Intramolecular mobility in network polymer systems

Abstract

A study has been made crosslinked polymethacrylic acid with luminescing groups, using the polarized luminescence (PL) method. The acid with anthracene containing luminescent groups (markers) (PMAA-C-LG) was dispersed in liquid media. The luminescence polarization of these systems was investigated in relation to the viscosity of the liquid medium. Agreement was found between PL parameters of the marker for the dispersed PMAA-C-LG and for soluble linear PMAA-LG, which means that parameters of molecular mobility are reflected in the PL of dispersed polymer systems. In the analysis of PMAA-C-LG (with ethylene dimethacrylamide (2·5 mole %) as the crosslinking agent) we determined relaxation times characterizing the intramolecular mobility (IMM) of fragments of crosslinked PMAA and changes in the latter due to the ionization of carboxyl groups. Crosslinking led to a marked reduction in IMM compared with the linear PMAA-LG. In the crosslinked PMAA-C-LG as in the linear PMAA-LG a considerable cooperative increase in IMM occurs during the ionization of carboxyl groups within a narrow interval of change in the ionization degree, an interval that practically coincides with that in which a marked change in the IMM of linear PMAA occurs. © 1977.