Influence of polymer architecture on the averaging effects in PGSE NMR attenuations for bimodal solutions of linear and star poly(vinyl acetates)

Pulsed gradient spin-echo (PGSE) NMR is a non-invasive technique that is useful for studying the self-diffusion of molecules in solution. However, even when the solutions are dilute the data analysis can be complicated by the effects of macroscopic and microscopic averaging. Here the averaging effects were measured for dilute bimodal solutions of linear poly(vinyl acetate) (PVAc) or 4-arm star PVAc. Star polymers are useful for biomedical applications due to their compactness and high functionality. Since synthetic polymers are polydisperse, the diffusive averaging effects, which have not yet been investigated in star polymer solutions, need to be considered as the magnitude of this may be important when designing star polymers for these applications. PGSE NMR attenuations were compared to predictions from two limiting case simulations. The results provide information on the magnitudes of the averaging effects for bimodal solutions of polymers with different polymer architectures and suggested that the averaging effects are not strongly dependent on polymer architecture.