²H NMR Studies of Polymer Multilayer Capsules, Films, and Complexes

The chain dynamics of aqueous suspensions of polyelectrolyte complexes, supported multilayers deposited on submicron silica colloids, and hollow capsules were characterized by wide-line 2 H NMR spectroscopy (DNMR) as a function of layer number, temperature, and ionic strength. The strong polyelectrolytes, poly(diallyldimethyl ammonium chloride) (PDADMAC) and poly(styrene sulfonate) (PSS) were employed with selective deuteration of the PDADMAC methyl group. DNMR line-shape analyses showed that there is enhanced chain mobility in the systems with excess positive monomer units, that is, supported multilayers and capsules capped with PDADMAC. Selective deuteration of the first, fifth, and ninth layers confirms that the alternation in chain mobility with the capping layer is a through-film effect. Differential scanning calorimetry (DSC)-detected phase transitions were found to occur between 32 and 45 °C for the PSS/PDADMAC complexes, supported multilayers, and capsules. Whereas the glass transitions of bulk-state polymers are detected by DNMR typically 30 to 40° above the DSC-detected T g, the onset of fast chain motion for the water-saturated polyelectrolyte complexes and supported multilayers coincides with calorimetric transitions.