Ordered Block Copolymer Thin Films Studied by Guided-Wave Depolarized Light Scattering

技术说明本提案寻求资金继续发展一种新的分析技术，用于表征光学透明嵌段共聚物薄膜中各向异性纳米结构（例如片层和圆柱体）的组织。从燃料电池到光电器件，组织的定量测量对于纳米技术的许多拟议应用至关重要。GWDLS允许低成本，非破坏性，实时测量光学透明薄膜中的有序形成和缺陷密度。在薄膜表征方法中，GWDLS的独特之处在于它提供了薄膜宏观长度尺度（~ 1cm）上缺陷密度的平均测量。研究缺陷结构的位置空间方法，如原子力显微镜（AFM）和扫描电子显微镜（SEM），可以测量局部缺陷结构，但无法获得宏观区域的统计平均值。GWDLS技术涉及将激光束耦合到由沉积在低折射率衬底上的嵌段共聚物薄膜组成的平面光波导的引导模式中。耦合成导模的光通过薄膜的全内反射传播。当光与薄膜中的各向异性颗粒相互作用时，产生去偏振散射光，该散射光以正交极化的引导模式传播。这种散射光被耦合出薄膜并被检测到。在本文中，我们将(1)改进现有的GWDLS装置，使用光栅耦合器研究偏振光在对称硅-聚合物-硅样品环境中的传播。(2)建立了量化薄膜中随机取向和部分取向晶粒的gwdls信号与统计特性之间关系的理论模型。(3)利用GWDLS测定了层状和柱状嵌段共聚物薄膜的有序-无序转变温度。(4)测量薄膜从无序态到有序态淬火后有序形成的动力学。(5)通过将实测信号与理论预测相比较，获得平均晶粒尺寸的定量度量。该项目所需的所有聚合物和基质将由学生准备。利用AFM， SEM和sims等互补技术对薄膜进行完整的表征。balsara将担任数学和科学暑期学院的教师讲师，该学院将大约60名来自当地高中的学生带到大学校园，参加为期六周的数学和科学丰富课程。通常一半的参与者是非裔美国人，四分之一的墨西哥裔美国人，剩下的四分之一是亚洲人、高加索人、菲律宾人和拉丁人。Garetz将继续他7年来在理工大学David Packard技术与教育联盟中心的工作。他的活动包括在纽约市科学/技术论坛上举办研讨会，来自纽约市公立学校的500名学生来到保利参加一个全天的课程，在那里他们会见了来自高等教育中心、医院和公司的杰出工程师和技术专家。从事该项目的研究生将接受多学科的科学训练，包括聚合物的合成和表征、光学、光刻和非平衡热力学。他们在表征和操纵纳米结构薄膜方面的背景与当前和未来的技术有关。

TECHNICAL EXPLANATIONThis proposal seeks funds to continue the development of a novel analytical technique forcharacterizing the organization of anisotropic nanostructures (e.g. lamellae and cylinders)in optically transparent block copolymer thin films. Quantitative measurement oforganization is critical for many proposed applications of nanotechnology, ranging fromfuel cells to optoelectronic devices. GWDLS allows the low-cost, non-destructive, realtimemeasurement of order formation and defect density in optically transparent thinfilms. Among methods for thin-film characterization, GWDLS is unique in that itprovides an average measure of defect density over macroscopic length scales (~1 cm) ina film. Position-space methods for studying defect structure, such as atomic forcemicroscopy (AFM) and scanning electron microscopy (SEM), can measure local defectstructure, but are impractical for obtaining statistical averages over macroscopic regions.The GWDLS technique involves the coupling of a laser beam into a guided mode of aplanar optical waveguide consisting of a block copolymer film deposited on a lowrefractive index substrate. Light coupled into a guided mode propagates through the filmby total internal reflection. As the light interacts with anisotropic grains in the film, itgenerates depolarized scattered light which propagates in guided modes with orthogonalpolarization. This scattered light is coupled out of the film and detected. In the proposedwork, we will (1) Modify the current GWDLS apparatus to study the propagation ofpolarized light in a symmetric silica-polymer-silica sample environment using a gratingcoupler. (2) Develop a theoretical model for quantifying the relationship between theGWDLS signal and statistical properties of randomly oriented and partially orientedgrains in thin films. (3) Use GWDLS to determine the order-disorder transitiontemperature of block copolymer thin films with both lamellar and cylindrical order. (4)Measure the kinetics of order formation in thin films after quenching from the disorderedto the ordered state. (5) Obtain a quantitative measure of the average grain size bycomparing the measured signal with theoretical predictions. All of the polymers andsubstrates required for the project will be prepared by the students. Completecharacterization of the films using complementary techniques such as AFM, SEM, andSIMS will be carried out. NON-TECHNICAL EXPLANATIONBalsara will serve as a faculty instructor in the Math and Science Summer Academywhich brings approximately 60 students from local high schools to the University campusto participate in a six-week enrichment program in math and science. Typically half ofthe participants are African American, one quarter Chicano, and the remaining quarterAsian, Caucasian, Filipino and Latino. Garetz will continue his 7-year involvement withPolytechnic University's David Packard Center for Technology and EducationalAlliances. His activities include conducting workshops at the New York CityScience/Technology Forum where 500 students from New York City public schoolscome to Poly for a full-day program where they meet outstanding engineers andtechnologists representing centers of higher education, hospitals, and corporations. Thegraduate students working on this project will receive multidisciplinary scientific trainingencompassing synthesis and characterization of polymers, optics, lithography, and nonequilibriumthermodynamics. Their background in characterization and manipulatingnanostructured thin films is relevant for current and future technologies.