Source: NBD NANOTECHNOLOGIES INC. submitted to
SUPERHYDROPHOBIC COATINGS FOR ENHANCED FOG HARVESTING IN ARID COASTAL REGIONS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
1002879
Grant No.
2014-33610-21965
Project No.
MASW-2014-00254
Proposal No.
2014-00254
Multistate No.
(N/A)
Program Code
8.4
Project Start Date
Jun 1, 2014
Project End Date
Jan 31, 2015
Grant Year
2014
Project Director
Zhang, B. J.
Recipient Organization
NBD NANOTECHNOLOGIES INC.
41 SHERWOOD AVE
DANVERS,MA 019232322
Performing Department
(N/A)
Non Technical Summary
Large areas across the United States and around the world are afflicted by drought, a condition that inflicts damage to local economies and particularly to agriculture. While some communities are turning to expensive energy-intensive processes such as desalination and long distance transport to address water shortages, NBD Nanotechnologies, Inc. is working to reduce stress on watershed resources by tapping into an underutilized fresh water resource - fog. Approximately 0.04% of the earth's fresh water is in the form of fog. In areas where fog droplets are heavy and the fog is thick, it can be collected by means of fog nets - simple systems with both minimal technology requirements and capital expenses. Fog harvesting has been so effective in some locations, that some developing communities are able to depend solely on fog nets to supply water for agriculture, cooking, and washing. Positive economic effects due to fog harvesting have already been observed in local populations along the arid coastal regions of Chile, Peru, and Nepal, among others. To date, fog nets are effective for harvesting water only in coastal regions where wind speeds are sufficiently high to support large fog droplets. In areas where fog is abundant but the size of the droplets is smaller, such as along the west coast of California, conventional polypropylene fog nets do not efficiently collect water. NBD Nanotechnologies, Inc. aims to optimize the surface chemistry and geometrical properties of the fog nets in order to harvest fog droplets too small for conventional netting. If successful, the technology would allow water to be harvested along the arid coastal regions of California, among others, to be used on site for irrigation or transported to drier regions. The proposed technology has already been proven by academic partners at laboratory scale. During Phase I of this project, NBD Nanotechnologies, Inc. will improve the chemistry of the coatings and scale up the manufacturing of the fog net prototypes. These prototypes will be tested under actual operating conditions in outdoor environments. Furthermore, NBD Nanotechnologies, Inc. will test the quality of the water collected as well as investigate the durability and wear performance of the coated fog nets over time and under accelerated wear conditions. If successful, Phase II of this project will focus on further scale up and marketing issues. The initial target market for the advanced fog net coatings will be vineyard businesses where a commercial size fog net would be capable of continuously irrigating six vine plants in full foliage. Through this work, NBD Nanotechnologies, Inc. hopes to create a profitable business, provide an inexpensive technology to harvest fog water, reduce the stress on existing watershed resources, increase job opportunities in the clean technology sector, and raise awareness of fog as a potential water source, particularly in California.
Animal Health Component
30%
Research Effort Categories
Basic
0%
Applied
30%
Developmental
70%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
11102102020100%
Knowledge Area
111 - Conservation and Efficient Use of Water;

Subject Of Investigation
0210 - Water resources;

Field Of Science
2020 - Engineering;
Goals / Objectives
The major goal of this project is to successfully commercialize a proprietary surface coating for fog net applications to exploit underused fresh water resources in fog laden areas. Accordingly, the commercialization success will reduce the strain on watershed resources in drought afflicted regions while providing a valuable source of fresh water in isolated rural communities.In the Phase I component of this work, the goal is to demonstrate the feasibility of the product at a scale larger than the 20 mm x 20 mm sized nets reported in literature. By producing the surface-treated fog nets at 1 m x 1 m size scales, we will be able to address some of the issues related to the scale up and implementation of the fog nets in order to prepare the technology for commercialization. If successful, a Phase II program will be proposed that will allow scale up of the coating technology to commercial scale fog nets at sizes of 30 m2 and greater.In order to achieve the Phase I goal, the following objectives have been identified as significant milestones in this Phase I program:1. Eliminate the use of C8-fluorocarbon chemistry used in the fog net coating formulations as described in literature by replacing it with the less environmentally hazardous C6-fluorocarbon chemistry to conform to environmental policies.2. Determine the coating formulations with the best performance to cost ratio in field tests.3. Identify the most environmentally friendly, cost-effective, and efficient process of applying the coating, and if possible, by reducing or eliminating the use of volatile organic compounds as solvents.4. Ensure water quality and safety by guaranteeing the absence of chemical leeching from the fog nets.5. Study the durability of the fog nets and fog net coatings to determine the recommended operating conditions.6. Optimize the mesh designs according to the anticipated fog quality of the specific region.7. Identify the best formulations, processes, sources, and personnel for scaling up manufacture.
