Strandwitz Nicholas C, Khan Anzar, Boettcher Shannon W, Mikhailovsky Alexander A, Hawker Craig J, Nguyen Thuc-Quyen, Stucky Galen D
Materials Department, University of California Santa Barbara, Santa Barbara, California 93106, USA.
J Am Chem Soc. 2008 Jul 2;130(26):8280-8. doi: 10.1021/ja711295k. Epub 2008 Jun 5.
The development of one- and two-photon induced polymerization using CdS semiconductor quantum dots (QDs) and amine co-initiators to promote radical generation and subsequent polymerization is presented. Two-photon absorption (TPA) cross-section measurements, linear absorption, and transmission electron microscopy are used to characterize the QDs. The effectiveness of the co-initiators in increasing the efficiency of photopolymerization (polymer chains formed per excitation) is examined. Triethylamine was observed to be most effective, yielding quantum efficiencies of initiation of >5%. The interactions between the co-initiators and QDs are investigated with steady-state photoluminescence and infrared spectroscopies. Possible initiation mechanisms are discussed and supported by electrochemical data. Making use of the surface chemistry developed here and the large QD TPA cross-sections, two-photon induced polymerization is demonstrated. The large TPA cross-sections coupled with modest quantum efficiencies for initiation reveal the unique potential of molecularly passivated QDs as efficient two-photon photosensitizers for polymerization.
本文介绍了利用硫化镉半导体量子点（QDs）和胺类共引发剂促进自由基生成及后续聚合反应，从而实现单光子和双光子诱导聚合的发展情况。采用双光子吸收（TPA）截面测量、线性吸收和透射电子显微镜对量子点进行表征。研究了共引发剂在提高光聚合效率（每次激发形成的聚合物链）方面的有效性。观察到三乙胺最为有效，引发量子效率大于5%。通过稳态光致发光和红外光谱研究了共引发剂与量子点之间的相互作用。讨论了可能的引发机制，并得到电化学数据的支持。利用本文开发的表面化学和较大的量子点TPA截面，证明了双光子诱导聚合。较大的TPA截面与适度的引发量子效率相结合，揭示了分子钝化量子点作为高效双光子聚合光敏剂的独特潜力。
