Date of Award

3-1-1991

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Abstract

Polymers which possess thermal and thermo-oxidative stability and processibility have many industrial applications. Aromatic groups in the backbone of a polymer are known to increase the thermal stability, however processibility is limited. A solution to this problem was found to be the addition of flexible links between the aromatic rings. To summarize, a polymer that fits the above objectives has the basic structure depicted below:$$\eqalign{&\rm \quad(Ar - Z)\sb{n}\cr\rm Ar&= \rm aromatic\ group\cr\rm Z&= \rm non{-}aromatic\ linking\ group\cr}$$There are several ways structures of these types could be prepared. One possible way would be to utilize Friedel-Crafts chemistry. This reaction is an established procedure for alkylating or acylating aromatic groups. Another potential method is to use a lithium-halogen exchange reaction in order to produce an aromatic anion followed by subsequent addition of a suitable substrate (eg. alkyl halide, aldehydes, or acyl halides).Friedel-Crafts chemistry has been frequently used in the functionalization of aromatic nuclei. The alkylation and acylation reaction are well understood and yet little research has been done on synthesizing polyaromatic products using Friedel-Crafts chemistry. One goal of this research was to examine the scope of Friedel-Crafts alkylation polymerizations focusing on polybenzyls prepared from polynuclear homocyclic aromatic substrates. That is, to study the structural consequences which result from variations in catalyst, alkylating agents, solvents, and temperatures, with the specific aim of developing soluble, linear polymers. The aromatic nuclei examined include naphthalene, anthracene, and phenanthrene and the flexible linkage or bridging group was a methylene group. The thermal and thermo-oxidative stability of these poly(arylene methylene)s was looked at also.Preparation of polyketones containing naphthalene and anthracene nuclei was also attempted. Several methods were attempted in hopes of preparing the carbonyl-bridged polymers of naphthalene and anthracene. Friedel-Crafts acylation and lithium-halogen exchange followed by subsequent nucleophilic reaction were examined. The former reaction was found to be unsuccessful, thus the lithium-halogen reaction was investigated. To determine the feasibility of the lithium-halogen exchange reaction in the preparation of polyketones, model studies were deemed necessary. Model systems which would lead to the formation of oligomeric materials were investigated.

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