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Inorganic oxides with unique physical and chemical properties have attracted much attention because they can be applied in a wide range of fields. Herein, recycled cigarette filters are deacetylated to cellulose filters (CFs), which are then applied as templates to prepare fiber-like inorganic oxides (titanium dioxide, TiO2, and silicon dioxide, SiO2). Inorganic oxides are prepared using CF as a template by a typical sol-gel reaction of metal alkoxides. Owing to the fibrous structure of the CF template, the prepared inorganic oxides (TiO2 and SiO2) show similar fibrous structures, which was confirmed by scanning electron microscopy and nitrogen adsorption-desorption analysis. Moreover, the prepared inorganic oxides (TiO2 and SiO2) show high surface areas and pore volumes. Furthermore, the TiO2 fiber-like materials are evaluated for their photocatalytic properties by analyzing the methylene blue (MB) and methyl orange (MO) degradation. In this study, we provide a clean method, which can convert cellulose acetate-based waste into useful templates to prepare inorganic oxides with relatively simple steps, and the prepared inorganic oxides can be applied in water treatment.

A polyethylenimine-grafted cellulose monolith was developed for efficient bacterial capture in a continuous flow system. The amino-functionalized monolith showed superior capture capacity for high concentration of both gram-negative (Escherichia coli) and gram-positive (Bacillus subtilis) bacteria compared with the unmodified one. The efficiency and structural stability of the monolith were consistent during bacterial filtering at a high flow velocity. Bacteria were observed to be anchored to the skeleton surface of the monolith. The performance was attributed to the well-interconnected porous structure and strong electrostatic interaction with cells, which endowed the large surface area with retention force allowing for the local adhesion of bacteria in a flow process.

In the present study, we report a simple and eco-friendly method for the synthesis and immobilization of silver nanoparticles (AgNPs) onto functional films using green tea extract as a reducing and capping agent. The freestanding flexible immobilized AgNPs composite was obtained from a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated tea cellulose (TTC) process. Scanning electron microscopy analysis revealed the homogeneous coating of the AgNPs on the surface of the TTC nanofibers. Ag-TTC-poly(vinyl alcohol) (PVA) composite film was prepared through a simple solvent casting method, which displayed higher antioxidant activity than the TTC-PVA film, and the rate of release of Ag was reduced owing to the immobilized AgNPs. The photocatalytic performance of Ag-TTC-PVA composite film was evaluated along with the investigations of the optical transparency, morphology, and thermal properties. Ag-TTC-PVA composite film showed enhanced photocatalytic property than TTC-PVA film. This study presents a simple approach for the green synthesis of materials with controlled leakage based on Ag-TTC-PVA composite film, which has good potential application prospects in the development for the photocatalytic degradation of certain toxic dyes, thereby paving the way for waste treatment.

In this work, nanocomposites of poly(methyl methacrylate) (PMMA) with cellulose nanofiber (CNF) were prepared by a solution casting technique. CNF was modified by propionic anhydride (PA) to form surface-propionylated CNF (CNFp) to improve its compatibility with the PMMA matrix. CNF, CNFp, and acetylated CNF were compared with respect to their influence as fillers in PMMA composite films by ultraviolet-visible transmittance, haze values, tensile strength testing, and water contact angle measurement. It was demonstrated that 1 wt % of CNFp has good compatibility and uniform dispersion in the PMMA matrix, as demonstrated by the formation of a smooth surface composite film with good transparency, enhanced tensile properties, improved toughness, and lower wettability. Therefore, PMMA/CNFp composite films have great potential for use in several applications such as lightweight transparent materials, window substitutes, and see-through packaging.

Functional materials that can recognize the tumor microenvironment, characterized by acidic or reducing conditions, are needed for the designing of drug delivery carriers for cancer treatment. Hydrogels are potential protein drug carriers because they contain a large amount of water and stimuli-responsive functions can easily be introduced in them. However, it is difficult to introduce multi-stimuli-responsive functions and degradability at the same time. Here, we synthesized thermo- and pH-responsive hydrogels via a coupling reaction between poly(ethylene glycol) diglycidyl ether (PEGDE) and cystamine (CA). The prepared hydrogels showed lower critical solution temperature-type thermoresponsive behavior and pH-responsive swelling changes due to the protonation of secondary and/or tertiary amino groups arising from the crosslinking agent CA. Under reducing conditions, the hydrogels were degraded via the thiol exchange reaction in the presence of dithiothreitol or glutathione. The loading and release properties of FITC-labeled model proteins from the hydrogels were investigated. The loaded amount of the protein increased with decreasing molecular weight or hydrodynamic radius, which is based on the size of the network structure of the hydrogels. Notably, loaded proteins in the hydrogels were released only under reducing conditions, which mimic the tumor microenvironment. Thus, the prepared multi-responsive degradable hydrogels are expected to be used as functional drug delivery carriers for cancer treatment.

