Gallol-containing homopolymers and block copolymers: ROMP synthesis and gelation properties by metal-coordination and oxidation. (9th May 2018)

• Record Type: Journal Article
• Authors: Liu, Fangfei; Long, Yanru; Zhao, Qiuxia; Liu, Xiong; Qiu, Guirong; Zhang, Li; Ling, Qiangjun; Gu, Haibin
• Is Part Of: Polymer. Volume 143(2018)
• Page Start: 212
• Page End: 227
• Publication Date: 2018-05-09
• Subjects: Gallol-functionalized polymers -- Ring-opening metathesis polymerization -- Metallogels; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2018.04.016
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Gallol-functionalized polymers are highly desirable for their addressable functions in the fields of materials science, nanotechnology and biomedicine, owing to gallol's unique chemistry including excellent chelating properties to metals, easily oxidability and superior ability to bind proteins. Herein, we report the controlled synthesis of the first polynorbornene-based side-chain gallol-containing homopolymers and block copolymers with pendent triethylene glycol (TEG) moieties by the ring-opening metathesis polymerization (ROMP) using the 3rd generation Grubbs catalyst1 as the initiator. We describe the direct synthetic route by the ROMP of a gallol-containing norbornene monomer, and the indirect approach via an acetoxyl protection/deprotection route. Among the tested metal ions of Fe 3+, Mg 2+, Cr 3+ and Al 3+, Fe 3+ is the most effective metal ion to induce the gelation of the present gallol-containing polymers, and UV–visible spectroscopy indicates that bis-coordinated state dominates for the interaction between side-chain gallol groups and Fe 3+ ions in DMF. The gelation rate, interior structure, thermal and mechanical properties of the Fe 3+ -induced metallogels can be effectively tuned by changing the gallol/Fe 3+ molar ratio, polymeric molecular weight, and by introducing of organic TEG block. Furthermore, the oxidant-induced organogels were fabricated by adding the oxidant of NaIO4 into the DMF solution of the gallol-containing polymers, and the gelation rate highly depends on the gallol/IO4 − molar ratio and the introduction of TEG block. We are convinced that the effective synthesis of well-defined gallol-containing polymers, as illustrated by the present work, will pave the way for their functional applications as smart organogels, coatings, adhesives, capsules, etc. Graphical abstract: Image 1 Highlights: First ROMP synthesis of side-chain gallol-containing homopolymers. First ROMP synthesis of side-chain gallol-containing block copolymers. The gallol polymers were synthesized by an acetoxyl protection/deprotection route. Fe(III)-induced metallogels of the gallol polymers are investigated. Oxidant-induced organogels of the gallol polymers are investigated by using NaIO4 .