Excessive radicals and UV irradiation can trigger oxidative and physiological stresses, which cause tissue aging, human disease, food spoilage, and material degradation. In this study, a ...multifunctional cellulose ester containing hindered phenol groups, cellulose 3,5-di-tert-butyl-4-hydroxybenzoate (CBH), with free-radical-scavenging and UV-resistant activities was synthesized and used as a functional material. The obtained CBHs can effectively scavenge reactive nitrogen free radicals and hydroxyl free radicals in both solid and solution states. Moreover, CBHs have no cytotoxicity, and, on the contrary, they promote the proliferation of human epidermal keratinocytes. Benefiting from excellent solubility, processability, and formability, CBHs have been readily processed into flexible films, transparent coatings, and nanoribbons membranes. The highly transparent and flexible CBH film completely absorbs the light of 200–300 nm range and partially absorbs the light of 300–400 nm range, indicating a UV-shielding capability. After the CBHs were loaded on an ordinary facial mask by electrospinning or added into a hand cream, the resultant facial mask and hand cream exhibited outstanding free-radical-scavenging properties. In addition, CBHs can also be used to fabricate functional sprays with antioxidative and UV-shielding activities. Accordingly, the obtained CBHs have a huge potential in cosmetics, personal care products, biopharmaceuticals, papermaking, and art protection because of their excellent antioxidation, nontoxicity, UV resistance, formability, and odorless properties.
The results ofthe sorption properties of cellulose acetate (CA) with different degrees of substitution (SD) are summarised. It has been shown that the sorption capacity of CA in water vapour ...decreases naturally with increasing content of acetate groups in monomeric units of cellulose ethers. The experimental isotherms are analysed according to the double sorption model. Hydrate numbers of hydroxyl and acetate groups were determined. The paired parameters of the Flory–Huggins interaction were calculated. It is shown that the decrease of the Langmuir component is due to the replacement of hydroxyl groups by ester groups, whose local sorption capacity by water vapour is lower than the sorption capacity of OH groups. In the area of high humidity, there is an increase in vacancy sizes due to plasticisation of the sorbents.
As an electrolyte additive, the acidified cellulose ester has been demonstrated to be effective in inhibiting lithium dendrite growth and improving the coulombic efficiency of lithium metal ...batteries.
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Because of their high capacity and low potential, lithium metal anodes are considered to be promising candidates for next generation electrode materials. However, the safety concerns and limited cycling life associated with uncontrollable dendrite growth hamper practical applications. In this work, the acidified cellulose ester, which is a mixed fiber microporous membrane film, was used as a novel electrolyte additive that effectively improves the cycle stability of the lithium metal anode and inhibits dendrite growth. The focus of this paper is on inhibiting the formation and growth of lithium dendrites. The coulombic efficiency of a Li|Cu battery with this acidified cellulose ester additive remains stable at 99% after 500 cycles under a current density of 1mA/cm2. Symmetric batteries also remain stable after 500 cycles (1000 h) under a current density of 1 mA/cm2. These superior properties can be ascribed to the induced nucleation and the uniform distribution of lithium ion flux. This study uncovers an approach for effectively enabling stable cycling of dendrite-free lithium metal anodes.
Homogeneous esterification of cellulose with octanoyl chloride (a long-chain fatty acid) was investigated in lithium chloride/N,N-dimethyl acetamide (LiCl/DMAc) medium. Cellulose was readily ...esterified by the octanoyl chloride, as shown by 1H NMR analysis. The effects of the ratio of octanoyl chloride to cellulose hydroxyl groups, the reaction temperature, and the reaction time on the yield and degrees of substitution (DS) of cellulose esters (CEs) were investigated. CEs with high DS (2.2) were achieved after 8 h at 100 °C with a 1.6 to 1.8 of molar ratio of octanoyl chloride to cellulose hydroxyl groups. Furthermore, hydrophobic, fully transparent CE films and aerogels were prepared using CE tetrahydrofuran (THF) solutions. The CE aerogels exhibited high porosity and were formed with evenly distributed porosity, as revealed by scanning electron microscopy (SEM).
