紫外阳离子光引发剂及其发展动态

阳离子型光引发聚合是一种快速、高效、低能耗和低污染的聚合方式。着重介绍阳离子光引发剂的主要种类、各自的特点及其光引发机理,简述阳离子光引发剂在涂料中的应用和发展,并对今后的研究方向进行了展望。     

阳离子聚合光引发剂及其阳离子反应机理

综述了阳离子聚合光引发剂的种类、制备和应用，介绍了它们的光分解和由此引发的光引发阳离子聚合反应机理。     

LED光源可激发光引发剂的研究进展

传统的光引发剂在光固化领域的应用主要是通过高压汞灯等光源来实现的，通过 UVB波段（ 280~320 nm）光子激发导致引发剂分子的裂解或者夺氢反应，产生自由基或阳离子等，引发相应的自由基或者阳离子聚合。但是，当 LED光源被发明之后，特别是 UVA波段和可见光波段的 LED光源，其特有的节能、环保等优势对于光固化行业的促进是有目共睹的。因此，传统光引发剂的吸收光谱和新 LED光源的发射光谱匹配性较差成为光固化领域被广泛关注的问题。一般来说，可以从 2个方向解决：一是 UVB波段的 LED光源的产业化；二是把光引发剂的吸收带红移到 UVA和可见光区。本文从光引发剂吸收带红移的角度论述了自由基型和阳离子型光引发剂的研究进展。     

改善鎓盐类阳离子光引发剂光敏性的研究概况

鎓盐类阳离子型光引发剂是一类新型高效的紫外光固化引发剂,它在紫外光固化领域中有着十分重要的地位。重点介绍了增强鎓盐光敏性的方法及相关机理,简单介绍了鎓盐类阳离子光引发剂的特点和研究进展。     

二茂铁四氟硼酸盐的阳离子光引发性能的研究

制备并研究了[CpFeCp]BF4作为阳离子光引发剂在高压汞灯下引发环氧类预聚物的光引发活性。发现其在紫外及可见光区均有较强吸收（λm=355nm、620nm)；对环氧类预聚物，具有优良的光引发活性，感度值可达41.8mJ/cm^2，优于其它的阳离子光引发剂；[CpFeCp]BF4的最佳使用浓度为3％（质量分数）左右，由于光照后仍有强后聚合活性，发现其在较低浓度（质量分数1％）引发后放置，仍可使聚合完全；同其它的阳离子光引发剂相比，[CpFeCp]BF4制备简单，非常有应用价值。     

二苯基碘Weng氟硼酸盐引发AGE阳离子光聚合与光交联的研究

用合成的二苯基碘Ｗｅｎｇ硼酸盐作为光敏引发剂,研究了含乙烯基和环氧基两种不同官能基的烯丙基缩水甘油醚（ＡＧＥ）的阳离子光聚合前后微观结构的变化,讨论了其阳离子光聚合的特征和机理,测定了光聚合经起光交联的凝胶转化率曲线。     

光聚合现状与展望

本文叙述了自由基和阳离子聚合光引发剂体系的最新进展,并且提供了不同引发模式下在所有光引发体系中有关引发效率、波长限制和环境安全问题的解决办法。在过去10年里,通过光聚合制备了复杂或纳米结构的大分子,因此本文也介绍了光聚合在生物材料、表面改性和纳米复合材料领域的新兴应用。     

环氧有机硅阳离子型光敏预聚物的合成及其光敏性能的研究

合成了环氧有机硅光敏预聚物及阳离子光引发剂甲苯茂铁四氟硼酸盐，研究光引发剂种类、预聚物与单体配比、增感剂结构等因素对固化速度的影响，发现预聚物体系的感度较高，最小感度值为165mJ/cm^2；并讨论了甲苯茂铁四氟硼酸盐的暗聚合能力。     

基于响应面法优化混杂UV固化胶粘剂配方

以环氧丙烯酸酯树脂、环氧树脂(EP)、自由基光引发剂和阳离子光引发剂为主要原料,制备混杂UV(紫外光)固化胶粘剂,并且采用响应面法对混杂UV固化胶粘剂的配方进行优化;以预聚体配比、光引发剂配比作为自变量,以混杂UV固化胶粘剂在玻璃上的附着力作为因变量,采用Design Expert软件对2个自变量进行多次拟合,建立相应的数学模型和3维曲面,得到最优的混杂UV固化胶粘剂配方并进行验证。研究结果表明:二项式是描述因变量和自变量之间关系的最佳模型,当环氧丙烯酸酯树脂/EP质量比为1.19、自由基光引发剂/阳离子光引发剂质量比为1.00时,制成的混杂UV固化胶粘剂在玻璃基材上的附着力(9级)相对最强。     

稠环化合物敏化硫鎓盐引发阳离子光聚合的研究

合成了三芳基硫六氟磷酸盐光引发剂。研究了不同稠环化合物对硫盐引发阳离子光聚合速度的影响,用光致电子转移(光氧化还原)理论解释了这些稠环化合物的光敏机理。     

光致阳离子聚合引发剂的进展

光致阳离子聚合体系具有聚合速度快、不受氧干扰以及对水不敏感等优点,为了适应光致阳离子聚合体系的发展,可进行光致阳离子聚合的单体和光致阳离子引发剂的研究越来越受到人们的重视,本文就其中的一方面光致阳离子引发剂的种类、制备以及引发机理进行了综述。     