The photocatalytic process using TiO2 materials under UV light illumination has shown great advantages in wastewater treatment. However, it is necessary to recover the catalyst from the suspension, and the small particle size of the catalyst can cause secondary pollution. Hierarchically porous TiO2 monolithic materials are potential candidates for water remediation, as they can be easily recovered and can be used in flow systems. In this study, we used an ecofriendly cellulose material as a template to prepare a hierarchically porous TiO2 monolith. The cellulose monolith template was prepared from cellulose acetate by a thermally induced phase separation method. A composite monolith was then prepared in the presence of the cellulose monolith by a typical sol–gel reaction of titanium isopropoxide (TTIP). This composite monolith was then converted to a TiO2 monolith by burning it in air to remove the cellulose monolith. Owing to the hierarchically porous structure of the cellulose monolith template, the obtained TiO2 monolith showed a similar hierarchically porous structure, as confirmed by scanning electron microscopy and nitrogen adsorption–desorption analyses. The pore structures could be controlled by changing the fabrication parameters, such as the type of cellulose monolith and TTIP content. The photocatalytic performance of the TiO2 monolith was evaluated by studying its effect on the degradation of methylene blue (MB) in a flow system.

Protein phosphorylation and glycosylation, as two of the most important post-translational modifications of proteins, are of great significance to humans. The development of materials that can selectively enrich phosphopeptides and glycopeptides from complex biological samples has considerable value. In this work, an environmentally friendly bionic cellulose-derived monolithic material (TiPCM) with a coral-like structure was prepared using a thermally induced phase separation (TIPS) method and exhibited good hydrophilicity, a satisfactory porous structure, and a large quantity of titanium ions allowing it to simultaneously enrich both phosphopeptides and glycopeptides or enrich phosphopeptides alone from biological samples. The prepared TiPCM material could enrich phosphopeptides and glycopeptides, respectively, from a BSA/β-casein (molar ratio, 5000/1) and BSA/IgG (molar ratio, 1000/1) mixture demonstrating that it has excellent selectivity for phosphopeptides and glycopeptides. Meanwhile, it is worth mentioning that TiPCM materials show reusability in the enrichment of phosphopeptides, which has not been studied much in the literature. Moreover, three replicate analyses from 200 μg of tryptic digest of milk identified 119 unique phosphopeptides from 38 phosphoproteins, while identifying 180 glycopeptides from 93 unique glycoproteins and their corresponding 148 independent glycosylation sites. These results demonstrate the potential of TiPCM materials in the analysis of phosphorylated and glycosylated proteomics.

Hydroxyapatite (HA) shows promising applications in the clinical treatment of bone defects owing to its excellent physicochemical properties, such as biocompatibility, bioactivity, and osteoconductivity. However, it is difficult to maintain a porous structure in HA materials because of processing difficulties. In this study, a hard template method was developed to prepare a porous HA monolith with a hierarchical pore structure and high porosity. The cellulose monolith template was prepared from cellulose acetate using a thermally induced phase separation method. The cellulose monoliths were then immersed into the HA slurry to form a cellulose_HA composite monolith, which was converted to an HA monolith by burning in air to remove the cellulose monolith. Owing to the hierarchically porous structure of the cellulose monolith template, the obtained HA monolith demonstrated a hierarchically porous structure. Furthermore, the HA monolith was explored to study the adsorption and release properties of bovine serum albumin (BSA), which indicated that the HA monolith had a high adsorption capacity (388.6 mg g−1) and sustained release from the BSA-loaded HA monolith. Thus, HA monoliths have potential applications in the field of protein purification and biomaterials.

A cost-effective and facile method was developed for the fabrication of two polyimide-based (PI-based) monoliths (pure PI monolith and hybrid PI monolith) with a hierarchically porous structure that avoids the shortcomings of traditional methods. In this case, the thermally induced phase separation (TIPS) method was used to prepare polyamic acid (PAA) monoliths for the first time, then PI-based monoliths were fabricated by thermal imidization. Through the introduction of octakis(glycidyldimethylsiloxy)octasilsesquioxane into the PAA prepared from 4,4′-oxydianiline and pyromellitic dianhydride, both the hydrophobicity and mechanical strengths of the PI-based monoliths were improved. Moreover, the resulting PI-based monoliths exhibited suitable permeability, homogeneous morphologies, and superior thermal stability. Adsorption tests demonstrated that the resulting hybrid PI monoliths exhibited better adsorption performance for organic solvents and silicone oil than the pure PI monolith. Furthermore, the surface of a polyhedral oligomeric silsesquioxane (POSS) hybridized PI (PI-co-POSS) monolith can be modified into a hydrophilic layer by reaction between the hydrophilic polymer and epoxy groups exposed on the surface. This indicates that PI-co-POSS monoliths have potential in liquid diode application to achieve oil–water separation.

