The growing problem of invasive mussel species in the Great Lakes has prompted researchers to create innovative solutions aimed at preventing their spread to inland lakes and reservoirs. These mussels attach to various surfaces, both in the upper (epilimnion) and deeper (hypolimnion) layers of lakes. During the winter months, mussels will die off, leaving the large structures constructed of their shells on the lakebed. Their colonies recede into the deeper waters where water temperature is warmer than the icy conditions on the surface. In the spring and summer, the mussels return shoreward, recoating the left-behind shell structures and adding layers of shell material to the submerged landscape. Juvenile mussels are released from fish hosts and can migrate or float to nearly any structure or vehicle, with bilge water from ships often transporting them to new locations. Once attached, mussels begin their reproductive cycle, and this adherence is key to their spread. If prevented from attaching, they are forced to relocate, increasing competition for space and resources.

To combat fouling, researchers have developed a clear, tri-cure hybrid silsesquioxane coating that is inexpensive, easy to apply, and safe for aquatic environments. When applied to glass or fiberglass, materials they readily attach to, this coating prevents the bonding of mussel proteins to surfaces, making them resistant to fouling. By coating boat hulls, boat owners can reduce mussel attachment, slowing the spread of invasives, saving on costly maintenance, reducing drag, and contributing to the protection of other aquatic ecosystems.

Introduction

Marine biofouling, which is the undesirable accumulation of microorganisms, plants, and animals on submerged surfaces, poses significant operational and environmental challenges to maritime industries and aquatic infrastructure.^1-3ÌýThe consequences of biofouling are far-reaching. It causes increased hydrodynamic drag on vessel hulls which reduces fuel efficiency and speed, while simultaneously contributing to higher greenhouse gas emissions.^4-7ÌýIn addition, biofouling accelerates the corrosion of submerged metal and concrete surfaces, clogs pipelines in coastal and nuclear facilities, and disrupts water flow and nutrient exchange in aquaculture systems.^8,9

One of the most practical and effective strategies for mitigating biofouling is the use of protective surface coatings or coating additives. These are broadly classified into biocidal and nonbiocidal types. Biocidal coatings rely on the controlled release of toxic agents from a polymer matrix to prevent organism settlement and are considered antifouling coatings.¹⁰ÌýThe efficacy of such coatings is governed by the biocide’s release rate and its environmental compatibility that should ideally combine strong antifouling activity with low toxicity and moderate fresh and sea water solubility. Unfortunately, only a limited number of biocides meet these stringent requirements for safe and sustained marine use.¹¹

Nonbiocidal coatings primarily include fouling-resistant and fouling-release coatings (FRCs). Fouling-resistant coatings are typically based on hydrophilic polymers such as poly(ethylene glycol) (PEG) and zwitterionic materials, which prevent initial organism adhesion.¹²ÌýHowever, their tendency to swell in saline environments leads to poor mechanical performance. In contrast, FRCs utilize hydrophobic, low-surface-energy materials that allow weakly adhered organisms to be easily removed under mild shear forces. Polysiloxanes are commonly used as FRCs and offer excellent thermal and photochemical stability, though their long-term performance is limited by hydrolytic degradation. To overcome these limitations, hybrid organo-silicon coating systems have been developed. These systems integrate organic and inorganic elements to combine durability, antifouling characteristics, and environmental resilience.^13,14ÌýFor instance, R-alkoxysilanes, particularly methoxy and ethoxy variants, have long been employed to consolidate porous substrates like stone by forming crosslinked siloxane networks with the ratio [RSiO_3/2], or silsesquioxanes that also contain organic bridges. When incorporated into coatings, these networks offer benefits such as low thermal conductivity, oxidative resistance, and mechanical integrity.

