In this dissertation, two approaches were taken to design aqueous dispersible or soluble high performance ion containing polymers to be used as composite system interfacial modifiers and processing aids. In the first approach, thermally stable pyridine containing poly(ary/ene ether)s were designed which could be ionized by protonation in acidic aqueous media. A novel pyridine containing bisphenol monomer, 2,6-(p-hydroxyphenoxy)pyridine, was synthesized and utilized as a monomer for the synthesis of these pyridine moiety containing, high performance polymers containing sulfone, sulfoxide, phosphine oxide, ketimine, and ketone moieties. These pyridine containing poly(arylene ether)s can function as electrostatic stabilizers, but not as the more efficient steric stabilizers. ThE: second approach endeavored to form controlled molecular weight poly(ether-irTlides) via water soluble poly(amic acid) salt precursors. In this approach controlled molecular weight poly(amic acid)s were synthesized, and treated with stoichiometric quantities of tertiary or quaternary ammonium bases to form poly(amic acid) salts. The imidization conditions, and chemistry of the conversion of the poly(amic acid) salts to imide were studied, with the aim of maintaining the targeted molecular weight distribution and properties analogous to a control polyimide. For the above mentioned aqueous dispersion prepregging process, it is required that the matrix resin be in the form of small uniform particles capable of penetrating the interstices of a tight carbon fiber weave. Sub ~lm dimension poly(ether ether ketone) (PEEK) particles useful for aqueous dispersion prepregging were prepared on a large scale by precipitation from high temperature solvent, quantitatively purified, and shown to display properties analogous to the commercial precursor material. In the final chapter of this dissertation, the synthesis and characterization of a polyolefin macromer, and it's incorporation into a polyester is detailed. These macromers, and the graft polymers resulting, have applicability in the area of polymer blend compatibilization. / Ph. D.