oc8b00137_si_001.pdf (963.67 kB)
Molecular Origin of the Glass Transition in Polyelectrolyte Assemblies
journal contribution
posted on 2018-04-13, 16:56 authored by Yanpu Zhang, Piotr Batys, Joshua T. O’Neal, Fei Li, Maria Sammalkorpi, Jodie L. LutkenhausWater plays a central
role in the assembly and the dynamics of
charged systems such as proteins, enzymes, DNA, and surfactants. Yet
it remains a challenge to resolve how water affects relaxation at
a molecular level, particularly for assemblies of oppositely charged
macromolecules. Here, the molecular origin of water’s influence
on the glass transition is quantified for several charged macromolecular
systems. It is revealed that the glass transition temperature (Tg) is controlled by the number of water molecules
surrounding an oppositely charged polyelectrolyte–polyelectrolyte
intrinsic ion pair as 1/Tg ∼ ln(nH2O/nintrinsic ion pair). This relationship is found to be “general”, as it
holds for two completely different types of charged systems (pH- and
salt-sensitive) and for both polyelectrolyte complexes and polyelectrolyte
multilayers, which are made by different paths. This suggests that
water facilitates the relaxation of charged assemblies by reducing
attractions between oppositely charged intrinsic ion pairs. This finding
impacts current interpretations of relaxation dynamics in charged
assemblies and points to water’s important contribution at
the molecular level.