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In order to reduce the enzyme cost of lignocellulosic enzymatic hydrolysis, upper critical solution temperature (UCST) additives are used to recover and reuse cellulase by regulating the temperature. A sulfobetaine polymer, PSPE, showed a sensitive UCST response in buffer, and its UCST-performance was optimised by adjusting the molecular weight of the polymer. PSPE-3 (Mw = 355.1 kDa) was added to the cellulase buffer at 50 °C, and PSPE-3 and cellulase were co-precipitated by cooling to the room temperature of 25 °C. PSPE-3 and cellulase co-precipitated mainly through hydrophobic interactions via cooling. Compared with octadecyl sulfobetaine (SB3–18), PSPE-3 had a more sensitive UCST response and stronger cellulase recovery ability. Adding only 40% PSPE-3 (accounting for the mass fraction of cellulase) can save more than 50% cellulase in the enzymatic hydrolysis system of eucalyptus chips pre-treated with dilute acid (Eu-DA). However, for the Eu-DA system, adding 100% SB3–18 can only save about 30% of cellulase. In this work, efficient recycling of cellulase was achieved at room temperature by adding UCST-type PSPE. The process is green without consuming acid and alkali, and this work provides a new idea for reducing the production cost of cellulosic ethanol. [ABSTRACT FROM AUTHOR]

Highly recyclable pH-responsive lignin-polyethylene glycol (L-PEG) was synthesized to achieve enhanced lignocellulosic hydrolysis and recycling cellulase. The performance of L-PEG could be easily regulated by adjusting the molecular weight and the amount of PEG. The large molecular weight facilitated L-PEG to reduce the invalid adsorption of cellulase on lignin during hydrolysis and enhance its flocculation effect at around pH 3.0. L-PEG1000-40 obtained by adding 40 wt% (based on lignin) PEG1000 could effectively enhance the enzymatic hydrolysis of lignocelluloses and recover most of cellulase after hydrolysis through simply adjusting the pH of hydrolysate. During eucalyptus hydrolysis, using L-PEG1000-40 to recycle cellulase could not only save 40% cellulase, but also increase the glucose yield by 121%. Due to the low synthesis cost of L-PEG and the simple and convenient recovery operation, this new method is beneficial to the improvement of lignocellulosic saccharification process and the high-value utilization of lignin. [ABSTRACT FROM AUTHOR]

Developing poly(3,4‐ethylenedioxythiophene) (PEDOT) conducting polymers (CPs) aqueous dispersions with high film conductivity is an attractive task in scientific and industrial communities. Herein, we proposed to apply small molecular perfluorooctanoic acid (PFA) as assistant dopant to cooperate with major polymeric dopant of lignosulfonate (LGS) to prepare PEDOT aqueous dispersions together. Through optimizing the usage amount of PFA, a high film conductivity of 0.1255 S⋅cm−1 was obtained. In contrast, the film conductivity of the CP prepared without PFA was only 0.0228 S⋅cm−1. By lucubrating the structure of CPs, we found that PFA is capable of promoting the polymerization, doping and aggregation of PEDOT in the preparation process of PEDOT:LGS CP and the conductivity enhancement can be attributed to the enhancement of molecular weight, doping degree and aggregation of PEDOT. Moreover, the other physical‐chemical properties of PEDOT:LGS CPs including transmittance, work function and waterproofness were not obviously affected by PFA. This facile strategy based on physical mixing of small molecular and polymeric dopants may opens up a new window for the preparation of high performance CPs aqueous dispersions. [ABSTRACT FROM AUTHOR]

A linear pH-responsive zwitterionic copolymer P(MDB) was synthesized from functional monomers methacrylic acid, 2-(dimethylamino) ethyl methacrylate (DMA) and benzyl methacrylate (BMA) through free radical polymerization to recover cellulases and enhance the enzymatic hydrolysis. The hydrophobicity and molecular weight of the copolymer was controlled by the feed ratio of monomers and the mass ratio of initiator to monomers, respectively. UV-turbidity showed P(MDB) exhibited sensitive pH-responsiveness with dissolution–precipitation ΔpH about 1 pH unit. The precipitation pHφ of P(MDB) was 5.0–5.5 and over 90% of P(MDB) could precipitate in the vicinity of its isoelectric point. Increasing the hydrophobicity or molecular weight of P(MDB) could improve its pH sensitivity and precipitation rate. P(MDB) could enhance the enzymatic hydrolysis of dilute acid pretreated Eucalyptus by 10–25%. P(MDB) could recover the free cellulases in enzymatic hydrolysate by co-precipitation. SDS-PAGE analysis showed that P(MDB) could recover 100% β-glucosidase (β-GL) and the recovery rates of cellobiohydrolase (CBH) and endoglucanase (EG) increased as the hydrophobicity and molecular weight of P(MDB) increased. The mechanism was proposed that hydrophobic affiliation was the main binding force of P(MDB) to cellulases. Increasing the hydrophobicity and molecular weight of copolymer could increase its binding force and the number of binding sites to cellulases thus the overall cellulase recovery performance was improved. [ABSTRACT FROM AUTHOR]

