Synthesis and photoinitiation property of a cinnamyl formamide disulfide compound

doi:10.11949/0438-1157.20240758

Abstract

Abstract:

Aromatic disulfides have attracted much attention as a new type of LED photoinitiator in recent years. However, the reported aromatic disulfide photoinitiators have a short absorption wavelength and cannot be used in photopolymerization systems triggered by long-wavelength LED light sources with stronger penetration. Therefore, a cinnamyl formamide disulfide photoinitiator (O-BSCF) with long absorption wavelength was designed and synthesized, and its light absorption, photodegradation, and photoinitiating property were investigated in detail. The research results indicated that O-BSCF exhibited a maximum absorption wavelength at 217 nm, with significant light absorption also observed at 405 nm and 455 nm. O-BSCF efficiently initiated the photopolymerization of the Bis-GMA/TEGDMA system under 405 nm and 455 nm LED irradiation. After 200 s of 405 nm and 455 nm LED exposure, final double bond conversion rate of the Bis-GMA/TEGDMA system initiated by O-BSCF achieved 85.2% and 72.5%, respectively, with maximum double bond polymerization rates of 3.05%/s and 1.69%/s, surpassing those of the control group initiated by CQ/DMAEMA. The degradation mechanism of O-BSCF involves S—S bond cleavage under light irradiation, generating arylthiyl radicals that can initiate the photopolymerization of acrylate monomers. Moreover, O-BSCF demonstrated excellent photobleaching performance, suggesting its significant potential for applications in colorless and deep LED curing fields.

Key words: LED photopolymerization, cinnamyl formamide, disulfide compound, photoinitiator

摘要：

芳香二硫类化合物作为一类新型LED光引发剂近年来备受关注，但已报道的芳香二硫类光引发剂的吸收波长较短，无法应用于穿透性更强的长波长LED光源所触发的光聚合体系。因此，设计并合成了一种长波长对甲氧基肉桂酰甲酰胺基二硫化合物光引发剂（O-BSCF），详细探讨了O-BSCF的光吸收、光降解及光引发性能。研究结果表明，O-BSCF最大吸收波长在217 nm 处，在波长405以及455 nm有一定的光吸收。O-BSCF在405以及455 nm LED光照下均能高效地引发双酚A缩水甘油酯（Bis-GMA）/三乙二醇二甲基丙烯酸酯（TEGDMA）体系的光聚合。在405以及455 nm LED光照下辐照200 s时，O-BSCF所引发的Bis-GMA/TEGDMA的最终双键转化率分别为85.2%和72.5%，最大双键聚合速率分别为3.05%/s和1.69%/s，均高于对照组CQ/DMAEMA所引发的。O-BSCF的降解机理是在光照下S—S键断裂产生芳硫自由基，引发丙烯酸酯类单体光聚合。并且，O-BSCF展现出优秀的光漂白性能，其在无色和深层LED固化领域具有巨大的应用潜力。

关键词: LED光聚合, 肉桂酰甲酰胺, 二硫化合物, 光引发剂

CLC Number:

TQ 572. 4

Ruixue CUI, Yuhan ZHANG, Fang SUN. Synthesis and photoinitiation property of a cinnamyl formamide disulfide compound[J]. CIESC Journal, 2025, 76(3): 1305-1311.

崔瑞雪, 张玉含, 孙芳. 对甲氧基肉桂酰甲酰胺基二硫化合物合成及其光引发性能[J]. 化工学报, 2025, 76(3): 1305-1311.

Figures/Tables 8

Fig.1 Synthesis routes of O-BSCF

Fig.2 UV-Vis absorption spectrum of O-BSCF in anhydrous acetonitrile (c: 1 × 10-4 mol/L)

Table 1 λmax and ε at 385， 405 and 455 nm for O-BSCF

二硫化合物	λ_max/nm	ε /(L/(mol·cm))
二硫化合物	λ_max/nm	ε_max	ε₃₈₅	ε₄₀₅	ε₄₅₅
O-BSCF	217	30278	3439	1248	50

Fig.3 Photodegradation curves of O-BSCF in anhydrous acetonitrile (c: 1.0 × 10-4 mol/ L)

Fig.4 ESR spectra and fitting curves of O-BSCF under the irradiation condition of 405 nm LED point source (1 G=10-4 T)

Fig.5 The possible mechanism of O-BSCF generating free radicals upon 405 nm LED irradiation

Fig.6 The photopolymerization kinetics of Bis-GMA/TEGDMA (4∶6, mass ratio) system induced by O-BSCF and CQ/DMAEMA (1∶2, mass ratio); under 405 nm 455 nm LED (I: 100 mW/ cm2): (a) double bond conversion; (b) rate of polymerization

Fig.7 Photobleaching experiments of Bis-GMA/TEGDMA/OBSCF under LED at 455 nm and 405 nm

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