ABSTRACT
I. INTRODUCTION M iscib ility o f polyurethane (PU) with lightly sulfonated polystyrene (PSSSA) in blends has been the subject o f several investigation (1,2). In early studies, a protontransfer mechanism from the PSSA to the hard segment o f the PU (which contained a tertiary amine as part o f the chain extender) was postulated in analogy with other polymer mixtures employing similar miscibility enhancement techniques (2). The ionic interaction between the sulfonate anions on the styrene and the cations on the PU enhanced the miscibility o f the system. More recently, nuclear magnetic reso nance (NMR) o f the blends o f the same PU with PSSSA as well as model com pounds in DSMO solutions, along with two-dimensional spectra, showed that the labile protons o f the SSA groups were transferred preferentially to the secondary structures (allophanates), followed by the urethane nitrogens and finally by the ter tiary nitrogens o f the Af-methyldiethanoloamine (MDEA) (3).
