Effect of cyclic acetals structure on efficiency of photoinitiation

Abstract

Cyclic acetals were proposed as free radical polymerization photoinitiators or co‐initiators. The photopolymerization kinetics was recorded by real‐time infrared spectroscopy (RTIR). 2‐proply‐1,3‐benzodioxole (PBDO) and 2‐hexyl‐1,3‐benzodioxole (HBDO) were efficient photoinitiators for the polymerization of 1,6‐hexanedioldiacrylate (HDDA). Polymerization occurred at the highest rate with 1,3‐benzodioxolane (BDO) as a co‐initiator. When 1.82 wt % benzophenone (BP) was used as a photoinitiator, the addition of PBDO increased the rate of polymerization (Rp) and the final double bond conversion (DCf) of HDDA, and an optimum cure rate (0.982 min−1) was obtained at 1.64 wt % of PBDO. Combination of p‐chlorobenzophenone (CBP) and PBDO had the highest initiating reactivity. Cyclic acetals were inefficient co‐initiators for isopropylthioxanthone (ITX). Copyright © 2009 John Wiley & Sons, Ltd.

Naturally Occuring or Derived Photoinitiators for Medical Applications

“…[113] Meanwhile, a few cyclic acetals (Scheme 6) have been reported as efficient coinitiators incorporated with commercially available photoinitiators for free radical photopolymerization. [114][115][116] The newly developed CQ/cyclic acetals (e.g., sesamin, BDO, etc.) photoinitiating systems exhibited comparable photoinitiation abilities to the CQ/amine ones.…”

“…To comprehensively understand the effect of substituents on photoinitiation, a study on CA9-12 with selected substituents was conducted. [116,119] Notably, 2-monosubstituted BDO (i.e., CA9 and CA10) demonstrated exceptional photoinitiation abilities in terms of double bond conversion of HDDA due to their sensitivity to hydrogen abstraction. [116,119] In contrast, unlike the 2-monosubstituted BDOs, the oxidation of 2,2-disubstituted CAs primarily occurred on the benzene ring rather than the dioxole ring.…”

“…[116,119] Notably, 2-monosubstituted BDO (i.e., CA9 and CA10) demonstrated exceptional photoinitiation abilities in terms of double bond conversion of HDDA due to their sensitivity to hydrogen abstraction. [116,119] In contrast, unlike the 2-monosubstituted BDOs, the oxidation of 2,2-disubstituted CAs primarily occurred on the benzene ring rather than the dioxole ring. [116] Therefore, while the corresponding benzophenone (BP)-based photo initiat-ing systems with CA11 and CA12 presented adequate efficacy for the photopolymerization of HDDA, their polymerization rate was significantly compared to the 2-monosubstituted CAs.…”

“…Interestingly, CA9, CA10, and CA16 were found to function as one-component photoinitiating systems. [114,116] The free radicals formed via 𝛽-scission from the radical on C2 (Scheme 8). CA9 and CA10 as photoinitiators demonstrated sufficient photoinitiation abilities in polymerizing HDDA, comparable to CA2 in terms of double bond conversion, but weaker than BP.…”

Patient‐reported outcome measures suitable to assessment of patient navigation

“…Numerous papers deal with CQ‐amine system‐initiated photopolymerization in dental formulations and we have discussed it in our review 29. Recent papers by Nie and coworkers186–189 concern the use of cyclic acetals such 1,3‐benzodioxolane or its derivatives as coinitiator in CQ‐induced photopolymerizations. Thus, the natural component sesamin SA (Scheme ) was used as coinitiator for dental composites.…”