greymouser7
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Chemicals in the shells of shrimp may lead to coatings that can heal themselves.
Wikipedia:
Potential industrial use
Scientists have recently developed a polyurethane coating that heals its own scratches when exposed to sunlight, offering the promise of scratch-free cars and other products. The self-healing coating uses chitosan incorporated into traditional polymer materials, such as those used in coatings on cars, to protect paint.
When a scratch damages the chemical structure, the chitosan responds to ultraviolet light by forming chemical chains that begin bonding with other materials in the substance, eventually smoothing the scratch. The process can take less than an hour.[28]
Marek W. Urban, a scientist working on this project, said the polymer can only repair itself in the same spot once, and would not work after repeated scratches.[29] Whether this technology can be applied to industrial materials, however, depends on a number of factors (long-term persistence of "healability", stiffness and heat resistance of coating, knowledge of the exact mechanism of healing, etc.) not present initial studies; further investigation into these factors can potentially take decades to rectify.
http://www.gizmag.com/self-healing-car-paint/11254/ :
Biswajit Ghosh and Marek W. Urban from the School of Polymers and High Performance at The University of Southern Mississippi, Hattiesburg, advise that their new material will have a lot of practical applications and could coat anything that can be scratched including electronics, aircraft, cars etc.
The self-healing coatings could minimize upkeep and repair on a variety of products, saving consumers money and reducing waste.
For the boffins amongst us, Ghosh and Urban report that the compound network consists of an oxetane-substituted chitosan precursor incorporated into a two-component polyurethane.
Upon mechanical damage of the network, four-member oxetane rings open to create two reactive ends. When exposed to ultraviolet light, chitosan chain scission occurs, which forms crosslinks with the reactive oxetane ends, thus repairing the network. Now you know!
This repair process is not moisture-sensitive, meaning it should work in all climates. And making the new coating wont break the bank, according to Urban Its very economical, he said. You can get chitosan for almost nothing. I wish the lobster or crab came at a similar price!
One limitation is that the mending reactions dont seem to work a second time, so each part of the coating can repair itself only once. But Urban doesnt see this as much of a drawback in the real world. Even if you try to hit the same spot, within a couple of microns, statistically the chances of it happening are very small, he said.
Other self healing compounds
The new compound is not the first man-made self-healing material. In 2001, researchers at the University of Illinois embedded tiny liquid-filled capsules in a polymer coating. When the coating forms a crack, the capsules rupture spilling healing agents into the damaged area, repairing it.
In December 2005 we reported the worlds first clear paint that repairs scratches on painted car surfaces, Nissan Scratch Guard . "Scratch Guard" contained a newly developed high elastic resin that helps prevent scratches from affecting the inner layers of a cars painted surface. Repair took anything from one day to a week and Nissan has been offering this self-healing paint as an option on its X-Trail SUV since 2005. This product appears similar to the Chitosan containing compound, but achieves its results in a slightly different manner.
http://www.forbes.com/2009/03/11/self-repairing-paint-technology-breakthroughs-paint.html :
In a paper published this week in the journal Science, Biswajit Ghosh and Marek Urban of the University of Southern Mississippi reveal a polyurethane "network" that self-repairs when exposed to sunlight. Although it's still laboratory research, the scientists hope their work could one day result in a low-cost coating that could be swabbed over just about anything.
"There are an immense number of opportunities for this," says Urban, a professor of polymer science. "Basically anything externally exposed." Like the paint on a car, an airplane, or even furniture.
It's particularly handy that the compound is easy to make and uses well-known and readily available materials, namely organic compounds called oxetanes, and a material called chitosan which is produced in the shells of shrimp, lobsters and crabs, notes Craig Hawker, a polymer chemist at University of California, Santa Barbara who was not involved in the research project.
"The ability to combine industrially accepted and well-studied oxetane groups with a widely available renewable biomaterial such as chitosan is a powerful concept from an environmental and energy viewpoint," wrote Hawker in an e-mail exchange. "This could generate new materials with enhanced properties, yet be easy to prepare and dispose of."
