With trends leading to smaller device scales and increasingly complex polymer structures, there is a need for both a qualitative and quantitative understanding of the manner in which a polymer's network structure alters not only the rate, but also the mode of penetrant transport. To this end, poly(methyl methacrylate) (PMMA) was synthesized in an iniferter-mediated radical polymerization process to produce a variety of well-characterized polymer network structures. The effects of basic network parameters, including the degree of crosslinking, polymer mesh size, and the crosslink size, on the transport process were studied. The effects of sub-Tg annealing/aging, temperature, and the presence of un-reacted monomer were also investigated.
Utilizing both gravimetric sorption data and in-situ ultra-high-resolution X-ray computed tomography studies, the transport of methanol in PMMA discs was investigated. Changing the polymer network structure is shown to not only influence the rate of sorption but also the nature of the transport process.