Influence of hydrophilic silica nanoparticles to the conformation of hydrophilic polymer chain in dilute solution...

We studied interaction of hydrophilic polymer chain and hydrophilic silica nanoparticles in a dilute aqueous system using an idealized model system comprised of a well characterized polyvinyl alcohol of 100 Å R(g) and hard spherical LUDOX® silica of 80 Å radii. Interaction among the polymer chains forming polymer clusters with collective polymer structure factor induced by the polymer-mediated potentials of mean force between the nanoparticles, was observed. However, Gaussian nature of individual polymer chain remains unaltered. The dilute system of polymer with low silica volume fraction has the scattering form which was appropriately modeled as the sum of the individual profiles of spherical silica particles and polymer cluster of interchain packing. With increasing silica volume fraction in the dilute solution, the spatial range parameter between the particles is reduced; hence there is a net increase in the mean potential force and consequently to stronger interaction between the silica and polymer. In the dilute systems of high silica with low polymer volume fraction, the polymer chain apparently attracted closer to the silica and concurrently absorbed to the silica hard surface and their scattering data were excellently fit with a model form factor as comprising of one unit forming the core of the spherical silica particles and the interacting polymer as the corona. This result of severe change in polymer interchain conformation in a dilute system corroborated with reduced polymer viscosity observed.