A facile method for preparation superhydrophobic paper with enhanced physical strength and moisture-proofing property

Fabrication and characterization of an alginate-based film incorporated with cinnamaldehyde for fruit preservation

Sodium alginate (SA) is widely used in the food, biomedical, and chemical industries due to its biocompatibility, biodegradability, and excellent film-forming properties. This article introduces a simple method for preparing uniform alginate-based packaging materials with exceptional properties for fruit preservation. The alginate was uniformly crosslinked by gradually releasing calcium ions triggered by the sustained hydrolysis of gluconolactone (GDL). A cinnamaldehyde (CA) emulsion, stabilized by xanthan without the use of traditional surfactants, was tightly incorporated into the alginate film to enhance its antimicrobial, antioxidant, and UV shielding properties. The alginate-based film effectively blocked ultraviolet rays in the range of 400-200 nm, while allowing for a visible light transmittance of up to 70 %. Additionally, it showed an increased water contact angle and decreased water vapor permeability. The alginate-based film was also employed in the preparation of coated paper through the commonly used coating process in the papermaking industry. The alginate-based material displayed excellent antioxidant properties and antimicrobial activity against Escherichia coli, Staphylococcus aureus and Botrytis cinerea, successfully extending the shelf life of strawberries to 7 days at room temperature. This low-cost and facile method has the potential to drive advancements in the food and biomedical fields by tightly incorporating active oil onto a wide range of biomacromolecule substrates.

Facile fabrication of cellulose-based hydrophobic paper via Michael addition reaction

The inherent highly hydrophilic feature of cellulose-based paper hinders its application in many fields. Herein, a cellulose-based hydrophobic paper was fabricated based on surface chemical modification. Firstly, the hydrophobic acrylate components were bonded to the cellulose acetoacetate (CAA) fibers to obtain CAA graft acrylate (CAA-X) fibers through Michael addition reaction. Subsequently, CAA-X fibers were processed into paper via wet papermaking technology. The resulting paper exhibited good hydrophobic performance (water contact angle was up to 135°) with an air permeability of 24.8 μm/Pa·s. The hydrophobicity of paper was very stable and remained even after treating with different solvents. Moreover, the hydrophobic properties of this paper could be adjusted by changing the type of acrylate component. It should be noted that the surface modification strategy has no obvious effects on the whiteness (79.8%), writing, and printing properties of the cellulose fibers. Thus, it is a simple, benign, and efficient strategy for the construction of cellulose-based hydrophobic paper, which has great potential to be used in paper tableware, oil-water separation, watercolor protection, and food packaging fields.

Superhydrophobic cellulose paper with sustained antibacterial activity prepared by in-situ growth of carvacrol-loaded zinc-based metal organic framework nanorods for food packaging application

Cellulose paper packaging materials have gained considerable attention as substitutes for petroleum-based plastics owing to their biodegradability, renewability, flexibility, and good mechanical strength. However, high hydrophilicity and the absence of essential antibacterial activity limit their application in food packaging. In this study, a facile and energy-saving method was developed to improve the hydrophobicity of cellulose paper and endow it with a long-acting antibacterial effect by integrating cellulose paper substrate with metal-organic frameworks (MOFs). A dense and homogenous coating of regular hexagonal ZnMOF-74 nanorods was in-situ formed on a paper surface by layer-by-layer assembly followed by low-surface-energy polydimethylsiloxane (PDMS) modification to prepare a superhydrophobic PDMS@(ZnMOF-74)₅@paper. Excellent anti-fouling, self-cleaning, and antibacterial adhesion performances were obtained for this superhydrophobic paper. In addition, active carvacrol was loaded into the pores of ZnMOF-74 nanorods on PDMS@(ZnMOF-74)₅@paper to combine antibacterial adhesion together with bactericidal ability, ultimately resulting in a completely "bacteria-free" surface and sustained antibacterial performance. The resultant superhydrophobic papers not only showed overall migration values within the limit of 10 mg/dm² but also good stability against various harsh mechanical, environmental, and chemical treatments. This work gave insights into the potential of in-situ-developed MOFs-dopped coating as a functionally modified platform for preparing active superhydrophobic paper-based packaging.

