Carbon Nanotube Induced Polymer Crystallization, Structure and Morphology

技术综述：碳纳米管(CNTs)具有优异的力学、电学和光学性能，近年来引起了人们的极大关注。对含有碳纳米管的产品的需求产生了将这些性质从纳米尺度转移到宏观尺度的迫切需要。实现这一目标的一个重要步骤是组装/加工碳纳米管，这涉及将它们分散在有机溶剂/聚合物基质中。为此，软材料，特别是聚合物被用来修饰碳纳米管的表面。最近，皮S实验室利用控制溶液聚合物结晶方法证明了聚合物片状单晶可以在碳纳米管表面生长，从而形成了一种有趣的杂化纳米结构-纳米杂化烤肉串。NHSK提供了一个独特的纳米级平台，可用于各种应用。这项研究旨在系统地研究这一独特的混合系统的结构和形成机制。具体地说，PI将：1)使用不同的结晶条件制备NHSK，并探索结晶条件与NHSK特征之间的关系，如周期性以及烤串大小；2)证明NHSK是碳纳米管-结晶聚合物体系的一般特征。NHSK的共性有两个方面：a)NHSK可以用于不同类型的碳纳米管以及各种结晶聚合物；b)NHSK不仅可以通过溶液结晶形成，还可以通过其他结晶技术形成，如结晶聚合物的物理气相沉积以及本体结晶；3)使用嵌段共聚物(BCP)制备均匀图案化的NHSK。半晶型BCP将被用来形成CNT/BCP NHSK。可以预期，使用BCP代替均聚物可以改善NHSK结构的均匀性。由于结晶聚合物可以很容易地功能化，这种方法代表了一种独特的方法来功能化碳纳米管，它不同于所有其他已报道的方法。NHSK还提供了一个平台来实现碳纳米管的许多可能的应用，范围从纳米复合材料、传感器到催化载体。BCP NHSK可以通过精确的周期控制在碳纳米管上图案化，这是将碳纳米管应用于纳米电子学的主要障碍之一。摘要：碳纳米管具有优异的力学、电学和光学性能，已被证明是最近发现的最吸引人的材料之一。将碳纳米管推向市场的主要挑战之一是它们的可加工性较差。为此，皮？S实验室最近发现，聚合物单晶可以在碳纳米管上以可控的方式生长。由于聚合物可以很容易地末端官能化，这一发现立即导致了一种不同于所有现有方法的独特的碳纳米管官能化技术。这种杂化结构被称为纳米杂化烤肉串(NHSK)，与原始的碳纳米管相比，具有更高的比表面积。这有助于将碳纳米管用于传感器和催化载体应用。烤肉串的结晶性质也使机械载荷转移更有效，这可能直接导致更坚固的复合材料。该提案的教育部分包括：1)通过开发一种杂化的聚合物材料？解决现代聚合物纳米科学和纳米技术发展的教育需要。将用于纳米结构聚合物材料的模块？2)让高中生和教师，特别是代表不足的人群，参与拟议的研究活动。这些拟议的教育活动具有广泛的影响。首先，拟议的计划将通过一系列辅导计划让高中生和教师参与研究活动，从而帮助弥合教育发展水平之间的现有差距。其次，由于费城地区代表不足群体的人口很多，拟议的外联方案将专门针对鼓励代表不足群体的参与。第三，拟议的研究成果将通过科学期刊、会议报告和更多训练有素的中等教育教师的出版物广泛传播。

TECHNICAL SUMMARY:The extraordinary mechanical, electrical and optical properties of carbon nanotubes (CNTs) have attracted great attention in recent years. The demand for products containing CNTs has created a pressing need to transfer these properties from nano- to macro- scale. One essential step towards this goal is assembling/processing CNTs, which involves dispersing them in an organic solvent/polymeric matrix. To this end, soft materials, polymers in particular, have been used to modify CNT surfaces. By using a controlled solution polymer crystallization method, the PI?s lab recently demonstrated that polymer lamellar single crystals could grow on CNT surface, leading to an intriguing hybrid nanostructure named as Nano Hybrid Shish Kebab (NHSK). NHSK provides a unique nanoscale platform that can be used for a variety of applications. The proposed research aims at systematically studying the structure and formation mechanism of this unique hybrid system. Specifically, the PI will, 1) fabricate NHSKs using a variety of crystallization conditions and explore the correlation between crystallization conditions and NHSK features such as periodicity as well as the kebab sizes; 2) demonstrate that NHSK is a general feature for CNT-crystalline polymer systems. The generality of the NHSK is two-fold: a) NHSK could form for different types of CNTs as well as for a variety of crystalline polymers; b) NHSK can be formed not only by solution crystallization, but also by other crystallization techniques such as physical vapor deposition of crystalline polymers as well as bulk crystallization; 3) fabricate uniformly patterned NHSK using block copolymers (BCPs). Semicrystalline BCPs will be used to form CNT/BCP NHSKs. It is anticipated that the uniformity of the NHSK structure could be improved by using BCPs instead of homopolymers. Because crystalline polymers can be readily functionalized, this approach represents a unique way to functionalize CNT and it is different from all the other reported methods. NHSK also provides a platform to realize numerous possible applications of CNTs, ranging from nanocomposites, sensors to catalysis supports. BCP NHSKs could open the door to patterning on CNTs with a precise periodicity control, which is one of the major hurdles for applying CNTs in nano electronics.NONTECHNICAL SUMMARY: Due to their wonderful mechanical, electrical and optical properties, carbon nanotubes (CNTs) have been proven to be one of the most fascinating materials recently discovered. One of the major challenges of bringing CNTs to the marketplace is their poor processibility. To this end, the PI?s lab recently discovered that polymer single crystals could grow on CNTs in a controllable manner. Since polymers can be easily end-functionalized, this discovery immediately leads to a unique CNT functionalization technique which is different from all the existing methods. The hybrid structure generated, named as nano hybrid shish kebabs (NHSK), possesses much higher specific surface area compared to that of pristine CNTs. This could facilitate using CNTs in sensor and catalysis support applications. The crystalline nature of the kebabs also enables a more efficient mechanical load transfer, which could directly lead to stronger composite materials. The educational component of the proposal includes: 1) addressing the need for the education of modern developments in polymer nanoscience and nanotechnology by developing a ?Hybrid Polymeric Materials? module which will be used in the ?Nanostructured Polymeric Materials? course; 2) involving high school students and teachers, particularly under-represented populations, in the proposed research activities. These proposed educational activities encompass a broad impact. First, the proposed plan will help bridge the existing gap between levels of educational developments by involving high school students and teachers in research activities through a number of mentoring programs. Secondly, due to the high population of under-represented groups in the Philadelphia region, the proposed outreach program will be specifically geared towards encouraging the participation of under-represented populations. Thirdly, the proposed research results will be widely disseminated through publications in scientific journals, conference presentations and more highly trained secondary education teachers.