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theses

Conjugated polymers have been explored as an important class of organic electronics, such as organic light emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic solar cells. With the development of various synthetic methods and characterization techniques, the family of conjugated polymers have grown to a scope which goes beyond any single discipline. Functionalization of conjugated organic systems with main group elements represents an active research area of significant interest in the scientific community. One of the most employed elements is the electron-deficient boron that features an empty p orbital that enables the overlap with π orbitals of attached aryl groups. This leads to novel optical and electronic properties for organoborane containing conjugated polymers. The focus of this thesis is on the investigation of incorporation of organoborane into different conjugated systems. Chapter 1. Regioregular Organoborane-Functionalized Poly(3-alkynylthiophene)s A series of new alkynylphenylborane-functionalized monomers were synthesized and utilized to prepare regioregular borane acceptor-functionalized polythiophenes rr-P1, rr-P2 using Stille-type polymerization and P1 using Kumada technique. Theoretical calculations on model systems and fluoride anion binding studies confirm the assignment of the lowest energy absorption at ca. 500 nm to the polymer backbone and the higher energy bands at ca. 330-340 nm to a charge transfer state which is localized on the borane moieties. A comparison between polymer P1 and rr-P1 suggests a higher regioregularity which results in significant bathochromic shifts in both absorption and emission spectra. The borane acceptor effect is also reflected in the bathochromic shift of the lower energy absorption maximum of polymers rr-P1, rr-P2 and rr-P3HT which is envisioned as possible candidates for optical and sensory materials. Chapter 2. Amphiphilic Polythiophene Block Copolymers Containing Phenylboronic Acid Functionality The amphiphilic block copolymers poly (3-hexylthiophene)-block-polystyrene boronic acid (P3HT-b-PSBA) and poly (3-hexylthiophene)-block-poly (4-vinylpyridine-stat-styrene boronic acid) (P3HT-b-P(4VP-stat-SBA) are prepared using a combination of Grignard metathesis (GRIM), controlled radical polymerization (CRP) and click chemistry. This polymers represent a new type amphiphilic polythiophene block copolymers containing boronic acid-functionality for potential applications in material chemistry. Chapter 3. The First 1, 2-azaborine Polymer With a collaborative effort with Prof. Liu’s group (Boston College) who provided Bpin/Br-functionalized AB-type monomers and regioregular model compounds, we incorporated monocyclic 1,2-azaborine into extended π-conjugated systems using the Suzuki-Miyaura polymerization technique. Though the polymer main chain is isoelectronic to poly (paraphenylene), photophysical and computational studies indicate a closer similarity to polyacetylene which indicates promising applications as a new class of conjugated materials.

ETD_6664

Ph.D.

Includes bibliographical references

by Fang Guo

doi:10.7282/T3CV4KRJ

ETD doctoral

The author owns the copyright to this work.