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 .
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