Highlights: [•] A modified lignosulfonate GCL4-1 improves stability of DMM suspension significantly. [•] GCL4-1 fraction with Mw of 10,000–30,000 has strongest dispersive ability. [•] Dispersive ability of GCL4-1 is contributed to sulfonated degree and adsorbed amount. [•] GCL4-1 fraction with largest Mw has strongest adsorption, but may cause flocculation. [ABSTRACT FROM AUTHOR]

Sulfonation modification of alkali lignin from wheat straw pulping spent liquid, carried out under normal pressure and medium temperature, was investigated, and the properties of the resulting sulfonated lignin were characterized. It was found that condensed lignin was degraded into lignin fragments with lower molecular weight by oxidation reaction, producing more active sites to react with formaldehyde, consequently forming more active hydroxymethyl groups for sulfonation. Therefore, it is feasible to carry out the sulfonation of alkali lignin under conditions of normal pressure and medium temperature. As higher contents of sulfonic group were introduced, sulfonated lignin with 1.49 mmol/g of sulfonation degree exhibits 96.9% of solubility at neutral aqueous solution and good surface activity. Compared to commercial lignosulfonate, sulfonated lignin produced by the present work contributes higher adsorption amount and zeta potential to cement particles, and hence shows better dispersion effect to the cement matrix. [ABSTRACT FROM AUTHOR]

Five purified calcium lignosulfonate (CL) fractions with different molecular weights were obtained by fractionation using ultrafiltration and dialysis. The influence of molecular weight on their physicochemical properties was investigated by determining the properties of five fractions. TEM and ESEM imaging indicated that CL has a globular structure to form locally regular colloidal assemblies with the diameter of approximately 200 ∼ 300 nm. Fraction3 (Mw is 7621) with the molecular weight of 5,000-l0,000 has more sulfonic and carboxyl group, so the highest zeta potential (-36 mV) can be charged on the TiO2 particles. With the increase of molecular weight, the hydrophobicity and surface activity of CL in aqueous solution increase, so Fraction5 (Mw is 21646) which molecular weight is more than 30000 has the biggest adsorption amount. The adsorption characteristic of CL on solid-water interface have great impact on the dispersive properties of TiO2 particle in aqueous solution and the higher adsorption capacity is helpful to improve the dispersive ability of CL. On the other hand, the surface charge of TiO2 particle absorbing CL is another important factor to the dispersive ability of CL. Furthermore, when the CL concentration in TiO2 suspension is less than 4 mg/mL, Fraction3 has the best dispersive ability because the electrostatic repulsion effect is controlling factor. The dispersive ability of CL increases with the increase of molecular weight when the CL concentration in TiO2 suspension is more than 4 mg/mL, so Fraction5 has the best dispersive ability owing to the steric hindrance effect. [ABSTRACT FROM AUTHOR]

