Myelin Figures: Non-equilibrium organization of amphiphiles induced by hydration

非技术摘要：油和水不能混合。但许多普通的肥皂和洗涤剂通过允许这两种物质混合来否定这一谚语。这些柔软易碎的物质被称为表面活性剂，以复杂、微妙和微妙的方式与水(或油)相互作用。它们在水中的溶解通常伴随着不寻常的结构的形成，这些结构远远超出了分子的尺寸，产生了动态的马赛克，这是富含表面活性剂的水相的特征。一个这样的例子是一类被称为髓鞘图形的手指状圆柱形突起的形成，直径数十微米，长度数百微米，当干质量的表面活性剂与水相遇时就会出现。该项目包括控制实验室实验，以研究它们的形成，指导它们的生长，并利用它们的形态来生产新的纳米材料。该项目的发现将使许多领域的应用受益，包括食品、化妆品、肥皂和分散技术。该项目包括对一名研究生和一名博士后进行科学过程的培训和参与。它还通过垂直整合计划吸引本科生和STEM中代表性不足的群体，该计划为科学与社会提供学分和机会，让他们在多年的实验室研究中进行单一的综合项目。技术摘要：复杂流体的平衡通常伴随着不寻常的不稳定性，因为它们正朝着平衡的方向发展。髓鞘不稳定可能是最好的例证，当不溶的表面活性剂遇到水时，就会出现髓鞘不稳定。单个髓鞘--直径几十微米、长数百微米的圆柱形近晶液晶--以二维螺旋状运动曲折生长，与相邻的髓鞘紧密并列；相互配合地伸长；在形态上往往折叠成破坏对称的螺旋形状。本项目旨在了解它们的形成机制，控制它们的空间组织，研究它们对环境扰动的响应，并利用它们对模板合成纳米结构的纳米限制。它在实验上测试了这样的假设，即两亲水化的本质非平衡过程可以被可控地调节以解除平衡约束，拨入结构不稳定性，并动力学地捕获表征水化过程的自由能景观中的长寿命亚稳态。它还试图利用髓鞘图形作为自组织动态模板，将纳米材料合成成分级的、扩展的和复杂的超晶格。计划中的研究活动包括：(1)结合基于显微镜的定量测量，开发控制髓鞘图形的空间组织的方法(驯服混沌)；(2)表征髓鞘形态中的两亲物的相分离混合物(引入化学多样性)；(3)通过从局部微环境耦合物理-化学应力来获得髓鞘图形的高阶、对称的破坏组织(变形髓鞘)；以及(4)通过利用髓鞘限制(模板纳米合成)来模板化合成纳米材料。这项工作将为控制超分子组织的非平衡路线和设计合成的新方法带来新的见解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Abstract: Oil and water do not mix. But many ordinary soaps and detergent negate this proverbial expression by allowing the two substances to mix. Called surfactants, these soft and fragile materials interact with water (or oil) in complex, subtle, and nuanced manners. Their dissolution in water is often accompanied by the formation of unusual structures that extend far beyond the sizes of molecules producing a dynamic mosaic that characterize the surfactant-laden aqueous phase. One such example is the formation of a class of finger-like cylindrical protrusions called myelin figures, tens of micrometers in diameters and hundreds of micrometers in length, which appear when a dry mass of surfactant meets water. This project involves controlled laboratory experiments to study their formation, direct their growth, and exploit their morphologies to produce novel nanomaterials. The findings of the project should benefit many areas of applications, including food, cosmetics, soap, and dispersion technologies. The project includes the training and participation of a graduate student and a post-doc in the scientific process. It also engages undergraduate students and underrepresented groups in STEM through the Vertically-Integrated Program, which offers Science & Society credits and opportunities for laboratory research over multiple years on a single, consolidated project.Technical Abstract: The equilibration of complex fluids is often accompanied by unusual instabilities as they progress toward equilibrium. This is perhaps best exemplified by myelinic instabilities, which emerge when an insoluble surfactant meets water. The individual myelins ¬– cylindrical smectic liquid crystals tens of micrometers in diameter and hundreds of micrometers in length – grow sinuously, by a two-dimensional reptation-like motion, which tightly juxtapose with their neighbors; elongate, cooperatively; and, often fold morphologically, into symmetry-breaking helical shapes. This project seeks to understand their formation mechanisms, control their spatial organization, investigate their responsiveness to environmental perturbations, and exploit their nanometer scale confinements to template synthesis of nanostructures. It experimentally tests the hypothesis that the intrinsically non-equilibrium process of amphiphilic hydration can be controllably tuned to lift equilibrium constraints, dial-in structural instabilities, and kinetically trap long-lived metastable states within the free energy landscape that characterizes the hydration process. It also seeks to exploit myelin figures as self-organizing dynamic templates to synthesize nanoscale materials into hierarchical, extended, and complex superlattices. Using a combination of microscopy based quantitative measurements, the planned research activities include(1) develop methods to control the spatial organization of myelin figures (taming the chaos); (2) characterizing phase-separating mixtures of amphiphiles within myelin morphologies (introducing chemical diversity); (3) accessing higher-order, symmetric breaking organization of myelin figures by coupling physical-chemical stress from their local microenvironment (shape-shifting myelins); and (4) templating synthesis of nanomaterials by exploiting myelinic confinement (templated nanosynthesis). The effort should yield new insights into non-equilibrium routes for controlling supramolecular organization and novel approaches for synthesis-with-design.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.