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Lignin is the most abundant biomass source of aromatic hydrocarbons but, at present, is not effectively utilized. The development of simple and efficient methods for producing lignin-based polymers to replace petroleum-based products is an important strategy for promoting environmentally friendly and sustainable materials and controlling carbon emissions. In this work, lignin-based, light-driven shape memory polymers (ELIDs) with improved mechanical properties have been prepared from enzymatic hydrolysis lignin, itaconic acid and 1,12-dodecanediol, without any chemical modification of the lignin. The polymers contain large proportions of lignin (20-40 wt%, designated ELID20 to ELID40) and their mechanical properties are dependent on the lignin content. Maximum tensile strength (46.9 MPa) was achieved with ELID30, maximum elongation at break (93.7 %) was achieved with ELID20 and highest fracture energy (10.75 J cm

With the gradual global standardization of carbon emission policies, the development of renewable resources to replace traditional fossil resources is assuming increasing importance. Lignin is the most abundant natural source of aromatic compounds and has the potential to replace petroleum-based aromatic hydrocarbons. In this work, the rigid benzene ring structure and excellent photothermal properties of lignin were exploited to produce light-driven lignin-based shape memory polymers (ELEPs) that contain high proportions of lignin and have good mechanical properties. Enzymatically hydrolyzed lignin (EL), epoxy soybean oil (ESO) and polyethylene glycol (PEG 400) were copolymerized and cured to form ELEPs, which have a disordered three-dimensional network. An increase in the proportion of EL from 40 to 60 wt% enhanced the mechanical properties, as reflected by an increase in tensile strength from 11.3 to 30.8 MPa and in the glass transition temperature (T

An Fe3O4/carboxymethyl cellulose (Fe3O4/CMC) magnetic biosorbent was prepared using the ion-imprinting technology, where La(III) was used as the template ion. The morphology and structure of Fe3O4/CMC were characterized by SEM, FTIR and XRD. It is found that nano Fe3O4 with inverse spinel structure can distribute in CMC and endow the composite with good magnetic properties. The adsorption performance such as adsorption capacity, influence of pH and initial concentration were fully explored. The prepared Fe3O4/CMC is revealed to have good adsorption properties with Qmax of 61.5 mg g−1, in line with the pseudo-second-order kinetic model. When handling the multi-ion coexistence solution of Cu(II), Ni(II) and Cd(II), Fe3O4/CMC shows high selective adsorption for La(III). Meanwhile, cycling experiments find that the adsorption capacity is only slightly reduced (less than 5%) after 5-time reuse. Good adsorption properties, high selectivity and easy recovery give the newly-synthesized Fe3O4/CMC biosorbent broad application potential in the treatment of La(III)-containing wastewater.

Indoor pollutants, such as formaldehyde, pose an increasing threat to human health. Here, regenerated cellulose was combined with a novel visible light-responsive photocatalyst, La0.3Sr0.7TiO3, to ...

Intelligent materials have become an important objective in the development of polymer materials. Here, we depolymerized polymeric proanthocyanidins extracted from larch bark, using a stable composite catalyst, Pd/SO42−/ZrO2, to obtain oligomeric proanthocyanidins (OPC), which retained the structural proanthocyanidin units and were observed to have excellent antioxidant properties. The OPC were hydrogen bonded with acrylonitrile-butadiene rubber (NBR) to produce a thermally induced flexible shape memory material, L-NBR. The polyphenolic structure of the OPC improved the characteristic transition temperature, shape recovery rate and shape fixation rate of NBR, leading to improved tensile properties, thermal stability and resistance to aging. L-NBR has potential for use in fields such as stretchable electrodes, simulated robotic electronic skins and intelligent electronic components, and also provides a new use for renewable biomass resources.

A composite catalyst, Pd/C-SO3H, has been prepared to depolymerize plant-derived polymeric proanthocyanidins (PPC). Different reaction conditions were explored and the catalyst was shown to have good performance and recyclability, as well as good thermal and acid–base stability. UV, FTIR and 1H NMR analyses showed that the depolymerization products (oligomeric proanthocyanidins, OPC) retained a condensed flavanol polyphenol structure and that the basic structural units of the polymers had not been destroyed. The antioxidant activity of the OPC was better than that of the PPC, and also better than that of 2,6-di-tert-butyl-4-methylphenol, which is widely used in industry, including as a food additive. OPC could, therefore, be developed as a commercially useful radical chain-breaking antioxidant. The preparation of Pd/C-SO3H provides an example of the design and development of a new composite catalyst that has high practical value. The study also provides a new technical route for the depolymerization of PPC and thus makes a useful contribution to the high-value utilization of renewable plant resources.

