Combination of microsized mineral particles and rosin as a basis for converting cellulosic fibers into “sticky” superhydrophobic paper

Multiple cross-linked cellulosic paper-based waterproof and biodegradable mulch film for "green" agriculture

Biodegradable cellulosic mulch has been demonstrated as the promising alternative to traditional plastic mulch film in agriculture, whereas the highly hydrophilic property and poor wet strength severely restricted their practical application. Herein, a new waterproof dialdehyde cellulose (OR)-polyamide epichlorohydrin (P)-alkyl ketene dimer (A) (OR-P-A) was carefully designed as the green mulch film. The hydrogen bonds and Schiff base reaction between -CHO on dialdehyde cellulose fibers and -NH2 on PAE reinforced the interfacial interaction of cellulosic fibers. Furthermore, the formed β-keto ester bonds of -OH on cellulose with AKD improved the water resistance of paper fiber. Compared with the pristine cellulose film, the dry and wet tensile strength of OR-P-A2 were increased to 17 MPa and 3 MPa, respectively. Moreover, the water contact angle was increased from 25° for pristine cellulose film to 124° for OR-P-A2. In addition, the germination rate of cabbage seeds covered by OR-P-A2 was similar to that of commercial polyethylene film in practical application. This strategy proposed a novel method to improve the hydrophobicity of cellulose film, which boosting the development of biodegradable mulch film and "green" agriculture.

Fabrication of hydrophobic cellulosic paper via physical vapor deposition of alkenyl succinic anhydride

While plant fibers are abundant and biodegradable natural polymers, their high hydrophilicity often limits their applicability. To broaden the applicability of plant fiber materials across diverse fields, the present study employed cellulosic paper as a substrate and alkenyl succinic anhydride (ASA) as a low surface free energy material to fabricate a series of hydrophobic cellulosic papers (ASAP, ASA-P@Si, ASA-P@Ca, and ASA-P@Ti) through surface coating and physical vapor deposition of ASA. The results demonstrated that, in comparison to uncoated cellulosic paper, the coated variants exhibited significantly improved hydrophobicity. Notably, ASA-P@Si demonstrated superior hydrophobic performance with a contact angle of 140.90° and a sizing degree of 7.2 s, thereby meeting the requirements for specific fine paper grades. In contrast to the traditional ASA internal sizing process, the method in this study necessitates only approximately one-tenth of the conventional ASA internal sizing agent to achieve or even exceed the hydrophobic properties of paper attainable with ASA inter sizing process. Furthermore, the mechanism through which hydrophobic properties are conferred to paper can be elucidated by its surface roughness and low surface free energy, distinguishing it from the traditional ASA internal sizing approach.

Superhydrophobic modification of cellulosic paper-based materials: Fabrication, properties, and versatile applications

Cellulose is the cheapest and mostly widespread green raw material on earth. Due to the easy and versatile developed modification of cellulose, many cellulosic paper-based sustainable materials and their multifunctional applications have attained increasing interest under the background of the implementation of the "plastic ban" policy. However, intrinsic cellulose paper is hydrophilic and non-water-proof, which highly limited its application, thus becoming a bottleneck for the development of "cellulosic paper-based plastic replacement". Unquestioningly, the superhydrophobic modification of cellulosic paper-based materials and the extension of their high value-added applications are highly desired, which is the main content of this review. More importantly, we presented the comprehensive discussion of the functionalized applications of superhydrophobic cellulosic paper-based materials ranging from conventional products to high value-added functional materials such as paper straw and paper mulch film for the first time, which have great industrialization potential and value. This review would offer the valuable guidance and insightful information for the rational construction of sustainable superhydrophobic cellulosic paper for advanced functional devices.

Functional Chitosan-Calcium Carbonate Coatings for Enhancing Water and Fungal Resistance of Paper Materials

The objective of this study was to increase the water resistance of paper while providing fungal resistance using a bio-based coating made from chitosan. The water resistance was improved through the surface control of roughness using modified calcium carbonate particles. The higher the quantity of particles in the film-forming solution, the higher the surface hydrophobicity of the paper. The addition of particles was found to counterbalance the chitosan hydrophilicity through the control of the coatings' penetration in the paper bulk. As a consequence, the wetting time and liquid water resistance were enhanced. The antifungal activity of the film-forming solutions and coated paper was also investigated against the growth of Chaetomium globosum, which was selected as a model strain able to contaminate paper materials. The results reveal that the antifungal activity of chitosan was improved by a possible synergic effect with the bicarbonate ions from the mineral particles.

Diatomite Modified with an Alkyl Ketene Dimer for Hydrophobicity of Cellulosic Paper

Multifunctionalization of papermaking chemicals is one of the main developing strategies. Fillers and internal sizing agents are often mutually restricted in practice. Therefore, it is feasible to prepare a new papermaking chemical by combining the functions of both. A process of diatomite modified with an alkyl ketene dimer (AKD) was developed in this study. The modified diatomite (AD) can concurrently play the role of a mineral filler and sizing agent in the papermaking process. With the equal dosage of AKD, the AD showed better sizing and retention performance than the commercial AKD emulsion in the case of cationic polyacrylamide (CPAM) and the CPAM/bentonite retention system. The sizing mechanism of the AD can be interpreted to be due to numerous hydrophobic sites and the microsurface structure of the paper sheet caused by the AD. Since ketones were not detected in Fourier-transform infrared spectra of the paper sheet filled by the AD, the chemical reaction may not be indispensable for its sizing performance. What is more, an interesting "sticky" hydrophobicity phenomenon was observed when filling with AD. The approach in this study to prepare the "sticky" hydrophobic paper sheet can find its applications in some nontraditional application fields of cellulosic paper.