Hydrophobic cellulose laurate (CL) with high degree of substitution has been successfully synthesized. The mechanical property, water-resistance, antimicrobial activity, barrier properties and food ...decontamination of cellulose-laurate-curcumin films (CL-Cux, x = 0.1, 0.5, and 1) were investigated. The results showed that the mechanical properties of CL-Cux hardly change after soaking in water for 24 h, probably due to the strong hydrophobicity of cellulose laurate. CL-Cu1 represented a good photoinduced antibacterial effect against S. aureus. After irradiation of white light at 60 mW·cm−2 for 20 min, the inhibition efficiency reached to 95 ± 2.02%, probably owing to the generated active 1O2. In comparison with CL-Cu1 stored in natural light, the bacteriostatic effect of CL-Cu1 in dark storage was better, and the inhibition rate of CL-Cu1 remained 80 ± 1.22 at 60th day. The stabler excited state of curcumin in hydrophobic cellulose laurate was probably assigned to inhibition of tautomerism or conformational transition, which was beneficial to the generation of singlet oxygen. CL-Cu1 can significantly inhibit the growth of TVBN and TVC values of chilled meat upon white light irradiation, indicating the potential application of cellulose-laurate-curcumin films in food decontamination.
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•Reactive extrusion process of cellulose laurate synthesis takes 1−10 min.•Process of high cellulose concentration (20 wt%) with great reaction efficiency (91 %).•The influence of ...process parameters on cellulose transformation is discussed.•No depolymerization of cellulose backbone during reactive extrusion is observed.•Reduced waste process with low environmental factor (0.93–1.91).
The recent progress in the manufacturing of new functional cellulose-derived materials shows that the renewable side of these materials does not ensure sustainable development. In contrast, reaction/process design and waste minimization play a key role here. Herein, reactive extrusion was used as a fast method for cellulose transesterification with vinyl laurate in 1-ethyl-3-methylimidazolium acetate (EmimOAc)/DMSO system. It was demonstrated that cellulose laurate can be synthesized with high reaction efficiency (91 %). The low amount of solvent during the process provides high cellulose concentration (20 wt%) mild chemical modification within minutes and without any depolymerization. Temperature has a significant influence on the reaction kinetics. To examine the sustainability of the process E-factor was employed. Processing properties of obtained cellulose laurates were investigated. Samples with DS of 2.5 and higher can be easily extruded showing low melt viscosity. EmimOAc was recovered and reused for subsequent cellulose transesterification exhibiting high catalytic activity.
As a traditionally used packaging material, natural cellulose-based paper has poor barrier properties to water and oxygen, which severely limits its wide application in food packaging. In this study, ...we report a new sustainable approach to producing hydrophobic, high-barrier, and antibacterial packaging materials from cellulose paper. In this process, commercially available microcrystalline cellulose was first modified by long-chain stearic acid to form hydrophobic microcrystalline cellulose ester and then mixed with stearic acid as filler in the subsequent surface coating of bagasse fibre paper. The microcrystalline cellulose ester/stearic acid-coated paper (MSP) exhibited good water repellency and oxygen barrier activity due to a continuous hydrophobic film that formed, which completely covered the pores of the original bagasse fibre paper. The coated MSP sample also showed excellent dimensional stability in water and a good wet tensile strength of 16 MPa. In addition, poly(hexamethylene guanidine) (PHMG) was chemically grafted onto the free carboxyl groups of the MSP surface layer, and the resulting MSP-g-PHMG samples exhibited excellent antibacterial activity against Escherichia coli and Listeria monocytogenes. The biodegradable cellulose-based MSP-g-PHMG sample significantly delayed the decay of raspberry during storage, indicating its potential application in food packaging.
•Microcrystalline cellulose-based eco-friendly coating agent for paper surface functionalization•The coated cellulose paper sheet showed good waterproofing, oxygen barrier, and antibacterial properties.•The designed cellulose-based paper sheet is well suited for food packaging.
Herein, a novel superdispersed calcium borate@polydopamine/cellulose acetate-laurate nanocomposite (CTAB-CB@PDA/CAL) is successfully synthesized by a double-template-regulated biomimetic ...mineralization strategy using PDA/CAL as a hard template and cetyltrimethylammonium bromide (CTAB) as a soft template and surface hydrophobic modifier. The results show that CB can grow uniformly on the CAL surface, and CTAB can improve the hydrophobicity of CTAB-CB@PDA/CAL due to the synergistic effect of the double templates, which contributes to the enhanced dispersibility and long-term dispersion stability of CTAB-CB@PDA/CAL in poly-alpha-olefin (PAO) base oil. Furthermore, CB can rapidly enter the friction interface due to the long substituents of CTAB and CAL, so CTAB-CB@PDA/CAL used as a lubricant additive in PAO base oil exhibits superior tribological performance compared to CB, CB/CAL, and CB@PDA/CAL.
