In this work, the interaction between polyvinyl chloride (PVC) and organic
solvents was first investigated through viscometric results and the donor-a
cceptor electron properties. The results clearly showed that the affinity o
f nitrobenzene (NrBz) to PVC is higher than that of chlorobenzene (ClBz). O
n the other hand, the critical gel concentrations C-gel* are 1.7 g dL(-1) a
nd 6 g dL(-1), respectively, for the PVC/ClBz and PVC/NrBz solutions at 30
degreesC, indicating that the polymer-solvent interaction directly affects
the gelation ability. Then, the structural formation and the molecular mobi
lity of PVC gels were investigated using pulsed H-1 NMR analyses. The CPMG
decaying signals from pulsed NMR measurement of the PVC gels could be decom
posed into three components, reflecting respectively the proton mobility in
the junction zone, in the polymer-rich phase and in the solvent-rich phase
of the gel network. The solutions began to appear the fraction of junction
zones at WC concentration above 1.5 g dL(-1) and 6 g dL(-1), respectively,
in the PVC/ClBz and PVC/NrBz solutions, while the formation of the junctio
n zones could interconnect the polymer chains into a three-dimensional netw
ork structure macro-domain. As the immobile junction zones were formed, the
mobility of the PVC chains was reduced and the mobility of the solvent mol
ecules could also be suppressed. This phenomenon typically appeared in the
polymer/poor solvent (PVC/ClBz) system. Through the observation of the diff
usion property of the solvent molecules, we can clearly show that the gel n
etwork in PVC/ClBz gels is denser than that of PVC/NrBz gels.