  Viscoelastic and thermodynamic properties of transient gels formed by
telechelic polymers are studied on the basis of the transient network theory
that takes account of the correlation among polymer chains via network
junctions. The global information of the gel is incorporated into the theory by
introducing the elastically effective chains according to the criterion by
Scanlan and Case. We also consider effects of superbridges whose backbone is
formed by several chains connected in series with several breakable junctions
inside. Near the critical concentration for the sol/gel transition,
superbridges becomes infinitely long along the backbone, thereby leading to the
short relaxation time $\tau$ of the network. It is shown that $\tau$ is
proportional to the concentration deviation $\Delta$ near the gelation point.
The plateau modulus $G_{\infty}$ increases as the cube of $\Delta$ near the
gelation point as a result of the mean-field treatment, and hence the
zero-shear viscosity increases as $\eta_0\sim G_{\infty}\tau\sim\Delta^4$. The
dynamic shear moduli are well described in terms of the Maxwell model, and it
is shown that the present model can explain the concentration dependence of the
dynamic moduli for aqueous solutions of telechelic poly(ethylene oxide).
