Author

Yujin Cha

Date of Award

Spring 2021

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Chuanbing Tang

Abstract

In this dissertation, cationic metallocene-containing polyelectrolytes were investigated for the construction of nano-objects by CDSA and the mechanical force-responsive polymer. The self-assembly behavior and mechanically induced polymer deformation were characterized and discussed.

In Chapter 1, the overall background and recent development of metallocene-containing polymers as well as their applications in self-assembly and polymer mechanochemistry were introduced. Primary research objectives were described.

The first section of the dissertation on the CDSA of cationic metallocene-containing block copolymers was provided in Chapter 2. The preparation of PCL-b-PCoAEMAs was achieved through ring-opening polymerization (ROP) of ε-caprolactone and reversible addition-fragmentation chain-transfer (RAFT) polymerization of cobaltocenium amidoethylmetacrylate hexafluorophosphate, followed by ion-exchange. The crystallization-driven self-assembly (CDSA) of these block copolymers was described. Moreover, a unique polymer composition-dependent shape transition was studied. The resultant 2D micelles showed unprecedented ionic strength-dependent stability.

The second part of the dissertation is the preparation and characterization of main-chain cobaltocenium-containing copolymers. In Chapter 3, the preparation of cobaltocenium cyclic olefins and main-chain cobaltocenium-containing polymers were described. The diallyl cobaltocenium, a precursor for cyclic olefin, was prepared through modification of cyclopentadiene (CP) with allyl bromide, followed by coupling with cobalt bromide. The resultant diallyl cobaltocenium showed thermal isomerization in the aqueous solution. The ring-closing metathesis of diallyl cobaltocenium isomers resulted in two different cobaltocenium cyclic olefins; [3]-asna- and [4]-ansa- cobaltocenophane. The main-chain cobaltocenium-containing copolymers were prepared by ring-opening metathesis polymerization (ROMP) of cobaltocenium cyclic olefin and cyclooctene derivatives, resulting in 2-5 % of labeling ratio. Chapter 4 is dedicated to mechanochemistry of main-chain cobaltocenium-containing metallopolymers. The cobaltococenium-containing polymers were prepared by ROMP. The computational studies proved the mechanistic insight of cobaltocenium mechanophore. A strikingly different dissociation mechanism was further proposed.

Finally, Chapter 5 provides a summary of this dissertation research and outlook for future research.

Available for download on Sunday, May 15, 2022

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