Alkali lignin is a component of the waste black liquor produced by the paper-making industry that is difficult to degrade. In recent years, the biological activities of lignin, such as free-radical scavenging and antioxidant capacity, have received increasing attention. Here, we prepared H3PW12O40/ZrO2 and used this catalyst together with the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) as a double-effect catalyst for the degradation of alkali lignin. Single-factor and orthogonal tests showed that the best degradation conditions were as follows: reaction time, 2 h; reaction temperature, 100 °C; mass ratio of H3PW12O40/ZrO2 to lignin, 1:4; and substrate concentration, 2.5%. The phenolic hydroxyl group content of the lignin degradation product increased by 231.2% and the total hydroxyl group content increased by 337.1% when the double-effect catalyst was used rather than [BMIM]Cl alone. Analysis by gel permeation chromatography showed that both the weight-average molecular weight and the number-average molecular weight of the product were reduced and that the lignin was degraded into small-molecular-weight compounds by the macromolecule. The product after the catalytic degradation of lignin showed a markedly increased antioxidant capacity, which was similar to that of the commercial antioxidant, 2,6-ditert-butyl-4-methylphenol. The study opens up a new direction for the better utilization of lignin.

In recent years, inverse gas chromatography (IGC) and molecular dynamics simulation methods have been used to characterize the solubility parameters and surface parameters of polymers, which can provide quantitative reference for the further study of the surface and interface compatibility of polymer components in the future. In this paper, the solubility parameters and surface parameters of two kinds of common alcoholysis, PVA88 and PVA99, are studied by using the IGC method. The accuracy of the solubility parameters obtained by the IGC experiment is verified by molecular dynamics simulation. On the basis of this, the influence of repeated units of polyvinyl alcohol (PVA) on solubility parameters is studied, so as to determine the appropriate chain length of the PVA for simulation verification calculation. The results show that the solubility parameters are not much different when the PVA chain length is 30 and above, the numerical trends of the solubility parameters of PVA88 and PVA99 at room temperature are the same as the results of molecular dynamics simulation, the dispersive surface energy γsd and the specific surface energy γssp are scattered with the temperature distribution and have a small dependence on temperature. On the whole, the surface energy of PVA99 with a higher alcoholysis degree is higher than that of PVA88 with a lower alcoholysis degree. The surface specific adsorption free energy (ΔGsp) indicates that both PVA88 and PVA99 are amphoteric meta-acid materials, and the acidity of PVA99 is stronger.

An Fe

A new method has been developed for the high-value utilization of larch bark, which is regarded as a low-value byproduct of the logging industry. Polymeric proanthocyanidins (PPCs) were extracted from the Larix gmelinii bark and depolymerized by catalytic hydrogenolysis, using ruthenium/carbon (Ru/C) as the catalyst. The method has been found that although the molecular weight of the depolymerized product was significantly lower, the basic structural units were not destroyed, and the product retained a condensed flavanol polyphenol structure; the depolymerized product contains very little Ru metal and thus complies with food safety standards; the antioxidant properties of both the depolymerized products and PPCs were better than those of the commonly used antioxidant 2,6-di-tert-butyl-4-methylphenol. The relative molecular weight and steric hindrance of the depolymerized products were lower than those of the PPCs, leading to better antioxidant performance. A new technical route for the depolymerization of PPCs from the L. gmelinii bark is provided. The route offers practical and commercial advantages, and the product could have many applications as an antioxidant.

Carbon dots have wide applications in bioimaging, encryption, sensing, and light-emitting devices, but most preparations of carbon dots require complicated separation and purification steps. Here, a clustering-induced emission luminogen, sodium alginate, was covalently "glued" by ethylenediamine to prepare carbon dots on a 100 g scale, without any separation or purification. The conversion yield was as high as 94.7%. Theoretical calculations suggested that the fluorescence emission of as-prepared carbon dots (N-CDs) was mainly attributable to through-space conjugation between oxygen atoms and carbonyl moieties. The N-CDs were shown to have applications as a fluorescent ink for encryption and as a phosphor for white light-emitting diodes. This work provides a convenient method for the large-scale preparation of carbon dots and a new understanding of fluorescent emission of carbon dots.

