Wege Hartmut A, Kim Sejong, Paunov Vesselin N, Zhong Qixin, Velev Orlin D
Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA.
Langmuir. 2008 Sep 2;24(17):9245-53. doi: 10.1021/la801634j. Epub 2008 Jul 23.
We report a simple method to produce foams and emulsions of extraordinary stability by using hydrophobic cellulose microparticles, which are formed in situ by a liquid-liquid dispersion technique. The hydrophobic cellulose derivative, hypromellose phthalate (HP), was initially dissolved in water-miscible solvents such as acetone and ethanol/water mixtures. As these HP stock solutions were sheared in aqueous media, micron sized cellulose particles formed by the solvent attrition. We also designed and investigated an effective and simple process for making HP particles without any organic solvents, where both the solvent and antisolvent were aqueous buffer solutions at different pH. Consequently, the HP particles adsorbed onto the water/air or water/oil interfaces created during shear blending, resulting in highly stable foams or foam/emulsions. The formation of HP particles and their ability for short-term and long-term stabilization of interfaces strongly depended on the HP concentration in stock solutions, as well as the solvent chemistry of both stock solutions and continuous phase media. Some foams and emulsion samples formed in the presence of ca. 1 wt% HP were stable for months. This new class of nontoxic inexpensive cellulose-based particle stabilizers has the potential to substitute conventional synthetic surfactants, especially in edible, pharmaceutical and biodegradable products.
我们报告了一种简单的方法，通过使用疏水性纤维素微粒来制备具有非凡稳定性的泡沫和乳液，这些微粒是通过液-液分散技术原位形成的。疏水性纤维素衍生物羟丙甲纤维素邻苯二甲酸酯（HP）最初溶解于与水混溶的溶剂中，如丙酮和乙醇/水混合物。当这些HP储备溶液在水性介质中剪切时，通过溶剂磨损形成微米级纤维素颗粒。我们还设计并研究了一种无需任何有机溶剂制备HP颗粒的有效且简单的方法，其中溶剂和反溶剂均为不同pH值的水性缓冲溶液。因此，HP颗粒吸附到剪切混合过程中产生的水/空气或水/油界面上，从而形成高度稳定的泡沫或泡沫/乳液。HP颗粒的形成及其对界面的短期和长期稳定能力在很大程度上取决于储备溶液中的HP浓度，以及储备溶液和连续相介质的溶剂化学性质。在约1 wt% HP存在下形成的一些泡沫和乳液样品可稳定数月。这类新型无毒且廉价的纤维素基颗粒稳定剂有潜力替代传统的合成表面活性剂，尤其是在食用、制药和可生物降解产品中。
