Hypothesis

The self-assembly of long-tail surfactants results in the formation of nanoscale structures, e.g. worm-like micelles, with the ability to modify the rheology of the system. However, micelle formation, and thus the alteration of the rheology, is subject to the high Krafft temperature of saturated long-tail surfactants. Hexadecylmaltosides are sustainable surfactants that, in solution, form tailorable viscoelastic fluids. The preparation of monounsaturated sugar-based surfactants is hypothesised to reduce the Krafft point compared to the saturated analogues, therefore increasing the temperature range where the surfactant remains in the micellar form.

Experiments

Here we report the synthesis and characterisation of a novel sugar-based surfactant with an unsaturated C16-tail, namely palmitoleyl-β-d-maltoside (β-C_16-1G₂). Differential scanning calorimetry was used to probe the temperature stability of the system. The rheology of β-C_16-1G₂ solutions was investigated by means of rotational and oscillatory rheology, and these results were connected to the mesoscopic structure of the system as shown by small-angle neutron and X-ray scattering, and dynamic light scattering.

Findings

The presence of a double bond on the alkyl chain moiety leads to a depression in the Krafft point, allowing the surfactant to form a thermodynamically stable micellar solution over a wide range of temperatures, i.e. 5–95 °C. The surfactant self-assembles into worm-like micelles which, upon entanglement in the semi-dilute regime, result in the formation of a non-Newtonian, viscoelastic fluid. These observations have important implications in the development of new sustainable formulated products, enabling the preparation of surfactant phases with remarkable thermal resilience.

中文翻译：

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尾巴不饱和度可调节自组装糖基表面活性剂的热力学和流变性

假设

长尾表面活性剂的自组装导致形成纳米级结构，例如蠕虫状胶束，并具有改变系统流变性的能力。但是，胶束的形成以及流变学的改变都受到饱和长尾表面活性剂的高Krafft温度的影响。十六烷基麦芽糖苷是可持续的表面活性剂，在溶液中可形成可定制的粘弹性流体。假设与饱和类似物相比，单不饱和糖基表面活性剂的制备可降低Krafft点，因此增加了表面活性剂以胶束形式保留的温度范围。

实验

此处我们报告一个新的基于糖的表面活性剂的合成和表征用不饱和C16-尾，即棕榈油-β- d -maltoside（β-C _16-1 ģ ₂）。差示扫描量热法用于探测系统的温度稳定性。通过旋转和振荡流变学研究了β- _C16-1 G ₂溶液的流变学，这些结果与系统的介观结构有关，如小角度中子和X射线散射以及动态光所示。散射。

发现

烷基链部分上双键的存在会导致Krafft点降低，从而使表面活性剂在很宽的温度范围内（即5–95°C）形成热力学稳定的胶束溶液。表面活性剂自组装成蠕虫状的胶束，在半稀释状态下缠结后会形成非牛顿的粘弹性流体。这些观察结果对新型可持续配方产品的开发具有重要意义，从而使制备具有显着热弹性的表面活性剂相成为可能。