The high value utilization of lignin is attracting increased attention because of environmental problems and resource depletion. Although these are numerous reports describing the modification and degradation of enzymatic hydrolysis lignin (EHL), quantitative characterization is lacking. In this work, EHL was efficiently degraded using H3PW12O40/ZrO2 (HPW/ZrO2) as catalyst. Following degradation, the total hydroxyl group content and phenolic hydroxyl group content, measured by acid-base titration and ultraviolet spectrophotometry, were increased by 259% and 152%, respectively. Hansen solubility parameters were calculated using the specific retention time of probe solvents, measured by inverse gas chromatography (IGC), quantitatively characterizing changes in surface properties.

Degradation of alkali lignin (AL) is important for practical applications of this valuable natural resource. 12-Tungstophosphoric acid (TPA), supported on materials with a high surface area, has been shown to be an effective catalyst for the degradation of AL. This complex catalyst is, however, relatively unstable and there are a limited number of suitable supporting materials. To overcome these problems, we prepared ZrO2-supported TPA and demonstrated that this is an effective catalyst for the degradation of AL. Catalysts with different TPA loadings (10–40 wt%) were prepared using different calcinations temperatures (200–500 ℃). The catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), and surface area measurements. Catalyst loaded with 20% TPA and prepared at 200 ℃ demonstrated the highest catalytic efficiency when the catalyst-to-lignin ratio was 1:8. Under these conditions, total hydroxyl groups and phenolic hydroxyl groups increased by 203.9% and 148.4%, respectively. The catalyst could be reused at least three times, without significant loss of activity. This method thus represents a green and effective alternative for the degradation of AL into valuable small molecules.

The bark of larix, a major tree species in the coniferous forests of China's Greater Khingan Mountains, is typically treated as waste. The bark is, however, rich in flavonoids, known as proanthocyanidins, although their high degree of polymerization and high molecular weight reduce their biological activity and potential applications. Ionic liquids, a new type of “green solvent”, characterized by low vapor pressure and good stability, have been developed and used as new solvents for naturally occurring macromolecules. Here, we used 1-butyl-3-methylimidazole chloride ([BMIM]Cl) as the ionic solvent to reduce the degree of polymerization of larix bark proanthocyanidins by Pd/C-catalyzed hydrogenolysis. The optimal reaction conditions, determined using an orthogonal experimental design, were: reaction temperature, 90 °C; reaction time, 1.5 h; catalyst loading, 4 g L−1 (Pd/C: [BMIM]Cl); and hydrogen pressure, 2.5 MPa. Characterization of the reaction products by UV-Vis and IR spectroscopy and gel permeation chromatographys showed that they retained the proanthocyanidin structure. We showed that whilst both the native and depolymerized proanthocyanidins were able to block UV light when added to commercially available skin creams and sunscreens, the depolymerized proanthocyanidins were more effective at a given concentration. This study expands the applications of a new “green” ionic liquid solvent, provides a technical foundation for the low-cost depolymerization of larix bark proanthocyanidins, and also explores a potential high-value use for waste larix bark as the source of a UV-blocking additive for cosmetics.

N-doped TiO2 (N-TiO2) photocatalyst was prepared by the sol-gel method, using butyl titanate and urea as raw materials, and then loaded onto diatomite to prepare a composite photocatalyst. Bleached sulfate softwood pulp fiber was dissolved and mixed with the composite photocatalyst and then regenerated to prepare composite fillers for the manufacture of visible light-responsive photocatalytic paper suitable for the removal of toxic formaldehyde gas. Photocatalytic paper containing 20% composite filler with a ratio of 4/6 N-TiO2 (60% N-doping)/diatomite had good photocatalytic activity, with 50.1% formaldehyde degraded after 10 h under visible light irradiation. This photocatalytic paper also had good physical properties, with a paper density of 0.36 g cm���3, a burst index of 3.0 kPa��m2 g���1 and a tensile index of 43.33 Nm g���1, indicating that it has good prospects for removal of indoor air pollutants.

