Anionic Ring-Opening Homo- and Copolymerization of Lactams by Latent, Protected N-Heterocyclic Carbenes for the Preparation of PA 12 and PA 6/12

详细信息    查看全文

• 作者：Stefan Naumann ; Friedrich Georg Schmidt ; Maria Speiser ; Margit B枚hl ; Stefan Epple ; Christian Bonten ; Michael R. Buchmeiser
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：November 12, 2013
• 年：2013
• 卷：46
• 期：21
• 页码：8426-8433
• 全文大小：369K
• 年卷期：v.46,no.21(November 12, 2013)
• ISSN：1520-5835

文摘

Laurolactam (LL) is polymerized in the bulk using strongly basic N-heterocyclic carbenes (NHCs) as initiators at temperatures of 180鈥?00 掳C to prepare the corresponding polyamide (PA 12). In-situ rheology of the polymerization progress reveals that an anionic mechanism is active, which is supported by the strong dependence of initiator activity on the basicity of the NHCs. GPC data and kinetic investigations show the process to be moderately controlled and fast, allowing high or quantitative yields in short polymerization times. Fifteen different NHC鈥揅O₂鈥揳dducts and NHC鈥搈etal complexes were used as thermally labile but room temperature stable NHC-precursors. Depending on the ring size and N-substituent, some of these protected NHCs allow forming a mixture of monomer and NHC-precursor that is suitable for long-term storage and readily polymerizable by simple heating. All polymerizations are executed without activator or other additives and thus represent a true one-component system for the production of PA 12. Finally, LL is copolymerized with 蔚-caprolactam (蔚-CLA). It is found that a copolymer with a considerable gradient is formed, with 蔚-CLA being incorporated preferentially at the onset of the polymerization.