Molecular and Hybrid Simulations of Nanobubble Stability

PI: Shell， M. Scott提案号：1403259机构：加州大学圣巴巴拉分校标题：纳米气泡稳定性的分子和混合模拟本提案解决了界面科学中最重要的挑战之一，即疏水表面上长寿命纳米气泡稳定性的关键问题。对这一问题的成功解决将对一系列新兴技术产生重大影响，这些技术依赖于稳定的纳米气泡显著改变固体表面特性的能力，包括防污和表面清洁技术、微流体装置中的传输、医学治疗的输送、涉及生物或气液反应的化学过程、表面诱导结晶和催化。这些私人项目还将建立在他们参与多个层次学生的记录上，包括那些来自代表性不足的群体的学生（例如，壳牌集团通过UCSB的GRIP和SABRE项目接待了两名来自HBCU学校的少数族裔学生作为暑期研究实习生），以及通过UCSB的不同项目（本科生和高中生的暑期研究机会，在UCSB的少数族裔协会和专业协会的活动中发表演讲）。特别是，pi和研究生将参与由顶尖高中毕业生参加的SIMS暑期项目。本提案的主旨是批判性地解决纳米气泡稳定性的几个假设，使用最先进的分子和混合分子连续体模拟方法，为当前的实验提供补充。目标是发展纳米气泡稳定性的热力学图像，因为有一些证据表明纳米气泡实际上可能是热力学稳定的。为此，PI将使用分子模拟来计算纳米气泡形成的自由能，作为气泡大小、形状、组成和溶液条件的函数。结果将量化气泡的稳定性，并阐明它们是否以及何时与全局或局部（亚稳态）自由能最小值相关。这些自由能还将与宏观期望（例如，基于体表面张力和溶解度）进行比较，以评估在纳米尺度上可能打破这些论点。为了实现这些目标，该提案提供了明确的假设，包括热力学和动态传输机制，将被解决。

PI: Shell, M. Scott Proposal Number: 1403259 Institution: University of California-Santa Barbara Title: Molecular and Hybrid Simulations of Nanobubble Stability This proposal addresses one of the foremost challenges in interfacial science, the critical issue of long-lived nanobubble stability on hydrophobic surfaces. A successful attack on this problem will have a significant impact on a range of emerging technologies that rely on the ability of stable nanobubbles to dramatically modify the properties of solid surfaces, including anti-fouling and surface cleaning techniques, transport in microfluidic devices, delivery of medical therapeutics, chemical processes involving biological or gas-liquid reactions, surface-induced crystallization, and catalysis. The PIs will also build on their record of involving students at multiple levels, including those from underrepresented groups (e.g., The Shell group has hosted two minority students from HBCU schools as summer research interns through UCSB's GRIP and SABRE programs), through different programs at UCSB (summer research opportunities for undergraduates and high school students, giving talks in events from minority associations and professional associations at UCSB). In particular, the PIs and graduate students will be involved with the SIMS summer program that involves top high school graduates. The main thrust of this proposal is to critically address several hypotheses for nanobubble stability, using state-of-the-art molecular and hybrid molecular continuum simulation methods that provide a complement to current experiments. The goal is to develop a thermodynamic picture of nanobubble stability because there is some evidence that the nanobubble may actually be thermodynamically stable. To that end, the PI will use molecular simulations to compute free energies of nanobubble formation as a function of bubble size, shape, composition, and solution conditions. The results will quantify the stabilities of the bubbles, and clarify whether and when they are associated with global or local (metastable) free energy minima. These free energies will also be compared with the macroscopic expectation (e.g., based on bulk surface tensions and solubilities) to assess the possible breakdown such arguments at the nanoscale. To achieve these goals, the proposal provides clearly formulated hypotheses, including both thermodynamic and dynamic transport mechanisms, that will be addressed.