Among silicon-oxygen-based coating systems derived from alkoxysilanes, tetraethoxysilane (TEOS) is a widely used precursor.^15,16ÌýHowever, its slow curing rate often necessitates acidic or basic catalysts and long reaction times. As an alternative, photocuring methods that utilize photoinitiators to trigger rapid organic polymerization under light have gained popularity for enabling fast curing without complex handling or component separation. Moreover, using R-functional trialkoxysilanes with epoxy, amine, thiol, or fluorocarbon side groups allows tailoring of surface adhesion, hydrophobicity, and internal stress relief within the final silsesquioxane-based coating.¹⁷

Bioinspired approaches have further guided the design of antifouling surfaces. Many plants and insects feature microstructured, waxy coatings that combine hydrophobicity with self-cleaning properties. Mimicking these strategies, coatings with nanoscale surface roughness and low-surface-energy materials (e.g., fluoropolymers) have been developed to enhance water repellency and reduce biological adhesion.

This research investigates the effects of whey protein coating on the chemical, bacterial, and sensory properties, proximate analysis, and shelf life of common kilka during frozen storage.

For this experiment, common kilka were coated with 9% whey protein while non-coated kilka were used as a control sample. Both the coated and non-coated samples were stored at -18 oC for six months. Results showed that total bacterial counts (1.47–2.49 log CFU/g) and Staphylococcus bacteria (1.02–1.71 log CFU/g) were lower in the coated samples compared to the control samples (P > 0.05). Coliform, E. coli, and Pseudomonas bacterial contamination were undetectable in both the coated and control samples throughout the storage period. Humidity (73.92–46.18%), protein (18.24–19.07%), lipid (4.27–4.01%), ash (1.82–2.12%), and calorie (108.85–120.78 kcal/kg) were higher in the test samples compared to the control samples. Values for peroxide (0.15–5.12 meq/kgoil), free fatty acids (1.32–12.40 g/100), thiobarbituric acid (0.14–0.98 mg/kg), total volatile basic nitrogen (TVB-N) (6.32-21.79 mg/100g), and pH (6.32-7.45) were lower in the test samples.

Significant decreases in chemical factors were observed in the coated samples compared to the control samples (p<0.05). The overall acceptance score had a better quality in the coated samples (80) compared to the control samples (113) (p<0.05). According to the results of experiments and statistical analysis, the coated samples had a favorable quality until the end of the storage period but the control samples had lost their quality. Therefore, a 9% whey protein coating is recommended for kilka fish as a better alternative to using disposable packaging dishes with a cellophane coating.

Introduction

Kilka fish belong to the genus Clupeonella, in the family Clupeidae. These fish are composed of three species consisting of Clupeonalla delicatula, C. engrauliformis, and C. grimmi (Coad, 2017). They can be processed into salted, smoked, pickled conserved, dried, and frozen fish. In Iran, kilka products are sold fresh, canned, or in frozen packaging. From 2016 to 2021, the annual catch ranged from 20,138 to 22,429 tons. Approximately 10-12% of this catch was used for human consumption, and the remaining 88-90% was used for animal feeds. 6,307 – 6,626 tons of the fish were caught in the Guilan Province, of which 5-12% was used for human consumption and the remaining 88-95% for animal feeds (Program and Budget Office, 2022). Consumption of fresh kilka fish dropped from 6% to 2.20% during the period of 2004 to 2009. Consumption of canned kilka also dropped during the same period, whereas consumption of frozen kilka rose during the same years (Seifzadeh, 2014). The frozen fish packs had a much higher sales rate in comparison to the sales of fresh fish because of their longer storage time and wider distribution. Sales of frozen fish were also higher. The fish packs were frozen for less than three months because longer frozen-storage time may lead to color changes, surface dryness, and peroxide accumulation. Even so, the first indication of a decline in quality after only one month of frozen storage was a reduction in the weight of frozen packed fish, which in turn had a deteriorating effect on the texture and taste of the small-sized fish. There was a 3.5% decline in fish weight after three months of frozen storage (Moeini, 2009).

Kilka fish, which have valuable protein and digestible fats, rich vitamins, and minerals, have attained an important position in the food-product market. Overall, the value of food products, such as kilka, depends on their nutritional specifications and acceptability in society; therefore, accurate processing and the preparation of appealing product varieties are crucial for the market (Khanipor et al., 2017).

