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Reaction-Induced Phase Separation (RIPS) in Amine-Cured Epoxy/Epoxy Thermosets.2. Visualization of Heterogeneity using Fluorescence Lifetime Imaging Microscopy (FLIM)
Published
Author(s)
Jeremiah Woodcock, Stephan J. Stranick, Anthony Kotula, Gale A. Holmes
Abstract
The strategic integration of a rhodamine-spirolactam (RS) mechanophore into a transparent bis-epoxide/bis-epoxide/amine and corresponding bis-epoxide/amine networks has revealed, for the first time using fluorescence lifetime imaging microscopy (FLIM), multiple phases in the cured epoxies despite observing only a single glass transition temperatures (T_g) in the solid rheology data. For the bis-epoxide/bis-epoxide blend composed of the diglycidyl ether of bisphenol-A (DGEBA) and the diglycidyl ether of 1,4-butanediol (DGEBD) cured with meta-phenylenediamine (m-PDA), the heterogeneous morphology is caused by differences in the reaction kinetics of the two miscible bis-epoxides with m-PDA. Heterogeneity in the DGEBA/m-PDA network is partially associated with network under-curing. In the fully cured DGEBD/m-PDA network, heterogeneity appears to be caused by the high-molecular mass oligomers in the 60 wt. % DGEBD that likely self-associate in the predominately DGEBD monomer medium, thereby creating discrete regions of low crosslink density.
Woodcock, J.
, Stranick, S.
, Kotula, A.
and Holmes, G.
(2023),
Reaction-Induced Phase Separation (RIPS) in Amine-Cured Epoxy/Epoxy Thermosets.2. Visualization of Heterogeneity using Fluorescence Lifetime Imaging Microscopy (FLIM), Macromolecules, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933080
(Accessed October 9, 2025)