Project Methods
This project will be conducted in collaboration between the awardee, NBD Nanotechnologies, Inc., and its partner, WindtoWater, with the aim of commercializing hydrophobic coatings that enhance the fog harvesting capabilities of fog nets.NBD Nanotechnologies, Inc.'s methods will involve scaling up the chemical synthesis of NBD's patented hydrophobic compounds in quantities sufficient for creating prototypes. These hydrophobic compounds will be mixed with a binder to produce durable coatings and efforts will be exerted to determine the coating formulation with the highest performance to cost ratio. Performance will be gauged in the laboratory through water contact angle measurements and a fog machine apparatus specifically designed for this project. The most promising coatings will be applied to fog net prototypes for in-field testing.In-field testing of the coated fog nets will be performed by WindtoWater along the coast of California. Statistical data regarding the amount of water collected by the coated fog net prototypes will be obtained by WindtoWater and shared with NBD Nanotechnologies, Inc. for analysis. Samples of the collected fog water will be sent to third party laboratories for testing to ensure unbiased assessment of the water's safety.Durability and wear behavior of the fog nets will be studied both in the laboratory and under normal operating conditions in the field. Laboratory tests will include accelerated testing methods such as abrasion testing, thermal cycling, exposure to ultraviolet light, and saline sprays according to standard tests. To test the durability of the coated fog nets in the field, the fog nets will be left exposed to the environment over several months. The quality of the water will be regularly examined to detect any chemical runoff due to wear and sections of the exposed fog nets will be analyzed under scanning electron microscopy to observe any damages to the coating.Based on the data collected from the in-field experiments and durability and wear testing, an optimal coating will be selected. NBD will review different coating processes for their suitability in a manufacturing process.WindtoWater will demonstrate the coated fog nets in Californian vineyards, promote their use among agricultural businesses, and analyze the market conditions in order to estimate the value of the technology.

Progress 06/01/14 to 01/31/15

Outputs
Target Audience: Water is a vital but limited resource since 97% of the earth’s water is found in the saline oceans. Only, 0.3% out of 3% is suitable for use in lakes, rivers, and swamps. 0.04% of the earth’s fresh water is held in the earth’s atmosphere in the form of clouds, humidity, and fog, which is untapped resource in most places except for select regional environmental conditions. Global climate changes have directly influenced the access of suitable water resources, leading to global drought. Based on data from NIDS (National Integrated Drought Information System), over 25% of the United States is considered to be under severe or worse drought conditions. Recently, California is experiencing the worst drought in the past century, affecting 96% of California is suffering from severe or worse droughts. Serious lack of water directly impacts availability for feed and irrigation in the agriculture industries although California remained the number one state in cash farm receipts with 11.3% of the US total in 2012 (15% for crops and 7.1% for livestock and its products). To help overcome this historical drought in California, NBD is working on implementing advanced coating technologies on fog nets along the coastal bay areas. NBD has successfully demonstrated approximately 3-5 fold enhancement of water harvesting from fog compared to non-coated fog nets. NBD’s potential customers will be vineyards in northern California. With the support of the USDA SBIR, NBD is accelerating the innovation of its proprietary coating technologies and leveraging the commercialization of fog nets for existing farmlands in northern California. Currently, NBD is examining the feasibility of inland fog nets (non-coastal) of California. Upon a successful demonstration of the feasibility test, fog net may be attractive to residential customers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? With the support of the USDA SBIR, NBD has been developing and expanding the expertise and skill-sets of the participants in this project. NBD researchers participated in an annual conference of American water works association (AWWA) in Boston, which was held on June 7-10, 2014. During the conference, NBD learned about the innovative technologies for water resources (supply and management) and benefited from presentations given by academic and industrial researchers. NBD connected with several experts in the water sectors. Next, NBD researchers participated in the bi-annual conference of fluoropolymer chemistry of American chemical society (ACS) in San Diego, California from October 13-16, 2014. The conference provided various research results of high end efforts with fluoropolymer chemistry from all over the world. NBD learned about the new trends in fluorochemistry and strategies for highly liquid repellent technologies. Thirdly, NBD associates visited twice the proto-type test site in