emulsions stabilized solely by bacterial cellulose nanofibers (BCNs), which were hydrophobized by esterification with organic acids of various chain lengths (acetic acid, C-2-; hexanoic acid, C-6-; dodecanoic acid, C-12-), were produced and characterized. When using freeze-dried C-6-BCN and C-12-BCN, only a maximum water volume fraction (phi(w)) of 60% could be stabilized, while no emulsion was obtained for C-2-BCN. However, the maximum phi(w) increased to 71%, 81%, and 77% for C-2-BCN, C-6-BCN, and C-12-BCN, respectively, 150 h after the initial emulsification, thereby creating high internal phase water-in-toluene emulsions. The observed time-dependent behavior of these emulsions is consistent with the disentanglement and dispersion of freeze-dried modified BCN bundles into individual nanofibers with time. These emulsions exhibited catastrophic phase separation when phi(w) was increased, as opposed to catastrophic phase inversion observed for other Pickering emulsions.