The final step of the food-production chain is packaging, which occupies the middle ground of production, distribution, and consumption. Many small and large companies all over the world are very active in packaging industry. Competition among packaging manufacturers has led to improved quality and more types of packaging. Currently, numerous packaging and preservation methods, including nonbiological decomposable synthetic chemicals, are used for food preservation. Recently, new packaging materials—such as edible films that are biologically decomposable—have entered the market (Aguilar-Rivera et al., 2023; Kandasamy et al., 2018).

Consumer demand is high for high-quality seafood products, especially those that can retain their superior quality of taste, texture, and general fresh appearance following a prolonged period of cold or frozen storage (Bayram et al., 2021). The use of edible films for packaging kilka seems to be an ideal method for proper preservation during periods of long storage.

Edible coatings are completely water soluble and glossy; they perform just like a secondary skin and have favorable properties such as rapid attachment to foodstuff, label attachment, antibacterial, and antioxidant properties (Seifzadeh, 2022). These types of coatings protect the aroma, taste, and food color as well as help to maintain the nutritional components. Coating food products with these films can lead to preservation of food moisture and the lowering of oxygen absorption, which can substantially improve the appearance of food products. These coatings are invisible to the naked eye (Londoño-Hernandez et al., 2018; Yu et al., 2019).

Whey protein is derived from milk and is composed of protein, lactose, and inorganic salts. It is anti-bacterial, antiproteolysis, and preserves food moisture (Setiadi and Sauria, 2020). Edible films made of whey protein have been used for packaging salmon, hotdogs, sausages, crackers, and frozen fish filets, and have improved their quality and shelf life (Seifzadeh, 2014). The objective of this study is to investigate the effects of a whey protein coating on the chemical, bacterial, and sensory properties, proximate analysis, and shelf life of frozen kilka.

Unbeknownst to many, microplastics do not originate solely in the ocean. In fact, most microplastic accumulation primarily occurs on land and then moves to the waterways. Oceans have been polluted between 83,000 to 236,000 tons of microplastics yearly. Agricultural soils of all kinds, including agricultural soils, have 107,000 to 730,000 tons of microplastics dumped into the soil each year through processed sewage, mulches, slow-release fertilizers, and even seed coatings.¹

During the last few years, there have been ongoing discussions about what defines a microplastic. Microplastics are plastic particles ranging in size from 5 mm to 1 nm. Primary microplastics are intentionally manufactured in smaller sizes for use in consumer cosmetics and biomedical products. Secondary microplastics are plastic waste particles that break down from larger plastic materials. Secondary microplastics brought about by degradation of larger discarded plastics are the subject of this article.

Only 1% of total microplastics are due to seed coatings.² However, with a rather forceful kick from the European Chemicals Agency (ECHA), seed manufacturers are being required to eliminate microplastics that are generated due to seed coatings by October 2028. The rest of the world is not far behind. In fact, France has pulled implementation ahead to January 1, 2027. California has already proposed legislation that would eliminate 75% of plastic waste by 2030. While this does not yet affect seed coatings, history suggests that a broader set of regulations will germinate from this legislation.

Certain seed coatings are exempt from the October 2028 regulation:³
• Liquids: Must not form films upon drying.
• Natural origin coatings: No chemical modifications allowed. Even the simplest chemical modification might cause eventual microplastic formation. Commercially used natural polymers can contain additives, processing aids, or impurities that could hinder biodegradation or contribute to microplastic pollution.
• Water soluble coatings: Must have a solubility of ≤ 2 g/l.
• Biodegradable: Not to be confused with compostable materials.
• Coatings with no carbon atoms in the molecular chain structure

Manufacturers have embraced the challenge of eliminating microplastics from seed coatings. Even though seed coatings are 1% of the problem, producers across the globe are determined to become ZERO percent contributors to microplastic pollution.

The first step has been to make the microplastic coating fragments that detach from seeds as biodegradable as possible. Degradation rates vary, and no standard has yet been set. The lowest degradation rate so far is ≤ 48 days obtained from some commercially available polymeric coating mixtures. Biodegradable plastic formulations degraded completely in 32 days. Coatings selectively doped with certain plant growth promoting bacterium (Bacillus subtilis) degraded in ≤24 days.⁴ A good start, but still not enough.

