Date of Award

1991

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

William H. Daly

Abstract

Poly(arylene ether sulfones) were synthesized by aromatic nucleophilic polymerization of the monomers; 4,4$\sp\prime$-biphenol, 4-chlorophenyl sulfone, hydroquinone, and tert-butylhydroquinone. Different conditions of temperature and solvent systems were used to determine the best synthetic approaches for the preparation of poly-(4,4$\sp\prime$-biphenol/4-chlorophenyl sulfone) (1:1), poly-(4-4$\sp\prime$-biphenol/4-chlorophenyl sulfone/hydroquinone) (1:2:1), and poly (4-4$\sp\prime$-biphenol/4-chlorophenyl sulfone/tert-butylhydroquinone) (1:2:1). The use of aprotic high boiling solvent mixtures of N-methyl-2-pyrrolidone (NMP), and N-cyclohexyl-2-pyrrolidone (CHP), facilitated the formation of polymers with structures which can easily be controlled by varying the ratio of monomers, and by varying the concentration of reactants. The polymers were functionalized and modified by silylation, amination and aminomethylation. Directed silylation by electrophilic substitution ortho to the ether group was effected by bromination, followed by lithiation with butyllithium before quenching with chlorotrimethyl-silane. Silylation ortho to the sulfonyl group was effected by metal hydrogen exchange with butyllithium before quenching with chlorotrimethysilane. A maximum of two trimethylsilyl substituents can be introduced for every repeat unit. Modification by amination was accomplished by the introduction of a nitro group and subsequent reduction of the nitro group to an amine. Sodium dithionite was more effective than sulfur/sodium borohydride, or titanium tetrachloride/lithium aluminum hydride as a reducing agent. Degrees of functionalization up to 2 amino groups per repeat unit were achieved. Aminomethylation was performed in a two step process. The first step involved introduction of an N-methylphthalimide substituent by condensation of the activated arylene repeat units with N-hydroxymethyl-phthalimide in the presence of a highly protic solvent mixture, trifluoroacetic acid and trifluoromethanesulfonic acid. The second step involved hydrazinolysis to cleave the phthalimide group and to release aminomethyl substituents. The polymers and their functionalized derivatives were characterized by $\sp1$H and $\sp{13}$C NMR, infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and viscosity measurements. $\sp{13}$C NMR chemical shifts calculated from additivity rule were compared with the assigned chemical shifts. The spectroscopic results are consistent with the assigned structures. The glass transition temperatures (Tg) of the polymers were compared with predicted values based upon molar additivity of incremental values for the structural units. As predicted, tert-butyl substituents raised the Tg while introduction of the more flexible trimethylsilyl groups reduced the Tg's compared to unsubstituted polymers.

Pages

249

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