Industry already employs some "self-repairing" materials: Nissan's (nasdaq: NSANY - news - people ) upscale Infiniti vehicles are covered with a clear coat of resin that can conceal shallow scratches from things like the brushes of car-wash machines. After the car is scratched, the resin slowly seeps into the scratches, covering them. The process takes about a week--less if it's hot outside.
But the resin only covers the most superficial scratches. Scratch the surface deeply enough to hit the paint, and your car is headed to the body shop after all.
Ghosh and Urban's material is different. Their self-repairing mechanism could be integrated into a polyurethane paint. Just how it works involves some impressive chemistical gymnastics.
They incorporated four-sided oxetane "rings" and a chitosan precursor into a polyurethane. When the material is scratched, oxetane rings split, exposing reactive sites, like arms that want to grab something. Ultraviolet light breaks open chitosan, a complex carbohydrate called a polysaccharide, revealing another set of reactive arms.
The chitosan arms and the oxetane arms attract one other, bond, and--presto!--your paint job is as good as new. To see the process in action, see "Better Than Watching Paint Dry." http://www.forbes.com/2009/03/12/self-repairing-paint-technology-breakthroughs-metadata.html
This stuff isn't perfect. After a scratch, the rings bond with the chitosan, making this magical repair a one-shot deal. A scratch in the exact same spot would remain a scratch. That makes overlapping scratches awkward: When Ghosh and Urban scratched an 'x' in their material, it didn't repair at the center.
And Urban cautions that much work and testing still needs to be done. He's still puzzling out the chemical reactions at play. He knows that the binding reactions occur, for example, but he doesn't yet know exactly where along the molecules they happen. Even figuring out this much took years after his researchers had developed and tested the material.
"Visually it's pretty simple, but chemically it is very difficult to prove," he says.
Urban says chemical companies are interested in his work, but he declines to name them or say just how interested.
For all of the promise of self-repairing materials, big commercial successes have remained elusive. UC Santa Barbara's Hawker says that is bound to change. Perhaps even with Ghosh and Urban's polyurethane.
"It is just a matter of time for industry to appreciate the design advantages with these new materials and to develop procedures for large-scale production," he writes.
http://www.pcimag.com/articles/the-use-of-chitosan-in-paint-detackification :
The paints used in automotive-finishing operations are a tacky material and tend to adhere to the surfaces of spray booths, particularly in the sump and drain areas. To maintain the design intent of the paint spray booth, the paint overspray must be constantly removed from the sump to prevent clogging of the sump drain and recirculating system.
In order to assist in the removal of the oversprayed paint from the air and to provide efficient operation of the down-draft, water-washed paint spray booths utilize paint detackifying chemical agents. The detackification products are commonly introduced into the water that is recirculated in the paint spray booth system.
Automatic Spray Operation
Paint spray booths are typically 100 300 feet in length and usually contain many robotic and manual spray zones. The temperature and humidity are rigorously controlled in these systems. As vehicles are painted in these booths, a certain amount of paint does not contact the article being painted and forms a fine mist of paint in the air space surrounding the article.
This paint must be removed from the air. To accomplish this, the contaminated air is pulled through the paint spray booth by exhaust fans. A curtain of circulating water is maintained across the path of the air in such a way that the air must pass through the water curtain to reach the exhaust fans.
As the air passes through the water curtain, the paint mist is scrubbed from the air and carried to a sump basin (sludge pit), usually located below the paint spray booth. In this area, the paint particles are separated from the water so that the water may be recycled and the paint particles disposed of as paint sludge (Figure 1).
Common Detackifiers
The paint detackifiers (or denaturants) commonly added to these systems are either melamine-formaldehyde based (Figure 2) or based upon acrylic acid chemistry (Figure 3).
Chitosan Detackifier
The innovative nature of the BC4200NP technology lies in the fact that it is derived from chitin, the waste product of food production, namely shell fish harvesting. The solid chitin derived from these operations is treated with sodium hydroxide at an elevated temperature to produce chitosan, also called poly(glucosamine), that represents a deacetylated chitin.