Cellulose-based functional materials have gained immense interest due to their low density, hydrophilicity, chirality, and degradability. So far, a facile and scalable preparation of fibrillated cellulose by treating the hydroxy groups of cellulose with citric acid (F-CAC) has been developed and applied as a reinforcing filler for polypropylene composite. Herein, a size-selective preparation of Au nanoparticles (NPs) stabilized by F-CAC is described. By modifying the conditions of transdeposition method, established in our group previously, a transfer of Au NPs from poly(N-vinyl-2-pyrrolidone) (PVP) to F-CAC proceeded up to 96% transfer efficiency with retaining its cluster sizes in EtOH. Meanwhile, the deposition efficiency drastically decreased in the case of nonmodified cellulose, showing the significance of citric acid modification. A shift of binding energy at Au 4f core level X-ray photoelectron spectroscopy from 82.0 to 83.3 eV indicated that the NPs were stabilized on an F-CAC surface rather than by PVP matrix. The reproducible particle size growth was observed when 2-propanol was used as a solvent instead of EtOH, expanding the range of the available particle size with simple manipulation. The thus-obtained Au:F-CAC nanocatalysts exhibited a catalytic activity toward an aerobic oxidation of 1-indonol in toluene to yield 1-indanone quantitatively and were recyclable at least six times, illustrating high tolerance against organic solvents.

Recently, several studies have reported using an oxidation method, such as plasma, to introduce polar functional groups to the polymer surface. However, these methods are difficult to use to oxidiz...

Thermoresponsive phase separation mechanisms of aqueous poly(N-isopropylacrylamide) (PNIPAM) solutions were investigated using an optical tweezer combined with a Raman microspectroscope. A near-inf...

Hydrogels are biocompatible polymer networks; however, they have the disadvantage of having poor mechanical properties. Herein, the mechanical properties of host-guest hydrogels were increased by adding a filler and incorporating other noncovalent interactions. Cellulose was added as a filler to the hydrogels to afford a composite. Citric acid-modified cellulose (CAC) with many carboxyl groups was used instead of conventional cellulose. The preparation began with mixing an acrylamide-based αCD host polymer (p-αCD) and a dodecanoic acid guest polymer (p-AADA) to form supramolecular hydrogels (p-αCD/p-AADA). However, when CAC was directly added to p-αCD/p-AADA to form biocomposite hydrogels (p-αCD/p-AADA/CAC), it showed weaker mechanical properties than p-αCD/p-AADA itself. This was caused by the strong intramolecular hydrogen bonding (H-bonding) within the CAC, which prevented the CAC reinforcing p-αCD/p-AADA in p-αCD/p-AADA/CAC. Then, calcium chloride solution (CaCl

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) is one of the biomass plastics synthesized by intracellular fermentation of plant oils and saccharides, which has good flexibility and mechanica...

The development of tough, self-healing materials is a notable accomplishment. Previously, self-healable materials were soft materials with a tensile stress less than 10 MPa. Herein, we describe cit...

Inspired by a bacteriogenic, iron-based oxide material and a traditional Japanese red pigment, a bright yellowish-red pigment was prepared by heating an Al-containing iron oxyhydroxide precursor. The obtained red pigment had a unique porous disk-like structure, comprising Al-substituted hematite particles and crystalline alumina nanoparticles. Although these disk-like structures loosely gathered to form an aggregate in powder, they can be easily dispersed into a single, disk-like structure by simple ultrasonic irradiation. The powder exhibited a bright yellowish-red color and high thermostability, making it attractive as a coloring material for various industrial products needing a bright-red color, high weather resistance, and durability. Quantitative color measurements revealed extremely high L*, a*, and b* values that are much greater than those of commercially available hematite. The thermostability test showed that even after exposure to high temperatures, the pigment retained the red color, indicating its high thermostability. The unique microstructure should be strongly related to the bright yellowish-red color and the high thermostability of the developed red pigment.

The effect of the addition of alcohol to a Na3PO4-based electrolyte on plasma electrolytic oxidation (PEO) of AZ31B magnesium alloy was investigated. Anodization with spark discharge was conducted in Na3PO4-based electrolyte containing various alcohols (e.g., ethanol, ethylene glycol, and glycerol) at a constant current density of 200 A m−2 and a constant temperature of 25 °C. Voltage–time curves during the PEO process, the film structure, surface roughness, crystallographic structure, composition, corrosion resistance, and withstand voltage were investigated using various analytical equipment and electrochemical measurements. When the electrolyte containing alcohol was used, the initial bending voltage was higher than that observed using the basic electrolyte without alcohol addition, as was the oscillation voltage during the PEO process. For a given amount of electricity supplied, the addition of alcohol into the basic electrolyte tended to increase the thickness and corrosion resistance of PEO films formed while effectively reducing surface roughness. In particular, the addition of a polyhydric alcohol (i.e., ethylene glycol and glycerol) could act not only as a leveler for the formation of compact film but also as an enhancer for film qualities, such as corrosion resistance and withstand voltage. The patterns observed for Na3PO4-based electrolyte containing alcohol also hold for Na2SiO3-based electrolyte containing alcohol.

A novel cellulose monolith supported ZIF-8 metal organic framework as a hierarchical porous material was designed by using a highly effective pump injection method, which is used for a flow-based reaction.

