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Advances in soft robotics have enabled rapid progress in shape memory hydrogels, including unidirectional, bidirectional and multidirectional shape memory hydrogels. However, shape memory hydrogels with editable feature have hardly been reported. Here, chitin based bilayer hydrogels were prepared based on alkali/urea aqueous system. Due to the different swelling properties of the two layers, namely...
In the present paper, NaOH/zinc nitrate aqueous solution was successfully developed as a novel solvent to dissolve cellulose from cotton linter pulp via cooling. The 13C NMR result proved that the dissolution was a physical process without derivatization. Dynamic light scattering, viscometry and rheology measurements were used to investigate the solution properties of cellulose in different concentration...
Herein, one-step conversion of cellulose dissolved in 1.75 mol L−1 NaOH/0.074 mol L−1 ZnO aqueous solution to organic acids was realized through a hydrothermal degradation without heterogeneous catalyst. The effects of solvent, the concentrations of NaOH and ZnO, O2 pressure, temperature and the reaction time on the yield of organic acids were investigated and discussed. The components of the degraded...
Cellulose is the most abundant natural polymer on the earth, and effective solvents are essential for its wide application. Among various solvents such as alkali/urea or ionic liquids, cations all play a very important role on the cellulose dissolution. In this work, the influence of cation on the cellulose dissolution in alkali/urea via a cooling process was investigated with a combination of MD...
TiO2/cellulose composite aerogels were easily fabricated by the in situ synthesis of TiO2 nanoparticles in a cellulose matrix at a mild temperature (≤80 °C). The TiO2/cellulose aerogel structure and morphology were analyzed with scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermal gravimetric analysis, and nitrogen adsorption–desorption tests as well as tensile...
Ultra-lightweight cellulose foams were prepared by regeneration of sodium dodecyl sulfate (SDS)/cellulose/NaOH/urea blend solution via mechanical agitation and then freeze-drying. The morphology and properties of the blend solutions and foams were investigated via optical microscope, rheometer, BET and SEM. As a result, it was found that the inclusion complex structure between cellulose macromolecules...
Antibacterial sponges with the silver nanoparticles (Ag NPs) were constructed by freeze-drying of cellulose composite hydrogels, which were prepared in NaOH/urea aqueous system with cooling, where the interconnecting pores of the sponge not only were used as micro-reactors to synthesize Ag nanoparticles but also inhibited the aggregation of Ag NPs. The Ag nanoparticles with size range from 4 to 50 nm,...
Novel cellulose–chitosan nanocomposite particles with spherical shape were successfully prepared via mixing of aqueous biopolymer solutions in three different ways. Macroparticles with diameters in the millimeter range were produced by dripping cellulose dissolved in cold LiOH/urea into acidic chitosan solutions, inducing instant co-regeneration of the biopolymers. Two types of microspheres, chemically...
Plastics with good flame retardant and gas barrier properties have been widely applied in the electrical industry. On the basis of the affinity between clay and cellulose, cellulose/montmorillonite (MMT) biobased plastics were constructed via a simple hot pressing of cellulose/MMT hydrogels prepared from a mixture of the cellulose solution and MMT suspension solution. The results of Fourier transform...
The dissolution of different cellulose pulps from different sources such as wood, bamboo and ramie pulp in 7 wt% NaOH/12 wt% urea aqueous solution was investigated in the present article, as well as the structure and properties of the resultant regenerated films. All of the cellulose samples with molecular weight below 1.2 × 105 could be quickly and completely dissolved in NaOH/urea aqueous solution...
Water responsive SiO2/cellulose nanocomposite hydrogels and films were constructed, for the first time, by dispersing SiO2 nanoparticles into cellulose solution in LiOH/urea solvent, and then by crosslinking with epichlorohydrin or regeneration in coagulation bath, respectively. The cellulose nanocomposite materials were characterized by Field emission scanning electron microscopy, FTIR, dynamic rheology,...
In this work, we developed a strategy for Ag3PO4/cellulose nanocomposite hydrogels via in situ reduction and oxidation of Ag3PO4 nanoparticles in a cellulose matrix. The results of FT-IR, X-ray diffraction and X-ray photoelectron spectroscopy proved that the Ag3PO4 nanoparticles were successfully synthesized in situ in the cellulose hydrogels. Moreover, scanning electron microscopy and transmission...
Regenerated cellulose (RC) membranes were prepared from cellulose carbamate—NaOH/ZnO aqueous solutions by coagulating with H2SO4 solution. Structure, morphology and properties of the membranes were investigated by using scanning electron micrograph (SEM), X-ray diffraction, Fourier transform infrared spectroscopy, flow rate method, and tensile testing. The results from SEM and water permeability revealed...
In this article, solid-state 13C CP/MAS NMR combined with extended Hückel charges was applied to investigate the interaction between urea and cellulose in the NaOH/urea aqueous solvent system. Direct experimental evidence was provided to support the interaction between urea and cellulose. The solid-state 13C CP/MAS NMR results revealed that complicated complexes are formed by urea, NaOH and cellulose...
Urea can improve the solubility and stability of cellulose in aqueous alkali solution, while its role has not come to a conclusion. To reveal the role of urea in solution, NMR was introduced to investigate the interaction between urea and the other components in solution. Results from chemical shifts and longitudinal relaxation times show that: (1) urea has no strong direct interaction with cellulose...
On the basis of the requirements for both biobased economy and energy storage materials, we are interested in using cellulose-based microporous film as a template for in situ synthesis of polyaniline (PANI). Multifunctional carbon nanotube (CNT)/cellulose composite films were also prepared from a CNT/cellulose suspension in a NaOH/urea aqueous system. Subsequently, PANI was synthesized in situ in...
Regenerated nanocomposite cellulose membranes embedded with silver nanoparticles (AgNP) and AgNP-graphene oxide (AgGO) were prepared in this study. The as-synthesized AgNP and AgGO were added respectively to a cellulose solution that was prepared by dissolving cellulose in a precooled NaOH/urea (NU) solvent. The solution mixtures were further regenerated into nanocomposite membranes through coagulation...
Fluorescent-labeled polymers, carbazole-substituted methylcelluloses (Cz-MCs) were synthesized through a two-step reaction by firstly introducing epoxy group to carbazole, and then reacting with MC. Structure of Cz-MC was characterized by using FTIR, NMR, elemental analysis and UV–vis spectroscopy. Aggregation behavior of Cz-MCs in dilute aqueous solution was investigated by a thermotropic study performed...
To investigate the potential application of microcrystal cellulose (MCC) and cellulose whisker (CW) in the electrospun vascular tissue scaffolds, cellulose acetate (CA) and cellulose composite scaffolds containing MCC and CW were electrospun from CA solutions and deacetylation. Structure and morphology of MCC, CW and the fibrous composite scaffolds were investigated using FT-IR, SEM, TEM and AFM....
Sol–gel transition of cellulose solution in NaOH/urea aqueous solution with the addition of epichlorohydrin (ECH) was investigated by rheological means. The gelation was controlled by a synergy of chemical and physical cross-linking processes, namely, the etherification reaction between cellulose and ECH as well as the self-association and entanglement of cellulose chains via hydrogen bonding re-construction...
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