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Controlling shadow cure in cationic photopolymerizations using physical cues and processing variables
Author(s) -
Schissel Sage M.,
Jessop Julie L. P.
Publication year - 2020
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.48290
Subject(s) - photopolymer , cationic polymerization , materials science , photoinitiator , polymerization , shadow (psychology) , composite material , polymer chemistry , polymer , monomer , psychology , psychotherapist
Cationic photopolymerizations offer unique advantages for many applications. The long‐lived active centers may proceed long after the irradiation has ceased, leading to dark cure or postpolymerization. In addition, these active centers possess mobility through reactive diffusion and may lead to polymerization in unilluminated regions (shadow cure). Shadow cure may allow effective polymerization in optically thick and pigmented systems or for systems in which areas are effectively masked from the illumination source. In this work, we demonstrate and optimize active center mobility, and thus shadow‐cure growth, by challenging shadow cure in different geometries and through design of experiments. Based on central‐composite‐design results, shadow‐cure length is most influenced by sample depth, while gel fraction is most affected by effective irradiance. Both responses are increased by maximizing the respective factors. These shadow‐cure relationships can be used to expand photopolymerization use in light‐restricted applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137 , 48290.