The present study reported the flexible and highly efficient one-step synthesis of chiral hierarchical porous monoliths via cross-linking and polymerization-induced phase separation using substituted acetylene and cross-linker in the presence of porogenic solvent (tetrahydrofuran and methanol) in which the complex doping and complicated procedures were not required. It was demonstrated that hierarchical pore structure with through-pore and high surface area existed in the monoliths, which provides more chiral sites and space for interaction between monolithic materials and the solution. The porous structures and pore size can be adjusted by changing the conditions of phase separation. Moreover, the prepared monoliths exhibited good optical activity, thermal stability and mechanical properties. Therefore, the hierarchically porous monoliths with optical activity were applied in enantioselective crystallization and showed good performance.

An ultralight bacterial cellulose/polypropylene-graft-maleic anhydride (BC/PP-g-MA) composite cryogel was fabricated using a facile temperature induced phase separation (TIPS) method followed by fr...

In this study, we contribute the facile fabrication of tough polyolefin monoliths from their polymer solutions using a phase separation method. Compressive stress–strain tests demonstrate that the monoliths have excellent mechanical properties. The monoliths show macroporous structures where the pore sizes can be tuned from sub-1 to 16 µm by adjusting the fabrication conditions. The monoliths exhibit high hydrophobicity/ oleophilicity and good resistance toward different chemicals. Based on the above properties, we applied the monoliths to the selective absorption of oil from an oil/water mixture. By simply squeezing the monoliths, the absorbed oil can be recovered. The monoliths are useful for more than 10 cycles of absorption and recovery, showing a good stability for industrial-scale oil spill treatment.

Metal–plastics adhesion has received much attention from researchers due to its potential use in various industrial applications. However, the adhesion of plastics with metals is poor due to the lo...

This study investigates an alternative green strategy based on non-toxic and readily biodegradable chlorocholine chloride/urea deep eutectic solvents (DESs), which act both as functionalization agents and solvents that allow for the cationization of cellulose monoliths to form novel adsorbents for removal of anionic reactive dye from water. Cellulose monolith was produced by deacetylation of cellulose acetate monolith which was fabricated via thermally induced phase separation (TIPS) method using binary solvents of DMF and 1-hexanol. Cationization of cellulose monolith was confirmed by SEM, FTIR, elemental analysis, TGA and BET surface area analysis. For the flow-through applications, the permeability and mechanical properties were also analysed in this study. The cationized cellulose monoliths were employed to remove acid red 70 dye from aqueous solutions in dynamic adsorption experiments. Results showed exceptional affinity for adsorption of acid red 70 dye due to the charge-induced adsorption aided by quaternary ammonium groups. A high adsorbed percentage of 83% could be obtained at initial concentration of 70 ppm. Moreover, the adsorbed dye could be easily desorbed. Combining their ultrafast adsorption kinetics with excellent properties of high adsorption capacity and rapid adsorption/desorption rates remained during the five consecutive cycles, the DES-modified cellulose monolith has large potential for effluent treatment applications.

An oxide system Sc2−xFexO3 prepared by a conventional solid-state reaction method was found to change its color from the well-known reddish color at x = 2.0 to a yellowish color at x ≈ 0.6 and to a greenish-yellow color at 0.2 ≤ x ≤ 0.4. According to the structural characterization results for this system, the monophasic corundum phase region persists for 1.6 ≤ x ≤ 2.0, whereas the bixbyite-type phase is monophasic for 0 ≤ x ≤ 1.0. The intermediate region of 1.2 ≤ x ≤ 1.4 is a mixed region. Because green is a rare color for iron oxides, powder of the most typical composition, x = 0.4, with (L*, a*, b*) coordinates of (77.3, −0.5, 51.0) was tested as a pigment for a Japanese-style painting and also as an overglaze enamel on porcelain; reasonably good results were obtained.

Polypeptide-based hydrogels have potential applications in polymer therapeutics and regenerative medicine. However, designing reliable polypeptide-based hydrogels with a rapid injection time and controllable stiffness for clinical applications remains a challenge. Herein, a class of injectable poly(γ-glutamic acid) (PGA)-based hydrogels were constructed using furfurylamine and tyramine-modified PGA (PGA-Fa-Tyr) and the crosslinker dimaleimide poly(ethylene glycol) (MAL-PEG-MAL), through a facile strategy combining enzymatic crosslinking and Diels-Alder (DA) reaction. The injectable hydrogels could be quickly gelatinized and the gelation time, ranging from 10 to 95 s, could be controlled by varying the hydrogen peroxide (H2O2) concentration. Compared with hydrogels formed by single enzymatic crosslinking, the compressive stress and strain of the injectable hydrogels were remarkably enhanced because of the occurrence of the subsequent DA reaction in the hydrogels, suggesting the DA network imparted an outstanding toughening effect on the hydrogels. Furthermore, the mechanical strength, swelling ratio, pore size, and degradation behavior of the injectable hydrogels could be easily controlled by changing the molar ratios of H2O2/Tyr or furan/maleimide. More importantly, injectable hydrogels encapsulating bovine serum albumin exhibited sustained release behavior. Thus, the developed hydrogels hold great potential for applications in biomedical fields, such as tissue engineering and cell/drug delivery.