California. Working with our local collaborators, Wind2Water, NBD associates became aware of urgency for water resource in California and learned about the policies and movements implemented to keep conserve water resources in California. How have the results been disseminated to communities of interest? At the beginning of the project initiation, NBD targeted the agricultural business owners that have property in fog abundant areas along the Californian coastal line. By educating them and outreaching to them, to enhance public understanding and interest for fog nets will be one of proprieties of the project initiation, progress, and success. During USDA SBIR, NBD has put significant efforts to outreach to the general public who are not aware of NBD's fog net technology. Especially, NPR (national public radio) interviewed NBD’s associates in Aug 2014 and aired NBD’s fog harvesting story in September 17, 2014 in California. During broadcast, NBD emphasized urgency of conserving water resources and explained how NBD could move forward to water collection from fog using fog nets. It was not only technical to deliver the potential and capacity of fog nets but also educational to arouse the urgency to the public (the link below): http://kalw.org/post/fog-harvester-0 Recently, the local TV channel in Boston, Massachusetts interviewed NBD regarding advanced technology of water collection and controlling the motion of water. Boston is unique because most people in Boston are highly educated and have strong interest in water and energy resources. Also, many high end technology-based companies and institutions have pay attention to policy and movement of conserving water/energy resources. During the broadcast, NBD’s efforts and expertise to collect and control water were delivered effectively to most people (the link below): http://www.wcvb.com/news/beetles-being-used-solve-waterloving-waterhating-issues/29693582 What do you plan to do during the next reporting period to accomplish the goals? NBD is continuing its efforts to optimize the water collection out of the fog nets. To boost the performance of fog nets, NBD is building multi-layered fog net systems and integrating (hydrophilic and hydrophobic) patterned fog nets. The data collected from the updated version of the fog nets will be analyzed and assessed. Furthermore, NBD is expanding proto-type test sites from coastal region to in-land region. By moving in-land test sites, NBD could serve the needs for more efficient water resources for a larger population of customers (residential and agricultural users) with ease of excess. NBD is looking to partner with the National Geological Survey to identify the optimal places for fog collection in California to run multiple new pilot tests and continue the data gathering in different locations across the state.

Impacts
What was accomplished under these goals? At the beginning of the USDA SBIR program, NBD established the following seven major goals of the projects: 1. Transition from C8-fluoroalkyl carbon to C6-fluoroalkyl carbon Recently, there has been a concern of bioaccumulation of longer fluoroalkyl chain (C8-fluorocarbon) among the scientific and engineering communities that push to make shorter version of it. In order to stay up-to-date with the movement of environmental policies, NBD directed its efforts to synthesize the shorter version of C6-fluorocarbon and successfully integrated it into fog nets. The coated-fog nets were proto-type tested over six months on the coastal region in California. During that period of time, they were exposed to harsh environments such as sun light (strong UV), corrosive salts, wind (mechanical stress), and wide range of temperature fluctuation. Compared with the performance of C8-fluorocarbon, the fog net integrated with C6-fluorocarbon performed successfully without deterioration. 2. Cost effective formulations At the beginning of the project, NBD tested the C8-fluoroalkyl chain-based coating for fog nets. The basic formulation was a proprietary C8:polyethyl methacrylate (PEMA)=1:1 dissolved by 1 wt% loading in AK-225. To prepare a fog net, a half of liter of the solution was used by paint brushing. Approximately $10.35/ea for C8-fluoroalkyl formulation. Changing the basic formulation into C6-fluoroalkyl chain lengths saves on raw material cost (for C8, $10.35/ea vs for C6, $9.66/ea, 6% raw material cost reduction). The major portion of the manufacturing cost is the cost of C6-fluoroalkyl chemistry. In order to further reduce the manufacturing cost, the key is to reduce the amount of C6-fluoroalkyl in the formulation without compromising the performance of fog net. During the proto-type test, NBD assessed various formulations such as C8:PEMA=1:1, C6:PEMA=1:1, and C6:PEMA=1:4. For each of the different formulations, there was no significant loss of performance observed which indicates that lower levels of fluorochemical loading are acceptable. Eventually, assuming that the fomulation is set to C6:PEMA=1:4, cost reduction is 50% (for C6:PEMA=1:1, $9.66/ea, forC6:PEMA=1:4, $4.82/ea). Lastly, to save additional manufacturing cost, NBD is investigating the chance of a roll-to-roll process. In general, brush painting covers a limited surface area and takes 30-40 minutes to coat the overall surface area (3′ x 3′). During the process, much of the solution is lost via evaporation and brush (it absorbs and holds lots amount of the solution). The roll-to-roll process in a controlled environment (reduced evaporation) is expected to save significant amounts of the coating materials and labor and boost mass production with efficiency. 