Novel photolabile crosslinkers based on O-acyloxime moiety
Novel photolabile crosslinkers based on O-acyloxime moiety
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DOI：
10.1039/c5ra00574d
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发表时间：
2015-04
期刊：
影响因子：
3.9
通讯作者：
K. Suyama;Hideki Tachi
中科院分区：
文献类型：
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作者：
K. Suyama;Hideki Tachi
受控解交联是功能材料和聚合物回收领域中一项有吸引力的技术。光触发解交联对于轻松远程激活和时空控制特别有利。然而，只有少数光不稳定单元被用于交联剂的裂解。在此，提出了1,4-二乙酰苯1,4-双(O-甲基丙烯酰基)二肟和1,3,5-三乙酰苯1,3,5-三(O-甲基丙烯酰基)三肟作为新型交联剂。它们具有带有两个或三个臂的苯环，其中引入了 O-酰基肟部分作为一种新型的光不稳定单元。这些交联剂是由芳香酮分两步制备的。使用二苯基(2,4,6-三甲基苯甲酰基)氧化膦作为光引发剂和310 nm以上的紫外光进行丙烯酸甲酯和交联剂的光聚合。获得的聚合物膜是交联的且不溶于四氢呋喃(THF)。这些膜进一步用254 nm的光照射。通过紫外和红外光谱测量证实了这些交联剂中 O-酰基肟单元的光解作用。在 THF 中浸泡后薄膜厚度的减少证明了 254 nm 照射下解交联的优先性。对解交联聚合物的可溶部分进行尺寸排阻色谱分析，发现它们的分子量与在不存在交联剂的情况下通过光聚合膜获得的分子量相似。这些结果表明，所提出的化合物是新型光不稳定交联剂的潜在候选者。
Controlled decrosslinking is an attractive technique in the fields of functional materials and polymer recycling. Photo-triggered decrosslinking is especially advantageous for easy remote activation and spatiotemporal control. However, only a few photolabile units have been used for the cleavage in crosslinkers. Herein, 1,4-diacetylbenzene 1,4-bis(O-methacryloyl)dioxime and 1,3,5-triacetylbenzene 1,3,5-tris(O-methacryloyl)trioxime are proposed as novel crosslinkers. They have a benzene ring bearing two or three arms in which O-acyloxime moiety is introduced as a novel type of photolabile unit. These crosslinkers were prepared from aromatic ketones in two steps. Photopolymerization of methyl acrylate and the crosslinkers was performed using diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide as a photoinitiator and UV light above 310 nm. Obtained polymer films were crosslinked and insoluble in tetrahydrofuran (THF). These films were further irradiated at 254 nm of light. The photolysis of O-acyloxime units in these crosslinkers were confirmed by UV and IR spectral measurements. The precedence of decrosslinking on 254 nm irradiation was evidenced by the decrease in thickness of the films after soaking in THF. Soluble fraction of the decrosslinked polymers were subjected to size exclusion chromatography, and their molecular weights were found to be similar to that obtained by photopolymerized film in the absence of the crosslinker. These results demonstrated that the proposed compounds are potential candidates for novel photolabile crosslinkers.