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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.
Citation
Macromolecules

Keywords

epoxy, thermoset, mechanophore, fluorescence lifetime imaging microscopy, reaction-induced phase separation, rhodamine-spirolactam

Citation

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 April 20, 2024)
Created February 25, 2023, Updated March 16, 2023