Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4 ' MDI

Autor(es)

Antonino, Leonardo Dalseno ; Gouveia, Julia Rocha ; de Sousa Junior, Rogerio Ramos ; Garcia, Guilherme Elias Saltarelli ; Gobbo, Luara Carneiro ; Tavares, Lara Basilio ; dos Santos, Demetrio Jackson

• Tipo de documento: Artigo Científico
• Fonte: Molecules; v. 26, n. 8, p. 12-pg., 2021-04-01.

Resumo

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4 '-diphenylmethane diisocyanate (MDI) was investigated. P-31 NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers. (AU)

• Processo FAPESP: 17/22936-9 - Refratometria ótica com modulação de temperatura: uma perspectiva molecular na cinética de cura e separação de fases de poliuretanos a partir de lignina
• Beneficiário: Demetrio Jackson dos Santos
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 19/05460-6 - Adesivo poliuretano termoativado baseado em lignina kraft modificada
• Beneficiário: Leonardo Dalseno Antonino
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 20/00876-7 - Desenvolvimento de filamentos sustentáveis para impressão 3D a partir de PLA e lignina kraft modificada
• Beneficiário: Júlia Rocha Gouveia
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisa Inovativa em Pequenas Empresas - PIPE