The chitosan produced in this way yields a glucosamine polysaccharide structurally similar to cellulose. The degree of deacetylation can be controlled by temperature and reaction time. The chitosan produced, also in a solid state, is not readily soluble in water, but can be rendered more water soluble by the addition of various acids such as acetic, sulfuric, hydrochloric, citric, sulfamic and mixtures thereof.
The deacetylation of chitin to produce chitosan is represented in Figure 4.The melamine-formaldehyde detackifiers that BC4200NP is replacing are derived from non-renewable natural gas supplies and contain residual amounts of free formaldehyde as a necessary consequence of the resin production operation.
The acrylic acid-based detackifiers are derived from non-renewable crude oil feed stocks and their price is therefore subject to the global oil market. Further, since the chitosan-based product is less acidic than the traditional products, less sodium hydroxide is necessary in an operating system to control pH, resulting in less overall chemical usage.
Additional field studies have also indicated that less detackifier is necessary to treat a given amount of paint, and this also makes the BC4200NP more attractive from an application cost perspective.
Successful Chitosan Operations
The BC4200NP technology has been running successfully at the Mitsubishi Motors facility in Normal, IL, for over a year and a half with excellent results. Sodium hydroxide usage has been reduced by 87%, very little residual sludge has accumulated in their sludge pit, and plant operators claim to have very little involvement with the process. The sludge characteristics are the same or better than with the previous melamine-formaldehyde technology. The BC4200NP product also contributes no additional VOC to plant processes. Significant milestones in regard to this technology are as follows:
Environmental Advantages of BC4200NP Technology
The environmental advantages of this technology are summarized as follows.
Wikipedia what it is:
Chitosan (pron.: /ˈkaɪtɵsæn/) is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It is made by treating shrimp and other crustacean shells with the alkali sodium hydroxide.
Chitosan has a number of commercial and possible biomedical uses. It can be used in agriculture as a seed treatment and biopesticide, helping plants to fight off fungal infections.
In winemaking it can be used as a fining agent, also helping to prevent spoilage. In industry, it can be used in a self-healing polyurethane paint coating. In medicine, it may be useful in bandages to reduce bleeding and as an antibacterial agent; it can also be used to help deliver drugs through the skin. -wikipedia
Chitosan is produced commercially by deacetylation of chitin, which is the structural element in the exoskeleton of crustaceans (such as crabs and shrimp) and cell walls of fungi.
The degree of deacetylation (%DD) can be determined by NMR spectroscopy, and the %DD in commercial chitosans ranges from 60 to 100%. On average, the molecular weight of commercially produced chitosan is between 3800 and 20,000 Daltons.
A common method for the synthesis of chitosan is the deacetylation of chitin using sodium hydroxide in excess as a reagent and water as a solvent. This reaction pathway, when allowed to go to completion (complete deacetylation) yields up to 98% product.[2]
The amino group in chitosan has a pKa value of ~6.5, which leads to a protonation in acidic to neutral solution with a charge density dependent on pH and the %DA-value. This makes chitosan water soluble and a bioadhesive which readily binds to negatively charged surfaces such as mucosal membranes.
Chitosan enhances the transport of polar drugs across epithelial surfaces, and is biocompatible and biodegradable. Purified quantities of chitosans are available for biomedical applications.
Chitosan and its derivatives, such as trimethylchitosan (where the amino group has been trimethylated), have been used in nonviral gene delivery.
Trimethylchitosan, or quaternised chitosan, has been shown to transfect breast cancer cells, with increased degree of trimethylation increasing the cytotoxicity; at approximately 50% trimethylation, the derivative is the most efficient at gene delivery. Oligomeric derivatives (3-6 kDa) are relatively nontoxic and have good gene delivery properties.[3]
Wikipedia:
Potential industrial use
Scientists have recently developed a polyurethane coating that heals its own scratches when exposed to sunlight, offering the promise of scratch-free cars and other products. The self-healing coating uses chitosan incorporated into traditional polymer materials, such as those used in coatings on cars, to protect paint.