The complex chemical structure and broad molecular weight distribution of lignin lead to heterogeneity and unsatisfactory performance, essentially restricting its high-value utilization. A novel lignin fractionation process is proposed here to solve this problem and overcome the shortcomings of common fractionation methods. Using enzymatic hydrolysis lignin (EHL) as raw material, five lignin fractions were obtained by cooling precipitation in the ethanol/water mixed solvent. Their chemical structure and physicochemical properties were compared. All lignin fractions presented reduced heterogeneity compared to the EHL and a gradual decrease of molecular weights accompanied by increasing hydrophilic group content. In addition, temperature-induced self-assembly for forming lignin colloidal spheres co-occurred during cooling precipitation. Interestingly, a fraction with light color and high UV-blocking activity was obtained. By combining this color-light sample with pure hand cream, a lignin-based sunscreen was prepared, which had a 40 % higher sun protection factor (SPF) than EHL sunscreen. [Display omitted] • Lignin fractions were obtained by step cooling precipitation. • Lignin colloidal spheres were formed by temperature-induced self-assembly. • A lignin fraction with light color and strong anti-ultraviolet could be obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • This work successfully synthesizes high concentration PCEs at room temperature via a photoinitiated one-pot method. • The high concentration PCEs prepared by a photoinitiated one-pot method have reasonable structure and good dispersion performance. • The conversion rate and molecular weight of PCEs increase with the reaction concentration in a photoinitiated one-pot method. Polycarboxylate superplasticizers (PCEs) are primarily liquid products (40 wt%) with narrow application range, which incur high transportation and storage costs. However, the high reaction viscosity makes it challenging to produce high concentration PCEs. In our study, high concentration PCEs are successfully synthesized by a photoinitiated one-pot method at room temperature. The results show that the reaction viscosity of photoinitiation is slightly higher than that of traditional initiation systems, but the photoinitiated reaction remains stable and controllable, with no occurrence of violent polymerization. The impact of varying reaction concentrations on the polymerization rate, molecular structure, and properties of PCEs has been studied under the photoinitiated one-pot method. The results indicate that an increase in reaction concentration leads to a rise in polymerization rate, molecular weight, and molecular gyration radius of the polymers. The conversion rate of the macromonomer exceeds 80%, while the polydispersion index (PDI) for molecular weight is below 2 with a narrow distribution. Furthermore, the monomer polymerization ratio of the product remains close to the feeding ratio at different reaction concentrations. Finally, it is observed that PCEs with a high concentration of 80 wt% exhibit favorable dispersion, rheology and adsorption properties. This study presents a new method for synthesizing high concentration PCEs using photoinitiation. [ABSTRACT FROM AUTHOR]

Lignin is a future feedstock for the production of low molecular weight aromatics, and hydrogenolysis is probably the most promising process for lignin depolymerization. Effect of the benzylic alcohol group, aromatic methoxyl and phenolic hydroxyl groups on the hydrogenolysis of β -O-4 bonds in lignin model compounds was investigated in Pd/C hydrogenolysis system. It was found that the β -O-4 bonds in compounds with no a benzylic alcohol group were cleaved directly and quickly to form two aromatic monomers in near-quantitative yield. However, both dehydrogenation and dehydroxylation occurred for the model compounds containing a benzylic alcohol group, and resulted in more complicated products distribution. The dehydrogenation of a benzylic alcohol group hindered the cleavage of β -O-4 bonds to form aromatic monomer products. The results also indicated that both the aromatic methoxyl and phenolic hydroxyl groups had no impact on products distribution. The aromatic methoxyl group in non-phenolic and phenolic compounds promoted the cleavage of β -O-4 bonds, while the phenolic hydroxyl group had a slightly negative impact on cleavage of β -O-4 bonds. [ABSTRACT FROM AUTHOR]

Abstract: This article studied the effect of molecular weight of sulphonated acetone-formaldehyde condensate (SAF) on the adsorption and dispersion properties in cementitious system. SAF was separated into four different molecular weight fractions using ultrafiltration membranes. The adsorption behaviors were investigated by measuring the adsorption amount, zeta potential, and thickness of the adsorbed films obtained from various SAF fractions. Results show that the SAF fraction with a higher molecular weight has larger adsorption amount, higher absolute value of zeta potential, and thicker adsorbed film, which induces better dispersibility of the corresponding cement paste. An adsorption model of SAF on cement surface is presented. The SAF fraction with a higher molecular weight is more likely to twist and be adsorbed on cement particles through “loop and tail” adsorption. On the contrary, SAF fraction with a lower molecular weight tends to be adsorbed on cement particles through “flat train” adsorption. [Copyright &y& Elsevier]

Abstract: The effect of the molecular weight of sulfanilic acid-phenol-formaldehyde condensate (SPF) on the properties of cementitious system was investigated. It is found that SPF with the molecular weight of 35,000 Dalton (Da) gives a good adsorption capacity on the surface of the cement particles, hence a larger zeta potential to cement particles and a good fluidity to the cement paste. In addition, this fraction has a high chelating capacity to calcium in the cement slurry, causing a long retardation of the cementitious system. However, the fractions of a high molecular weight (42,000 Da, and 45,000 Da) exhibit lower bleed water as a percentage of total mix water (BWP). It can be deduced that there is an ideal molecular weight for the best performances of the superplasticizer investigated, which can be used for optimizing the technical parameters in the preparation. [Copyright &y& Elsevier]