The thermodynamic and kinetic phenomena involved in the formation of sub-micron polyimide particles from polyimide/solvent/nonsolvent ternary systems were studied. A quantitative equilibrium approach was considered in the B-bonding studies of these ternary systems. The effect of H-bonding on the physical properties and phase behavior of the ternary systems was investigated. The critical requirements for the control of polymer particle size and size distribution during particle formation by precipitation from solution are discussed. It was found that the equilibrium constants, enthalpies and entropies of H-bonding in the ternary systems containing water can be obtained by analysis of the ^lH_NMR data. Using the calculated equilibrium constants, the determination of the concentration of H-bonds between N-methylpyrrolidinone (NHP) and water is possible. We found a very good correlation between the B-bond concentrations and the deviations of the specific volume and viscosity from ideal mixing in the NHP/water mixtures. / Ph. D.