Bio-based Coatings Research Articles

Self-healing poly(oxime–carbamate) films with tunable mechanical properties derived from rosin

Thermoset polymers with superior dimensional stability and creep resistance have been widely used in various electronic and energy devices. However, they are difficult to reprocess and recycle, and with the gradual decrease in nonrenewable resources, there is an urgent need for new sustainable materials as alternatives to thermoset polymers. Polymer materials with self-healing properties can provide high durability and sustainability for devices. In this work, we prepared a series of rosin-based poly(oxime–carbamate) films by reacting rosin acrylate/glycidyl methacrylate ester with toluene 2, 4-diisocyanate using dimethylglyoxime as the chain extender and triethanolamine as the crosslinking agent. The introduction of rosin with a rigid tricyclic phenanthrene structure in the prepared films resulted in excellent tensile strength (4.9 ± 0.03 MPa) while maintaining high elongation at break (973.2 % ± 4.8 %) and toughness (20.9 ± 0.1 MJ m−3). The good self-healing properties of the prepared films (90.6 % ± 1.5 %, 60 °C for 3 h) were attributed to the introduction of dynamic oxime–carbamate bonds. In particular, the tunable mechanical and self-healing properties of the films can be achieved by varying the molar ratio of rosin acrylate/glycidyl methacrylate ester to dimethylglyoxime. Furthermore, the prepared rosin-based films exhibited good adhesion, welding, and anticorrosion properties. Considering the reversible exchange mechanism of dynamic oxime–carbamate bonds and their use in self-healing and recycling applications, a new strategy for developing sustainable high-performance biobased self-healing coatings is presented.

Preparation of organic–inorganic bio-based epoxy coatings with high anti-corrosive performance

Preparation of organic–inorganic bio-based epoxy coatings with high anti-corrosive performance

Improving the post-harvest quality of fruits during storage through edible packaging based on guar gum and hydroxypropyl methylcellulose

Fruits are particularly susceptible to post-harvest decay. In this context, bio-based coatings could be a useful and sustainable approach to overcome this problem. The EU Commission is very restrictive about food additives and materials in contact with food, regulated respectively by Reg. UE (CE) 1333/2008 and Reg. UE (CE) 10/2011. In this research, different percentages of hydroxypropyl methylcellulose (H)-guar gum (G) (1–2% w/v) and potassium sorbate (PS) (0–2% w/v) were used to produce coatings to be applied on tomatoes (Solanum lycopersicum) and oranges (Citrus sinensis). The efficacy of the coatings was firstly evaluated through an accelerated test (28 °C 90% RH, 20 days) on artificially wounded fruits, and then under storage conditions (8 °C 95% RH, 6 weeks). The physical and chemical parameters of the fruits were periodically analyzed and used to evaluate the effect of the coatings on the fruit quality through a multivariate approach (PCA). All coatings were effective in preserving fruits under refrigeration against Penicillium spp. and Alternaria spp., but PS led to significant fruit weight loss despite its strong fungistatic activity. Biopolymers showed potential for preserving fruit freshness, but alternative antifungal agents without adverse weight effects should be explored using a similar statistical approach.

Incorporating of Oxidized Cellulose Nanofibers@d-Limonene Pickering Emulsion into Chitosan for Fully Biobased Coatings toward Fruits Protection

Incorporating of Oxidized Cellulose Nanofibers@<scp>d</scp>-Limonene Pickering Emulsion into Chitosan for Fully Biobased Coatings toward Fruits Protection

The potency of spores and biosurfactant of Bacillus clausii as a new biobased sol-gel coatings for corrosion protection of carbon steel ST 37 in water cooling systems

