We report a near-complete dissolution of wood lignin at less than 80°C for 20 min using an easily recyclable hydrotrope.

Pretreatment of Douglas-fir by steam explosion produces a substrate containing approx 43% lignin. Two strategies were investigated for reducing the effect of this residual lignin on enzymatic hydrolysis of cellulose: mild alkali extraction and protein addition. Extraction with cold 1% NaOH reduced the lignin content by only approx 7%, but cellulose to glucose conversion was enhanced by about 30%. Before alkali extraction, addition of exogenous protein resulted in a significant improvement in cellulose hydrolysis, but this protein effect was substantially diminished after alkali treatment. Lignin appears to reduce cellulose hydrolysis by two distinct mechanisms: by forming a physical barrier that prevents enzyme access and by non-productively binding cellulolytic enzymes. Cold alkali appears to selectively remove a fraction of lignin from steam-exploded Douglas-fir with high affinity for protein. Corresponding data for mixed softwood pretreated by organosolv extraction indicates that the relative importance of the two mechanisms by which residual lignin affects hydrolysis is different according to the pre- and post-treatment method used.

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In this work, a sample library of well-defined comblike polystyrenes (PS) has been prepared for the study of average conformation in dilute solutions. The dependences of radius of gyration (R g), intrinsic viscosity ([η]), viscometric radius (R η), and persistence length (l p) on the molar mass (M), grafting density (σ), and degree of polymerization of graft side chains (N g) have been established. First, we have revealed the universal abnormal elution behavior of comblike chains in different size exclusion chromatography (SEC) column systems. A combined theoretical analysis and elution experiment indicates the possible thermodynamic origin, i.e., for chains with the highest stiffness, the anisotropic characteristics and chain end orientation can potentially increase the partition coefficient and retention volume, while the flow-induced forced penetration plays a negligible role. Moreover, the established scalings R η ∼ N g 0.40±0.03σ1/3, R g ∼ (N gσ)0.37±0.01, and l p ∼ σ 0.85±0.09 further indicate that (1) the equivalent viscometric volume is proportional to the mass of individual comblike chains when σ is increased, corresponding to the quasi-3D mass-size growth pattern; (2) the proper consideration of the swelling conformation of side chains is important to capture the essentials of conformational behavior for comblike polymer systems with flexible backbones; and (3) the experimentally established l p–σ dependence by considering the excluded-volume effect is much weaker than the theoretical predictions (l p ∼ σ17/8 and l p ∼ σ7/3). This work provides a comprehensive perspective for understanding the conformational evolution of comblike chains.