Without sunscreens, UV rays in sunlight cause skin damage, ranging from dark spots and premature aging to skin cancer. Present sunscreens, however, are readily photodegraded, producing highly reactive radicals that can damage cells. To address this problem, we have now used ultrasound to prepare core–shell microcapsules, which offer improved protection against UV light and improved UV stability. The composite microcapsules have oligomeric proanthocyanidins (OPCs), which are amphiphilic plant-derived secondary metabolites, as the shell and octyl methoxycinnamate (OMC), which is a UVB absorber, as the core. The polyphenolic flavonoid structure of OPCs improves the UV stability of OMC and thus avoids the skin damage caused by OMC photodegradation products. In the microcapsules, π–π stacking interactions between OPCs and OMC molecules enhance the ability of OMC to absorb UV radiation and extend the absorption range from the UVB region (280–320 nm) to include the UVA and UVC regions (200–400 nm). The composite microcapsules were shown to be stable on storage and to be non-irritant to human skin. The ultrasound-assisted preparation of OMC/OPCs composite microcapsules is simple, efficient and green and provides a feasible strategy for the development of novel, more effective, sunscreens.

A composite catalyst, Pd/C-SO

Combining adsorption and photocatalysis is an effective strategy for degrading organic pollutants. Here, BiVO

Almost 90,000 tons of larch bark, which contains 10–16 % anthocyanins by weight, is produced as waste in China each year. Here, proanthocyanidins from the bark of Larix gmelinii were used to prepare oligomeric proanthocyanidin nanospheres (OPCM). The OPCMs were then blended with poly(vinyl alcohol) (PVA) to produce OPCM/PVA nanocomposite films. Incorporation of OPCM not only improves the performance of the film but also expands the applications of proanthocyanidins and provides a way to reduce the environmental impact of waste bark. Scanning electron microscopy images showed that the OPCM were uniformly dispersed in the PVA, without macroscopic phase separation. OPCM/PVA nanocomposite film had improved mechanical and thermal properties compared with pure PVA film because of intermolecular hydrogen bonding between the OPCM and PVA. The tensile strength of nanocomposite film containing 3 wt% OPCMs was 95 % higher than that of PVA film and its toughness and elongation at break were also enhanced to some extent. Compared with PVA film, the glass transition temperature (Tg) and peak decomposition temperature (Tmax) of nanocomposite film containing 10 wt% OPCM were increased by 10.4 °C and 20.2 °C, respectively. The addition of OPCMs also overcomes a major disadvantage of PVA film, which is that the melting temperature is close to Tmax, and thus facilitates melt processing of PVA composite materials. The composite film also had increased resistance to oxidation and better surface wettability than PVA film. Although the composite film had enhanced UV-blocking properties compared with PVA film, even films with the highest proportion of OPCM still showed good transmittance of visible light. Because both OPCs and PVA are biodegradable, the resulting nanocomposites are also biodegradable and can be regarded as suitable candidates for agricultural film and packaging materials.

In PAA-g-lignin, phase separation, caused by the difference in expansion properties between lignin and polyacrylic acid, is used to build a porous hydrogel. In this study, PAA-g-APL was produced by grafting polyacrylic acid with acid-pretreated alkali lignin. Acid-pretreated alkali lignin acts as a hierarchical pore-forming agent that enhances the simultaneous adsorption capacities for Pb

The effect of hydrothermal conditions on enzymatic hydrolysis lignin (EHL) degradation in water-isopropyl alcohol co-solvent and optimal conditions were investigated. The yields and reactivity toward formaldehyde of degraded enzymatic hydrolysis lignin (DEL) were determined. The optimal conditions of temperature, time, and ratio of solids to liquids were 250 °C, 60 min, and 1:10 (w/v), respectively. The EHL and DEL were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H NMR), thermal gravity (TG), and differential scanning calorimetry (DSC) analyses. The results revealed that the molecular weight and polydispersity of DEL were lower than that of EHL. Although the fundamental structure of lignin before and after hydrothermal degradation was retained, the ether (β-O-4, α-O-4, etc.) content decreased, while that of hydroxyl (phenolic and aliphatic) increased. The DTGmax and Tg values shifted from 334 and 117 °C to 304 and 105 °C, respectively.