This work presents that a novel superdispersed calcium borate@polydopamine/cellulose acetate-laurate (CTAB-CB@PDA/CAL) nanocomposite was synthesized by a double-template-regulated bionic mineralization method using PDA/CAL as hard template and CTAB as soft template and surface hydrophobic modifier. The results showed that CB NPs could grow uniformly and firmly distributed on the CAL surface, and CTAB could improve the hydrophobicity of CTAB-CB@PDA/CAL benefiting from the synergistic effect of the double templates, which contributed to the enhanced dispersibility and long-term dispersion stability of CTAB-CB@PDA/CAL in poly-alpha-olefin (PAO) base oil. Furthermore, the CTAB-CB@PDA/CAL used as a lubricant additive in PAO base oil exhibited superior tribological performance. This work offers a new method for the synthesis of lubricant nanomaterials with excellent tribological and dispersion properties. Display omitted
•Successful synthesis of CTAB-CB@PDA/CAL nanocomposite using double-template-regulated biomimetic mineralization strategy.•Synergistic effect of the double templates can enhance the dispersity of CB and the hydrophobicity of CTAB-CB@PDA/CAL.•CTAB-CB@PDA/CAL shows outstanding dispersibility and long-term dispersion stability in PAO base oil.•CTAB-CB@PDA/CAL used as a lubricant additive in PAO base oil exhibits superior tribological performances.
•Amorphous solid dispersions in cellulose esters stable to 90% curcumin (Cur).•Amorphous dispersions afford large increases in Cur solution concentration.•Cellulose ester dispersions unexpectedly ...stabilize Cur in solution.•Hydrophobic cellulose esters give very slow Cur release.
Amorphous solid dispersions (ASD) of curcumin (Cur) in cellulose derivative matrices, hydroxypropylmethylcellulose acetate succinate (HPMCAS), carboxymethylcellulose acetate butyrate (CMCAB), and cellulose acetate adipate propionate (CAAdP) were prepared in order to investigate the structure–property relationship and identify polymer properties necessary to effectively increase Cur aqueous solution concentration. XRD results indicated that all investigated solid dispersions were amorphous, even at a 9:1 Cur:polymer ratio. Both stability against crystallization and Cur solution concentration from these ASDs were significantly higher than those from physical mixtures and crystalline Cur. Remarkably, curcumin was also stabilized against chemical degradation in solution. Chemical stabilization was polymer-dependent, with stabilization in CAAdP>CMCAB>HPMCAS>PVP, while matrices enhanced solution concentration as PVP>HPMCAS≫CMCAB≈CAAdP. HPMCAS/Cur dispersions have useful combinations of pH-triggered release profile, chemical stabilization, and strong enhancement of Cur solution concentration.
•Regio-, chemoselective chlorination of cellulose esters.•Efficient subsequent displacement with nucleophiles (e.g. azide, amines, and thiols).•Gateway to broad range of cellulose ester derivatives, ...including cationic and anionic.
Regioselective chlorination of cellulose is challenging due to its low reactivity, the small reactivity differences between cellulosic hydroxyl groups, and the high and diverse reactivity of most common chlorinating agents. Halogenation of cellulose affords useful precursors for subsequent nucleophilic substitution reactions, permitting incorporation of new functionality. Herein we report a simple and efficient pathway for preparation of 6-chloro-6-deoxycellulose esters and their derivatives. Cellulose acetate (degree of substitution (DS) 1.75, CA320S) can be chlorinated by essentially quantitative reaction of the primary alcohol groups with methanesulfonyl chloride (MsCl), yielding 6-chloro-6-deoxy cellulose acetate. Characterization methods including 1H NMR, 13C NMR, FT-IR spectroscopy, and elemental analysis, demonstrated chemo- and regioselective C-6 chlorination. We also demonstrate that chlorinated cellulose acetate is a useful intermediate for displacement reactions with nucleophiles including sodium azide, amines, and thiols to prepare functional cellulose ester derivatives.
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