Location: Cotton Quality and Innovation Research
2023 Annual Report
Objectives
Enhanced Cotton (EC) for Value Added Applications research proposed here is performed within the Cotton Chemistry Utilization Unit (CCU) and intends to enable cotton’s use in expanded high value applications. The objectives cover a broad range of potential product types and thus are divergent to some extent. However, we strive to overlap in shared collaborative direction as illustrated below. The objectives of the EC Project are:
1. Resolve modifications in cotton-based textiles to enable new commercial applications of skin and wound contacting materials.
2. Enable, through chemical technologies, commercial production of conventional cotton-based (barrier protective) materials.
3. Derive novel cotton value-added products through nanocellulosic materials and conventional processes.
The research objectives proposed above, in conjunction with the Cotton Nonwovens research project, are targeted to improving U.S. cotton production by increasing the demand for domestic cotton. Increasing domestic consumption will come from identifying key consumer unmet needs specific for cotton, and areas where domestic cotton is required for end use products. Historically, solutions to downturns in U.S. cotton consumption have come from infusing cotton with new technologies that impart a competitive edge to cotton (e.g. permanent press) over synthetic fibers, or creating a customer-expedited supply of high quality cotton products that compete well with overseas production. However, in the current global market, development of proprietary technologies specific to the domestic consumption of cotton, are needed. Each of the research areas listed above is critically important at this time because each, if successful, will contribute greatly to increasing the domestic demands of cotton.
Approach
For Objective 1, a broad set of characteristics requires a varied approach to de novo design and preparation of cotton-based prototypes as body-contacting material. The target products of the approach are hemostatic, antimicrobial, chronic wound dressings and incontinence topsheet absorbents. Although each of these product areas share similar fabric characteristics they differ in functionality. Experiments for these four fabric groups will vary based on the functional target use. Evaluation of the influence of fiber structure on fabric surface polarity is important to hemostatic and incontinence fabrics, and design features at the cellulose crystallite level and molecular modifications are important to the chronic wound dressing. These will be assessed for activity through in vitro assessment models based on current leads, and prototypes developed from structure/function relations. Structure-activity relations of the fiber/fabric derivatizations will be examined at the fiber, microfibrillar and molecular level using fiber surface chemistry, electrokinetic, fluorescence, colorimetry, infrared spectroscopy, x-ray crystallography, and computational chemistry. The derivatized cotton materials will utilize chemical and physical cotton fabric modifications as are required to optimize activity and may employ some synthetic modifications i.e. protease sensor constructs are outlined in Obj. 3.
For Objective 2, discovery and development are outlined in three phases. In Phase 1, principle focus will be on the Layer-by-Layer (LbL) technology which will be applied to cotton nonwovens and compared on both bleached and greige cotton. Multifunctional activities will be explored i.e. antimicrobial, UV protection, and flame retardant activity. Phase 2 will predominantly be devoted to optimizing LbL functional properties to correspond with environmentally friendly, non-toxic approaches to conferring functionality i.e. antimicrobial, UV protection, and flame retardant activity while exploring ways to improve fabric hand. Phase 3 focus will be on working with stakeholders to identify LbL fabric technology with interest in applications i.e. military, sporting, wilderness medicine, fire barriers etc., and identifying key functionalities for cotton-based marketing and price point economy.
For Objective 3, mechanical milling of feedstock materials will yield a uniform-sized intermediate raw material, which will be subjected to alkaline and oxidative chemical treatments to remove pectin, hemicellulose and lignin. The ensuing suspension of nanocellulose will be hydrolyzed with dilute sulfuric acid and then subjected to high-pressure homogenization, leading to a sulfated cellulose nanofiber (sCNF). The sCNF products obtained by this process will be characterized by an array of analytical methods as detailed in the Methods section of (Jordan, Easson et al. 2019). From these isolated and characterized products, hydrogels, thin films and aerogels will be prepared and nanomaterial-treated cotton analogs will be prepared to obtain an initial nanomaterial-treated composites. Several lead compounds will be prepared to explore different chemistries.