For the controlled release of pesticides, a novel composite porous hydrogel (LBPAA) was prepared based on lignin and polyacrylic acid for use as the support frame of a pore structure for water delivery. The LBPAA was analyzed to determine its water-swelling and slow release properties. The controlled release properties of LBPAA were evaluated through experiments in relation to the cumulative release of pesticides, with particular emphasis on environmental effects and release models. The porous LBPAA hydrogel showed improved properties compared to polyacrylic acid, and could therefore be considered an efficient material for application in controlled release systems in agriculture.

Combining adsorption and photocatalysis is an effective strategy for degrading organic pollutants. Here, BiVO4@diatomite composite photocatalyst (BiVO4@diatomite CP) was prepared by hydrothermal synthesis from Bi(NO3)3·5H2O glycerin solution, NH4VO3 solution and diatomite. BiVO4@diatomite/microcrystalline cellulose/PVB composite fibers (BiVO4@diatomite/MCC/PVBCFs) were prepared from BiVO4@diatomite CPs, microcrystalline cellulose (MCC) and PVB ethanol solution using the electrospinning method. BiVO4@diatomite/MCC/PVBCFs were then mixed with pulp fibers to prepare the visible light-responsive photocatalytic paper. BiVO4@diatomite CP with a BiVO4/diatomite ratio of 6:4 had good interface states and displayed good photocatalytic activity with 64.32% degradation of methylene blue (MB) after 4 h. A PVB ethanol solution (6%) was formulated with BiVO4@diatomite CP and MCC to provide an ethanol spinning solution (12% solid) to prepare BiVO4@diatomite/MCC/PVBCFs (3:3:4). The resulting fibers had smooth surfaces, compact structures and exhibited good photocatalytic activity (66.80% and 56.80% degradation of MB and formaldehyde (HCHO), respectively, after 4 h). Photocatalytic paper containing 18% BiVO4@diatomite/MCC/PVBCFs had good photocatalytic activity with 50.20% degradation of HCHO after 4 h. This paper also had good physical properties and has the potential to be used for the photocatalytic degradation of indoor air pollutants, such as HCHO.

In PAA-g-lignin, phase separation, caused by the difference in expansion properties between lignin and polyacrylic acid, is used to build a porous hydrogel. In this study, PAA-g-APL was produced by grafting polyacrylic acid with acid-pretreated alkali lignin. Acid-pretreated alkali lignin acts as a hierarchical pore-forming agent that enhances the simultaneous adsorption capacities for Pb2+, Cu2+ and Cd2+ ions from wastewater. Notably, PAA-g-APL acted as a selective adsorbent for Pb2+ ions has an excellent selective removal coefficient α (20.22) in contaminated wastewater contained Cu2+ ions. Its molar partition coefficient for Pb2+ ions (68 %) is higher than that for either Cu2+ ions (28.6 %) or Cd2+ ions (3.4 %). At equilibrium, the total adsorption capacities of PAA-g-APL for Pb2+, Cu2+ and Cd2+ were 1.076 mmol g−1, 0.3233 mmol g−1 and 0.059 mmol g−1, respectively. The experimental kinetic data fitted well to a pseudo-second order model and to an intra-particle-diffusion model. The Freundlich isotherm model gave the best fit with the experimental equilibrium data. The ΔG° for PAA-g-APL is

Larix bark oligomeric proanthocyanidins (LOPC) were prepared from larix bark polymeric proanthocyanidins (LPPC) by catalytic hydrogenolysis using SO42&minus, /ZrO2 solid superacid as the catalyst. The catalyst to polymeric proanthocyanidins ratio was 0.2:1 (m/m). The LOPC, obtained after hydrogenolysis at 100 &deg, C for 4 h under 3 MPa hydrogen pressure, retained the structural characteristics of proanthocyanidins. The average degree of polymerization was reduced from 9.50% to 4.76% and the depolymerization yield was 53.85%. LOPC has good antioxidant properties and, at the same concentration, the reducing ability of LOPC was much higher than that of LPPC. The IC50 values of LOPC for scavenging DPPH&bull, and ABTS&bull, + radicals were 0.046 mg/mL and 0.051 mg/mL, respectively. LOPC is biocompatible and has fluorescent properties that are affected by external factors, such as solvent polarity, pH and the presence of different metal ions. These features indicate that LOPC could be developed as a new biological fluorescent marker. The depolymerization of low-value polymeric proanthocyanidins to provide high-value oligomeric proanthocyanidins and the development of new applications for proanthocyanidins represent significant advances.