Photo-sensitive PMMA microgels: light-triggered swelling and degradation
Photo-sensitive PMMA microgels: light-triggered swelling and degradation
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DOI：
10.1039/c0sm00638f
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发表时间：
2011-01-01
期刊：
影响因子：
3.4
通讯作者：
Landfester, Katharina
中科院分区：
文献类型：
--
作者：
Klinger, Daniel;Landfester, Katharina
合成了两类（A 型和 B 型）基于邻硝基苄基衍生物的新型光不稳定二乙烯基官能化交联剂，并研究了它们在紫外线照射下的光解性能。分子结构的系统变化导致根据照射条件不同的降解速率。因此，通过调整应用的波长或照射时间可以实现连续且独立的裂解。各自的分子用于通过在细乳液聚合过程中与MMA进行自由基共聚来构建可光降解的PMMA微凝胶。通过时间依赖性浊度测量来监测紫外光诱导的溶胀微凝胶的降解，并且发现所得动力学与溶液中各自交联剂的光解速率相关。通过 lambda > 315 nm 的紫外线照射实现 B 型交联点的照射波长控制选择性部分裂解，并产生由高度膨胀的网络组成的体积大幅增加的颗粒。此外，还实现了含有 B 型交联剂的颗粒的受照射时间控制的选择性完全降解。通过使用波长为 lambda < 315 nm 的宽带紫外光，观察到 B 型和 A 型微凝胶的连续完全颗粒崩解。因此，合成的微凝胶的具体性能可以通过所使用的紫外光波长、剂量和强度来精确触发，从而作为新型光响应纳米材料具有巨大的潜力。
Two classes (type A and type B) of novel photolabile divinyl functionalized crosslinkers based on o-nitrobenzyl derivatives were synthesized and investigated with regard to their photolytic performance upon UV irradiation. The systematic variation of the molecular structure resulted in different degradation rates depending on the irradiation conditions. Thus, the successive and independent cleavage is enabled by either adjusting the applied wavelengths or irradiation times. The respective molecules were used to build up photodegradable PMMA microgels by free radical copolymerization with MMA in a miniemulsion polymerization process. UV light-induced degradation of the swollen microgels was monitored by time dependent turbidity measurements and the resulting kinetics were found to correlate with the photolysis rates of the respective crosslinkers in solution. The irradiation wavelength-controlled selective partial cleavage of type B crosslinking points was achieved by UV irradiation with lambda > 315 nm and resulted in particles with extensively increased volumes consisting of highly swollen networks. In addition, the irradiation time-controlled selective complete degradation of particles containing type B crosslinkers was accomplished. By using broadband UV light containing wavelengths of lambda < 315 nm, the successive complete particle disintegration of type B and type A microgels was observed. Hence, the specific performance of the synthesized microgels can be precisely triggered by means of the used UV light wavelengths, doses and intensities, thus representing a great potential as new light-responsive nanoscaled materials.