Systematic theoretical mapping of the structure-function relationship in technology-oriented conjugated polymers

• Grant number: 99/07339-4
• Support type: Research Projects - Thematic Grants
• Duration: July 01, 2000 - June 30, 2005
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Marilia Junqueira Caldas
• Grantee: Marilia Junqueira Caldas
• Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Co-Principal Investigators: Douglas Soares Galvão

Abstract

Conducting polymers constitute a new class of materials with unusual properties and high potential for technological applications. In spite of many years of theoretical and experimental work some of basic questions concerning their structure (more specifically the physical mechanisms behind the high conductivity) remain unclear. In contrast to conventional polymers where a large and very reliable amount of simulations are available, for conducting polymers no systematic study from monomers to 3D structures has been carried out. The main reasons for this situation are the lack of large experimental data as in the case of conventional polymers and, more important, the intrinsic difficulties posed by modeling the complex phenomena of electron-phonon coupling. This strong coupling is responsible for the very differentiated behavior of conducting polymers, from insulators to high conducting materials. In this project we intend to carry out a systematic study of the electronic and structural properties of four major families of conducting polymers: poly(para-phenylenes), poly(para-phenylenevinylne), polyanilines and polythiophenes. All these polymers share a common topological feature of a linear backbone with ring-structured chains. The rings may be joined directly or through conjugate linear chains (poly-para-pbenylene-vinylene); there may be heteroatoms in the backbone (polyanilines) or within the rings (polythiophenes) with all these differences and growing complexity, and present semiconducting properties with some of them also presenting a well-defined transition to metallic regime under chemical doping others with very special optical properties... (AU)