A Seed Coating Primer

The first question in eliminating a problem material is to determine whether the material is really needed. Seed coatings are critically important for:
• Promoting germination and robust growth
• Providing resistance to pests and fungal infections
• Improving drought tolerance through osmopriming⁵ (for germination in low-moisture soils)
• Facilitating mechanical planting
• Increasing overall yield

While there are significant advantages for coated seeds (higher germination percentage, healthier roots and shoots as well as stronger established plants), there are also disadvantages (limited shelf life of treated seed, pesticide breakdown, incomplete crop protection, and surplus cannot be repurposed for grain). However, when weighing the risks, the ability to feed the world trumps any disadvantage. Eliminating seed coatings is not practical, so improvements to guard against microplastic formation and pollution must be the conclusion.

There are three basic methods of seed protection: film coating, encrustation, and seed pelleting.⁶

Film coating involves applying thin layers of coating solution (a total of less than 10% seed weight) onto the seed surface (Figure 1). For precise control over thickness and composition, a rotating drum or fluidized bed apparatus is used. Film coating allows the seed to maintain the original size and shape. In addition to resistance to environmental stressors, these seeds are well suited for mechanical planting and precision field applications.

FIGURE 1. Schematic of various protective film coating layers applied to seeds.⁷

Seed encrusting forms a protective matrix around seeds that is 100–500% seed weight. This allows for targeted delivery and sustained release of active ingredients throughout germination and early growth for pest and disease resistance, even in adverse soil conditions. A film is not formed. Many organic farmers take advantage of seeds treated with this technique.

Pelleting agglomerates seeds into uniform spherical pellets by coating them with a mixture of binding agents and additives that is >500% seed weight. This technique is especially good for small seed crops and precision planting. The enhanced seed-to-soil contact leads to good moisture retention, better germination rates, and uniform stand establishment.

Commercial Seed Film Coating Materials

Traditional seed film coatings are manufactured from polyethylene glycol (PEG), polyvinyl alcohol (PVOH) or chitosan (a glucosamine polymer).

Polyethylene Glycol is effective for improving seed germination and seedling establishment of sorghum under adverse moisture conditions. Osmopriming strengthens the antioxidant system further by increasing the osmotic adjustment of the seed resulting in increased stress tolerance.⁸

Lignan-modified PEG has a high molecular weight, takes a little longer to dissolve, and is less easily converted into water. The high-viscosity solutions do not transport oxygen, leading to no absorption by the seed, eliminating genetic or physical damage. Coating with 5-lignin PEG improved the germination percentage of maize seeds from 86.6% to 93.3%.⁹

Polyvinyl alcohol seed film coatings are extremely useful because water solubility and mechanical strength can be controlled. These coatings are used as a binder for adhering layers to the seed surface. Seed physical properties are improved and the delivery of active ingredients can be controlled. PVOH coatings decrease dusting and improve germination.¹⁰

Chitosan is one of the truly natural seed treatments and growth enhancers. This glucosamine polymer is developed from a sugar that comes from the outer skeleton of shellfish like crab, lobster, and shrimp. The material bonds to seeds via hydrophobic or cation-Ï€ interaction. Chitosan is a cationic source in an aqueous solution. Free amine groups form crosslinked polymer networks with dicarboxylic acids to improve mechanical properties.¹¹

Unlike other polymeric materials used for film seed coatings, Chitosan influences the biochemistry and molecular biology of the plant cell. The targeted plasma membrane and nuclear chromatin causes changes in cell membranes, chromatin, DNA, calcium, MAP kinase, oxidative burst, reactive oxygen species, cellulose pathogenesis-related genes, and phytoalexins. It is an ecofriendly biopesticide that boosts the innate ability of plants to fight fungal infections.¹² In addition, it allows for an innate immunity response in developing roots that destroys parasitic cyst nematodes without harming beneficial nematodes and organisms.

The Future

Sometimes the additives used in current seed coating formulations can lead to microplastic free products. Acting as rheology modifiers, film formers, and stabilizers, these biodegradable materials help to create porous films and coatings, enabling early seed germination.

