This manuscript demonstrates the synthesis of glassy polymer network isomers to control morphological variations and study solvent ingress behavior independent of chemical affinity. Well-controlled network architectures with varying free volume average hole-sizes have been shown to substantially influence solvent ingress within glassy polymer networks. Bisphenol-A diglycidyl ether (DGEBA), bisphenol-F diglycidyl ether (DGEBF) and tetraglydicyl-4,4'-diamino-diphenyl methane (TGDDM) were cured with 3,3- and 4,4'-diaminodiphenyl sulfone (DDS) at a stoichiometric ratio of 1:1 oxirane to amine active hydrogen to generate a series of network architectures with an average free volume hole-size (V-h) ranging between 59 and 82 angstrom(3). Polymer networks were exposed to water and a broad range of organic solvents ranging in van der Waals (vdW) volumes from 18 to 88 angstrom(3) for up to 10,000 h time. A clear relationship between glassy polymer network V-h and fluid penetration has been established. As penetrant vdW volume approached V-h uptake kinetics significantly decreased, and as penetrant vdW volume exceeded V-h a blocking mechanism dominated ingress and prevented penetrant transport. These results suggest that reducing the free volume hole-size is a reasonable approach to control solvent properties for glassy polymer networks. (C) 2011 Elsevier Ltd. All rights reserved.