When a scratch damages the chemical structure, the chitosan responds to ultraviolet light by forming chemical chains that begin bonding with other materials in the substance, eventually smoothing the scratch. The process can take less than an hour.[28]
Marek W. Urban, a scientist working on this project, said the polymer can only repair itself in the same spot once, and would not work after repeated scratches.[29] Whether this technology can be applied to industrial materials, however, depends on a number of factors (long-term persistence of "healability", stiffness and heat resistance of coating, knowledge of the exact mechanism of healing, etc.) not present initial studies; further investigation into these factors can potentially take decades to rectify.
http://www.gizmag.com/self-healing-car-paint/11254/ :
Biswajit Ghosh and Marek W. Urban from the School of Polymers and High Performance at The University of Southern Mississippi, Hattiesburg, advise that their new material will have a lot of practical applications and could coat anything that can be scratched including electronics, aircraft, cars etc.
The self-healing coatings could minimize upkeep and repair on a variety of products, saving consumers money and reducing waste.
For the boffins amongst us, Ghosh and Urban report that the compound network consists of an oxetane-substituted chitosan precursor incorporated into a two-component polyurethane.
Upon mechanical damage of the network, four-member oxetane rings open to create two reactive ends. When exposed to ultraviolet light, chitosan chain scission occurs, which forms crosslinks with the reactive oxetane ends, thus repairing the network. Now you know!
This repair process is not moisture-sensitive, meaning it should work in all climates. And making the new coating wont break the bank, according to Urban Its very economical, he said. You can get chitosan for almost nothing. I wish the lobster or crab came at a similar price!
One limitation is that the mending reactions dont seem to work a second time, so each part of the coating can repair itself only once. But Urban doesnt see this as much of a drawback in the real world. Even if you try to hit the same spot, within a couple of microns, statistically the chances of it happening are very small, he said.
Other self healing compounds
The new compound is not the first man-made self-healing material. In 2001, researchers at the University of Illinois embedded tiny liquid-filled capsules in a polymer coating. When the coating forms a crack, the capsules rupture spilling healing agents into the damaged area, repairing it.
In December 2005 we reported the worlds first clear paint that repairs scratches on painted car surfaces, Nissan Scratch Guard . "Scratch Guard" contained a newly developed high elastic resin that helps prevent scratches from affecting the inner layers of a cars painted surface. Repair took anything from one day to a week and Nissan has been offering this self-healing paint as an option on its X-Trail SUV since 2005. This product appears similar to the Chitosan containing compound, but achieves its results in a slightly different manner.
http://www.forbes.com/2009/03/11/self-repairing-paint-technology-breakthroughs-paint.html :
In a paper published this week in the journal Science, Biswajit Ghosh and Marek Urban of the University of Southern Mississippi reveal a polyurethane "network" that self-repairs when exposed to sunlight. Although it's still laboratory research, the scientists hope their work could one day result in a low-cost coating that could be swabbed over just about anything.
"There are an immense number of opportunities for this," says Urban, a professor of polymer science. "Basically anything externally exposed." Like the paint on a car, an airplane, or even furniture.
It's particularly handy that the compound is easy to make and uses well-known and readily available materials, namely organic compounds called oxetanes, and a material called chitosan which is produced in the shells of shrimp, lobsters and crabs, notes Craig Hawker, a polymer chemist at University of California, Santa Barbara who was not involved in the research project.
"The ability to combine industrially accepted and well-studied oxetane groups with a widely available renewable biomaterial such as chitosan is a powerful concept from an environmental and energy viewpoint," wrote Hawker in an e-mail exchange. "This could generate new materials with enhanced properties, yet be easy to prepare and dispose of."
Industry already employs some "self-repairing" materials: Nissan's (nasdaq: NSANY - news - people ) upscale Infiniti vehicles are covered with a clear coat of resin that can conceal shallow scratches from things like the brushes of car-wash machines. After the car is scratched, the resin slowly seeps into the scratches, covering them. The process takes about a week--less if it's hot outside.
But the resin only covers the most superficial scratches. Scratch the surface deeply enough to hit the paint, and your car is headed to the body shop after all.
Ghosh and Urban's material is different. Their self-repairing mechanism could be integrated into a polyurethane paint. Just how it works involves some impressive chemistical gymnastics.