The structures of water cooling systems are prone to microbially-influenced corrosion (MIC) due to the favorable conditions for microbial growth. Biofilm formation accelerates corrosion, leading to reduced system efficiency, structural damage, and significant financial losses. Encapsulating viable bacterial spores and biosurfactant within a silica-based sol-gel coating offers an eco-friendly approach to prevent this type of corrosion. Bacillus clausii, known for its antimicrobial biosurfactant production capability, was utilized in this study to investigate the impact of spores and biosurfactant addition to silica-based sol-gel coatings in inhibiting biofilm formation and preventing corrosion in water cooling systems. Microbiological analysis of the biofilm was conducted using the total plate count method, while the corrosion process was analyzed through electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The viability of B. clausii spores within the sol-gel matrix was determined to be 20.8 %. The presence of bacterial spores and biosurfactant significantly increased the hydrophobicity of the sol-gel coating. Incorporating spores within the sol-gel matrix delayed biofilm formation for up to 12 days, while biosurfactant addition showed the smallest biofilm abundance (2.23×105 CFU/mL) at its maturation phase compare to others. After 180 days of incubation, analysis of Bode and Tafel plots demonstrated that the sol-gel coating containing biosurfactant maintained excellent anti-corrosion performance, exhibiting an impedance of 104 Ω cm2, Ecorr of -0.398 V vs SCE, and icorr of 0.51 µA/cm2. SEM-EDS analysis of the surface sample revealed a comparably smooth and uniform surface with a minimal abundance of exposed Fe atoms at 0.12 %. In conclusion, this study demonstrated the high potency of the sol-gel coating supplemented with biosurfactant in inhibiting biofilm formation and corrosion on metals in water cooling systems.

Shelf life of cocktail tomato extended with chitosan, chia mucilage and levan

Tomato is among the most important parts of the human diet globally. However, due to its short shelf life, the produce faces the non-desired huge postharvest losses that can be ascribed to high ethylene emission, high respiration rate, and weight loss. Conventional approaches used to enhance the shelf life of cocktail tomatoes come with certain disadvantages such as chilling injury and investment cost. This study aimed to investigate the effects of bio-based coatings on the shelf life of cocktail tomatoes. The breaker stage tomato fruit were treated with chitosan (CS), chitosan+levan (CS-LVN), chitosan+mucilage (CS-MCLG), and chitosan+ mucilage+levan (CS-MCLG-LVN) edible coatings. Control (CTL) fruit received no treatment. Tomatoes were kept in cold storage (CST) for 30 days (d) at 10 °C temperature and 90–95% relative humidity (RH). At every removal, the fruit was kept for an additional 3 d at 20 °C and 60 ± 5% RH to determine the shelf life (SL) performance. Edible coating treatments minimized the weight loss, ethylene emission, respiration rate, and amount of unmarketable fruit and slowed down the synthesis of lycopene. The minimum weight losses and amount of unmarketable fruit were determined in the CS-MCLG-LVN coating treatment. CS-MCLG-LVN and CS-MCLG-treated fruit had the lowest ethylene emission and respiration rates. CS coating treatment manifested the highest L* value and malic acid content while the maximum total phenolic and total flavonoid contents were in CS-LVN. It can be concluded that CS-LVN, CS-MCLG, and CS-MCLG-LVN edible coatings maintained the postharvest quality of tomatoes for 30 d.

Study on reduction potential of curing agent in sustainable bio-based controlled release coatings

Sustainable polyurethane coated fertilizer is attracting much attention. Reducing the amount of curing agent is promising to improve the bio-content and biodegradability of coating material. In order to achieve the aim, the research attempted to select palm oil with balanced unsaturation as feedstock, hydrochloric acid as both catalyst and nucleophilic reagent for bio-polyols with low hydroxyl values by the epoxidation/ring-opening reaction. The chemical structures of palm oil-based polyols and properties of polyurethanes were tailored by controlling hydrochloric acid amount, and the effect was investigated by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), etc. With the increase of hydrochloric acid amount, hydroxyl value, functionality and viscosity of palm oil-based polyol were gradually increased. The resultant coatings prepared by the palm oil-based polyol with hydroxyl value exceeding 120 mg KOH g−1 and functionality of more than 2 had good macroscopic performances including controlled nutrient release property as a result of high crosslinking density. The optimum amount was 10%, for the viscosity of the relative palm oil-based polyol was beneficial to the coating process. The bio-content of the coating was 67% and the nitrogen release duration of the coated urea was 73 days at the coating rate of 7% even without paraffin. Overall, the way offers a bio-based platform to create a variety of polyurethane coated fertilizer that promises economic and environmental benefits.

