Light-responsive multillamellar vesicles in coumaric acid/alkyldimethylamine oxide binary systems: Effects of surfactant and hydrotrope structures

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• 作者：Kangle Jia ; Junwen Hu ; Jinfeng Dong ; Xuefeng Li ; ^{lixuefeng@whu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Multilamellar vesicles ; Micelles ; Phase separation ; Light-responsive systems ; Viscosity
• 刊名：Journal of Colloid and Interface Science
• 出版年：2016
• 出版时间：1 September 2016
• 年：2016
• 卷：477
• 期：Complete
• 页码：156-165
• 全文大小：3174 K

文摘

Herein, we report a series of novel light-responsive multilamellar vesicles based on the surfactant/hydrotrope binary systems. The phase behaviors of alkyldimethylamine oxide (C_mDMAO, m = 10, 12, 14) and trans-coumaric acid (trans-CA) isomerides, including trans-ortho-coumaric acid (trans-OCA), trans-meta-coumaric acid (trans-MCA) and trans-para-coumaric acid (trans-PCA), show that the multilamellar vesicle (MLV) formation region is commonly presented in the trans-CA/C_mDMAO systems except trans-PCA/C₁₂DMAO. Moreover, the molecular structures of C_mDMAO and trans-CA affect the multilamellar vesicle formation region significantly. Generally speaking, the bigger the m, the larger the MLV region. Various techniques such as rheology, polarized optical microscopy (POM), ¹H NMR, ²H NMR, cryogen transmission electron microscopy (cryo-TEM) and freeze-fracture transmission electron microscopy (FF-TEM) are used to characterize the aggregate structures. The multilamellar vesicles can transform into a homogeneous and transparent micelle phase or a two-phase system in the trans-OCA/C_mDMAO binary systems under UV light irradiation, which depends on the chain length of C_mDMAO and the molar ratio of [trans-OCA]/[C_mDMAO]. Specifically, the light-stimuli response of multilamellar vesicles in the trans-OCA/C₁₂DMAO system is representatively studied in detail. UV–vis spectra and ¹H NMR measurements illustrate that the light-induced trans-OCA to cis-OCA isomerization is essential during the transitions and the light-induced two-phase formation is attributed to the enrichment of surfactants, because the trans-cis isomerization can not only strengthen the hydrophilicity of cis-OCA but also increase the steric hindrance between cis-OCA and C₁₂DMAO, and thereby altering the morphology of aggregate and the rheological response of bulk phase significantly.