Effect of Stress Relief and Ionic Charge on Polyelectrolyte Brush Behavior

应力消除和离子电荷对聚电解质刷行为的影响

• 批准号: 1709660
• 负责人: Christopher Ober
• 金额: $ 38.91万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709660&HistoricalAwards=false
• 关键词: Effect; Stress; Relief; Ionic; Charge

Polymers are large molecules formed by linking together hundreds of small molecular sub-units called monomers into long chains. Depending upon on the chemical structure of the monomer, the polymer can either be slippery (like Teflon) or sticky (like tape). By changing the monomer, one can create surfaces that prevent adhesion of cells, making them better for medical uses. Nature accomplishes this by attaching charged polymer segments to surfaces, forming structures that resemble brushes. While these brush polymers offer unique properties that could have substantive societal impacts, they also pose significant challenges. The dense packing of the charged groups can stretch the chemical bonds and, in extreme cases, the bonds can break. With the support of the Macromolecular, Supramolecular and Nanochemistry program of the Chemistry Division, Professor Ober at Cornell University is creating and studying new polymer brushes that are effective coatings but also have long lifetimes (i.e., do not have bonds that easily break). Collaborators, Professor Ryan (University of Sheffield) and Professor Ruehe (University of Freiburg), are helping to characterize the polymer structures. In addition to its scientific impact, the project benefits society by educating undergraduate and graduate students to become globally aware, interdisciplinary scientists. Surface-bound bottlebrush polymers are potentially synthetic mimics for shock absorbing components in the human body, thus, the broader scientific impact of this project outside of macromolecular chemistry is potentially quite large. Insights into the polyelectrolyte brush behavior may also help in the understanding the attachment of biomolecules, cells and microorganisms to surfaces and thus be used to control into unwanted adhesions on ships for the marine industry.The research team is creating and studying a series of stable model polymer brushes with carefully tailored placement of ionic groups in both single strand and bottlebrush architectures. Physical phenomena associated with charge, binding and attachment of soluble species, and the rather unusual case of mechanochemistry that leads to brush breakage are being investigated. Professor Ober and his collaborators are preparing specially tailored polyelectrolyte brushes with selected vertical and horizontal brush architectures and studying their physical properties. Ionic groups are attached directly to the acrylate or methacrylate polymer backbone or through tailored sequences of peptoid units of precise ionic group spacing and location. Confinement is controlled by the use of nanopatterning in which the pattern sizes are comparable to brush height (tens of nanometers). The effect of cation charge is studied using a range of mono- and multivalent cations. Characterization activities include: X-ray scattering studies of brush swelling and shrinkage under a range of wetting and electrolyte conditions and neutron reflectivity studies using labeled polymer chains to separately gather information about the different components (backbone, sidearm, ions) to develop a detailed picture of the charged polymer brush. Graduate students serve as mentors and role models to undergraduate students, while at the same time gaining supervisory skills. Undergraduates from Cornell University take part during the academic year while REU students from other schools with an emphasis onunderrepresented students participate in research during the summer months. Lessons learned from these research programs are integrated into lessons for high school teachers in a Research Experiences for Teachers (RET) program and in teachers' workshops.

聚合物是通过将数百个称为单体的小分子亚单数链接在一起的大分子。根据单体的化学结构，聚合物可以很滑（例如Teflon）或粘性（如胶带）。 通过更改单体，可以创建表面以防止细胞的粘附，从而使它们更适合医疗用途。大自然通过将带电的聚合物段连接到表面，从而形成类似于刷子的结构来实现这一目标。尽管这些刷子聚合物提供了可能产生实质性社会影响的独特特性，但它们也构成了重大挑战。带电组的致密堆积可以拉伸化学键，在极端情况下，债券可能会破裂。在化学部的大分子，超分子和纳米化学计划的支持下，康奈尔大学的Ober教授正在创建和研究新的聚合物刷，这些新聚合物刷是有效的涂料，但寿命很长（即，没有容易破裂的债券）。合作者，谢菲尔德大学（Ryan）教授和鲁伊（Ruehe）教授（弗莱堡大学）正在帮助表征聚合物结构。除了科学的影响外，该项目通过教育本科和研究生成为全球意识的跨学科科学家来使社会受益。表面结合的瓶洗聚合物可能是人体中吸收减震成分的合成模拟物，因此，该项目在大分子化学之外的更广泛的科学影响可能很大。 对聚电解质刷子行为的见解也可能有助于理解生物分子，细胞和微生物在表面上的依恋，因此可用于控制海洋行业的船上不必要的粘连。研究团队正在创建和研究一系列稳定的模型刷子，并精心研究了一系列稳定的模型小组。与电荷，可溶性物种的结合和依恋相关的物理现象以及导致刷子断裂的机械化学的相当异常的情况。 Ober教授及其合作者正在准备特殊量身定制的聚电解质刷，并使用选定的垂直和水平刷子建筑并研究其物理特性。离子基直接连接到丙烯酸酯或甲基丙烯酸酯聚合物主链或通过精确离子组间距和位置的肽单元的定制序列。限制是通过使用纳米图案来控制的，其中模式大小与刷子高度（数十纳米）相当。阳离子电荷的效果使用一系列单相和多价阳离子进行了研究。 表征活动包括：在一系列润湿和电解质条件下，使用标记的聚合物链在一系列润湿和电解质条件下进行刷毛肿胀和收缩的X射线散射研究，以分别收集有关不同成分（骨架，侧链，侧链，离子，离子）的信息，以开发带电聚合物刷的详细图片。 研究生是本科生的导师和榜样，同时又获得了监督技能。康奈尔大学的本科生在学年参加，而其他学校的REU学生则强调了以替代学生为代表的学生参加夏季的研究。从这些研究计划中学到的经验教训被整合到高中教师的教训中，在教师计划和教师讲习班中的研究经验中。

项目成果

MEMS analogous micro-patterning of thermotropic nematic liquid crystalline elastomer films using a fluorinated photoresist and a hard mask process

• DOI: 10.1039/c7tc03958a
• 发表时间: 2017-12
• 期刊: Journal of Materials Chemistry C
• 影响因子: 6.4
• 作者: David Ditter;Wei‐Liang Chen;A. Best;H. Zappe;K. Koynov;C. Ober;R. Zentel

Biologically Complex Planar Cell Plasma Membranes Supported on Polyelectrolyte Cushions Enhance Transmembrane Protein Mobility and Retain Native Orientation

• DOI: 10.1021/acs.langmuir.7b02945
• 发表时间: 2018-01-23
• 期刊: LANGMUIR
• 影响因子: 3.9
• 作者: Liu, Han-Yuan;Chen, Wei-Liang;Daniel, Susan
• 通讯作者: Daniel, Susan

Entropic death of nonpatterned and nanopatterned polyelectrolyte brushes

• DOI: 10.1002/pola.29384
• 发表时间: 2019-06-15
• 期刊: JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
• 作者: Menzel, Matthias;Chen, Wei-Liang;Ruehe, Juergen
• 通讯作者: Ruehe, Juergen