Synthesis of Bottlebrush Polymers with Conjugated Backbones and Nonconjugated Sidechains for Improved Solubility
Open Access
- Author:
- Buckingham, Emily
- Area of Honors:
- Chemical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Enrique Daniel Gomez, Thesis Supervisor
Ali Borhan, Thesis Honors Advisor - Keywords:
- Bottlebrush polymer
Conjugated backbone
Nonconjugated sidechain - Abstract:
- Conjugated polymers are important materials for a variety of applications such as organic photovoltaics to biomedical devices. Conjugated polymers tend to be limited by their poor solubility, so sidechains are often added to conjugated polymers to impart desired properties of the sidechains with a balance of maintaining the properties of the conjugated polymers. This paper aims to detail synthesis of bottlebrush polymers with conjugated backbones and nonconjugated sidechains, varying the size of the sidechains to compare the properties of the resulting bottlebrushes with the goal of improving solubility of the conjugated polymer. In this study, P(methylmethacrylate)-alkyne-terminated sidechains were grafted onto P(3HT-stat-3-(6-azido)hexylthiophene) backbones using an azide-alkyne “click” reaction, synthesizing PT-graft-PMMA polymers. The molecular weights of P(methylmethacrylate)-alkyne-terminated sidechains were estimated with end-group analysis of 1H NMR spectroscopy, and other polymer molecular weights were determined by Gel Permeation Chromatography (GPC). The optical properties and solubility of each polymer were compared using UV-Vis spectrophotometry. As expected, grafting longer P(methylmethacrylate)-alkyne-terminated sidechains onto P(3HT-stat-3-(6-azido)hexylthiophene) backbones resulted in graft polymers with a higher average molecular weight and increased solubility in methanol compared to grafting smaller P(methylmethacrylate)-alkyne-terminated sidechains onto the same P(3HT-stat-3-(6-azido)hexylthiophene) backbone. UV-Vis analysis also indicated that attaching PMMA sidechains did not significantly affect the conformation of P(3HT-stat-3-(6-azido)hexylthiophene) when dissolved in a favorable solvent.