Investigating the Structure of Flexible Polyelectrolytes

该奖项由加州大学圣巴巴拉分校材料研究部生物材料项目颁发，旨在研究可变电荷密度的聚电解质的结构，从而建立弱电荷聚合物的经典“静电斑点”图像与“蛇形链”（SLC）模型之间的关系，后者似乎适用于高电荷聚合物。此外，本项目旨在广泛确立柔性聚电解质的SLC性质。带电的柔性聚合物在生物和技术领域无处不在，但其结构背后的基本物理学还没有建立起来。研究者最近的研究表明，这些结构最好被定义为所谓的“蛇形链”。本项目将研究软单体斥力在利用梳状聚合物用侧链间的熵斥力取代静电斥力创建SLC结构中的一般作用。该项目将使用低力单分子弹性测量来研究这些系统，并将其与模拟和理论进行比较分析。本提案中描述的工作是高度跨学科的，因此代表了培养年轻科学家的绝佳机会。为了利用这一机会，该项目计划支持研究生，并继续调查员实验室涉及本科生研究人员的极其强大的记录。本科研究经历被证明对学生新生的科学事业有显著的积极影响，本项目已经确定了与本提案相关的具体潜在实习项目。聚电解质是一种长串状分子，携带大量电荷。这种电荷和线状结构本身的松软性质相结合，使得聚电解质可以采用各种不同的结构，从而赋予技术和生物学上重要的特性。例如，聚电解质用于涂层技术（例如，减少窗户的紫外线透射），以及尿布中的水溶性材料。在生物学领域，DNA、RNA和许多蛋白质可以被认为是聚电解质，它们的电荷影响它们的结构，从而影响它们的生物学功能。这项提议将使用新颖而强大的实验探针来更好地理解单个聚电解质的物理特性。所获得的信息将建立聚电解质结构的预测模型，反过来，可用于改进聚电解质的技术应用，以及我们对某些基于电荷的双分子交易的理解。更广泛的科学影响将是大大提高对聚合物行为的理解，从长远来看，这可能会导致更好的材料开发。教育和推广活动包括从各种校园项目中招募本科生，包括为传统上在物理科学领域代表性不足的群体的学生提供研究活动。

This award by the Biomaterials program in the Division of Materials Research to University of California Santa Barbara is to investigate the structure of polyelectrolytes of variable charge density so as to establish the relationship of the classical 'electrostatic blob' picture of weakly-charged polymers to the 'snake-like chain' (SLC) model, which appears to hold for highly-charged polymers. Additionally, this project is to broadly-establish the SLC nature of flexible polyelectrolytes. Charged, flexible polymers are ubiquitous in biology and technology, yet the basic physics underling their structure is poorly established. The investigator's recent studies indicated that these structures are best-defined as a so-called 'snake-like chain'. This project will investigate the general role of soft monomer repulsions in creating SLC structure using comb polymers that replace electrostatic repulsions with entropic repulsions between side-chains. This project will investigate these systems using low-force single-molecule elasticity measurements, and analyze them in comparison to both simulation and theory. The work described in this proposal is highly interdisciplinary, and so represents an excellent opportunity for training young scientists. To exploit this opportunity, the project plans to support graduate students and to continue investigator lab's extremely strong record of involving undergraduate researchers. Undergraduate research experiences are proven to have significant positive effects on student's nascent scientific careers, and this project has identified specific potential internship projects associated with this proposal.Polyelectrolytes are long, string-like molecules that carry a large electrical charge. The combination of this electric charge and the floppy nature of the string-like structure itself permits polyelectrolytes to adopt a wide range of different configurations that impart technologically- and biologically-important properties. For example, polyelectrolytes are used in coating technologies (e.g. to reduce UV transmission of windows), and as water soluble-materials in diapers. In the biological arena, DNA, RNA, and many proteins can be considered polyelectrolytes whose charge affects their structure, and thus their biological functions. This proposal will use novel and powerful experimental probes to better understand the physics of individual polyelectrolytes. The information obtained will establish predictive models of polyelectrolyte configuration that, in turn, can be used to improve both technological application of polyelectrolytes, and our understanding of certain charge-based bimolecular transactions. The scientific broader impact would be a greatly improved understanding of polymer behavior, which in the long term could lead to better materials development. The educational and outreach activities included recruitment of undergraduate students from a variety of on campus programs including those enabling research activities for students from groups traditionally underrepresented in the physical sciences.