Macroporous Epoxy Networks via Chemically Induced Phase Separation

Control of pore size in epoxy systems.

“…Similar cases to the present, where NG is the only visible morphology throughout the curing process, were found by Okada et al [33], Kiefer et al [26,34], Siddhamalli et al [35], and Inoue [22]. Typically, NG is found in systems with low-molecular weight components as the phase separating part, such as cyclohexane by Kiefer et al [26] or dimethylheptanone by Plummer et al [34]. The formation of a co-continuous network in the present work should be possible, based on theoretical considerations and prior experimental work, by increasing the reaction rate while simultaneously decreasing miscibility.…”

“…The relatively large size of the alcohol, while having a negative influence on inter-diffusion rates, is shown to be a minor factor by studies that have shown high-molecular weight polymers to have the capability to phase separate into a co-continuous morphology [32,27,22]. Similar cases to the present, where NG is the only visible morphology throughout the curing process, were found by Okada et al [33], Kiefer et al [26,34], Siddhamalli et al [35], and Inoue [22]. Typically, NG is found in systems with low-molecular weight components as the phase separating part, such as cyclohexane by Kiefer et al [26] or dimethylheptanone by Plummer et al [34].…”

“…For future work, the utility of a commercially-available high-throughput SEM from FEI Company could be investigated. 26 Using the high-throughput approach, a relatively large number of materials were prepared in a relatively short period of time. The results obtained allowed for the identification of the appropriate poragens and process conditions required to obtain porosity.…”

“…Also critical in the TIPS of block copolymers is the distinction between spinodal decomposition (SD) or nucleation and growth (NG), where the former is induced by a sudden large change in temperature or composition and leads to a bicontinuous network, and the latter is induced by slow changes and leads to spherical inclusions in a continuous matrix [25]. In CIPS, both SD and NG are accessible [22,26,23,27], and selection between these two routes depends on three factors: phase separation rate (driven by thermodynamics), reaction rate, and chain mobility (rate of interdiffusion). In general, as the ratio of phase separation rate to reaction rate increases, NG is more likely; and as chain mobility decreases relative to phase separation rate, SD is more likely.…”

Gradient porosity poly(dicyclopentadiene)

“…24 -27 Epoxy and cyanate systems with well-defined porosity have been produced after extraction of the separated substance (low molecular weight liquids can be extracted by drying for example). [28][29][30][31] This substance is, in such cases, often referred to as a porogen, as it will template the final porosity.…”