3. Reducing and/or removing fluorinated solvent NBD is focusing on environmentally friendly, cost-effective and efficient processes for applying the coating. First, to make environmentally friendly coating, NBD synthesized the shorter version of fluoroalkyl (C8 to C6). Without losing its performance, NBD will pursue shorter chain lenghts (C4) to reduce the amount of fluoroalkyl groups length and to increase solubility in organic solvents. Secondly, to meet the requirement of cost-effectiveness and efficiency, NBD is looking forward to having an opportunity of roll-to-roll process. By implementing roll-to-roll process, NBD can pursue cost-effectiveness and efficiency of coating. Thirdly, most fluorinated coatings have an issue of solubility. To increase solubility, NBD has used a fluorinated solvent such as AK-225, which is a volatile organic chemical. Currently, NBD is focusing on copolymerizing C6-fluoroalkyl block with polymer resins such as methylmetharcrylate (MMA) and other blocks to integrate covalent moieties such as phosphate and isocyanide groups. These functional groups will provide enhanced solubility and durability by forming covalent bonds with substrates. 4. Quality of water collected from coated fog nets This project potentially targets agricultural (vineyards and farmlands in California) applications. Any small portion of precipitation and/or dissipation of hazardous chemicals from the fog net will prevent any application for agriculture. During the proto-type test runs, NBD submitted sample for water quality tests and confirmed that no hazardous chemicals such fluoride and silicone were detected in the collected water. Since the water samples were obtained from fog net directly, some amount of bacteria was detected. In order to be used as portable water for livestock, additional filtration will be required. However, in this project, NBD targets irrigation and/or watering plants and vegetation (vineyard), in which water collected directly from the net will be able to be used without further purification. 5. Durability of fog net coatings For industrial use of fog nets, durability is one of the most crucial factors to market. Durability of coatings addresses the chemical (corrosion) and mechanical (erosion, bending) robustness of coatings. NBD has installed several prototype fog nets with different formulations, materials, and dimension along the California coastal area for over a half year. Visual inspection of the fog nets before and after testing has been conducted using SEM (scanning electron microscopy). The fog nets coated with C8- and C6-fluoroalkyl-based formulation showed intact coatings that prevented corrosion and dust contamination within the net pores compared with non-coated fog nets. In other words, the coating is stable and robust enough to demonstrate chemical and mechanical resistance. To further assess durability with quantitative and qualitative data, NBD is building a UV irradiation chamber and will outsource the salt spray test. 6. Optimization in mesh design To optimize fog net design for water collection, NBD is carrying out FEM (finite element method)-based simulation to examine variations in mesh size and wire diameter. The theoretically simulated results in AutoCAD will be incorporated with onsite experimental results to optimize design metrics and understanding of air flow through nets. Additionally, NBD is investigating methods to increase water collection efficiency per unit area. NBD proposes a multi-layered fog net system to increase the extraction of water with the fog nets by optimizing the inter-spacing of the fognets with the mass transfer efficiency of the fog. The inter-spacing is being manipulated in-situ at the prototype testing site. Secondly, NBD has developed patterned hydrophobic-hydrophilic coatings to boost water droplet motions (coalescence and rolling-off). In-house tests revealed that hydrophilic and hydrophobic patterned surfaces performed better than non-patterned surface with C6-fluoroalkyl-based formulation. Thirdly, fog events are dynamic and depend on wind directions. Currently, fog nets are static and passive toward wind direction during water collection. NBD is designing fog nets which are dynamic and active toward wind. The active fog nets will enhance the amount of water collected during a fog net event. 7. Synthetic optimization in formulations, processes, and sources As described in the major goals of this project, NBD is focusing on optimizing the water collection performance of fog nets by evaluating best formulations, processes, sources and personnel for scale up. NBD is close to fulfilling the objectives and major goals during the proto-type testing pase with the support of the USDA SBIR. The know-how that NBD has attained will be transferred to scaling up the coated fog net manufacturing in California under a JDA (joint development agreement) and/or exclusive license. NBD’s efforts will provide a turn-key solution by installing and managing the fog nets for customers.