In this study, we investigated the effect of the addition of cellulose nanofiber (CNF) fillers on the performance of poly(lactic acid) (PLA). Modification of the hydroxyl group of cellulose to the acyl group by acid anhydrides changed the compatibility of the CNF with PLA. CNF was modified by acetic anhydride, propionic anhydride, and butyric anhydride to form surface-modified acetylated CNF (CNFa), propionylated CNF (CNFp), and butyrylated CNF (CNFb), respectively, to improve the compatibility with the PLA matrix. The effects of the different acid anhydrides were compared based on their rates of reaction in the acylation process. PLA with modified cellulose nanofiber fillers formed smoother surfaces with better transparency, mechanical, and wettability properties compared with the PLA/CNF composite film. The effects of CNFa, CNFp, and CNFb on the PLA matrix were compared, and it was found that CNFp was the best filler for PLA.

Cellulose-based functional materials have gained immense interest due to its low density, hydrophilicity, chirality, and degradability. So far, a facile and scalable preparation of fibrillated cellulose by treating the hydroxy groups of cellulose with citric acid (F-CAC) have been developed, and applied as a reinforcing filler for polypropylene composite. Herein, a size-selective preparation of Au nanoparticles (NPs) stabilized by F-CAC is described. By modifying the conditions of trans-deposition method, established in our group previously, a transfer of Au NPs from poly(N-vinyl-2-pyrrolidone) (PVP) to F-CAC proceeded up to 96% transfer efficiency with retaining its cluster sizes in EtOH. Meanwhile, the deposition efficiency drastically decreased in the case of non-modified cellulose, showing the significance of citric acid-modification. A shift of binding energy at Au 4f core level X-ray photoelectron microscopy (XPS) from 82.0 eV to 83.3 eV indicated that the NPs were stabilized on a F-CAC surface rather than by PVP matrix. The reproducible particle size growth was observed when 2-propanol was used as a solvent instead of EtOH, expanding the range of the available particle size with simple manipulation. The thus-obtained Au:F-CAC nanocatalysts exhibited a catalytic activity toward an aerobic oxidation of 1-indonol in toluene to yield 1-indanone quantitatively, and were recyclable at least 6 times, illustrating high tolerance against organic solvents.

A series of quinoidal oligothiophenes terminated with carbonyl groups (nTDs, n = 2&ndash, 4) are studied as p-type organic semiconductors for the active materials in organic field-effect transistors (OFETs) both by the theoretical and experimental approaches. The theoretical calculations clearly show their high-lying highest occupied molecular orbital (HOMO) energy levels (EHOMOs), small reorganization energies for hole transport (&lambda, holes), and large contribution of sulfur atoms to HOMOs, all of which are desirable for p-type organic semiconductors. Thus, we synthesized nTDs from the corresponding aromatic oligothiophene precursors and then evaluated their physicochemical properties and structural properties. These experimental evaluations of nTDs nicely proved the theoretical predictions, and the largest 4TDs in the series (4,4&prime, &prime, dihexyl- and 3&prime, 4,4&Prime, 4&prime, tetrahexyl-5H,5&prime, H-[2,2&prime, 5&prime, 2&Prime, 5&Prime, 2&prime, quaterthiophene]-5,5&prime, dione) can afford solution-processed OFETs showing unipolar p-type behaviors and hole mobility as high as 0.026 cm2 V&minus, 1 s&minus, 1.

High water content is hard to be achieved in conductive hydrogels because a mass of conductive constituent is needed to form an internal conductive pathway. Here, we developed anisotropic electrically conductive hydrogels with high water content based on bacterial cellulose (BC). Polystyrene sulfonate (PSS) was grafted to the acryloyl chloride-modified BC to provide a template for the subsequent synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT). The BC

Monolithic flow reactors are widely applied in numerous reactions due to its high efficiency and good reusability, but the green and efficient fabrication of monolithic flow catalytic system is still a challenge. Herein, the cellulose monolith prepared using a facile temperature-induced phase separation method was utilized to generate and immobilize the gold nanoparticles by a continuous-flow strategy, in which the cellulose monolith served as both reducing agent and supporting material. This process was conducted at room temperature and avoided the tedious surface modification of cellulose. The obtained cellulose-Au monolith can be directly applied as a green flow reactor in both water and organic solvents, and exhibited superior catalytic efficiency and good stability. This work provides a highly efficient, scalable and sustainable strategy for developing green catalytic system based on environmentally friendly cellulose monolith materials.