Progress Report
Progress was made on all three objectives, all of which fall under National Program 306, Component 2, Quality and Utilization of Agricultural Products, Non-Food. Progress on this project focuses on Problem 2A to increase or protect the market demand for (or increase the value of) existing U.S.-produced non-food bio-based products derived from agricultural products and byproducts. Agricultural Research Service (ARS) researchers in New Orleans, Louisiana, have developed new products, applications, and processes for expansion of domestic cotton in the areas of: (1) moisture control properties and hygienic and cotton fabric hand applications; (2) conversion of biomass to nanocrystals; (3) flame retardant cotton; (4) sensors that utilize a form of high surface area cellulose to detect disease biomarkers; (5) cotton-based blood clotting, and antibacterial fabrics for wound dressings.
Treating battlefield injuries associated with blood loss and infection is a high priority U.S. military especially targeted to prolonged field care of seventy two hours or more. In support of Objective 1, Agreement 6054-41430-009-002I with the Defense Health Agency and Material Transfer Agreement 18928 with Virginia Commonwealth University we developed cotton-based nonwoven materials designed to both promote blood clotting and prevent infection. We determined blood clotting activity of the materials. Zeolite is a high surface area aluminosilicate that enhances blood clotting. Zeolite was applied to cotton dressings with pectin, and calcium formulations designed to promote adherence of the compound to cotton fibers. We found that when placed on a cotton wound dressing ammonium forms of zeolite promote clotting more rapidly than the sodium form of zeolite. The formulation on cotton also halted severe hemorrhage as judged in a hemorrhage control model approved by the Army Institute of Surgical Research. Based on these results a lead candidate for testing in animal models was selected and evaluated by a collaborator. It was found that the ammonium form of zeolite performed better in the animal model for bleeding.
The ability to monitor, predict and improve wound healing is an important tool for the healthcare industry. Proteins play a significant role in the way wounds heal. Proteases are specialized proteins that break down other proteins. Thus, increased levels of proteases in a wound can prevent other proteins from functioning in wound healing. Sensors that detect dangerous levels of proteases improve healthcare. In support of Objectives 1 and 3, we designed a sensor with cellulose nanofiber isolated from cotton gin motes. This improved sensor detection and performance. We made further improvement by preparing a special form of the cellulose nanofiber to sensitively detect destructive levels of proteases in wounds. The special nanofiber increased the surface area and pore size volume and can swell when hydrated. By this method, we were able to improve the sensitivity of the sensor. Progress from this research has shown that these materials can improve sensor performance. The special cellulose nanofiber is also being studied as a scaffold for important wound healing factors. This research provides a starting point to develop different sensors for point of care monitoring and treatment in the future.
There is a worldwide demand for effective, safe, and economical textile fabrics that prevent the spread of infectious diseases. Microbial growth on textiles pose the potential for contamination to the user especially when accessible medical care is inhibited. In support of Objectives 1 and 2 and Defense Health Agency Agreement 6054-41430-009-002I, we have developed antibacterial cotton fabrics consisting of vitamin C and silver treated fabrics that prevent the growth of bacteria and viruses at the 99.99 percent level. This past year, we made larger volumes of the antibacterial treatments of unbleached nonwoven cotton in a pilot scale operation. Furthermore, we treated the resulting fabrics with zeolite formulations shown to promote blood clotting with the goal of conferring wound dressing properties for severe hemorrhage control. We have transferred the fabrics to collaborators for their ability to halt uncontrolled hemorrhage. We anticipated that the modified cotton fabrics will be applicable to a wide range of textile uses including facemasks, wound dressings, hygienic wipes, and fabrics used as barriers to the spread of microbes and viruses in hospitals.
