טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentSuckeveriene Ran
SubjectHybrid Electrically Conducting Systems: Polyaniline/Carbon
Nanotubes
DepartmentDepartment of Polymer Engineering
Supervisors Professor Yachin Cohen
Professor Emeritus Moshe Narkis
Full Thesis textFull thesis text - English Version


Abstract

What do the Apple iPhone, Samsung Galaxy smartphone, Nanosolar photovoltaic, and Nintendo DS have in common? Each of these top of the edge devices uses a material that is transparent to visible light and yet electrically conductive as an essential element in the device. Currently, LCD is by far the largest user of transparent conductive materials but many devices are showing rapid growth in popularity such as touch panels (362 million units in 2010 with annual growth of 20% through 2013), E-paper (30 fold growth expected from 2008 to 2014), thin film solar (expected sales of over $13 billion by 2017), and flexible displays. Transparent conducting oxides (TCOs) are widely used for that purpose. The main TCO used is the tin doped indium oxide (ITO), which alone is expected to grow to be a $3 billion dollar market in 2010, with a 20% growth rate through 2013. However, since indium resources are limited, it is estimated that it will be fully consumed within 20 years. In order to overcome this problem, while meeting the market growing demand, several alternatives were introduced. Two main alternatives that are currently investigated are carbon nanotubes (CNT) and electrically conductive polyaniline (PANI). The conductive thin transparent films major requirements are surface resistance - 500 Ω/□ and 80% transparency in the visible region (VLT).

Polymeric nanocomposites consist of nano-particles imbedded in organic polymers comprising a new class of materials. The combination of conducting nano-particles and conducting polymers, described as hybrid electrically conducting nanocomposites, is a new emerging field. These materials may exhibit unprecedented properties, attractive for both the industry and academia. There is a variety of applications for conductive nanocomposites, i.e. sensors, actuators, touch screens, etc. The combination of conductive polymers with conductive carbon nanotubes has already shown some synergistic properties.

In our work flexible films (ITO is brittle) having values of ~80% VLT and <100 Ω/□ have been achieved, with good adhesion to the substrate surface (flexibility and adhesion are very important characteristics), using advanced hybrid polyaniline (PANI)/Carbon nanotubes (CNT) dispersions developed in our laboratory, thus, meeting the market requirements. Our work comprises a breakthrough of thin, transparent and electrically conductive films. A patent regarding this unique work has been submitted.

Two reference systems were thoroughly studied: 1) dispersion of neat CNT within different solvents using surfactants, and 2) styrene-acrylamide copolymer by surfactant-free sonicated dynamic interfacial polymerization, in the presence of CNT.