Investigation of grafting silane coupling agents on superhydrophobicity of carbonyl iron/SiO2 particles for efficient oil/water mixture and emulsion separation

The present study demonstrated the wettability properties of grafting silane coupling agents on carbonyl iron (CI)/SiO₂ particles for efficient oil/water mixture and emulsion separation. CI particles were first reacted with Tetraethoxysilane (TEOS) to create a magnetic component. Then, CI/SiO₂ particles were altered by 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS) and Hexamethyldisilazane (HDMS) to create magnetic superhydrophobic/superoleophilic, recyclable, and reusable sorbent powders. The water contact angle (WCA) values of the as-prepared particles, CI, CI/SiO₂, CI/SiO₂@FAS, and CI/SiO₂@HMDS, were 5.4° ± 1.3°, 6.4° ± 1.4°, 151.9° ± 2.1°, and 170.1° ± 1.1°, respectively. In addition, the oil contact angles (OCAs) of a variety of oils were found to be equivalent to 0°. Hence, superhydrophobic/superoleophilic particles for kind of different oils were shown sorption capacities of 1.7-3.1 g/g and 2.5-4.3 g/g for CI/SiO₂@FAS, and CI/SiO₂@HMDS, respectively. Besides, for 1%w/w hexane/water emulsion separation efficiency higher than 99%, the lowest mass was obtained at 50 and 200 mg for CI/SiO₂@HDMS and CI/SiO₂@HDMS, respectively, suggesting a new effective material for separating tiny oil droplets. Also, the reusability and chemical durability of the superhydrophobic samples made them a prime candidate for use in different harsh conditions.

Layer-by-Layer Self-Assembly Coating for Multi-Functionalized Fabrics: A Scientometric Analysis in CiteSpace (2005-2021)

Surface-engineered coatings have been increasingly applied to functionalize fabrics due to the ease of deposition of the coatings and their effectiveness in endowing the fabric with abundant properties. Among the surface modification methods, layer-by-layer (LbL) self-assembly has emerged as an important approach for creating multifunctional surfaces on fabrics. In this review, bibliometric analysis with the visualization analysis of LbL self-assembly coatings on fabrics was performed on publications extracted from the Web of Science (WOS) from 2005 to 2021 based on the CiteSpace software. The analysis results showed that research on LbL self-assembly coatings on fabrics has attracted much attention, and this technique has plentiful and flexible applications. Moreover, research on the LbL self-assembly method in the field of functionalization of fabrics has been summarized, which include flame retardant fabric, antibacterial fabric, ultraviolet resistant fabric, hydrophobic fabric and electromagnetic shielding fabric. It was found that the functionalization of the fabric has been changing from singularity to diversification. Based on the review, several future research directions can be proposed. The weatherability, comfort, cost and environmental friendliness should be considered when the multifunctional coatings are designed.

Challenges and recent trends with the development of hydrogel fiber for biomedical applications

Hydrogel is the most emblematic soft material which possesses significantly tunable and programmable characteristics. Polymer hydrogels possess significant advantages including, biocompatible, simple, reliable and low cost. Therefore, research on the development of hydrogel for biomedical applications has been grown intensely. However, hydrogel development is challenging and required significant effort before the application at an industrial scale. Therefore, the current work focused on evaluating recent trends and issues with hydrogel development for biomedical applications. In addition, the hydrogel's development methodology, physicochemical properties, and biomedical applications are evaluated and benchmarked against the reported literature. Later, biomedical applications of the nano-cellulose-based hydrogel are considered and critically discussed. Based on a detailed review, it has been found that the surface energy, intermolecular interactions, and interactions of hydrogel adhesion forces are major challenges that contribute to the development of hydrogel. In addition, compared to other hydrogels, nanocellulose hydrogels demonstrated higher potential for drug delivery, 3D cell culture, diagnostics, tissue engineering, tissue therapies and gene therapies. Overall, nanocellulose hydrogel has the potential for commercialization for different biomedical applications.