The Effects of Zinc Oxide/Silicon Dioxide Composite Coating on Surface Wettability and the Mechanical Properties of Paper Mulching Film

In order to improve the hydrophobic and mechanical properties of paper mulch film, ZnO/SiO2 composite coated paper mulch film was prepared with a brush coating method. Hydrophobicity and durability of the original paper mulch film and the coated paper mulch film were measured by static contact angle and mechanical torsion tests, and the mechanical properties of the two kinds of paper mulch films were measured by tensile and tear tests at different temperatures. The two kinds of paper mulch films were characterized by their micro-morphology and surface element distribution. The results show that the contact angle of the ZnO/SiO2 composite coated paper mulch film reaches 161.46°, and the contact angle can still reach 153.15° after 80 mechanical torsion cycles, which shows good superhydrophobic and hydrophobic durability. Compared with the original paper mulch film, the mechanical properties of the coated paper mulch film are also improved to some extent. Combined with the surface micro-morphology, it is found that a ZnO/SiO2 composite coating fills the pores between fibers in the paper mulch film and promotes the adhesion between fibers, thus improving the hydrophobicity, durability, and mechanical properties of the paper mulch film.

Crude Wood Rosin and Its Derivatives as Hydrophobic Surface Treatment Additives for Paper and Packaging

The aim of this work is to obtain better water resistance properties with additives to starch at the size press. A further goal is to replace petroleum-based additives with environmentally friendly hydrophobic agents obtained by derivatization of wood rosin. A crude wood rosin (CWR) sample was methylated and analyzed with gas chromatography-mass spectrometry (GC-MS). Methyl abietate, dehydroabietic acid, and abietic acid were the main constituents of the sample. The crude wood rosin samples were fortified with fumaric acid and then esterified with pentaerythritol. Fortified and esterified wood rosin samples were dissolved in ethanol and emulsified with cationic starch to make them suitable as hydrophobic additives for surface treatment formulations in mixtures with starch. These hydrophobic agents (2% on a dry weight basis in a cationic starch solution) were applied to paperboard, bleached kraft paper, and test liner paper using a rod coater with a target pickup of 3-5 gsm. The solution pickup was controlled by varying the rod number. The amounts of hydrophobic material applied in the preparation of the paper samples were 32.2, 48.6, and 35.1 lb/ton pickup compared to three types of base papers. Basic surface features of fortified and fortified and esterified rosin-treated paper were compared with base paper and paper treated with starch alone. Lower Cobb₆₀ values were obtained for fortified and esterified samples than for linerboard samples that had been surface-sized just by starch. Thus, as novel hydrophobic additive agents, derivatives of CWR can be a green way to increase hydrophobicity while reducing starch consumption in papermaking.

Preparation and characterization of highly transparent hydrophobic nanocellulose film using corn husks as main material

In this paper, nanocellulose was extracted from agricultural waste corn husks. Transparent hydrophobic membranes containing silica were fabricated through two facile methods including surface coating and internal grafting. The results showed that: the nanocellulose prepared by TEMPO-mediated oxidation and high pressure homogenization not only retained the type and crystal structure of the original cellulose, but also increased the crystallinity to 64.5% and improved the thermal stability. Both surface coating and internal grafting methods had successfully loaded silica onto films. The internal grafting film had a silica content of 10.5%, which was mainly present inside the film. The light transmittance of this film was 84.4% and the surface contact angle to water was 152.6°. The content of silica on the surface coating film was 5.7%, and they were mainly distributed on the surface of the film to form a nano-scale rough surface. The light transmittance of the surface coating film was 87.8% and the surface contact angle to water was 165.7°. Compared to the film prepared by internal grafting method, the nanocellulose film prepared by surface coating method contained less nano silica and had better properties including higher transparency, higher surface roughness and excellent hydrophobic anti-fouling properties.

Advances in Rosin-Based Chemicals: The Latest Recipes, Applications and Future Trends

A comprehensive review of the publications about rosin-based chemicals has been compiled. Rosin, or colophony, is a natural, abundant, cheap and non-toxic raw material which can be easily modified to obtain numerous useful products, which makes it an excellent subject of innovative research, attracting growing interest in recent years. The last extensive review in this research area was published in 2008, so the current article contains the most promising, repeatable achievements in synthesis of rosin-derived chemicals, published in scientific literature from 2008 to 2018. The first part of the review includes low/medium molecule weight compounds: Especially intermediates, resins, monomers, curing agents, surfactants, medications and biocides. The second part is about macromolecules: mainly elastomers, polymers for biomedical applications, coatings, adhesives, surfactants, sorbents, organosilicons and polysaccharides. In conclusion, a critical evaluation of the publications in terms of data completeness has been carried out with an indication of the most promising directions of rosin-based chemicals development.