Publications


    Progress 06/01/14 to 01/31/15

    Outputs
    Target Audience: Water is a vital but limited resource since 97% of the earth's water is found in the saline oceans. Only, 0.3% out of 3% is suitable for use in lakes, rivers, and swamps. 0.04% of the earth's fresh water is held in the earth's atmosphere in the form of clouds, humidity, and fog, which is untapped resource in most places except for select regional environmental conditions. Based on data from NIDS (National Integrated Drought Information System), over 25% of the United States is considered to be under severe or worse drought conditions due to global climate changes. Recently, California has experienced the worst drought in the past century, affecting 96% of California is suffering from severe or worse droughts. Serious lack of water directly impacts availability for feed and irrigation in the agriculture industries although California remained the number one state in cash farm receipts with 11.6% of the US total in 2013 (15% for crops and 7.0% for livestock and its products). Compared to 2012, no significant improvement has been observed (11% of the US total in 2012, 13.6% for crops and 7.2% for livestock and its products). To help overcome this historical drought in California, NBD is primarily working on implementing advanced coating technologies on fog nets along the coastal bay areas in California. NBD has successfully demonstrated approximately 3-5 fold enhancement of water harvesting from fog compared to non-coated fog nets. At maximum, above 5 gallons of water from a single 1m2 fog net can be collected per day. NBD's potential customers will be vineyards along the coastal regions in California. Numerous vineyards not only in northern California near Sonoma and Napa but also in southern California near Santa Barbara have shown strong interest in NBD's fog nets for irrigation. With the support of the USDA SBIR Phase I, NBD has been accelerating the innovation of its proprietary coating technologies and leveraging the commercialization of fog nets for existing farmlands in northern California. Currently, NBD is examining the feasibility of inland fog nets (non-coastal regions) of California. Recently, with the support of California state officials, NBD has successfully installed an inland testing facility at San Bruno mountain state park (~2 miles off from the coastal line). Upon successful demonstration of the feasibility test, fog nets may be attractive to residential customers in addition to commercial vineyards. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? With the support of the USDA SBIR, NBD has been developing and expanding the expertise and skill-sets of the participants in this project. NBD researchers participated in an annual conference of American water works association (AWWA) in Boston, which was held on June 7-10, 2014. During the conference, NBD learned about the innovative technologies for water resources (supply and management) and benefited from presentations given by academic and industrial researchers. NBD connected with several experts in the water sectors. Next, NBD researchers participated in the bi-annual conference of fluoropolymer chemistry of American chemical society (ACS) in San Diego, California from October 13-16, 2014. The conference provided various research results of high end efforts with fluoropolymer chemistry from all over the world. NBD learned about the new trends in fluorochemistry and strategies for highly liquid repellent technologies. Thirdly, NBD associates visited the proto-type test site in California twice. Working with our local collaborators, Wind2Water, NBD associates became more aware of the urgency for facilitating water resources in California and learned about the policies and movements implemented to conserve water resources in California. How have the results been disseminated to communities of interest? NBD's fog net technology is simple, efficient, and cost effective to collect water compared with any other current state of the art fog nets. When the project initiated, NBD targeted the agricultural business owners that have property in fog abundant areas along the Californian coastal line. Educating them and carrying outreach and awareness, to enhance the public understanding and interest in fog nets will be one of proprieties for the project's progress and success. During USDA SBIR Phase I, NBD has reached out to the general public who are not aware of NBD's fog net technology. Specifically, NPR (national public radio) interviewed NBD's associates in Aug 2014 and aired NBD's fog harvesting story in September 17, 2014 in California. During the broadcast, NBD emphasized the urgency of conserving water resources and explained how NBD could facilitate water collection from fog using fog nets. Not only did it deliver the technical awareness on the potential and capability of fog nets but it also raised the urgency to the public (http://kalw.org/post/fog-harvester-0). Since the broadcast on a public radio channel, California state