Effect of Bio-Based Protein Coating on the Quality and Shelf Life of Fig Fruit (Ficus Carica L.)

Effect of Bio-Based Protein Coating on the Quality and Shelf Life of Fig Fruit (Ficus Carica L.)

Sustainable polyurethane coatings based on functional Camelina oil-based polyols

Polyurethane (PU) coatings have garnered considerable attention across diverse applications and industries, owing to their versatile physiochemical attributes. Despite their widespread use, the environmental implications associated with their carbon footprint have raised concerns in recent years. To address this issue, we explored the potential of Camelina oil as a base chemical for synthesizing polyesteramide polyols as a viable alternative to petrochemical-based materials. Consequently, we formulated biocarbon-rich polyurethane coatings using the synthesized polyols. Initially, we synthesized a fatty amide intermediate through a transamidation reaction, involving the interaction of diethanolamine and triglyceride. Subsequently, we produced three distinct polyesteramide polyols using citric acid, itaconic acid, and phthalic acid. To confirm the formation of ester and amide linkages, we employed various structural analyses, including Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopy, on the Camelina-oil-derived polyols. Furthermore, we utilized quantitative techniques such as titration to ascertain hydroxyl number, acid number, and amine value. Our structural analyses corroborated the establishment of ester linkage and the incorporation of OH functionality in Camelina oil, while titration results indicated a remarkable 1200 % surge in hydroxyl value. We subsequently employed the three polyesteramide polyols to fabricate polyurethane coatings, subjecting them to a battery of tests. The resultant biobased coatings were assessed using Dynamic Mechanical Analysis (DMA), Thermo-Gravimetric Analysis (TGA), and an array of surface characteristics such as gloss, hardness, impact resistance, water contact angle, and saline resistance. All tested samples exhibited satisfactory thermal stability, with the biocarbon content of the final PU coatings measuring at least 61.6 %. Moreover, our study demonstrates that the derived polyurethane coatings hold promise for non-wet applications, particularly in the realm of interior coatings.

Interaction of porous substrate and vegetable oil-based hydrophobic thermoset coatings during UV-polymerization

In the current study, we report the progress in developing new UV polymerizable hydrophobic biobased coatings from modified vegetable oil for porous substrates like paper and wood. The aim was to produce novel hydrophobic coatings on porous substrates and investigate how the porous nature of the substrates will be affected by different chemical formulations that penetrate into the interior of the substrate during the exposure to different intensities of UV light, and what hydrophobic properties that interaction will result in. The curing formulations were based on acrylated epoxidized linseed oil (AELO) as a prepolymer. For the UV polymerization, 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) was used as a photoinitiator; isobornyl acrylate (IBA) and isosorbide methacrylate (IM) were used as bio-based diluents; hexadecyltrimethoxysilane (HDTMS), vinyl-polydimethylsiloxane (v-PDMS), triethoxyoctylsilane (TEOS) were used as hydrophobic additives and they were added in different concentrations to the AELO curing formulations. The formulations were then cured under UV light on wood and paper substrates. FT-IR analysis showed that the AELO resin was successfully polymerized on both paper and wood substrates, and by contact angle measurements it was found that the highest hydrophobicity was achieved for the coatings that contain HDTMS (108° in average). The layer thickness on wood substrates was in between 9 and 20 µm, and on paper substrates between 8 and 24 µm. Only about a 5° difference in contact angle was observed between the coatings with respect to change in diluents and different UV light intensity. All cured samples showed a good chemical resistance to acetic acid, citric acid and ethyl alcohol after 1 hour exposure; to acetone and ethylbutyl acetate after 10 s, and to benzine after 2 minutes. Outstanding hydrophobic behavior was observed for the HDTMS coatings, however, better physical properties were determined for the coatings containing v-PDMS and TEOS, on which the scratching was observed after the applied force of 1.5 and 0.6 N in comparison to HDTMS coatings (0.4 N). The resulting properties achieved for the AELO coatings indicated that it has a potential to be used for wood coating and packaging application.

