Photopolymerization of N,N‐dimethylaminoethylmethacrylate studied by photocalorimetry

Photopolymerization of dimethylaminoethylmethacrylate (DMAEMA) is studied in bulk and in solutions in the presence of different photoinitiators using differential photocalorimetry (DPC). The rate of DMAEMA photopolymerization is slow compared to that of alkylmethacrylates. Bimodal DPC curves of DMAEMA photopolymerization in bulk are obtained. The type I photoinitiators (IRGACURE® 651 and IRGACURE® 1700), which produce free radicals by homolytic fragmentation of photoexcited molecules, are more effective in promoting photopolymerization of DMAEMA. The type II photoinitiators (benzophenone and IRGACURE® 500), which initiate DMAEMA photopolymerization through an H‐abstraction mechanism involving an amino group from the monomer (polymer), are less efficient and favor the formation of partly crosslinked products. The effects of the photoinitiator concentration, temperature, and solvent on the kinetic data are evaluated and discussed. A scheme of photopolymerization of DMAEMA, including the formation of intermediate DMAEMA based macromonomers, is proposed. The main point of the suggested scheme is a high chain transfer to the DMAEMA monomer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 579–588, 2002     

二芳基碘鎓盐型阳离子光引发剂的 合成和光引发性能测试

通过两步反应合成了6种二芳基碘鎓盐, 研究了4,4′－二乙酰胺基苯基碘六氟磷酸盐的合成,确定了最佳工艺条件：乙酰苯胺与碘酸钾的摩尔比为2.2∶1.0,15 ml乙酸在25 ℃反应24 h,产率为47.6%。通过应用实验,测试了6种产物的光引发剂性能,对碘鎓盐光引发剂的构效关系进行了探讨。实验证明4种负离子为PF-6和BF-4的产物具有较好光引发性和抗氧阻能力。引入共轭基团的二芳基碘鎓盐其最大吸收波长明显增大,光引发性增强。     

不同颜色体系的UV丝印油墨中光引发体系的选择

使用紫外-可见分光光度计测得了黄、蓝、橙、紫4种颜料的紫外吸收图谱;在模型化的丝印油墨配方中改变光引发剂的种类,运用指压法和指抠法研究了多种光引发剂对含有这4种颜料的UV油墨的引发速度的影响。结果表明不同颜色的颜料对紫外光的吸收区域和吸收强度是不同的。对于黄色油墨,907的引发效果最佳;对于蓝色油墨,907+ITX+EDAB和910+ITX+EDAB都具有很高的引发速度;而对于橙色油墨和紫色油墨,907+ITX+EDAB则是速度最高的引发剂组合。     

Development of new dyeing photoinitiators based on 6H-indolo[2,3-b]quinoxaline skeleton

The series of new dyes, which structures are based on 6H-indolo[2,3-b]quinoxaline skeleton that possess characteristic electronic absorption band at a boundary of UV and visible light were tested as potential light absorbing chromophores for photoinitiated polymerization.The studied dyes can be classified into two different groups. The first is the group, so called ‘the branched dyes’, which structures possess the part of molecule that can rotate without restraints and are characterized by low photoinitiation ability. The second, planar and rigid group of molecules provides another chromophores, which possess quite different properties in comparison to that observed for the branched dyes. Their photoinitiation ability is comparable to that observed for many commercially available photoinitiating systems.The location of electronic absorption spectra at a boundary of UV and visible light makes the tested dyes the good candidates for the photoinitiating system applied in dental restorative materials. Their high molar absorption coefficient allows to decrease the dyes concentration in dental formulation in comparison to commonly used camphorquinone.     

高温下白卡纸中二苯甲酮和1-羟基环己基苯基甲酮向食品模拟物质的迁移

研究了在70℃和90℃下,采用直接浸泡法使白卡纸中的固化剂二苯甲酮(BP)和1-羟基环己基苯基甲酮(HCH)向水、3%乙酸、15%乙醇、50%乙醇、95%乙醇等食品模拟物质迁移,采用高效液相色谱仪(HPLC)分别检测迁移后模拟物质中的迁移量。结果表明两种固化剂在0.64~40mg/L的质量浓度范围内呈良好线性,相关系数不小于0.9995。温度越高,迁移时间越长,迁移量也越大;随着乙醇浓度的增高,BP、HCH的迁移量也增加;对于3%乙酸,BP和HCH迁移率最小。     

低温下采用快速液相色谱-质谱联用法分析包装食品中UV油墨光引发剂的迁移

A fast method of liquid chromatography coupled to tandem mass spectrometry(LC-MS/MS) was developed for the analysis of eleven UV ink photoinitiators in packaged food.Chromatographic separation was achieved in a pentafluorophenylpropyl (PFPP) column at 5X2 and acetonitrile:25mM formic acid-ammonium formate(pH 2.7) in gradient elution. To reduce sample treatment,a QuEChERS(quick,easy,cheap,effective,rugged and safe) method for the extraction and clean-up of UV photoinitiators in packaged foods was evaluated.Triple quadrupole working in H-SRM on Ql mode was used for both quantitation and confirmation purposes and the most intense and selective transitions were chosen.Quality parameters of the developed QuEChERS LC-MS/MS method were established and applied for the analysis of photoinitiators in food packaged at ng/kg levels.     

