氯化钠对包覆维生素C多重乳液的影响

Effects of sodium chloride on the multiple emulsion encapsulating Vitamin C

以辛酸/癸酸甘油三酯(GTCC)为油相,月桂基PEG-9聚二甲基硅氧乙基聚二甲基硅氧烷为油溶性乳化剂、双亲性无规共聚物为水溶性乳化剂,两步法制备了水包油包水(W1/O/W2)型多重乳液,并将维生素C包覆于内水相(W1)中,通过NaCl调节内外水相渗透压提高多重乳液稳定性。考察了NaCl加入量对相界面张力、乳液粒径及黏度的影响,通过显微镜微观拍照和乳液外观评价乳液稳定性。实验表明,W1相添加NaCl可显著降低W1/O界面张力,减小乳液粒径,增加乳液黏度;外水相(W2)添加NaCl超过0.2%时,O/W2界面张力显著增大;与NaCl相比,维生素C对降低W1/O界面张力的能力较小。控制W1/O/W2乳液中内外水相NaCl含量均为0.2%,考察W1中维生素C添加量对多重乳液微观及外观影响。当维生素C包覆量为0.75%时,多重乳液粒径均匀且外观稳定。

Water-in-oil-in-water(W1/O/W2)multiple emulsion was prepared by two-step method with caprylic/capric triglyceride as oil phase,lauryl PEG-9 polydimethylsiloxyethyl dimethicone as oleophilic emulsifier and the amphiphilic random copolymer as hydrophilic emulsifier.The multiple emulsion was used to encapsulate Vitamin C in internal aqueous phase(W1).Sodium chloride(NaCl)regulated the osmotic pressure between the internal and external aqueous phases to improve the stability of the multiple emulsion.The effects of the amount of NaCl on the interfacial tension,droplet size of emulsion and viscosity were investigated.The stability of the multiple emulsion was evaluated by optical microscope and emulsion appearance.The results show that,the addition of NaCl in W1 lead to significant decrease of W1/O interfacial tension,smaller size of the emulsion droplets,and higher viscosity of the emulsion.The interfacial tension at O/W2 interface would be obviously increased if the content of NaCl in W2 is higher than 0.2%.In contrast to NaCl,the addition of Vitamin C merely slightly decrease the interfacial tension between W1/O interface.Thus,in this work the amount of NaCl is kept at 0.2%both in internal and external aqueous phases of W1/O/W2,and the effects of Vitamin C concentration in W1 on the microscopic states and appearance of the multiple emulsion are investigated.A homogeneous and stable multiple emulsion could be obtained with the encapsulation of Vitamin C at 0.75%.