Construction of waterborne flame-retardant itaconate-based unsaturated polyesters and application for UV-curable hybrid coatings on wood

Developing a strategy to improve the flame retardancy and water resistance of waterborne bio-based coatings on wood is an effective route to enhance safety and applicability of timbers. In this work, the waterborne itaconate-based unsaturated polyester (IAF) were synthesized from biomass-derived itaconic acid (IA) and flame retardants FRC-6 by melt polycondensation in one pot, which was investigated as an ideal waterborne resin for UV-curable coating applications. A series of UV-cured hybrid coatings on wood were prepared consisting of IAF, N-(Hydroxymethyl) acrylamide (NMA), and γ-methacryloxypropyltrimethoxysilane (MPS) in various proportions via UV-curing and sol-gel process. The incorporation of MPS enhanced the rigidity, cross-linkage, and water resistance of UV-cured hybrid coatings, but the excessive silicone gel limited the further improvement of coating performances due to the phase separation and reduced film-forming property. Moreover, the UV-cured hybrid coatings appeared exceptional charring properties and endowed wood with superior flame retardancy. It was noticed that P/N/Si synergistically promoted the formation of remarkable, dense, and stable char layer on wood as a barrier, retarding the spread of heat, oxygen, or flammable volatile and the further combustion of substrates. Besides, the free radical capture of phosphorus and the dilution effect of inert gas played an essential role in gas-phase flame retardancy.

Biobased polyurethane coatings with fast self-healing and tunable mechanical properties derived from curcumin and castor oil

Biobased thermosetting polymers have attracted interest owing to their renewable source materials, long service life, and properties comparable to those of petroleum-based materials. However, the fabrication of those that merge exquisite mechanical properties with fast self-healing performance has not been demonstrated to date. In this work, a biobased polyurethane coating was constructed using curcumin dioxime (CD), castor oil (CO), and isophorone diisocyanate (IPDI) to fulfill these features. The biobased CD monomer was prepared using curcumin and hydroxylamine hydrochloride and confirmed by nuclear magnetic resonance, flourier-transform infrared (FT-IR) spectra, and high-resolution mass spectrometry (HR-MS). To investigate the correlation between the mechanical properties and self-healing performance, a series of polyurethane coatings were fabricated by varying the ratio of CO to CD. The results showed that the crosslinking density (ve), glass transition temperature (Tg), and Young modulus of these coatings increased with the decrease in the ratio of CO to CD, leading to tunable mechanical properties. In particular, the tensile strength and elongation of the COPU-4 coating were as high as 17.2 MPa and 295 %, respectively. The stress relaxation experiments revealed that these coatings exhibited low activation energy (Ea), as low as 28.3 kJ/mol for COPU-5. Besides, all COPU-X coatings demonstrated self-healing efficiency higher than 71 % within 1 min at 90 °C, and some of them even reached >90 % after 8 min. The results demonstrate the promising tunable mechanical and excellent self-healing properties of these novel biobased polyurethane coatings and pave the way for the development of bioderived sustainable thermosetting polymers.