Mechanically adaptive hydrogels can change their mechanical characteristics in response to external stimuli and have potential applications in biomechanical fields. To eliminate the undesired swelling/shrinkage in the responding process, poly(acrylic acid) (PAA) was grafted to acryloyl chloride (AC)-modified bacterial cellulose (BC) by free-radical polymerization. The obtained BC-g-PAA composite hydrogels showed adjustable stiffness in compression, remained soft at pH lower than 6 (compression strain over 49% at a stress of 0.1 MPa), and stiffened when pH reached 7 (compression strain lower than 27% at a stress of 0.1 MPa), while the volume change ratio was consistently lower than 15%. Based on this, the hydrogels showed interesting squat actuation to lift a weight. The BC composite hydrogels exhibited dual pH-responsiveness after grafting PAA with poly[2-(dimethylamino)ethyl methacrylate], confirming the general availability of this strategy in fabricating volumetrically stable and mechanically adaptive hydrogels. The surrounding solution-independent softening of BC-g-PAA hydrogels was observed in 8 min under UV irradiation via a photo-triggered pH jump reaction. By virtue of the selective UV irradiation, spatiotemporally controllable softening with actuation in BC-g-PAA hydrogels was realized. The developed pH-responsive mechanically adaptive BC composite hydrogels with high dimensional stability and UV-activated spatiotemporal squat actuating capability are expected to provide more options in developing novel bioimplants and smart structures.

Stimuli-responsive hydrogels have garnered the attention of the hydrogel industry, as they are able to change their physical and chemical properties based on changing external stimuli such as pH, temperature, ionic strength, electromagnetic fields, and light. However, stimuli-responsive hydrogel applications are hindered due to their inevitable swelling and shrinkage. Bacterial cellulose (BC), a natural hydrogel with tightly packed cellulose nanofibers (CNFs) was oxidized into dialdehyde BC (DABC) and was composited with chitosan (CS), a readily available natural polymer, to develop a mechanically adaptive hydrogel composite under different pH conditions. Composites exhibit pH sensitivity by presenting higher mechanical properties under acidic conditions and lower mechanical properties under basic conditions owing to the protonation of amino groups of the chitosan chains. Osmotic pressure is built up under acidic conditions, increasing the mechanical strength of the composites. The good three-dimensional stability of composites enables them to consistently maintain their volume when exposed to acidic or basic conditions.

As a natural polymer, chitin has excellent biological properties such as biodegradability and immunological, antibacterial, and wound-healing activities and has numerous applications in cosmetics, drug delivery, and pharmaceuticals. Organic polymer monoliths have also drawn significant attention, owing to their high permeability, large surface area, and high mechanical strength. They are usually applied to separation, ion exchange, catalysis, and chromatography. We have previously prepared cellulose monoliths using biopolymers; however, because chitin possesses amide groups on its side chain, it is superior to cellulose for further chemical modification and applications. However, the utilization of chitin is restricted by its insolubility in water and common organic solvents. In this study, for the first time, a monolith was prepared by chemical modification of chitin using a thermally induced phase separation (TIPS) method. First, we prepared dibutyrylchitin (DBC) as a starting polymer that is soluble in organic solvents. To prepare the monolith, DBC was dissolved completely in dimethyl sulfoxide (DMSO) while heating, and deionized water was added to the solution. It was then cooled at 20 °C to form a monolith via phase separation. The porous morphology of the DBC monolith was altered by regulating the DBC concentration, DMSO/H2O ratio, and aging temperature. The DBC monolith was converted to a chitin monolith by the alkaline hydrolysis of butyryl ester. The successful hydrolysis of butyryl ester was confirmed by the disappearance of the peak at 1735 cm−1 in the FT-IR spectra, which is related to the ester moiety of DBC. The chitin monolith has the potential to be utilized under water flow for catalysis, metal capture from wastewater, dye sorption, and drug delivery systems.

An anodic porous alumina prepared in phosphoric acid electrolyte was heat-treated under various conditions and structural transformations were investigated. Heating the anodic porous alumina resulted in crystallization from amorphous phase to transition alumina at ∼900 °C; subsequently, aluminum phosphate was formed in the anion-incorporated layer at ∼1000 °C, and finally, phase transition from transition alumina to α-alumina occurred above 1350 °C. The aluminum phosphate particles grew, and sintering of the alumina and phase transition to α-alumina was promoted with increasing temperature and total quantity of heat. When the temperature and total quantity of heat were further increased, aluminum phosphate passed into the gaseous phase and the gas migrated through straight pores to the membrane surface along with sintering of the α-alumina. By removing the aluminum phosphate particles, the introduction of mesopores inside the pore walls and expansion of the surface area can be easily achieved.

We prepared a through-hole α-alumina membrane with a hierarchical porous structure from an anodic porous alumina membrane prepared using phosphoric acid electrolyte as the starting material. By heating the anodic porous alumina membrane to 1400 °C, aluminum phosphate nanoparticles were segregated in the α-alumina matrix at the anion-incorporated outer layer and the high-purity alumina layer forming a cell boundary band sintered as a high-density α-alumina layer at the central core of the pore wall. When the heat-treated membrane was immersed in concentrated hydrochloric acid, a unique hierarchical porous α-alumina membrane structure was formed with straight macropores and mesopores inside the pore wall due to the dissolution of aluminum phosphate nanoparticles. The developed α-alumina membrane can be ultimately used as a multifunctional filter because of its unique hierarchical porous structure and extremely high chemical and thermal durability.

Organic–inorganic CaCO3 capsules were prepared by crystallization of CaCO3 on Pickering emulsion prepared using coacervate droplets made from thermoresponsive and degradable poly(2-methylene-1,3-dioxepane-co-2-hydroxyethyl acrylate) (poly(MDO-co-HEA)) in sole aqueous medium. The diameters of CaCO3-based Pickering emulsion could be controlled by varying several parameters: diameter of CaCO3 powders, initial polymer concentration, and copolymer composition. The CaCO3 Pickering emulsion was able to load low-molecular-weight hydrophobic substances at temperatures above the lower critical solution temperature (LCST) due to formation of polymer-concentrated phases, i.e., coacervate droplets. The diameter of CaCO3 capsules prepared by crystallization also depended on the diameter of the CaCO3 Pickering emulsion. The CaCO3 shell was composed of calcite-type crystals, the most stable polymorph among known CaCO3 crystals. The facially prepared CaCO3 capsules are valuable for use in functional biomaterials, such as ...

This study deals with the unique morphology and properties of methylene diphenyl diisocyanate (MDI)-modified bacterial cellulose/poly(N-isopropylacrylamide) (BC/PNIPAAm) composite hydrogel prepared by in situ polymerization method. The influence of the molar ratio of MDI/glucose unit of BC on the properties of the resulting hydrogel was investigated. Scanning electron microscopic analysis revealed that after the MDI modification the BC/PNIPAAm hydrogel could preserve the unique layered (known as anisotropic) structure. The mechanical property evaluated by stress–strain test was significantly enhanced when compared to that of neat PNIPAAm hydrogel, due to the presence of the BC matrix as well as the MDI modification. Based on the deswelling behaviors, the BC/PNIPAAm hydrogel exhibited improved and controlled responsive rate when compared with neat PNIPAAm hydrogel. Furthermore, the anisotropic thermo-sensitive property was proved by temperature-responsive test with the fact that the composite hydrogel could only deswell and swell in the axial perpendicular to the layers. Along with desired recyclability, the present composite hydrogel may have an application as artificial muscles.

A novel strategy for fabricating sea cucumber-mimicking hydrogels composed of a bacterial cellulose matrix and a stimuli-responsive polymer is presented. This mechanically adaptive hydrogel shows a unique reversible stiffness change in response to its ionic strength without any significant volume changes.

Starch is the most abundant biomass and potential replacement of single-use packaging; however, the lack of water durability and wet strength restrict the applicability of starches. Hemiacetal/acetals cross-linked starch film have water stability, however, the film possess poor wet strength owing to lack of crystallinity. In this study, we prepared TEMPO-oxidized cellulose nanofiber (TCNF)/starch composite films by mixing different-storage-duration native tapioca starch (NTS), hydroxypropyl starch (HPS), and di-aldehyde starch (Di-aldS) with TCNF. We demonstrate that the films prepared with the stored starch pastes exhibit improved mechanical properties and wet strength owing to the synergistic effect of enhanced crystallinity and hemiacetal crosslinking. However, long-term storage of the starch pastes negatively affected their properties. Thus, improving the film properties by optimizing the starch paste storage time is an environmentally friendly and energy-conserving method. Moreover, our experimental results suggest that TCNF/HPS films prepared with the HPS paste stored for three days (~22 °C, ~25% RH) can be a potential alternative to single-use packaging films.

As one of the polyhydroxyalkanoates (PHA), which are biodegradable and available in nature, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) is a good alternative to deal with the environmental problems caused by traditional plastics. However, only some studies have investigated the surface modification of PHBH to expand its applications. In this study, surface modification of the PHBH film/fibrous membrane was achieved via oxidation using the light-activated chlorine dioxide radical (ClO2•) gas. After surface oxidation, the ratio of the oxygen-containing functional groups on the PHBH film surface increased and the improvement in surface hydrophilicity was confirmed. In addition, the effects of the ratio of 3-hydroxyhexanoate in PHBH and the oxidation time were investigated. Surface modification via oxidation improved the adhesion property of the metal layer plated on the PHBH film surface and the dyeability of the PHBH fibrous membranes using cationic dyes. Therefore, this clean and effective oxidation method is a potential surface modification methodology that can broaden the practical applicability of the PHBH materials.

A novel thermoresponsive and biodegradable polymer, poly(MDO- co -HEA), was prepared by radical copolymerization of 2-methylene-1,3-dioxepane (MDO) and a hydrophilic vinyl monomer, 2-hydroxyethyl acrylate (HEA), in dimethylsulfoxide (DMSO), varying feed monomer compositions. Poly(MDO- co -HEA) showed lower critical solution temperature (LCST)-type phase separation in aqueous medium, forming coacervate droplets into which low molecular weight hydrophobic molecules could be loaded above the LCST. The LCST could be controlled not only by the chemical compositions of the hydrophobic MDO and hydrophilic HEA in the polymer chains, but also by ion and polymer concentration. Degradation tests in aqueous media indicated that poly(MDO- co -HEA) was converted into hydrophilic oligomers by hydrolysis of the ester groups in the polymer backbone. The facile preparation poly(MDO- co -HEA) are valuable for use in functional biomedical materials, such as base of drug delivery carrier and cell culture scaffold instead of non-degradable stimuli-responsive polymer.

