Conjugated Polymer-Quantum Rod Nanocomposites in Well-Defined Nanoscopic Geometries

Iowa State University, Ames IA

Investigators

Abstract

CBET-0824361 Lin Placing conjugated polymers in direct contact with quantum dots or quantum rods (i.e., preparation of conjugated polymer-quantum dot (CP-QD) or conjugated polymer-quantum rod (CP-QR) nanocomposites) provides a well-defined interface between CP and QD or QR, thus facilitating an efficient charge transfer between them. However, few studies have centered on such direct integration, and CP-QR nanocomposites confined in nanoscopic geometries have never been explored. The objective of this proposal is to explore the effects of confinement on the photophysical properties of CP-QR nanocomposites. Two unique strategies will be used to confine CP-QR nanocomposites: (1) directly immobilizing nanocomposites in highly ordered hexagonal arrays of straight cylindrical nanopores (i.e., a nanoporous alumina membrane); and (2) confining and shearing nanocomposites between two parallel plates, formed by bringing two crossed cylindrical mounts covered with mica sheets into contact, to film thicknesses ranging from molecularly thin to several hundred nanometers. The research findings will be used to enhance the general level of nanoscience education. Integrated educational activities will be pursued to expose several audiences, including K-12 students, to new knowledge in nanoscience, thereby promoting general awareness of its importance. The proposed research is based on an interdisciplinary effort that involves polymer chemistry, polymer physics, nanofabrication techniques, and photophysics. The intellectual merit of the work is manifested in the innovative studies of exploiting nanoscopic geometries as unique physical environments to control the conformation of CPs, which in turn regulates the charge transfer from CPs to QRs and, ultimately, the photophysical properties of CP-QR nanocomposites at the nanoscale. Four specific research goals will be pursued: (1) prepare CP-QR nanocomposites based on rational design; (2) reveal the effect of external nanoscopic confinement on the photophysical properties of CP-QR nanocomposites (first strategy); (3) establish correlations between the confined-and-sheared chain conformation and photophysical properties of CP-QR films ranging from the molecularly thin to several hundred nanometers thick (second strategy); and (4) exploit CP-QR nanocomposites for use in optoelectronic devices. The findings will also enhance understanding of other CP-related or QR-related nanocomposites confined at the nanoscale. The outcomes from the research are expected to contribute significantly to the advancement of nanomaterials science. The broader impacts of the proposed work include stronger nanoscience education across several levels. Female undergraduate students will be recruited for summer nanocomposite research, thus strengthening the involvement of an underrepresented group in the project. Summer workshops for K-12 teachers will also be created. High school interns will develop Web-based lesson plans on polymeric nanomaterials for 5th-8th graders nationwide. This activity will ultimately expose elementary- and middle-school students to the nano-world. Knowledge generated by this project may lead to the creation of novel nano-optoelectronic devices that are extremely critical to national security and the defense industry as well as civilian applications, thereby transitioning fundamental scientific discoveries into useful technologies that benefit society.