Introduction of bio-based hard segment as an alternative strategy to environmentally friendly polyurethane coated urea

Improved degradation performance of bio-based polyurethane coatings has become a significant challenge for agricultural applications of controlled-release fertilizers. In this work, petroleum-based isocyanate components were innovatively replaced with lysine diisocyanate (LDI) ingredients in various ratios by the in-situ reaction with castor oil to synthesize high bio-based content polyurethane coating materials. The chemical structure and properties of the coatings were also investigated to propose the mechanism of LDI-mediated coatings controlled release and degradation performance. The experiment results indicate that as the LDI content increased, the coatings’ thermodynamic stability, cross-linking density, and controlled release performance decreased while their hydrophilicity and degradation performance increased. Compared to other coated ureas, the coated urea with the 1:1 replacement ratio of petroleum-based isocyanate performed well and had adjustable controlled release performance. Its release period was regulated by adjusting the coating rate and reached 60 days with the 3 % coating rate. With the increase of the lysine component, the degradation performance of the coating materials was improved till the replacing ratio of petroleum-based isocyanate was higher than 1:1. In all, the introduction of bio-based isocyanate is an alternative way further to enhance the degradation performance of the coating materials, and the coatings were non-toxic to rice seeds. The coordination of the controlled release and degradation performance of the coatings can be achieved by adjusting the content of LDI. This research designed a novel strategy to solve the bottleneck problem of bio-based polyurethane coating degradation in coated fertilizers.

High-Performance Castor Oil-Based Polyurethane Composites Reinforced by Birch Wood Fibers

A new method for the preparation of coatings based on renewable biomaterials such as castor oil and birch flour is suggested in this study. The introduction of birch flour in a polyurethane matrix synthesized from castor oil and oligomeric methylene diphenyl diisocyanate (MDI) leads to a more than doubled value of tensile strength and almost doubled strength of adhesion to steel at 20 wt.% loading. The composite with such level loading has tensile strength equal to 7.1 MPa at an elongation at break of 31%, with an adhesion to steel of 3.71 MPa. Hence, the use of such level loading allows for an increase in tensile strength of 887.5% in comparison with that of polyurethane based on neat (as received) castor oil, leading to a decrease in the value of elongation at break. The adhesion to steel of these composites increases by 185.5% in comparison with starting polyurethane. FTIR and SEM studies identified the mechanism of the reinforcement effect of birch fibers. This reinforcement is based on the good wetting of birch fibers by polyurethane with the formation of chemical bonds between them, and the cellulose and lignin components of wood fillers. As a result, we obtained cheap bio-based coatings with acceptable mechanical and adhesion properties.

In-situ polymerized zinc phytate chelated Si-C-P geopolymer hybrid coating constructed by incorporating chitosan oligosaccharide and DOPO for flame-retardant plywood

Zinc phytate (ZnPA) chelated geopolymer and in-situ polymerized chitosan oligosaccharide (COS)/DOPO explored a challenging and exciting flame retardant organic–inorganic hybrid coating via sol–gel method to find halogenated high-efficiency bio-flame retardants are widely used as decorative materials for flame-retardant plywood. Herein, the results show that the appropriated ZnPA (0.5 wt%) enhances the flame retardancy of the geopolymer coating, the peak of heat release rate (p-HRR) decreases from 136.09 to 99.39 kW·m−2, the fire growth index (FGI) dropped from 0.47 to 0.28 kW m−2 s−1, the fire performance index (FPI) climbs from 1.00 to 2.52 s·m2·kW−1, and the flame retardancy index (FRI) climbs from 1.00 to 2.52. Meanwhile, through the microstructural analysis of the residual layer, a strong, compact and non-flammable resilient residues is obtained after combustion; Moreover, the pyrolysis kinetics show that the Z.-L.-T. three-dimensional diffusion reaction model governs the pyrolysis of hybrid coatings. Appropriated ZnPA increases the pyrolysis Eα from 138.95 kJ·mol−1 to 160.75 kJ·mol−1 at 741 ∼ 890 ℃ and improves the thermal stability of the coating. The Si-C-P structure improves the formaldehyde adsorption rate by 46.5%. Therefore, this study, by preparing COS-pretreated ZnPA and DOPO to co-construct alkali-excited cenospheres-based Si-C-P coating, reveals the sustainable development of modified bio-based geopolymer flame-retardant coatings in the construction industry.