They incorporated four-sided oxetane "rings" and a chitosan precursor into a polyurethane. When the material is scratched, oxetane rings split, exposing reactive sites, like arms that want to grab something. Ultraviolet light breaks open chitosan, a complex carbohydrate called a polysaccharide, revealing another set of reactive arms.
The chitosan arms and the oxetane arms attract one other, bond, and--presto!--your paint job is as good as new. To see the process in action, see "Better Than Watching Paint Dry." http://www.forbes.com/2009/03/12/self-repairing-paint-technology-breakthroughs-metadata.html
This stuff isn't perfect. After a scratch, the rings bond with the chitosan, making this magical repair a one-shot deal. A scratch in the exact same spot would remain a scratch. That makes overlapping scratches awkward: When Ghosh and Urban scratched an 'x' in their material, it didn't repair at the center.
And Urban cautions that much work and testing still needs to be done. He's still puzzling out the chemical reactions at play. He knows that the binding reactions occur, for example, but he doesn't yet know exactly where along the molecules they happen. Even figuring out this much took years after his researchers had developed and tested the material.
"Visually it's pretty simple, but chemically it is very difficult to prove," he says.
Urban says chemical companies are interested in his work, but he declines to name them or say just how interested.
For all of the promise of self-repairing materials, big commercial successes have remained elusive. UC Santa Barbara's Hawker says that is bound to change. Perhaps even with Ghosh and Urban's polyurethane.
"It is just a matter of time for industry to appreciate the design advantages with these new materials and to develop procedures for large-scale production," he writes.
http://www.pcimag.com/articles/the-use-of-chitosan-in-paint-detackification :
The paints used in automotive-finishing operations are a tacky material and tend to adhere to the surfaces of spray booths, particularly in the sump and drain areas. To maintain the design intent of the paint spray booth, the paint overspray must be constantly removed from the sump to prevent clogging of the sump drain and recirculating system.
In order to assist in the removal of the oversprayed paint from the air and to provide efficient operation of the down-draft, water-washed paint spray booths utilize paint detackifying chemical agents. The detackification products are commonly introduced into the water that is recirculated in the paint spray booth system.
Automatic Spray Operation
Paint spray booths are typically 100 300 feet in length and usually contain many robotic and manual spray zones. The temperature and humidity are rigorously controlled in these systems. As vehicles are painted in these booths, a certain amount of paint does not contact the article being painted and forms a fine mist of paint in the air space surrounding the article.
This paint must be removed from the air. To accomplish this, the contaminated air is pulled through the paint spray booth by exhaust fans. A curtain of circulating water is maintained across the path of the air in such a way that the air must pass through the water curtain to reach the exhaust fans.
As the air passes through the water curtain, the paint mist is scrubbed from the air and carried to a sump basin (sludge pit), usually located below the paint spray booth. In this area, the paint particles are separated from the water so that the water may be recycled and the paint particles disposed of as paint sludge (Figure 1).
Common Detackifiers
The paint detackifiers (or denaturants) commonly added to these systems are either melamine-formaldehyde based (Figure 2) or based upon acrylic acid chemistry (Figure 3).
Chitosan Detackifier
The innovative nature of the BC4200NP technology lies in the fact that it is derived from chitin, the waste product of food production, namely shell fish harvesting. The solid chitin derived from these operations is treated with sodium hydroxide at an elevated temperature to produce chitosan, also called poly(glucosamine), that represents a deacetylated chitin.
The chitosan produced in this way yields a glucosamine polysaccharide structurally similar to cellulose. The degree of deacetylation can be controlled by temperature and reaction time. The chitosan produced, also in a solid state, is not readily soluble in water, but can be rendered more water soluble by the addition of various acids such as acetic, sulfuric, hydrochloric, citric, sulfamic and mixtures thereof.
The deacetylation of chitin to produce chitosan is represented in Figure 4.The melamine-formaldehyde detackifiers that BC4200NP is replacing are derived from non-renewable natural gas supplies and contain residual amounts of free formaldehyde as a necessary consequence of the resin production operation.
The acrylic acid-based detackifiers are derived from non-renewable crude oil feed stocks and their price is therefore subject to the global oil market. Further, since the chitosan-based product is less acidic than the traditional products, less sodium hydroxide is necessary in an operating system to control pH, resulting in less overall chemical usage.