Processing and characterization of thermoplastic corn starch-based film/paper composites containing microcrystalline cellulose

BACKGROUND

Different thermoplastic starch (TPS) films were prepared with or without the addition of microcrystalline cellulose (MCC) obtained via the melt-extrusion method, and then the hot-press method was used to produce environmentally friendly TPS-based film/paper composites to replace petroleum-based materials.

RESULTS

The paper-plastic composites exhibited good interfacial adhesion from the scannign elctron microscopy images. It was seen that 5 wt.% MCC was added to reinforce the mechanical properties of TPS films, such that it also improved the barrier properties of MCC@TPS/paper composites and extended the path of water vapor through TPS films, which decreased the water vapor transmission rate of MCC@TPS/paper composites. TPS/paper composites and MCC@TPS/paper composites have better physical properties (i.e. smoothness, flexibility and folding resistance) than only paper. In particular, it was found that the water contact angle of MCC@TPS/paper composites and TPS/paper composites were higher than single-layer paper. Furthermore, MCC reinforced paper-plastic composites demonstrated good barrier properties which can meet the requirement of the need for lower water sensitive materials in the food packaging industry.

CONCLUSION

Thermoplastic corn starch-based film/paper composites have good application properties as a potential source of bioplastic materials. © 2021 Society of Chemical Industry.

Design and Preparation of Multiple Function-Integrated Lignin/Tannin/ZnONP Composite Coatings for Paper-Based Green Packaging

Lignin/tannin/ZnONP composite coatings were designed for paper-based green packaging. Multiple functions, such as high strength, moisture resistance, low air permeance, heat endurance, UV aging resistance, and antibacterial/mold properties, were successfully integrated into one biobased coating. Prepolymerization improved the physical properties of coatings at high lignin contents. The best ingredient ratio was: 40% lignin, 15% tannin, and 10% ZnONPs (based on tannin weight), and the as-prepared biocoating was labeled LTZn-10. After coated with LTZn-10, the tensile strength and bursting strength of the packaging were efficiently enhanced by more than 3 times and were dramatically increased by 51.6 and 5.6 times at the wet state, respectively, which reveals that the packaging has favorable moisture resistance and it can be used in high humidity environments. Scanning electron microscopy (SEM) proved that most of the pores on the paper were blocked by the coatings, which helped to decrease the air permeance by 10.3 times. Meanwhile, ZnONPs were evenly spread on the coatings, which endowed the packaging with excellent antibacterial/mold performance. No colony or mycelium was found in the test against Gram-negative/positive bacteria and eight common molds. Besides, antibacterial activity is only available while the bacteria come in contact with the coating and no active substances were released into the culture medium, which is a good property that can keep the cargo from contamination of antibacterial agents. In addition, the coated paper presented an improved T_g and thermal degradation temperature, indicating that the coated package has favorable thermostability and can maintain its outstanding physical properties in a wider temperature range. Lignin and tannin promoted the UV stability and service life of the coated paper, as a rare physical decrease was observed after UV aging for 72 h. The function-integrated biobased coating with favorable sustainability is a good candidate to be widely used in paper-based green packaging fields.

Improving air barrier, water vapor permeability properties of cellulose paper by layer-by-layer assembly of graphene oxide

A paper-based packaging material with improved air barrier and water vapor permeability (WVP) properties was synthesized based on layer-by-layer assembly consisted of poly(ethylenimine) (PEI)/graphene oxide (GO) on a filter paper substrate. The effect of the pH of GO suspension on the zeta potential and air permeability (AP) of the modified paper was investigated in detail. The results indicated that the pH of GO suspension resulted in significant difference in the AP of the modified paper. Compare with the pristine paper, the AP of the modified paper with (PEI/GO)₁₀ multilayer films synthesized at pH 2.5 decreased by 99.99 %, while the WVP increased by 15.82 %. The modified paper as packaging material could prolong the shelf-life of oyster mushroom, indicating the modified paper has huge potential application on the preservation of agricultural products.

Reduced graphene oxide-TiO2/sodium alginate 3-dimensional structure aerogel for enhanced photocatalytic degradation of ibuprofen and sulfamethoxazole

In this study, graphene oxide and titanium dioxide in combination with sodium alginate were used to synthesize the reduced graphene oxide-TiO₂/sodium alginate (RGOT/SA) aerogel. The potential of RGOT/SA aerogel was evaluated for the photocatalytic degradation of ibuprofen and sulfamethoxazole and was compared with that of bare titanium dioxide nanoparticles. More than 99% removal of both the contaminants was obtained within 45-90 min by using the RGOT/SA aerogel under UV-A light. Mineralization of both the pollutants was also higher in case of RGOT/SA aerogel as compared to bare TiO₂ nanoparticles. The optimal mass ratio of TiO₂ nanoparticles with respect to graphene oxide was 2:1 in RGOT/SA aerogel in the presence of 1 wt% sodium alginate solution. High photodegradation of Ibuprofen was observed at neutral pH and acidic to neutral pH was found suitable for the photodegradation of sulfamethoxazole. Three-dimensional interconnected macroporous assembly, large surface area for settling TiO₂ nanoparticles, efficient charge partitioning, and enhanced physical and chemical adsorption of ibuprofen and sulfamethoxazole on the surface of RGOT/SA aerogel were the significant characteristics of RGOT/SA aerogels. Moreover, ease of separation and recyclability of the RGOT/SA aerogel could further save the extra energy used to separate nanoparticles from the effluent.

Preparation of Fluorine-Free Superhydrophobic Paper with Dual-Response of Temperature and pH

Although various superhydrophobic materials have been manufactured and effectively used for oil–water separation, it is still highly desirable to explore materials which are eco-friendly, low-cost, and multifunctional. In this paper, a stable copolymer solution was prepared from the fluorine-free superhydrophobic copolymer with dual-responsiveness of temperature and pH. The functional superhydrophobic paper was prepared by immersing paper in copolymer solution by the dip-coating method. The surface element and structure analysis of the prepared superhydrophobic paper shows that the dual-responsive copolymer adheres successfully to the surface of the paper without destroying the fiber structure of the paper. At pH ≥ 7 and T > 25 °C, the paper has a good superhydrophobic performance, while under the conditions of pH < 7 and T < 25 °C, the paper comes into a hydrophilic state. Therefore, the dual-responsive superhydrophobic paper is more likely to adapt to the complicated oil-water separation environment than the single-response.

Superhydrophobic Surfaces with pH-Induced Switchable Wettability for Oil-Water Separation

The oily wastewater generated in the industrial field is adversely affecting the environment, while the current methods for oil-water separation are complex and costly. Therefore, it is significant to use low cost and environmentally friendly materials to prepare a smart responsive superhydrophobic coating for the effective separation of oil-water mixtures. In this paper, a fluorine-free copolymer with pH responsiveness was fabricated by a solution impregnation method, and it was compounded by silica nanoparticles/polydimethylsiloxane to prepare a superhydrophobic coating on the paper and cotton fabric. The prepared superhydrophobic coating remained in the superhydrophobic state after the alkali treatment, while it would be converted into the hydrophilic state after the acid treatment. Therefore, the pH-responsive superhydrophobic coating will be applied in controlled selective oil-water separation.

Facile Approach to Develop Hierarchical Roughness fiber@SiO2 Blocks for Superhydrophobic Paper

Papers with nanoscaled surface roughness and hydrophobically modification have been widely used in daily life. However, the relatively complex preparation process, high costs and harmful compounds have largely limited their applications. This research aims to fabricate superhydrophobic papers with low cost and nontoxic materials. The surface of cellulose fibers was initially coated with a film of SiO2 nanoparticles via sol-gel process. After papermaking and subsequent modification with hexadecyltrimethoxysilane through a simple solution-immersion process, the paper showed excellent superhydrophobic properties, with water contact angles (WCA) larger than 150°. Moreover, the prepared paper also showed superior mechanical durability against 10 times of deformation. The whole preparation process was carried out in a mild environment, with no intricate instruments or toxic chemicals, which has the potential of large-scale industrial production and application.

