Student Poster Presentation # 8( Session 1)
Development of Visible light induced thiol-ene reaction on natural lignin and its applications to synthesize new sustainable materials
Student Poster Presentation # 8( Session 1)
Development of Visible light induced thiol-ene reaction on natural lignin and its applications to synthesize new sustainable materials
Abstract
Hailing Liu, Hoyong Chung
Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Florida State University, Tallahassee, Florida, USA
Photo-redox catalyzed reaction gains high intention as sustainable and green chemistry synthetic methods due to low energy consumption and the excellent reaction performance under visible-light. 1 Recently, we have successfully applied the photo-redox catalyzed thiol-ene reaction to natural lignin modifications. Among various tested photochemical catalysts, 5 mol % Ru( bpy) 3Cl2 revealed the highest reactivity under 3W blue LED. The successful thiol-ene reaction resulted fast modification( within 1 hour) of lignin with thiol containing organic compounds including polymer, poly( ethylene glycol). The developed photoredox catalyzed thiol-ene modification of lignin was very conveniently controlled by simply turning the light source on and off. Excellent conversion, 95 %, of lignin thiol-ene modification was achieved even by natural sunlight after four hours of irradiation. Above all, this photochemical thiol-ene reaction for natural lignin modification is crucial from the standpoint of practical application. Due to the cost-effectiveness and environmentally benign nature of both sustainable basic materials and the modification method, various subsequent research and applications are inspired.
The high efficiency of visible light induced thiol-ene reaction allows fast and easy lignin modification through graft copolymerization with other polymers. The lignin-graft-chitin is a new polymer that is synthesized from all natural polymers. Chitin is a natural polymer from the cell walls of fungi, the exoskeletons of arthropods, and the beaks and internal shells of cephalopods. The chemical structure of chitin is a modified polysaccharide that contains nitrogen synthesized from units of 2-( acetylamino)-2-deoxy-D-glucose. The new lignin-graft-chitin has good biodegradability, sustainability and renewability. The second important application of the developed photoredox thiol-ene reaction of lignin is preparation of double networked lignin-polymer for ultra-strong lignin-based hydrogel. The fast and easy thiol-ene reaction is an ideal method to synthesize lignin-PEG crosslinking polymer. In the matrix of lignin-PEG crosslinked copolymer, another crosslinked poly( acrylic amide) is synthesized to form a dual crosslinked polymer network. The double crosslinked polymers behave two net cloth across in each other’ s meshes, becoming a strong and elastic material. This material is expected to be a synthetic elastomer from natural lignin.
Reference
1. Tyson, E. L.; Ament, M. S.; Yoon, T. P. Transition Metal Photoredox Catalysis of Radical Thiol-Ene Reactions. Journal of Organic Chemistry 2013, 78( 5), 2046-2050 DOI: 10.1021 / jo3020825.
17