Bio-Based Waterborne Poly(Vanillin–Butyl Acrylate)/MXene Coatings for Leather with Desired Warmth Retention and Antibacterial Properties

This study presents a solvent-free, facile synthesis of a bio-based green antibacterial agent and aromatic monomer methacrylated vanillin (MV) using vanillin. The resulting MV not only imparted antibacterial properties to coatings layered on leather, but could also be employed as a green alternative to petroleum-based carcinogen styrene (St). Herein, MV was copolymerized with butyl acrylate (BA) to obtain waterborne bio-based P(MV–BA) miniemulsion via miniemulsion polymerization. Subsequently, MXene nanosheets with excellent photothermal conversion performance and antibacterial properties, were introduced into the P(MV–BA) miniemulsion by ultrasonic dispersion. During the gradual solidification of P(MV–BA)/MXene nanocomposite miniemulsion on the leather surface, MXene gradually migrated to the surface of leather coatings due to the cavitation effect of ultrasonication and amphiphilicity of MXene, which prompted its full exposure to light and bacteria, exerting the maximum photothermal conversion efficiency and significant antibacterial efficacy. In particular, when the dosage of MXene nanosheets was 1.4 wt%, the surface temperature of P(MV–BA)/MXene nanocomposite miniemulsion-coated leather (PML) increased by about 15 °C in an outdoor environment during winter, and the antibacterial rate against Escherichia coli and Staphylococcus aureus was nearly 100% under the simulated sunlight treatment for 30 min. Moreover, the introduction of MXene nanosheets increased the air permeability, water vapor permeability, and thermal stability of these coatings. This study provides a new insight into the preparation of novel, green, and waterborne bio-based nanocomposite coatings for leather, with desired warmth retention and antibacterial properties. It can not only realize zero-carbon heating based on sunlight in winter, reducing the use of fossil fuels and greenhouse gas emissions, but also improve ability to fight off invasion by harmful bacteria, viruses, and other microorganisms.

Plant-Based Nano-Emulsions as Edible Coatings in the Extension of Fruits and Vegetables Shelf Life: A Patent Review.

Fresh fruits and vegetables are important sources of minerals, vitamins, fibers, and antioxidants, essential for human well-being. However, some fruits and vegetables are highly perishable with a very short shelf life during storage. Serious consumer concern over the use of chemical preservatives for this purpose has led to a green revolution and a sustainable era where the design and fabrication of edible coatings have attracted considerable interest. In recent years, scientific communities have paid great attention to the development of bio-based edible coatings to extend the postharvest shelf life of fruits and vegetables. Furthermore, nanotechnology has been distinguished as a great strategy for improving coating properties, including a better water barrier and better mechanical, optical, and microstructural properties, as well as gradual and controlled release of bioactive compounds. In this work, patent articles on plant-based nano-emulsions as edible coatings in the extension of fruit and vegetable shelf life were reviewed. The Patentscope search service and Espacenet portal were used, applying a query strategy composed of mesh terms and inclusion criteria. Through database searching, a total of 16 patent documents met the inclusion criteria. Further, to demonstrate the innovation trends in this topic, all relevant patents are described at the end of the study, along with the components, technology, application, and advantages of developed preparations.