One example is a microfibrillated cellulose viscous material that under high shear can be sprayed onto seeds. Under high shear, the fibrils break apart, lowering viscosity and allowing for consistent coating. After application, when high-shear conditions are removed, the fibrils reconnect forming solid films while still allowing for complete drying of the coating. These additives assist with germination, reducing or eliminating seed dusting and enabling longer shelf-life stability of liquid formulations.¹³

Seed coatings themselves are undergoing a metamorphosis as well. Petroleum-based polymers cannot always be made biodegradable and, at the same time, fully functional. The ideal would be to develop completely natural coatings that leave no residue, disappear without a trace, and retain critical seed protection and nutrient properties. Supramolecular engineered proteins have been developed over the past 15 years. They perform as well as synthetic polymer-based coatings but decompose naturally. This serves two purposes: mitigating soil degradation and eliminating microplastic pollution in farm fields.¹⁴

Thinking even further outside the box, these supramolecular engineered proteins might be the foundation for producing plant-based protein products to replace traditional single-use and even multiple-use carbon-chain plastics without the threat of microplastic pollution.

References

1. Petersen, K. S. There is an Alarming Amount of Microplastics in Farm Soil–and Our Food Supply. Environmental Health News. January 27, 2021.
2. Nielson, A.. The Seed Sector’s Battle Against Microplastics. Seed World. April 29, 2024
3. Verney, C.; DeGassert, G. Microplastic Seet Coatings the Perform Better than Conventional Ones: Myth or Reality? Agropages AgNews. June 14, 2024.
4. Accinelli, C. et al. Degradation of Microplastic Seed Film-Coating Fragments in Soil. Chemosphere. V 226. July 29, 2019. Pages 645-650.
5. Harish, D., et al. Effect of hydropriming and Osmopriming on the Germination of Seedling Vigor in East Indian Sandalwood (Santalum album L.). Forests. V 14, P. 1076. 2023.
6. Sharma, S. Enhanced Crop Potential: Exploring Seed Coating Techniques and Applications. LinkedIn. May 14, 2024.
7. King Quenson Group. A Farmer Friendly Technique for Producing Crops. King Quenson News. September 3, 2023.
8. Zang, Fei, et al. Seed Priming with PEG Induces Physiological Changes in Sorghum Seedling Under Suboptimal Soil Moisture Environments. National Institute of Health. October 15, 2015.
9. Yahong, G., et al. Preparation of Lignin Polyethylene Glycol Film-Forming Agent and Its Application in Chlorantraniliprole 5% Flowable Concentrate for Seed Coating. Industrial Crops and Products. V. 182. P 114877. August 2022.
10. Agriculture | Coating for Seeds, Fertilizers & FilmsPolyvinyl Alcohol. https://www.kuraray-poval.com/applications/agriculture (accessed September 10, 2024).
11. Chitosan. https://en.wikipedia.org/wiki/Chitosan (accessed September 10, 2024).
12. Hadwiger, L. A. Multiple Effects of Chitosan on Plant Systems: Solid Science or Hype. Plant Science. V. 208, 42-49. July 2013.
13. Electrolyte Tolerant Film Forming Agent for Seed Coatings. Borregaard https://www.borregaard.com/markets/agriculture/applications/seed-coating/products/film-forming-agent/ (accessed September 10, 2024).
14. Natural Alternatives to Microplastics Developed for the Seed Coating Industry. Environment Times. February 1, 2022. https://www.environmenttimes.co.uk/news/item/995-natural-alternatives-to-microplastics-developed-for-seed-coating-industry (accessed September 10, 2024).

The Cool Roof Rating Council (CRRC) was established in 1998 to develop fair, accurate, and credible methods for evaluating and labeling the surface radiative properties of roofing products, specifically solar reflectance and thermal emittance. In addition, a standard practice for calculating a solar reflectance index (SRI) has been developed for horizontal and sloped surfaces. In recent years, these ratings have also been used to develop “cool walls” and “cool pavements.”

One important part of the CRRC Product Rating Program is the real-time three-year weathering process that informs product field performance over time, augmented by the Rapid Ratings Program based on ASTM laboratory aging testing. ASTM methods are also used to define the properties of the paints needed for this application.

First, some important definitions: ¹

• Solar Absorption (SA): The fraction of sunlight absorbed by a surface.
• Thermal Emittance (TE): The efficiency with which a surface emits thermal radiation. Bare metal has low thermal emittance, while nonmetallic surfaces are high.
• Solar Reflectance (SR): The fraction of sunlight reflected from a surface. High SR is the most important property of a cool surface.
• Thermal Resistance (TR): The measure of a material or system ability to prevent heat from flowing through the substrate.
• Solar Reflectance Index (SRI): A calculated value based on SR and TE that determines a material’s surface value under the conditions outlined in E1980. The higher the value, the cooler the surface in the sun (Figure 1).

FIGURE 1 Schematic for High and Low SRI Values.²

Coating Standards

There are two basic types of cool-roof coatings: elastomeric and cementitious. The properties of elastomeric coatings are governed primarily by D6083/D6083M-24 Standard Specification for Liquid-Applied Acrylic Coating Used in Roofing. This specification defines the viscosity, volume, and weight solids required for cool coatings. It also establishes the minimum efficacy standards derived from successful in-service performance throughout the United States. These performance evaluations were conducted on more than 20 roofs ranging in age from a few months to 20 years old.⁴ There are no correlating standards for cementitious cool coatings. Table 1 lists standards for evaluating other physical properties required for acrylic elastomer cool coatings.

Cool Roof Material Standards

The primary standard for evaluating SRI is E1980, Standard Test Method for Measuring Solar Reflectance Index of Horizontal and Low-Sloped Opaque Surfaces. The combined effects of solar reflectance and thermal emittance are measured, depicting surface temperature and energy performance. Table 2 lists standards for measuring the main variables associated with SRI along with a standard methodology for laboratory simulation of the effects of aging exposure on reflectance and emittance properties.

The use of ASTM standards governing cool surfaces provides a systematic universal basis for evaluating a wide variety of substrates that correlate well with actual field exposure for paints that ultimately save energy and cool urban heat islands.

References

1. A Practical Guide to Cool Roofs and Cool Pavements. Cool Roof Toolkit. January 2012.
2. What is SRI or Solar Reflectance Index? (accessed August 12, 2024)
3. Muscio, A. The Solar Reflectance Index as a Tool to Forecast the Heat Released to the Urban Environment: Potentiality and Assessment Issues. Climate, 2018, (6)1, 12.
4. Seyfried, E. RCMA in Review: ASTM D-6083 Made Easy. RSI Magazine. March 2000.

By Kateryna Rudich, Yehor Polunin, Ayda Dadras, Mohiuddin Quadir, and Andriy Voronov

Introduction

The use of polymers as a seed coating is a prevalent agricultural practice because it helps to reduce the overall amount of chemicals needed, promoting more sustainable farming practices. Seed coating is the process of applying a protective layer, typically made of polymers, nutrients, or agrochemicals, to seeds before planting. The primary purposes of seed coatings are to enhance seed performance, protect against pathogens and pests, improve germination rates, and provide essential nutrients during early plant development, all while minimizing the risks associated with conventional seed treatment methods.¹ However, seed coatings mainly involve the use of petroleum-based, non-biodegradable polymers that significantly contribute to microplastic pollution.

This study explores the potential of biomass- and plant oil-based polymers recently developed by our group as a sustainable alternative to be applied in seed coatings. The resulting polymer, consisting of hemicellulose xylan modified by grafted chains made of babassu oil-based monomers (HX-g-BOBM), is designed as a sustainable film-forming material targeting advanced water barrier performance.² HX-g-BOBM is a highly biobased, tough, and processable bioplastic. Being biodegradable, it may offer a renewable alternative to applications of conventional petroleum-based polymers in food packaging. This study evaluates the feasibility of HX-g-BOBM as a seed coating by applying it to corn (Zea mays) seeds and assessing the effect on the seeds’ vigor and viability.

