Organic Crystal Growth on Flexible Templates

灵活模板上的有机晶体生长

• 批准号: 0221586
• 负责人: Guangzhao Mao
• 金额: $ 22.36万
• 依托单位: Wayne State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0221586&HistoricalAwards=false
• 关键词: Organic; Crystal; Growth; Flexible; Templates

Guangzhao Mao, Wayne State University"Organic Crystal Growth on Flexible Templates"This project will to explore the possibility of morphological control and confinement of organic crystals using polymeric templates. The nucleation and crystallization of model organic dyes will be studied on two-dimensional (2-D) polyelectrolyte templates, and in three-dimensional (3-D) polyelectrolyte shells by atomic force microscopy and other in situ methods. The proposed research aims at (1) understanding the effect of polyelectrolytes on organic crystallization; and (2) encapsulating organic crystals in polyelectrolyte shells.This research explores the rich interplay between the surface structure of polyelectrolytes and the habit of nascent crystals. Polyelectrolytes exert templating effect via preconcentration of lattice ions, geometric and stereochemical match, specific interactions, and adsorption-induced stabilization. Polymeric substrates differ from inorganic templates in that they do not show the order and rigidity implicit in the epitaxial mechanisms. However natural polymers are known to induce crystals of a uniform habit that is different from those grown without the polymers. Research in biomineralization has shown that the templating effect of polyelectrolytes does not require the same degree of geometric match as the inorganic counterparts. Polyelectrolytes may display rich stereochemical control because of their many surface conformations. There may exist several geometric matches for a given crystal face. Segments protruding into solution may stabilize side faces of the nascent crystal. Based on the above notions, an approach consisting primarily of experiments, but also utilizing the Cerius2 program, will be used to study the interfacial structure between the polyelectrolyte template and the nascent dye crystal. Initial experiments will focus on the crystallization of dyes on 2-D thin films so that the kinetics and crystal habit modification can be probed at the molecular scale. The kinetic parameters include critical supersaturation, pH, induction time, and rate of crystallization. The crystal habit variables include size, shape orientation, and correlation to the template structure. In the second stage, the study will focus on the dye crystallization inside the polyelectrolyte shell. The shell will consist of polyelectrolyte multilayers permeable to small polar molecules but not their crystals. In addition to the polyelectrolytes, supported phospholipid bilayers will be used as templates because they provide intermediate order and flexibility. This project is intended as a proof-of-concept study. Future work can go beyond the generic polyelectrolytes using polymers with higher architectural definitions such as amphiphilic polymers, ionomers, and biopolymers.This research may have broader impact in terms of its relationship to the concept of nano-science and technology especially in areas such as materials processing, color displays, information storage, nanocomposites, drug encapsulation, and sensors. For example, the encapsulated colloids can be used as tips for micropipettes, as chemical sensors to detect pollutants, and as heterogeneous catalysts.Also, the support will allow the P.I. to continue exploring the molecular mechanisms in the templated growth of organic with potential applications in encapsulation, coatings, and materials processing. It will also help the P.L to establish long-term collaboration and exchanges with a foreign research institution: the Max-Planck-Institute of Colloids and Interfaces. Some experiments will be conducted at the Institute with a number of characterization methods not present at the P.I.'s home institution. The planned educational and outreach activities include incorporation of research topics into materials engineering curricula, global education associated with the World Bridge program, mentoring of Detroit high school students in the Science Summer Camp program, and training science teachers from local community colleges.

韦恩州立大学的广为毛面，“灵活模板上的有机晶体生长”该项目将使用聚合模板探索有机晶体的形态控制和限制的可能性。模型有机染料的成核和结晶将通过原子力显微镜和其他原位方法研究在二维（2-D）聚电解质模板上，并在三维（3-D）聚电解质壳中进行研究。拟议的研究旨在（1）了解聚电解质对有机结晶的影响； （2）将有机晶体包裹在聚电解质壳中。这项研究探讨了聚电解质的表面结构与新生晶体的习惯之间的丰富相互作用。聚电解质通过晶格离子，几何和立体化学匹配，特定相互作用以及吸附诱导的稳定化来发挥模板效应。聚合物底物与无机模板不同，因为它们没有显示外延机制中隐含的顺序和刚性。但是，已知天然聚合物会诱导与没有聚合物的生长的统一习惯的晶体。生物矿化的研究表明，聚电解质的模板效应不需要与无机对应物相同的几何匹配。由于其许多表面构象，聚电解质可能显示出丰富的立体化学控制。给定的晶体面可能存在几种几何匹配。伸入溶液的片段可以稳定新生晶体的侧面。基于上述概念，一种主要由实验和使用CERIUS2程序组成的方法将用于研究聚电解质模板和新生染料晶体之间的界面结构。最初的实验将集中于二-D薄膜上染料的结晶，以便可以在分子尺度上探测动力学和晶体习惯的修饰。动力学参数包括临界过饱和，pH，诱导时间和结晶速率。晶体习惯变量包括尺寸，形状取向以及与模板结构的相关性。在第二阶段，该研究将集中于聚电解质壳内部的染料结晶。壳将由可渗透到小极性分子而非其晶体的聚电解质多层组成。除了聚电解质外，受支持的磷脂双层将被用作模板，因为它们提供了中间的顺序和柔韧性。该项目旨在作为概念验证研究。 Future work can go beyond the generic polyelectrolytes using polymers with higher architectural definitions such as amphiphilic polymers, ionomers, and biopolymers.This research may have broader impact in terms of its relationship to the concept of nano-science and technology especially in areas such as materials processing, color displays, information storage, nanocomposites, drug encapsulation, and sensors. 例如，封装的胶体可以用作微孔的尖端，作为检测污染物的化学传感器，并且作为异质催化剂。继续探索有机物的模板生长中的分子机制，并在封装，涂料和材料加工中潜在应用。它还将帮助P.L与外国研究机构建立长期合作和交流：Max-Planck胶体和界面。一些实验将在该研究所进行，并在P.I.家庭机构中不存在多种表征方法。计划的教育和外展活动包括将研究主题纳入材料工程课程，与世界桥梁计划相关的全球教育，在科学夏令营计划中指导底特律高中学生以及培训当地社区学院的科学老师。