Solubilization of lignin in copolymer micelles in aqueous solution

Mohammadali Azadfar; William C Hiscox; Shulin Chen

doi:10.1016/j.colsurfa.2016.05.031

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Solubilization of lignin in copolymer micelles in aqueous solution

Journal article

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Peer reviewed

Solubilization of lignin in copolymer micelles in aqueous solution

Mohammadali Azadfar, William C Hiscox and Shulin Chen

Colloids and surfaces. A, Physicochemical and engineering aspects, Vol.503, pp.1-10

08/20/2016

DOI: https://doi.org/10.1016/j.colsurfa.2016.05.031

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https://hdl.handle.net/2376/108907

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Abstract

Micelle

Lignin

Solubilization

Block copolymer

[Display omitted] •A block copolymer, Pluronic® F-68, was used to solubilize lignin in aqueous solution.•The solubilization resulted in upfield chemical shifts of blocks proton resonances.•The significant chemical shifts showed lignin is incorporated into copolymer micelles.•Lignin aliphatic oxygenated functional groups manipulate micelle-lignin aggregate structure.•Aromatic/conjugated groups manipulate micelle-lignin aggregate structure. The solubilization of lignin in self-aggregating triblock amphiphilic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) in aqueous solution has been studied utilizing liquid-state proton nuclear magnetic resonance spectroscopy (1H NMR) and diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY NMR). Our hypothesis for copolymer micelle incorporation of lignaceous species includes a “hydrophilic-aromatic interaction model”, in which lignin derivatives with amphiphilic characteristics, known to be abundant in the effluent from pulp mill and pretreatment of various lignocellulosic materials, have an affinity for these micelles, and tend to form relatively organized structures within them. Here we show how the chemical/structural features of lignin units and small molecule lignin models determine their solubilization behavior in the micelles. It was found that a buildup of concentration series of lignin and lignin-based model compounds guaiacol, eugenol, phenol, guaiacylglycerol-beta-guaiacyl ether, ferulic acid in Pluronic® F68-deuterium oxide solution results in significant upfield chemical shifts of PEO-(CH2-CH2) and PPO-(CH3) proton resonances, and at a critical guest concentration (CGC), dramatic upfield shifts due to gross structural transitions in the micelles. We present evidence that copolymer micelle-lignin interactions depend on both chemical functional group characteristics of solute (i.e., polarity, H-bonding ability) and π-π interactions between aromatic/conjugated groups. Our results demonstrate how the loci of incorporated solute in the block copolymer micelles are affected by these features.

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Title: Solubilization of lignin in copolymer micelles in aqueous solution
Creators: Mohammadali Azadfar - Department of Biological Systems Engineering, Washington State University, LJ Smith Hall 213, Pullman, WA 99164-6120, USA
William C Hiscox - Center for NMR Spectroscopy, Department of Chemistry, Washington State University, Pullman, WA 99164-6120, USA
Shulin Chen - Department of Biological Systems Engineering, Washington State University, LJ Smith Hall 213, Pullman, WA 99164-6120, USA
Publication Details: Colloids and surfaces. A, Physicochemical and engineering aspects, Vol.503, pp.1-10
Publisher: Elsevier B.V
Identifiers: 99900583062601842
Language: English
Resource Type: Journal article