Additional field studies have also indicated that less detackifier is necessary to treat a given amount of paint, and this also makes the BC4200NP more attractive from an application cost perspective.
Successful Chitosan Operations
The BC4200NP technology has been running successfully at the Mitsubishi Motors facility in Normal, IL, for over a year and a half with excellent results. Sodium hydroxide usage has been reduced by 87%, very little residual sludge has accumulated in their sludge pit, and plant operators claim to have very little involvement with the process. The sludge characteristics are the same or better than with the previous melamine-formaldehyde technology. The BC4200NP product also contributes no additional VOC to plant processes. Significant milestones in regard to this technology are as follows:
- Compositional patent granted, US 6,673,263, B2, 1/6/04;
- Process patent granted, US 6,858,093 B2, 2/22/05;
- Commercially launched at MMNA in Normal, IL, 8/23/05;
- Received 2005 Environmental Achievement Award from EMA, 3/23/06;
- Received 2006 Honorable Achievement Award from Environmental Protection Magazine, 9/15/06;
- Featured case study at CMS Forum in San Francisco, CA, 10/26/06;
- Nominated for Presidential Green Chemistry Award, December 2006; and
- Launched at Ford TCAP facility in St. Paul, MN, January 2007.
Environmental Advantages of BC4200NP Technology
The environmental advantages of this technology are summarized as follows.
- Program does not include the use of melamine-formaldehyde resins, therefore no residual free formaldehyde (a known carcinogen) is introduced.
- Raw material is not derived from natural gas and/or crude oil, and therefore does not utilize non-renewable resources.
- Raw material is obtained from the waste products of food production, i.e., crab, lobster and shrimp shells.
- Product is safer than other conventional technologies do to its lower acidity level.
- Chitosan, the main component of the BC4200NP technology, has been demonstrated to have anti-microbial properties and will therefore decrease the use of toxic and hazardous biocides.
Wikipedia what it is:
Chitosan (pron.: /ˈkaɪtɵsæn/) is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It is made by treating shrimp and other crustacean shells with the alkali sodium hydroxide.
Chitosan has a number of commercial and possible biomedical uses. It can be used in agriculture as a seed treatment and biopesticide, helping plants to fight off fungal infections.
In winemaking it can be used as a fining agent, also helping to prevent spoilage. In industry, it can be used in a self-healing polyurethane paint coating. In medicine, it may be useful in bandages to reduce bleeding and as an antibacterial agent; it can also be used to help deliver drugs through the skin. -wikipedia
Chitosan is produced commercially by deacetylation of chitin, which is the structural element in the exoskeleton of crustaceans (such as crabs and shrimp) and cell walls of fungi.
The degree of deacetylation (%DD) can be determined by NMR spectroscopy, and the %DD in commercial chitosans ranges from 60 to 100%. On average, the molecular weight of commercially produced chitosan is between 3800 and 20,000 Daltons.
A common method for the synthesis of chitosan is the deacetylation of chitin using sodium hydroxide in excess as a reagent and water as a solvent. This reaction pathway, when allowed to go to completion (complete deacetylation) yields up to 98% product.[2]
The amino group in chitosan has a pKa value of ~6.5, which leads to a protonation in acidic to neutral solution with a charge density dependent on pH and the %DA-value. This makes chitosan water soluble and a bioadhesive which readily binds to negatively charged surfaces such as mucosal membranes.
Chitosan enhances the transport of polar drugs across epithelial surfaces, and is biocompatible and biodegradable. Purified quantities of chitosans are available for biomedical applications.
Chitosan and its derivatives, such as trimethylchitosan (where the amino group has been trimethylated), have been used in nonviral gene delivery.
Trimethylchitosan, or quaternised chitosan, has been shown to transfect breast cancer cells, with increased degree of trimethylation increasing the cytotoxicity; at approximately 50% trimethylation, the derivative is the most efficient at gene delivery. Oligomeric derivatives (3-6 kDa) are relatively nontoxic and have good gene delivery properties.[3]
:finga:
