Collaborative Proposal: How to Gel Oil (or Water) in an Immiscible Oil-Water Mixture: A Systematic Study of Phase-Selective Gelation

每个人都知道油和水不能混合。该奖项将研究如何选择性地将这些液体中的一种转化为凝胶-这一过程被称为相选择性凝胶化。为了诱导这种凝胶，分子将被合成，这些分子将进入油层或水层，然后在那里进行“自组装”。自组装意味着分子会自发地连接并形成纳米级大小的结构——在这种情况下是长纤维。然后，纳米纤维会相互缠绕，从而将液体转化为糊状物质（具有番茄酱或发胶的稠度）。这将是第一次对相选择凝胶的系统研究。从这个奖项中获得的见解可以帮助设计新的材料来清理石油泄漏或修复被石油污染的地下水。该奖项的重点将放在相选择凝胶现象背后的基础科学上，目标是开发连接分子结构、界面性质和凝胶结构/流变学的设计规则。一系列两亲性分子将被合成，并将研究它们在混合物中使油相或水相凝胶化的能力。一个分子是相选择凝胶的关键标准是：(a)它不应使油水混合物乳化；(b)它也不应该在两相中被明显溶解。假设这种凝胶可以通过两亲分子之间的非共价相互作用来实现，比如头部基团之间的氢键以及尾部之间的π - π和范德华相互作用。拟议的研究还将与合作机构的教育、指导和外展活动相结合。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Everyone knows that oil and water do not mix. This award will study how one of these liquids can be selectively converted into a gel – a process that is termed phase-selective gelation. To induce such gelation, molecules will be synthesized that will find their way into either the oil or the water layer and then undergo ‘self-assembly’ there. Self-assembly implies that the molecules will spontaneously join and form structures – in this case, long fibers – with nanoscale sizes. In turn, the nanofibers will entangle with each other and thus convert the liquid into a paste-like material (with the consistency of ketchup or hair gel). This will be the first systematic study on phase-selective gelation. The insights from this award could help design new materials to clean-up oil spills or to remediate oil-contaminated ground water. The focus of this award will be on the fundamental science behind the phenomenon of phase-selective gelation, and the goal will be to develop design rules connecting molecular structure, interfacial properties, and gel structure/rheology. A range of amphiphilic molecules will be synthesized and their ability to gel either the oil or water phase in a mixture will be studied. Key criteria for a molecule to be a phase-selective gelator are: (a) it should not emulsify the oil-water mixture; and (b) it should also not get appreciably solubilized in either of the phases. The hypothesis is that such gelation can be accomplished by striking the right balance of non-covalent interactions between the amphiphilic molecules such as hydrogen-bonding between the head groups as well as pi-pi and van der Waals interactions between the tails. The proposed research will also be integrated with educational, mentoring, and outreach activities at the collaborating institutions.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.