Bolalipid fiber aggregation can be modulated by the introduction of sulfur atoms into the spacer chains

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• 作者：Gesche Graf^a ; ¹ ; Simon Drescher^a ; ^b ; Annette Meister^a ; ^c ; Vasyl M. Haramus^d ; Bodo Dobner^b ; Alfred Blume^a ; ^{alfred.blume@chemie.uni-halle.de}
• 关键词：Bolaamphiphiles ; Nanofibers ; Self-assembly ; Viscoelastic hydrogel ; Rheology
• 刊名：Journal of Colloid and Interface Science
• 出版年：2013
• 出版时间：1 March, 2013
• 年：2013
• 卷：393
• 期：Complete
• 页码：143-150
• 全文大小：664 K

文摘

The aggregation behavior in aqueous suspension of two symmetrical single-chain bolaamphiphiles, namely 12,21-dithiadotriacontane-1,32-diyl-bis [2-(tri-methylammonio)ethylphosphate] (PC-C32SS-PC) and 12,21-dithiadotriacontane-1,32-diyl-bis[2-(dimethylammonio)ethylphosphate] (Me₂PE-C32SS-Me₂PE), containing sulfur as heteroatoms in the chains, was studied using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), small angle neutron scattering (SANS), and transmission electron microscopy (TEM). The rheological properties of hydrogels formed by the aggregation into nanofibers were studied by oscillatory rheology. Based on the well-characterized behavior of bolalipids with long alkyl chains which at room temperature can form a network of nanofibers leading to the formation of a hydrogel, we investigated whether the incorporation of two heteroatoms of sulfur into the spacer chain of the molecules has an influence on the aggregation properties. Compared to the analogues without sulfur, the fibrous aggregates formed by sulfur containing compounds are less stable and build weaker viscoelastic gels. This is due to a perturbation of the packing of the chains as the sulfur atoms change the bond angle in the chain compared to the molecules with pure alkyl chains leading to kinks in the chain. For the bolaamphiphile with the Me₂PE headgroups this effect is less pronounced due to the possibility of forming stabilizing hydrogen bonds between the headgroups.