Thermoreversible gelation of syndiotactic poly(methyl methacrylate) (sPMMA)-polybutadiene (PBD)-sPMMA, triblock copolymers in o-xylene has been studied in the presence of isotactic PMMA (iPMMA) in a large range of syndio/iso mixing ratio (s/i). Differential scanning calorimetry (DSC) shows that two types of association contribute to the gel formation, i.e., the self-aggregation of the sPMMA outer blocks and the stereocomplexation of the sPMMA outer blocks with iPMMA. At low iPMMA contents (s/i = 30/1), self-association of the outer blocks accounts for the gelation process, although stereocomplexation occurs. Stereocomplexation becomes the dominant gelation mechanism at a high enough iPMMA content (s/i = 2/1). Thus, gelation is observed at a copolymer concentration as low as 1 wt %. The time dependence of the storage (G’) and loss (G") moduli has been measured in the 0.08-1Hz frequency range in order to probe the gelation process. At the gel point, where the loss angle (tan delta(c) = G"/G’) is independent of the probing frequency, the sample fits in the typical power law G’(omega) similar to G"(omega) similar to omega(Delta). While the gelation time is greatly influenced by the s/i mixing ratio, the scaling exponent Delta is essentially constant in the range of 0.70-0.75. The Delta value agrees with theoretical predictions as well as with experimental values reported for some chemical gels but it is different from the experimental values reported for most physical gels. The Delta value is also independent of the PBD microstructure and it also holds for sPMMA-polystyrene (PS)-PBD-PS-sPMMA (MSBSM) pentablock copolymers. Therefore, the value of Delta appears to be a typical exponent for thermoplastic gels based on triblock copolymers of the ABA type in o-xylene.