Phase separation of beam electron cross-linked thermo responsive PVME nanogels in the presence of spherical nano particles: with a view toward rheology and interactions.
(1) Department of Polymer Engineering, Amirkabir University of Technology - Tehran - Iran, (2) Polymer Engineering Group, Faculty of Engineering, Qom University of Technology - Qom - Iran
Volume phase transition of the nanogels systems is the most important part in their applications. In order to investigate the mentioned issue a study on the phase separation behavior and rheological properties of poly (vinyl methyl ether) (PVME) nanogels prepared by high energy pulse electron beam radiation was carried out by rheological measurements in the presence and absence of hard spherical hydrophilic Silica nano particle. Isochronoal temperature sweep test of the nanogels showed that hybrid nanogels have higher volume phase transition temperature due to less mobile chains compared to non-hybrid nanogels. Optical microscopy was employed to investigate morphological evaluation in the nanogel systems. The more rigid macromolecules caused the samples containing nano particles go through phase separation with viscoelastic phase separation (VPS) mechanism. To get a deep insight in phase separation mechanisms FT-IR measurements were carried out to determine the interactions. The presence of nano particles causes a hydrophobicity and more rigidity behavior in the polymeric chains. This phenomenon becomes more intense while phase separation occurs. These also were agreed by rheological measurements by an increase in the frequency curve of the nanogels containing nano particles at non-homogeneous state while frequency sweep curves of the pure nanogels were almost the same at both homogeneous and non-homogeneous states. Finally the conformity of the nanogels rheological behavior and the emulsions models at the non-homogeneous state was investigated.