officials reached out to NBD's local collaborator (Wind2water). NBD's fog net technologies are exactly well matched with California's needs and expected to air in resolving water dilemma within the near future. In January 2015, NBD's prototype test sites were expanded to San Bruno mountain state park under the support of California State government. NBD has also connected with Alicia Torregrosa at USGS in California to collaborate on the fog net technology. The USGS has operated several test sites at national parks and government properties for fog nets for a couple of years. With the support of USGS, NBD expanded additional test spots such as Monterey and Big Sur in January 2015. Through the collaboration, their expertise in geological survey and climate information can be integrated as valuable assets to expand NBD's fog net technology in California. Also, USGS has established strong connections and reputation with Californian State officials. It can bridge NBD's new technology with potential end users (vineyard, farm) in California. Notably, NBD has a great opportunity to discuss with influential vineyard owners such as Laurel Glen, Patz & Hall, Temecular wineries, and several local family vineyards. Some of them have allowed NBD to run several fog net tests and agreed with NBD to collect data at their properties. Any feasibility test demonstrated can trigger a huge interest with not only adjacent vineyards but also global agriculture industries in California. In November 2014, a local TV channel in Boston, Massachusetts interviewed NBD regarding advanced technology of water collection and controlling the motion of water. As a newly-established water cluster, Boston is unique with its highly educated population and strong interest in water and energy resources. Also, many high end technology-based companies and institutions have pay attention to policy and movement of conserving water/energy resources. During the broadcast, NBD's efforts and expertise to collect and control water were delivered effectively to the public (http://www.wcvb.com/news/beetles-being-used-solve-waterloving-waterhating-issues/29693582). What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? 1. Transition from C8-fluoroalkyl carbon to C6-fluoroalkyl carbon Recently, there has been a concern of bioaccumulation of longer fluoroalkyl chain (C8-fluorocarbon) among the scientific and engineering communities. These concerns have led most chemical developers and regulatory agencies to push for the conversion of C8-fluorocarbon to C6-fluorocarbon. In order to stay up-to-date with the movement of environmental policies, NBD directed its efforts to synthesize the shorter version of C6-fluorocarbon. Additionally, NBD has put more effort to reduce length of fluoroalkyl chain to an even shorter version such as C4 or hybridized fluorocarbon. C4-fluoroalkyl chain version showed no significant change in wetting characteristics as shown in Table 1. Table 1. Water contact angle measurements of FPOSS with different fluoroalkyl chains Name C8-FPOSS C6-FPOSS C4-FPOSS Water contact angle 117° 115° 113° Another approach to reduce the fluoroalkyl chain length is to hybridize different fluoroalkyl molecules such as C8/C4 and C6/C4. By hybridizing FPOSS, the overall number of fluoroalkyl chains was reduced for C8/C4 from 64 to 32 and for C6/C4 from 48 to 32 without losing liquid repellency as shown in Table 2, respectively (50% and 33% fluoroalkyl chain length reduction per FPOSS molecule). Table 2. Liquid contact angle measurements of hybridized FPOSS with different fluoroalkyl chains Name C8/C4-FPOSS C6/C4-FPOSS Water contact angle 117° 115° 2. Cost effective formulations NBD's proprietary formulation is C8 FPOSS:polyethyl methacrylate (PEMA)=1:1 dissolved in 1 wt% loading in AK-225, which costs $10.35/ea to prepare a fog net. To reduce manufacturing cost further, NBD has put effort to develop and optimize the existing formulation. First, changing C8-FPOSS to C6-FPOSS saves 6% raw material cost. Second, the key is to substituteAK-225 into organic solvents to reduce the manufacturing cost further. NBD developed the fluoride ion encapsulated FPOSS (F-@FPOSS) and copolymerized FPOSS demonstrating the same physical and chemical properties exception of solubility. It is notable that F-@FPOSS and FPOSS copolymer are soluble in most organic solvents. These organic solvents are quite cheaper than AK-225. Therefore, significant cost reduction (60-80% cost saving)of new formulations is achieved. 