HX-g-BOBM Synthesis

Agricultural wastes such as some lignocellulosic materials and plant oils are excellent renewable resources for the production of sustainable coatings due to their chemical versatility, availability, and often low cost.3-6 HX-g-BOBM is synthesized from hemicellulose xylan and babassu oil, which are believed to be inherently biodegradable or compostable by nature. Babassu oil-based monomer (BOBM) and HX-g-BOBM were synthesized following the procedures described in earlier publications.^1,7,8 The structure of BBM is shown in Figure 1A. A schematic representation of HX-g-BOBM synthesis is presented in Figure 1B. Before polymerization, xylan was reacted with maleic anhydride through an esterification reaction. During this process, an ester bond is formed between the maleic anhydride and hydroxyl groups of xylan, while the vinyl group of maleic anhydride remains intact, providing a reactive site for the attachment of BOBM-based grafted chains. After successful maleinization, the modified xylan was added to the BOBM along with the AIBN initiator (1.5 wt %). Grafting polymerization reaction was conducted in bulk at 80 °C for 8 hours under a nitrogen atmosphere. After purification from unreacted xylan and BOBM, a homogeneous solution of highly branched HX-g-BOBM was obtained. Multiple xylan macromolecules are decorated by BOBM chains, and BOBM homopolymer is also present in the resulting material.

FIGURE 1 The chemical structure of babassu oil-based monomer (BOBM) used in this study. R (x:y) – the structure of the fatty acids (x – the number of carbon atoms in the fatty acid chain, y – the number of double bonds in the fatty acid) (A). Synthetic scheme of HX-g-BOBM grafted polymerization (B).

HX-g-BOBM Emulsification

To simulate an industrial approach, where seeds are typically covered by spraying a water-based slurry containing polymers and additives over the seeds in a rotating drum machine, HX-g-BOBM was emulsified in water. Dodecylbenzenesulfonic acid, which serves as an emulsifying agent, was first dissolved in water, vortexed for 5 min, and ultrasonicated for 20 min. The HX-g-BOBM dispersion was then added dropwise and was vortexed for an additional 5 min and ultrasonicated for 20 min until a stable emulsion with a final polymer content of 15 wt % was achieved. Particle size measurement was conducted using a Malvern Zetasizer Nano-ZS90 (Figure 2A).

The viscosity of the emulsion was measured using an ARES G2 rheometer with 25 mm parallel plate clamps, gap size 0.5 mm, strain 1%, frequency range 1-500 rad/s, and temperature 25 ºC. The viscosity of the HX-g-BOBM emulsion exhibits non-Newtonian behavior, with apparent viscosity decreasing as the shear rate increases, indicating shear-thinning behavior. At low shear rates (< 1 rad/s), the emulsion displays high viscosity, suggesting good stability and minimal settling of particles. The apparent viscosity decreased significantly at higher shear rates (> 10 rad/s), indicating that the emulsion would flow more easily during the seed coating process, which is beneficial for uniform coating application in industrial applications (Figure 2B).

FIGURE 2 Particle size (A) and rheological behavior (B) of 15 wt % HX-g-BOBM water emulsion.

Seed Coating Procedure

Seeds were coated manually using a plastic bag with a subsequent transfer of seeds to the sieve and drying at room temperature (25 ±1°C) for 24 hours. In each case, 100 corn seeds were incubated with 2 ml of water-based polymer slurry and manually shaken for 5 minutes to simulate the industrial rotating drum coating procedure. The weight of the seeds was compared before and after the coating procedure. The average weight increase was found to be 2.0 ± 0.3 wt % from the initial mass of seeds.

HX-g-BOBM Coating Water Absorption

The water absorption test was conducted to evaluate the coating’s interactions with water. Coating film samples were submerged in 20 ml of distilled water and kept at room temperature. After immersion, excess water was removed, and the samples were weighed at specific time intervals to quantify the changes in mass. To ensure accuracy and reliability, each test was performed in triplicate. The resulting plot shows the relationship between time and weight gain (Figure 3A). The ability of the coating to swell is advantageous for enhancing water retention, by helping to keep the seeds hydrated after planting.