The thickness and corrosion resistance of films formed on AZ31 magnesium alloys through plasma electrolytic oxidation for the same amount of electricity supplied increased with decreasing electrolyte concentration irrespective of the current density. For all electrolytes of phosphate, silicate, and aluminate, the initial bending/breakdown voltage increased linearly with the logarithm of the decreasing electrolyte concentration and exhibited no dependence on the current density. The chemical composition of the films was independent of all electrolysis conditions such as electrolyte concentration, current density, and anodization time. This behavior is explained by a mechanism in which anion incorporation is governed by a chemical reaction/precipitation under plasma but not by the electric field, unlike the case for conventional anodizing of valve metals without sparking. The corrosion resistance of the films tended to increase as a function of the logarithm of the film thickness, irrespective of the electrolyte species and electrolysis conditions.

Alumina is classified as an intermediate oxide that cannot form a glass and is industrially used as a multifunctional material. Intensive studies on the atomistic structure of amorphous alumina have been conducted because a fundamental understanding of its structure can be meaningful to the design of new materials and devices. Here we focused on anodic alumina as a model material for clarifying the atomistic structure of amorphous alumina and prepared anion-free and anion-incorporated porous-type amorphous alumina by anodization using chromic acid electrolyte and typical electrolytes (e.g., sulfuric acid, oxalic acid, and phosphoric acid), respectively. The local structure around aluminum atoms in the anodic alumina was investigated by nuclear magnetic resonance spectroscopy. We found that the structure of anodic amorphous alumina comprises AlO4, AlO5, and AlO6 units with predominant fractions of AlO5. We also observed that the fraction of each unit was 37.7, 54.3, and 8.0%, with an average coordination n...

A transparent bacterial cellulose/atactic polypropylene (BC/at-PP) composite film was prepared by a very facile “sandwich” hot-press method. The resulting BC/at-PP composite film exhibited good transparency, hydrophobicity, and significantly enhanced mechanical properties, indicating its tremendous potential as transparent film for food packaging and optoelectronics applications.

The greatest challenge hindering the use of cellulose as a reinforcing filler in polymeric composites is its poor compatibility due to the inherent hydrophilicity of cellulose and the hydrophobic nature of polymeric matrices. To solve this issue, we demonstrate an effective water-based method to render the cellulose surface with high carboxyl content through the esterification of hydroxyl groups with citric acid in a solid phase reaction without the use of noxious solvents. The modified cellulose was then further hydrophobized by grafting magnesium stearate to the surface. Consequently, the flexural properties of PP composites reinforced by the hydrophobized cellulose fillers were greatly improved compared to those of composites containing hydrophilic cellulose and pure PP resin. The surface modification conditions and filler proportions in composites were optimized. Because of the innocuity and cost-efficiency of citric acid, we believe that citric acid-modified cellulose has immense potential as a sustainable and cost-effective reinforcing filler.

A highly effective, stable and reusable flow microreactor was developed by utilizing the environmentally sustainable porous monolithic cellulose based on a facile temperature induced phase separation (TIPS) method. The obtained microreator could be applied to efficiently and continuously catalysing the reduction reaction of 4-nitrophenol (an important reaction in water treatment) without any post-treatment or regeneration of catalysts. Moreover, the monolith overcame the brittleness of the crystalline cellulose and showed a good mechanical resilience, suggesting a great potential for the practical application in severe environment. Compared with previous reported Pd supported catalytic systems, this microreactor exhibited extremely high catalytic efficiency (turnover frequency, TOF = 4660 h−1, almost 4 times higher than that of cellulose nanocrystals supported catalyst) and long-term stability. This work provided a new strategy to construct highly effective and reusable metal NPs involved catalytic system by utilizing biodegradable cellulose materials.

In this study, we use advanced analysis techniques to examine the nanostructures of anodic films formed on aluminum in various electrolytes, including oxalic acid and sulfuric acid, in the original state (without being chemically dissolved) and reveal that pores grow with radially branched nanopores. Nanopores are generated in the main pores for the same reason that initial small pores are generated on the film surface: nanopores are created when the electric field is reduced due to the presence of a thick barrier layer. These radially branched nanopores appear in a form characteristic of a film formed in chromic acid, producing a feather-like pore wall. As a representative model, the atypical porous structures created in the film formed in chromic acid were classified into five categories: initial small pores, branched pores, side holes, spherical voids, and radially branched nanopores. We demonstrate that these structures are not unique to chromic acid films but are a universal phenomenon, particularly radial nanobranching, which occurs naturally during the anodizing of most electrolytes.