Novel Ferrocenyl-Terminated Linear鈥揇endritic Amphiphilic Block Copolymers: Synthesis, Redox-Controlled Reversible Self-Assembly, and Oxidation-Controlled Release

详细信息    查看全文

• 作者：Xueyi Chang ; Renfeng Dong ; Biye Ren ; Zhiyu Cheng ; Jun Peng ; Zhen Tong
• 刊名：Langmuir
• 出版年：2014
• 出版时间：July 29, 2014
• 年：2014
• 卷：30
• 期：29
• 页码：8707-8716
• 全文大小：665K
• ISSN：1520-5827

文摘

Novel linear鈥揹endritic amphiphilic block copolymers with hydrophilic poly(ethylene glycol) (PEG) block and hydrophobic Percec-type dendrons containing ferrocenyl terminals were synthesized by the esterification reaction of poly(ethylene glycol) methyl ether with ferrocenyl-terminated alkyl-substituted benzoic acid dendrons. On the basis of the results that the critical aggregation concentration (CAC_ox) of the oxidation state polymer is much higher than CAC_red of the corresponding reduction state, these polymers can reversibly self-assemble into various aggregates, such as spherical, wormlike micelles, and vesicles, and also disassemble into irregular fragments in aqueous solution by redox reaction when changing the polymer concentrations. Copolymer PEG₄₅-b-Fc₃ (3) with 3,4,5-tris(11-ferrocenylundecyloxy) benzoic acid (2) can self-assemble into nanoscale wormlike micelles when the polymer concentration in aqueous solution is above its CAC_ox. These wormlike micelles can be transformed into nanosized vesicles by Fe₂(SO₄)₃ and regained by vitamin C. Interestingly, copolymer PEG₄₅-b-Fc₂ (5) with 3,5-bis(11-ferrocenylundecyloxy) benzoic acid (4) can reversibly self-assemble into spherical micelles with two different sizes by redox reaction above the CAC_ox, indicating that the terminal hydrophobic tail number of dendrons plays a key role in determining the self-assembled structures. Furthermore, rhodamine 6G (R6G)-loaded polymer aggregates have been successfully used for the oxidation-controlled release of loaded molecules, and the release rate can be mediated by the concentrations of oxidant and copolymers. The results provide an effective approach to the reversible self-assembly of linear鈥揹endritic amphiphilic block copolymers and also promise the potential of these novel redox-responsive amphiphilic block copolymers in drug delivery systems, catalyst supports, and other research fields.