Lignin-Based Graft Copolymers<i>via</i>ATRP and Click Chemistry

Chung, Hoyong; Al-khouja, Amer; Washburn, Newell R.

doi:10.1021/bk-2013-1144.ch025

Cited by 13 publications

(17 citation statements)

References 56 publications

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“…DDMAT, which is a carboxyl-terminated thiocarbonate ( Figure S2, Supplementary Materials ), has a very high chain-transfer efficiency allowing control over the radical polymerization [ 57 ]. Attempts to solubilize DDMAT in water at low pH (around 4) and LS in organic solvents, such as tetrahydrofuran (THF) and pyridine [ 58 , 59 , 60 ] were unsuccessful. Additionally, other attempts were explored, such as preparing solvent mixtures by dissolving LS in water and DDMAT in other solvents namely THF and dimethyl sulfoxide among others.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Lignosulfonate-Based Dispersants for Application in Concrete Formulations

2021

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Lignosulfonates (LS) are products from the sulfite pulping process that could be applied as renewable environmentally-friendly polymeric surfactants. Being widely used as plasticizers and water-reducing admixtures in concrete formulations LS compete in the market with petroleum-based superplasticizers, such as naphthalene sulfonate formaldehyde polycondensate (NSF) and copolymer polycarboxylate ethers (PCE). In this work, different chemical modification strategies were used to improve LS performance as dispersants for concrete formulations. One strategy consisted in increasing the molecular weight of LS through different approaches, such as laccase and polyoxometalate-mediated polymerization, glyoxalation, and reversible addition-fragmentation chain transfer (RAFT) polymerization. The other strategy consisted of preparing LS-based non-ionic polymeric dispersants using two different epoxidized oligomer derivatives of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). Modified LS were used to prepare cement pastes, which were examined for their fluidity. Results revealed that the most promising products are PPG-modified LS due to the introduction of PPG chains by reaction with phenolic moieties in LS. The enhanced dispersant efficiency of the ensuing products is probably related not only to electrostatic repulsion caused by the sulfonic ionizable groups in LS but also to steric hindrance phenomena due to the grafted bulky PPG chains.

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Section: Resultsmentioning

confidence: 99%

Synthesis of Lignosulfonate-Based Dispersants for Application in Concrete Formulations

2021

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“…20,21 The second lignin−vinyl polymer integration method is graft-onto copolymerization. 16,22,23 This method has several advantages stemming from the use of experimentally simple click chemistry, resulting in high yields an extended scope, the freedom to use easily removable solvents, and byproducts which can be easily removed without complex purification methods. 22,24,25 In the graft-onto copolymerization method, synthetic polymers and chemically modified lignin are first prepared separately.…”

Section: Macromoleculesmentioning

confidence: 99%

Self-Healing Properties of Lignin-Containing Nanocomposite: Synthesis of Lignin-graft-poly(5-acetylaminopentyl acrylate) via RAFT and Click Chemistry

Liu

Chung

2016

Macromolecules

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Lignin can be an important source of synthetic commodity materials owing to its abundance in nature and low production cost. The current use of lignin as a raw material, however, is very limited and focused only on cheap and poorly defined nonfunctional materials. Herein we report a new lignin-containing functional polymer, lignin-graft-poly(5-acetylaminopentyl acrylate) (lignin-graft-PAA), which has been prepared by the covalent linkage of chemically modified lignin with PAA, which is an end-group functionalized polymer. This work makes two significant advances in the study of lignin-containing polymers: (1) lignin-graft-PAA is the first example of lignin being modified by a polymer with sophisticated structure, and (2) lignin-graft-PAA shows a special performance, autonomic self-healing properties, which have not yet been seen in lignin-containing polymers. The key synthetic step in this process utilizes a copper-catalyzed azide–alkyne cycloaddition or “click” reaction in order to join together the lignin and polymer moieties. The polymer, PAA, was itself prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization of monomers containing multiple hydrogen-bonding sites on their pendants in the form of acetylamino functional groups. The selected RAFT agents also resulted in a polymer with an azide group at its terminus, which is necessary for the desired click reaction. Separately, biomass lignin was chemically modified by 5-hexynoic acid to introduce an alkyne functionality onto lignin. The azide terminus of the polymer was joined to the alkyne group of lignin to form a covalent bond. The lignin-graft-PAA possesses a well-dispersed multiphase nanostructure, a rigid lignin phase and a soft-PAA phase, which has a rubber-like flexibility. The mechanical properties of the newly synthesized lignin-graft-PAA can be readily controlled by the mass ratio of lignin and polymer during synthesis. In this study, the mass ratio was varied by either polymer length or weight percentage of lignin. It was revealed that a lignin-graft-PAA composite with 15–20 wt % lignin demonstrated the most optimal rubber-like, flexible property. Thanks to the high degree of hydrogen bonding from the acetylamino functionalities, lignin-graft-PAA also showed self-healing properties, recovering up to 93% of its original maximum stress before fracture.

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“…In comparison, the "grafting from" 3 of 15 modification method allowed de Oliveira and Glasser to chemically modify hydroxypropylated lignin with ring-opening polymerization of ε-caprolactone [25] and subsequently lower Tg. Another widely used "grafting from" method is atom transfer radical polymerization (ATRP) [26]. ATRP was used by Hilburg et al to prepare lignin-based thermoplastic with improved mechanical properties, and by Kim and Kadla to obtain lignin-based thermoresponsive thermoplastic [27,28].…”

Section: Introductionmentioning

confidence: 99%

Melt Stable Functionalized Organosolv and Kraft Lignin Thermoplastic

2020

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A shift towards an economically viable biomass biorefinery concept requires the use of all biomass fractions (cellulose, hemicellulose, and lignin) for the production of high added-value products. As lignin is often underutilized, the establishment of lignin valorization routes is highly important. In-house produced organosolv as well as commercial Kraft lignin were used in this study. The aim of the current work was to make a comparative study of thermoplastic biomaterials from two different types of lignins. Native lignins were alkylate with two different alkyl iodides to produce ether-functionalized lignins. Successful etherification was verified by FT-IR spectroscopy, changes in the molecular weight of lignin, as well as 13C and 1H Nuclear Magnetic Resonance (NMR). The thermal stability of etherified lignin samples was considerably improved with the T2% of organosolv to increase from 143 °C to up to 213 °C and of Kraft lignin from 133 °C to up to 168 °C, and glass transition temperature was observed. The present study shows that etherification of both organosolv and Kraft lignin with alkyl halides can produce lignin thermoplastic biomaterials with low glass transition temperature. The length of the alkyl chain affects thermal stability as well as other thermal properties.

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Lignin-Based Graft CopolymersviaATRP and Click Chemistry

Cited by 13 publications

References 56 publications

Synthesis of Lignosulfonate-Based Dispersants for Application in Concrete Formulations

Synthesis of Lignosulfonate-Based Dispersants for Application in Concrete Formulations

Self-Healing Properties of Lignin-Containing Nanocomposite: Synthesis of Lignin-graft-poly(5-acetylaminopentyl acrylate) via RAFT and Click Chemistry

Melt Stable Functionalized Organosolv and Kraft Lignin Thermoplastic

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