鎓盐类阳离子聚合光引发剂的研究进展

碘鎓盐和硫鎓盐是最重要的和应用最广泛的阳离子聚合光引发剂。本文介绍了几种典型的碘鎓盐和硫鎓盐及其引发机理,并就碘鎓盐和硫鎓盐在增加光引发剂的光敏性、增加光引发剂在光引发阳离子聚合体系中的组分相容性以及在阳离子光引发剂中引入自由基等方面的发展状况进行了综述。     

光致阳离子聚合单体的进展

光致阳离子聚合体系具有聚合速度快、不受氧干扰以及对水不敏感等优点,为了适应光致阳离子聚合体系的发展,可进行光致阳离子聚合的单体和光致阳离子引发剂的研究越来越受到人们的重视,本文就其中的一方面可进行光致阳离子聚合的单体进行了综述。     

The synthesis and characterization of cationic photoinitiators bearing two and three photoactive triarylsulfonium groups in the same molecule

Summary A novel series of photoinitiators for cationic polymerization have been prepared which bear two and three photoactive triarylsulfonium groups in the same molecule. These compounds have been fully characterized by means of their UV and C-NMR spectra and liquid chromatography as well as by their elemental analyses. The multifunctional triarylsulfonium salts have been compared among themselves and against monofunctional triarylsulfonium salts in the photoinitiated cationic polymerization of dl-limonene dioxide.     

Photochemically initiated free radical promoted living cationic polymerization of isobutyl vinyl ether

A new photoinitiating system for living cationic polymerization of vinyl ethers such as isobutyl vinyl ether (IBVE) has been reported. The photoinitiating system comprises free radical photoinitiators such as 2,2-dimethoxy-2-phenyl acetophenone (DMPA), benzophenone or thioxanthone, together with an onium salt, such as diphenyliodonium chloride and zinc bromide. In the first step, photochemically generated free radicals are oxidized to the corresponding carbocations which subsequently react with vinyl ether monomer to yield an adduct. In the presence of zinc salt, this adduct initiates living cationic polymerization of IBVE.     

(η6‐N‐alkylcarbazole) (η5‐cyclopentadienyl) iron hexafluorophosphate salts in photoinitiated and thermal epoxy polymerization

(η6‐Carbazole)(η5‐cyclopentadienyl) iron hexafluorophosphate salts (CFS PF₆) are capable of photoinitiating cationic polymerization of epoxy monomers directly upon irradiation with long‐wavelength UV light. To improve the solubility of CFS ferrocenium salts in epoxides, two CFS photoinitiators have been prepared: [cyclopentadiene‐Fe‐N‐buylcarbazole] hexafluorophosphate (C4‐CFS PF₆) and [cyclopentadiene‐Fe‐N‐octylcarbazole] hexafluorophosphate (C8‐CFS PF₆), bearing C4 and C8 alkyl chains, respectively, on the nitrogen atom. Studies with real‐time infrared spectroscopy have shown that C4‐CFS and C8‐CFS photoinitiators exhibit high efficiency in polymerization of 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexane carboxylate (ERL‐4221) epoxy monomer, but lower efficiency in polymerization of di(2,3‐epoxypropyl)‐3,4‐epoxy‐1,2‐cyclohexanedioate (TDE‐85) epoxy monomer. Benzoyl peroxide (BPO) sensitizer was very effective in improving the photoinitiating activities of CFS in polymerization of both ERL‐4221 and TDE‐85. DSC studies have shown that C4‐CFS and C8‐CFS photoinitiators can also be employed as thermal initiators for the cationic ring‐opening polymerization of epoxides at moderate temperatures. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

［环戊二烯-铁-二苯甲烷］六氟磷酸盐的光催化研究

芳茂铁盐是一类有效的用于环氧聚合的光引发剂。通过二茂铁和二苯甲烷的配体交换反应,制备了新型的芳茂铁盐［环戊二烯-铁-二苯甲烷］六氟磷酸盐（［Cp-Fe-Bp］⁺PF₆^-）。研究了其紫外－可见吸收性能和光解,发现［Cp-Fe-Bp］⁺PF₆^-）由d-d跃迁产生的在300 nm以上的吸收使其适合长波紫外光源。通过实时红外研究了［Cp-Fe-Bp］⁺PF₆^-）的光引发活性,表明能有效地引发3,4-环氧基环己基甲酸-3′4′-环氧基环己基甲酯（ERL-4221）开环聚合,过氧化苯甲酰能使其光引发活性显著提高。     

Possibilities for photoimaging using onium salts

The recent discovery that the photolysis of certain onium salts produces strong Brønsted acids presents a unique opportunity to design novel photoimaging systems based on these materials. For example, when used as photoinitiators, they can induce the negative image wise cationic polymerization of multifunctional epoxides, vinyl ethers, and lactones. Alternatively, they may be used to catalyze the degradation of hydrolytically sensitive polymers to give positive photoresists. The ability of still other onium salts to generate radical species as well as strong acids has been exploited to develop photoimaging processes which have no parallel in present photoresist technology. The processes consist of simultaneous radical polymerization and acid-induced cationic polymerization. Finally, the recent observation that the onium salts can be dye-sensitized allows them to be responsive to both the ultraviolet and visible regions of the spectrum and to be used with many commercial optical imaging systems.