Microencapsulation has become an alternative way to improve the sustained release and stability and, rapidly growing technology used commercially to confer properties suitable for protection against microbes, mosquitoes, and flame retardant activity. The technology is adaptable for cotton textiles treatment. In support of Objective 2, we developed microcapsules using flame retardant, mosquito repellant, and antimicrobial compounds such as phosphorus–nitrogen containing small molecules, tea tree oil, essential oils, and microbial oleic acid, sophorolipid biosurfactants (SL-palmitic, SL-stearic and SL-oleic) and ascorbic acid. We prepared the microcapsules by depositing a thin polymeric coating on small solid particles or liquid droplets. In preliminary studies, we demonstrated that cotton fabric can be treated with the microcapsules.
Original approaches to prepare flame retardant cotton fabrics are required to advance the industrial efficiency of developing low-cost and effective flame retardant cotton. In support of Objective 2 we used microencapsulation and/or microwave technologies to modify cotton fabrics. The small amount of solvent used is an advance over current industrial processes to make flame retardant cotton. Thus, a rapid chemical treatment of cotton fabrics is use of microwave-assisted technology. The cotton fabrics designed contained environmentally friendly molecules including urea, diammonium phosphate, and phosphorous nitrogen rich containing compounds. We developed an efficient method for the chemical treatments of a series of fabrics. The fabrics tested positive for flame retardant activity. The treatment yields an effective flame retardant fabric, and places more chemical on the fabric (100 percent add-on). The compounds are also low-cost and commercially amenable to large-scale production of cotton fabrics.
In support of Objective 3 and Agreement 6054-41430-009-003R and Material Transfer Agreement 18565 with Cotton Incorporated, we made progress in the mechanical/chemical conversion of cotton denim apparel scraps to nanocellulose. The conversion process involves the mechanical grinding of apparel scraps to a particle size suitable for further chemical modification to form the nanocellulose product. Initial experiments successfully converted denim and apparel scraps into cellulose nanocrystals and nanofibers. Additional experimentation is required to obtain optimal yields and to further explore the possibility of obtaining additional value-added products from the cotton denim source material.
In support of Objective 3 research was done to standardize the procedure for the XRD analysis of cellulose samples. Nanocellulose samples patterns were analyzed to provide insight into the purity and structure of the samples. This approach more accurately determined the percentage of crystallinity in the cellulose.
In support of Objective 3 metallic nanoparticles were prepared within the intrafibrillar network of cellulose fibers inside of cotton fabrics. The prepared nanoparticles have shown excellent reusability as catalysts for bond-forming reactions and wastewater remediation of azo-dyes.
Accomplishments
1. Conversion of textile scraps to nanocellulose crystals and fibers. Apparel manufacturing contributes substantial amounts of textile scrap waste to landfills. ARS researchers in New Orleans, Louisiana have found a solution whereby the apparel waste is converted to value-added products. Rather than regarding the apparel scraps as zero-value waste and disposing the unwanted apparel scraps in landfills, a more profitable solution is to convert it to cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs). CNFs and CNCs have attracted a great deal of commercial interest as reinforcing agents in nanocomposites, polymers, gels, and emulsions due to their excellent tensile strength, sustainability and environmentally-friendly properties. Applications for CNCs and CNFs can be found in the construction, electronics and agricultural industries. Because of their biocompatibility, non-toxicity and benign decompositional by-products, CNCs and CNFs have found applications in medicine for bone regeneration, biosensors and wound care bandages. This wide-range of applications for CNCs and CNFs has increased their industrial demand at a combined annual growth rate of 18.4% since 2018. Using mechanical and chemical means, researchers have successfully converted scrap clothing material from textile apparel manufacturing into CNCs and CNFs. This accomplishment provides a process by which two products of value are produced which have a broad range of applications from what would otherwise be discarded as waste material. These value-added products will give the cotton industry an economic advantage over synthetic fiber manufacturers and will protect the environment by removing an unwanted waste stream of textile apparel scraps from landfills.