Layer-by-layer assembly of sustainable lignin-based coatings for food packaging applications

Packaging plays a critical role in ensuring food safety and shelf life by protecting against e.g., moisture, gases, and light. Polyethylene (PE) is widely used in food packaging, but it is mainly produced from non-renewable resources and it is an inefficient oxygen and light barrier. In this study, the layer-by-layer (LbL) assembly of a sustainably produced lignin-based polymer (EH) with polyethylenimine (PEI) or chitosan (CH) was used to fabricate (partially or fully) bio-based coatings with the aim of improving barrier properties of PE films. The charge density of EH was calculated using a polyelectrolyte titration method and the hydrodynamic diameters of EH, PEI and CH were determined by Dynamic Light Scattering (DLS). LbL assembly was monitored in situ via Quartz Crystal Microbalance with Dissipation (QCM-D) and Stagnation Point Adsorption Reflectometry (SPAR). PE films were coated with a variable number of PEI/EH or CH/EH bilayers (BL) using an immersive LbL assembly method. Coated films were studied in terms of light-blocking ability, wettability, thermal behaviour, surface structure, as well as oxygen and water vapor barrier properties. QCM-D and SPAR data showed a stepwise multilayer formation and strong interactions between the oppositely charged polymers, with PEI/EH coating having a greater amount of deposited polymer compared to CH/EH coating at the same number of BL. Overall, light barrier properties and wettability of the coated films increased with the number of deposited bilayers. Coated PE films maintained the overall thermal behaviour of PE. A number of BL of 20 was found to be the most promising based on the studied properties. Selected samples showed improved oxygen and water vapor barrier properties, with PEI/EH coating performing better than CH/EH coating. Taken altogether, we demonstrated that a novel and sustainable lignin-based polymer can be combined with PEI or CH to fabricate (partially or fully) bio-based coatings for food packaging.

Introducing hydroxyl-containing POSS to liquefaction of biomass: An alternative route to bio-based polyurethane nanocomposites for coated fertilizers

A new route, introducing POSS-OH to liquefaction of biomass, is developed for bio-based polyurethane nanocomposites and applied in the controlled release of chemicals. The effect of POSS-OH on the chemical structures and properties of biopolyols and their coatings was characterized by GC–MS, FTIR and others. The results indicated that after adding POSS-OH to liquefaction of starch, the hydroxyl content of the biopolyol synthesized was higher than that of the biopolyol from sole starch, and the resultant nanocomposite owned good thermal stability, water resistance and, importantly, non-toxicity to plants. Meanwhile, after coating the urea granules, the controlled release ability of the nanocomposite coating with 3% POSS-OH was the best, and in comparison with the coating without POSS-OH the nitrogen release duration was prolonged by a month. Overall, POSS-OH was used not only as both co-liquefier of biomass instead of the commonly used glycerol to affect the liquefaction process, but also as filler for bio-based polyurethane nanocomposite to improve the interaction. Thus, the substitution of petroleum-based polyols can be expected in synthesizing the green and bio-based coatings for controlled release of chemicals.

High-Performance, Degradable, Self-Healing Bio-Based Nanocomposite Coatings with Antibacterial and Antioxidant Properties.

The purpose of this study is to obtain a bio-based coating with good functional activity and self-healing ability, demonstrating its potential in food, materials, and other application fields. Plastic coatings can cause serious environmental pollution. It was a good solution to replace plastic coatings with degradable coatings. However, the development of degradable coatings in the fields of food and materials was limited due to their insufficient antibacterial ability and weak comprehensive properties. Therefore, chitosan nanoparticles (NPs) loaded with gallic acid (GA) were self-assembled with gelatin (GE) to prepare high-performance, degradable, self-healing bio-based nanocomposite coatings with antibacterial and antioxidant properties. The oxygen permeability of GE nanocomposite coatings decreased gradually with the addition of NPs, and the barrier properties increased significantly. At the same time, due to the excellent antioxidant and antibacterial ability of GA, the antioxidant effect of the nanocomposite coatings increased by 119%, and the antibacterial rate against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) increased by 32% and 58%, respectively, compared with the pure GE coatings. In addition, the nanocomposite coatings can be repaired within 24 h after being scratched at room temperature. Finally, GA coated with chitosan nanoparticles can significantly delay the escape of GA, and the retardation of gallic acid release exceeded 89% in simulated solutions after 24 h immersion, extending the service life of the nanocomposite coatings.