Free radical macrophotoinitiators: an overview on recent advances
Free radical macrophotoinitiators: an overview on recent advances
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DOI：
10.1016/s1010-6030(03)00175-8
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发表时间：
2003-07-14
影响因子：
4.3
通讯作者：
Allen, NS
中科院分区：
文献类型：
--
作者：
Corrales, T;Catalina, F;Allen, NS
综述了近年来紫外光固化用高分子光引发剂的研究进展。在过去的十年中，大分子光引发剂的合成已经取得了显着的发展，由于其大分子性质的优势，与其相应的低分子量类似物相比。特别地，描述了包含两种主要类型的自由基光引发剂的各种大分子：夺氢（噻吨酮、苯偶酰、蒽醌、蒽醌）和光致断裂发色团（苯偶姻醚、酰基氧化膦）。对于氢提取光引发剂，光引发活性已被检查在聚合物线圈中的取代基的体积和性质，以及它们的影响，以防止有利于它们与单体反应的自由基的重组。还报道了具有潜在的活性协同效应的带有发色团和胺基的共聚物。已经发现，叔胺接近发色团以产生相应的激基复合物取决于发色团和叔胺的单体或聚合物性质。报道了II型聚合物光引发剂，例如具有通过苄基芳族化合物连接至主链的苯偶姻甲基醚部分的苯偶姻醚衍生物。并提出了上述共聚物的断裂机理，包括形成稳定的醌型结构和脂肪族酰基自由基，这证明了它们的引发效率低于相应的低分子量模型。此外，描述了带有氧化膦部分的聚合物。发现所有光引发剂的聚合效率是相似的，并且与其结构中柔性间隔物的存在无关。然而，发现柔性低聚亚甲基间隔物增强了新型聚合物光引发剂在丙烯酸粘合剂制剂中的相容性。最后，聚硅烷作为光引发剂的报告。在紫外线照射下，聚硅烷经历主链断裂，导致能够与烯烃单体反应的自由甲硅烷基自由基。通过光解产生的甲硅烷基自由基可以被适当的鎓盐氧化以产生阳离子引发物质（光引发的自由基促进的阳离子聚合）。研究了具有不同脂族和芳族侧基的聚硅烷的光引发效率，并与市售的低分子量光引发剂苯偶姻进行了比较。(C)2003 Elsevier Science B.V.保留所有权利。
This paper provides an overview of the recent advances on polymeric photoinitiators for UV curing. During the last decade, significant developments have been achieved in the synthesis of macrophotoinitiators, due to the advantages derived of their macromolecular nature, in comparison with their corresponding low molecular weight analogues. In particular, a variety of macromolecules containing the two main types of free radical photoinitiators: hydrogen-abstracting (thioxanthone, benzil, anthraquinone, camphorquinone) and photofragmenting chromophores (benzoin ether, acylphosphine oxides) are described. For hydrogen-abstracting photoinitiator, the photoinitiation activity have been examined in terms of volume and nature of substituent in the polymeric coil, and their influence to prevent the recombination of radicals favouring their reaction with the monomer. Also, copolymers bearing chromophore and amine groups with potential synergistic effects of activity are reported. It has been found that the approach of the tertiary amine to the chromophore to produce the corresponding exciplexes is dependent on both the monomeric or polymeric nature of chromophore and the tertiary amine. Type II polymeric photoinitiators, such as benzoin ether derivatives having the benzoin methyl ether moieties connected to the main chain through the benzyl aromatic are reported. And a fragmentation mechanism involving the formation of an stable quinoid structure and aliphatic acyl radical is proposed for the above copolymers, which would justified their lower initiating efficiency than the corresponding low molecular weight model. In addition, polymers bearing phosphine oxide moieties are described. The efficiency in the polymerisation of all photoinitiators was found to be similar and irrespective of the presence of flexible spacer in their structure. However, it was found that the flexible oligomethylene spacer enhanced the compatibility of the new polymeric photoinitiators in acrylic adhesive formulations. Finally, polysilanes as photoinitiators are reported. Under UV irradiation, polysilanes undergo main-chain scission leading to free silyl radicals capable of reacting with olefinic monomers. The silyl radicals generated by photolysis can be oxidised by appropriate onium salts to yield cationic initiating species (photoinitiated radical promoted cationic polymerisation). The photoinitiation efficiency of polysilanes having different aliphatic and aromatic side groups has been investigated and compared with commercial low molecular weight photoinitiators as benzoin. (C) 2003 Elsevier Science B.V. All rights reserved.