Hydrophobization of Kraft-type Cellulose and Microfiber Cellulose Obtained from Soybean Husk in Ultrasonic Field

BACKGROUND

The addition of nanoparticles to cellulose paper can improve its mechanical strength, chemical stability, biocompatibility and hydrophobic properties. Silica nanoparticles are known to be inert, hydrophobic, biocompatible, biodegradable and have a good distribution in being deposited on surfaces. The main characteristics of 20 nm SiO2 nanoparticles are good chemical and thermal stability with a melting point of 1610-1728°3C, a boiling point of 2230°C with a purity of 99.5%.

OBJECTIVE

To carry out the hydrophobization of paper based on Kraft cellulose and on cellulose obtained from soybean husk with 20-nm size SiO2 nanoparticles and to study hydrophobicity, morphology and topography of the prepared composites.

METHODS

The ground and roasted soybean husk was treated with a NaOH, washed and dried. Hydrophobization of paper was carried in aqueous medium by SiO2 addition in weight ratios "paper-SiO2" of 0.01-0.05 wt.%, stirring, filtration and drying. The obtained cellulose sheet composites were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), FTIRspectroscopy, Mullen proofs of hydrophobicity, and contact angle measurements.

RESULTS

The mechanical properties of paper nanocomposites (tensile strength and compression) increased considerably by varying the concentrations. The tensile strength increased by 41-46% and the compressive strength increased by 55-56%. The existence of fiber nanofoils, good adhesion of 20-nm SiO2 nanoparticles to the paper surface, and their homogeneous distribution were observed.

CONCLUSION

Cellulose was successfully obtained from soybean husk, applying the alkaline-based extraction method. A good reinforcement of cellulose fibers is observed due to the outstanding characteristics of the silicon dioxide nanoparticles.

Recent Developments in Food Packaging Based on Nanomaterials

The increasing demand for high food quality and safety, and concerns of environment sustainable development have been encouraging researchers in the food industry to exploit the robust and green biodegradable nanocomposites, which provide new opportunities and challenges for the development of nanomaterials in the food industry. This review paper aims at summarizing the recent three years of research findings on the new development of nanomaterials for food packaging. Two categories of nanomaterials (i.e., inorganic and organic) are included. The synthetic methods, physical and chemical properties, biological activity, and applications in food systems and safety assessments of each nanomaterial are presented. This review also highlights the possible mechanisms of antimicrobial activity against bacteria of certain active nanomaterials and their health concerns. It concludes with an outlook of the nanomaterials functionalized in food packaging.

Superhydrophobicity, UV protection and oil/water separation properties of fly ash/Trimethoxy(octadecyl)silane coated cotton fabrics

The presented study proposed simple and low-cost approach for improvement in UV protection and superhydrophobic properties of cotton fabrics by coating of mechanically activated fly ash particles. The maximum UV blocking was observed for 3 wt% fly ash, where UV transmittance decreased from 14.19% of untreated fabric to 0.11% of coated fabric. After subsequent treatment of Trimethoxy(octadecyl)silane (OTMS) on fly ash coated fabrics, the water contact angle was increased to 143°, 147° and 153° for fly ash concentration of 1, 2 and 3 wt% respectively. From Cassie-Baxter theories, the unwetted fraction of air pockets were estimated to be 43%, 55% and 67% respectively for 1, 2 and 3 wt% of fly ash particles. Furthermore, the coated fabrics showed great potentials for separation of floating oil layer, underwater oil droplet or oil/water mixture. The separation efficiency of 98%, 96%, 97% and 95% was obtained for selected model oils toluene, n-hexane, chloroform and petro ether, respectively.