Trinh Thi Kim Hoang, Schrodj Gautier, Rigolet Séverinne, Pinaud Julien, Lacroix-Desmazes Patrick, Pichavant Loic, Héroguez Valérie, Chemtob Abraham
Institut de Science des Matériaux de Mulhouse, IS2M, UMR 7361 CNRS, Université de Haute-Alsace Mulhouse France
Université de Strasbourg Strasbourg France.
RSC Adv. 2019 Sep 4;9(48):27789-27799. doi: 10.1039/c9ra05831a. eCollection 2019 Sep 3.
Although metathesis photoinduced catalysis is now well established, there is little development in thin film preparation using photochemically activated ring-opening metathesis polymerization (ROMP). Herein, a N-heterocyclic carbene (NHC) photogenerator (1,3-bis(mesityl)imidazolium tetraphenylborate) is combined with an inactive metathesis catalyst ([RuCl(-cymene)]) to generate under UV irradiation an active catalyst (-cymene)RuCl (NHC), that is capable of producing in a single step cross-linked copolymer films by ROMP of norbornene with dicyclopentadiene. The study shows that the photoinitiated catalytic system can be optimized by increasing the yield of photogenerated NHC through a sensitizer (2-isopropylthioxanthone), and by choosing [RuI(-cymene)] as precatalyst to provide a long-term photolatency. The cross-linked polymer structure is investigated by a range of techniques including gel content measurement, FT-IR and solid-state C NMR spectroscopy, TGA and DSC, which reveal a cross-linking mechanism proceeding through both metathesis and olefin coupling.
尽管复分解光诱导催化现已得到充分确立，但在使用光化学活化的开环复分解聚合（ROMP）制备薄膜方面进展甚微。在此，一种氮杂环卡宾（NHC）光引发剂（1,3-双（均三甲苯基）咪唑四苯基硼酸盐）与一种非活性复分解催化剂（[RuCl(对异丙基苯)]）相结合，在紫外线照射下生成一种活性催化剂（对异丙基苯）RuCl（NHC），该催化剂能够通过降冰片烯与二环戊二烯的ROMP一步制备交联共聚物薄膜。研究表明，通过使用敏化剂（2-异丙基噻吨酮）提高光生NHC的产率，并选择[RuI(对异丙基苯)]作为前催化剂以提供长期光潜伏期，可以优化光引发催化体系。通过一系列技术对交联聚合物结构进行了研究，包括凝胶含量测量、傅里叶变换红外光谱和固态碳核磁共振光谱、热重分析和差示扫描量热法，这些技术揭示了一种通过复分解和烯烃偶联进行的交联机理。
