Interplay of the Electrical and Mechanical Properties of Conjugated Polymers
Doctoral thesis, 2022
This thesis will compare the mechanical and electrical properties of a soft polythiophene and a copolymer of the same material with hard urethane blocks, which enable the formation of a reversible network. Then, blending of a doped soft conjugated polymer with melt‑processable insulating polymers such as polycaprolactone is explored with the goal to prepare thermally stable blends for melt-processing. Conducting stretchable fibers of a doped conjugated polymer and a polyurethane elastomer are demonstrated that feature a high degree of electrical and mechanical stability. Further, the properties of composites with cellulose nanomaterials are described. The nanocomposites feature a high elastic modulus, and the presence of cellulose nanofibrils does not affect the electrical conductivity. Finally, the impact of molecular doping, which is an essential step for rendering the conjugated polymers conductive, on the nanostructure and thermomechanical properties of polythiophenes with oligoethylene glycol side chains is explored. In particular, doping is found to strongly increase the elastic modulus of the polymer. Evidently, a wide range of methods such as copolymerization, blending, the use of a reinforcing agent as well as molecular doping itself can be used for the which may facilitate the design of mechanically robust electrical conductors.
organic electronics
organic semiconductors
doping
copolymers
conjugated polymers
mechanical properties
composites
blends
electrical properties
conducting fibers
Author
Sepideh Zokaei
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Tuning of the elastic modulus of a soft polythiophene through molecular doping
Materials Horizons,;Vol. 9(2022)p. 433-443
Journal article
Electrically Conducting Elastomeric Fibers with High Stretchability and Stability
Small,;Vol. 18(2022)
Journal article
Toughening of a Soft Polar Polythiophene through Copolymerization with Hard Urethane Segments
Advanced Science,;Vol. 8(2021)
Journal article
Impact of oxidation-induced ordering on the electrical and mechanical properties of a polythiophene co-processed with bistriflimidic acid
Journal of Materials Chemistry C,;Vol. In Press(2022)
Journal article
However, the mechanical properties of these polymers need to be optimized for different applications without unduly compromising their electrical properties. This thesis focuses on modulating the mechanical properties of a soft conjugated polymer using different strategies.
First, the mechanical and electrical properties of a soft conjugated polymer is studied after introduction of a hard non-conducting domains that form a network within the conjugated polymer. Furthermore, the addition of an insulating polymer to improve the stiffness and melt-processability or an insulating elastomer to prepare stretchable conducting fibers for e-textiles is explored. Additionally, the introduction of cellulose nanomaterials from wood is shown to increase the stiffness of the material while maintaining the electrical conductivity. Finally, it is shown how the incorporation of dopants that are needed to increase the electrical conductivity of conjugated polymers, can also modify their mechanical properties. Therefore, through the addition of a single additive, both the desired electrical and mechanical properties may be achieved.
This thesis explores the structural, electrical and mechanical modifications of a soft conjugated polymer using the aforementioned methods. The results of this study will open up new possibilities for modulating the property portfolio of conjugated polymers suitable for, e.g., wearable electronics.
Subject Categories
Materials Engineering
Nano Technology
Chemical Sciences
Areas of Advance
Materials Science
ISBN
978-91-7905-648-3
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5114
Publisher
Chalmers
Lecture room Vasa A-salen
Opponent: Sahika Inal, Associate Professor, Organic Bioelectronic Laboratory, King Abdullah University of Science and Technology