3. Reducing and/or removing fluorinated solvent The bottleneck with most fluorinated coatings is solubility. In general, NBD has used a fluorinated solvent such as AK-225, which is a hazardous volatile organic chemical. In order to overcome this limitation, NBD has successfully copolymerized the C6-FPOSS with polymer resins such as methylmetharcrylate (MMA). C6-FPOSS-MMA copolymer does not show significant performance change (110o) compared to C6-FPOSS (116o). It is notable that C6-FPOSS-MMA copolymer provides enhanced solubility in various organic solvents such as acetone, MEK (methyl ethyl ketone), diethyl ether, tetrahydrofuran (THF), and etc. Therefore, NBD expects that there is a huge impact on FPOSS not only making more environmentally friendly coating but also further reducing cost by substituting AK-225 with organic solvents. NBD continues to work on other blocks to integrate covalent moieties such as phosphate and isocyanide groups. These functional groups will provide enhanced solubility and durability by forming covalent bonds with substrates. Fourthly, NBD modified FPOSS by encapsulating fluoride ion. The fluoride ion encapsulated FPOSS (F-@FPOSS) demonstrates the same physical and chemical properties exception of solubility. F-@FPOSS is almost soluble in organic solvents. Considering block copolymerization requires multiple processes to isolate, F-@FPOSS might be more straight forward to resolve the major technical issues of FPOSS such as solubility and cost effectiveness compared with C6-FPOSS-MMA. 4. Quality of water collected from coated fog nets Since NBD's fog net technique targets irrigation and/or watering plants, vegetation (vineyard), and livestock, no additional filtration or purification to get rid of hazardous chemicals will be required. To confirm water quality, NBD submitted water samples obtained directly from the coated fog net during the proto-type test runs. The test screened total 40 chemical species, which include inorganic materials regulated by EPA (US environmental protection agency) for potable water. The test results showed that none of EPA primary standards were detected. This test result is promising and convincing for NBD to commercialize the fog net technique. 5. Durability of fog net coatings For industrial use of fog nets, durability is one of the most crucial factors to market. Durability of coatings addresses the chemical (corrosion) and mechanical (erosion, bending) robustness of coatings. NBD has installed several prototype fog nets with different formulations, materials, and dimension along the California coastal area for over a half year. Visual inspection of the fog nets before and after testing has been conducted using SEM (scanning electron microscopy). The fog nets coated with C8- and C6-FPOSS-based formulation showed intact coatings that prevented corrosion and dust contamination within the net pores compared with non-coated fog nets. In other words, the coating is stable and robust enough to demonstrate chemical and mechanical resistance. To further assess durability with quantitative and qualitative data, NBD is building a UV irradiation chamber and will outsource the salt spray test. 6. Optimization in mesh design To optimize fog net design for water collection, NBD is carrying out FEM (finite element method)-based simulation to examine variations in mesh size and wire diameter. The base line comparison for this approach will be previous research (Park et al. Langmuir 29 (2013) 13269-13277). The theoretically simulated results in AutoCAD will be incorporated with onsite experimental results to optimize design metrics and understanding of air flow through nets. Additionally, NBD is investigating several methods to increase water collection efficiency per unit area. First, NBD proposed a multi-layered fog net system to increase the extraction of water with the fog nets by optimizing the inter-spacing of the fog nets with the mass transfer efficiency of the fog. The inter-spacing is being manipulated in-situ at the prototype testing site. With the collaboration of USGS (US geological survey), NBD has installed a prototype multi-layered fog net at San Bruno mountain park. Through the collaboration, USGS will provide valuable information that was assessed from multiple test sites in California from over a decade of recordings. Second, NBD has developed hydrophobic-hydrophilic patterned coatings to boost water droplet motions (coalescence and rolling-off). In-house tests revealed that hydrophilic and hydrophobic patterned surfaces performed 30% better than non-patterned surface with C6-FPOSS-based formulation. This technique was recently filed to USPTO (US patent and trademark office) a provisional patent (No. 62/108,318). With the combination of multi-layered fog net, the patterned fog net will escalate the efficiency of the current fog net technology tremendously. 7. Synthetic optimization in formulations, processes, and sources As described in the major goals of this project, NBD is focusing on optimizing the water collection performance of fog nets by evaluating best formulations, processes, sources and personnel for scale up. NBD is close to fulfilling the objectives and major goals during the proto-type testing with the support of the USDA SBIR Phase I. The know-how that NBD has attained will be transferred to scaling up the coated fog net manufacturing in California under a JDA (joint development agreement) and/or exclusive license. NBD's efforts will provide a turn-key solution by installing and managing the fog nets for customers.

    Publications