UV固化无溶剂型丙烯酸酯压敏胶的合成与性能表征

以丙烯酸异辛酯(2-EHA)、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)和四氢化糠基丙烯酸酯(THFA)为主要单体,以丙烯酸(AA)和N,N-二甲基丙烯酰胺(DMAA)为功能性单体,以4-丙烯酰氧基二苯甲酮(ABP)为光引发剂,以十二烷基硫醇(NDM)为链转移剂,通过本体聚合法制备了UV固化无溶剂型丙烯酸酯压敏胶(PSA)。分别探讨了两种功能单体AA和DMAA用量,光引发剂ABP和链转移剂NDM用量对PSA性能的影响。结果表明,当DMAA和AA用量分别为单体总质量的10%和2%时,PSA的120℃熔融黏度适中且粘接性能较优;光引发剂ABP用于PSA体系,且用量为单体总质量的0.2%时,光固化效果最佳;当NDM用量为单体总质量的1.5%时,PSA综合性能最佳。     

Xanthene dyes/amine as photoinitiators of radical polymerization: A comparative and photochemical study in aqueous medium

The efficiency of several xanthene dyes as photoinitiators of the free radical polymerization in aqueous medium was evaluated. These results show that dyes with triplet quantum yield higher than 0.1 present similar efficiencies, independently of their different chemical structure. A detailed study of the photophysics of the dyes under the polymerization conditions was carried out using laser time-resolved spectroscopies. These studies show that the active radicals are those which formed in the interaction of excited triplet state of the dye with the amine through an electron transfer process. In spite of this, the photoinitiation efficiency is not correlated with the triplet quantum yield. Also, the photophysics studies show that the quantum yield of the different pathways of the decomposition of the charge transfer intermediate is an important parameter to predict the efficiency of these photoinitiator systems. The experimentally measured active radical formation is well correlated with that calculated from the polymerization rate. The presence of heavy atoms in the xanthene ring increases the triplet quantum yield, but decreases the active radical yield, and then the polymerization rate.     

苯基亚膦酸二甲酯的合成

以苯、三氯化磷、甲醇为主要原料,经两步反应合成了苯基亚膦酸二甲酯,并通过正交实验优化了合成条件。第一步反应：苯和三氯化磷在三氯化铝催化剂作用下生成苯基二氯化膦,n（苯）：n（三氯化铝）：n（三氯化磷）=1：3：1．3,回流时间9h,三氯氧磷为处理剂,收率为95．5％。在第二步反应中苯基二氯化膦在三乙胺存在下与甲醇作用生成目的物,反应温度20～30％,优化的物料配比为n（苯基二氯化膦）：n（甲醇）：n（三乙胺）=1：2．2：2．7,在此条件下反应收率为88．4％。     

Polymeric Photoinitiators Containing Side-chain Ketoaromatic Moieties for Fast Ultraviolet Initiated Polymerisation of Acrylic Monomers

The synthesis of polymeric photoinitiators having side-chain cyclohexylphenylketone as well as benzophenone moieties at different distances from the backbone is described. Study of the activity of the former systems, in the ultraviolet initiated polymerisation of acrylic monomers, indicates that a remarkable increase in the polymerisation rate is observed when the cyclohexylphenylketone chromophore is attached to the main chain through an ethereal linkage rather than an ester group. In the case of the latter systems, considerable improvement is observed in the photoinitiating activity with respect to the corresponding low molecular weight model compounds in the polymerisation of acrylic monomers. Moreover, in general the copolymers of benzophenone-containing monomers show higher activity than the corresponding homopolymers. These results are discussed in terms of photoexcitation energy migration along the polymer chain, as well as of intramolecular hydrogen abstraction from both main and side chains. This last occurrence seems to be the main activation process, as suggested by a strict correlation between activity and hydrogen-donating properties of the co-units in the copolymers, Photophysical evidence supporting this point is also reported. Finally, the synthesis of polymeric photoinitiators, containing both benzophenone and tertiary amine groups in the same macromolecule, has been accomplished via copolymerisation of 4-acryloxybenzophenone with 4-(N,N-dimethylamino)styrene. Preliminary data concerning photoinitiating activity of these last copolymers indicate that conformational mobility affects the formation capability of exciplexes and then the activity itself.