纳米甲壳素稳定蜂蜡油凝胶Pickering乳液的性能研究

Properties of oleogel-in-water Pickering emulsion stabilized by nano-chitin

用盐酸蒸汽处理甲壳素原料来制备纳米甲壳素,其形貌为棒状结构且平均直径约为50~60 nm、具有较高的长径比。以蜂蜡和玉米油制成的油凝胶作为油相,用纳米甲壳素作为Pickering乳液稳定剂,制得O/W型油凝胶Pickering乳液。用光学显微镜、荧光显微镜、动态光散射粒度仪、流变仪对乳液进行表征。偏振光显微镜图片中的双折射现象表明蜂蜡油凝胶被包裹在油滴中。荧光显微镜的结果显示纳米甲壳素在油/水界面的吸附能力很强,在纳米甲壳素质量分数仅为0.2%时,即可乳化含有10%(质量分数)蜂蜡的油相得到稳定的油凝胶Pickering乳液(油/水质量比为1∶9),且干燥除水后能够维持原貌。油凝胶以及其乳液的流变行为表明纳米甲壳素在油/水界面具有较好的机械阻隔作用,且油凝胶可以在剪切作用下被释放。

Nano-chitin was prepared by treating raw chitin with hydrogen chloride(HCl)vapor followed by dispersing in water at high speed for 1 min.The obtained nano-chitin has rod-like morphology with average diameter of approximately 50-60 nm and high length-diameter ratio.The nano-chitin suspension thus prepared was used to stabilize an oleogel consisting of beeswax and corn oil to fabricate oleogel-in-water Pickering emulsion,and it was confirmed that the chitin without HCl vapor treatment could not stabilize the oleogel to form Pickering emulsion.The emulsions were characterized by optical microscope,polarized microscope,fluorescence microscope,dynamic laser scattering size analyzer and rheometer.The birefringence observed by polarized microscope shows that beeswax oleogel is successfully encapsulated.The results of fluorescence microscopy show that nano-chitin is adsorbed at the O/W interface,and the emulsions keep the original morphology after water being removed for the oleogel containing more than 5%beeswax.The rheology behaviors of oleogel Pickering emulsions stabilized by 0.6%nano-chitin suspension with varied beeswax concentration show much lower storage modulus than corresponding beeswax oleogels,indicating that the nano-chitin has acted as a barrier at the O/W interface of Pickering emulsion to protect it from breaking under shearing.Oleogel containing 10%beeswax could be stabilized at an O/W ratio of 1/9 using as little as 0.2%nano-chitin suspension.The resulting Pickering emulsion is able to maintain the original morphology after complete removal of water,and its rheology behavior is similar to the oleogel containing 10%beeswax,indicating that the beeswax oleogel is released under shearing.The rheology behaviors of emulsions with oleogel containing 10%beeswax encapsulated indicate that the beeswax oleogel can be control-released under shearing by adjusting the concentration of nano-chitin.