Is there a lowest upper bound for superconductive transition temperatures?

I show that for high temperature ceramic cuprates there is a smooth master curve T c max ( 〈 R 〉 ) for the highest superconductive transition temperatures Tc’s as a function of the average number 〈R〉 of Pauling resonating bonds/atom in the parent (undoped) insulator. The existence of such an 〈R〉-dependent optimized Tc is suggested by analogies with the microscopic theory of optimized molecular glass networks (such as window glass). The chemical model is part of a larger nanoscopically mixed multiphase structural model that also explains the canonical cuprate phase diagrams, as well as recent dynamical fs pump/ps probe optical relaxation experiments.