Merged Principles of Green Chemistry and Polyurethane


Dr. Pence's comments appear in Red

This wiki demonstrates that you should make sure that your editor doesn't fall ill with the flu for most of the week before the edited version is due. It has good bones, but it needed some reorganization and tidying up. The writing mechanics are pretty good among all three pieces, but it's not yet a truly integrated wiki.

Good use of pictures throughout.


The All Things Green Page



external image green-recycle-img.jpg



In today's world "green" is much more than a color. One of the definitions given for "Green" by Merriam-Webster's Online Dictionary is: "(a) relating to or being an environmentalist political movement, (b) concerned with or supporting environmentalism, or (c) tending to preserve environmental quality (as by being recyclable, biodegradable, or nonpolluting)." As there is nothing more all-encompassing than the environment, it can be imagined that "things green" can be found anywhere from the philosophical debates of academia to the mundane tasks of everyday life. This page serves as the transit station for all the other pages dealing specifically with these types of topics.

Green Chemistry:
Megan's Page: Introduction to Green Chemistry and the Twelve Principles
Chris' Page: A detailed explanation of Principles 7-12
James' Life of a Urethane Acryate Oligomer: (Applied Green Chemistry)

Green Buildings 1 &2
Green Power


Green Chemistry

Green chemistry, which is also referred to as sustainable chemistry, is designed from the philosophy of reducing or eliminating products {Really? getting rid of products entirely?} or processes that generate hazardous substances and wastes. The philosophy of green chemistry can be applied to all fields of chemistry (organic, analytical, inorganic, physical, etc.), in that its sole focus is on reducing waste and hazardous materials. However, the main application of green chemistry is to industry, as it is the largest producer of waste and hazardous substances.¹·²

Principles of Green Chemistry

The twelve principles of green chemistry originated from the work of Paul Anastas and John Warner. Their book, Green Chemistry: Theory and Practice, {Link?} aims to introduce the reader to the design, development, and evaluation processes of new Green Chemistry methodologies. The text focuses on alternative feedstocks, environmentally safe processes, designing safer chemicals and products, new reaction conditions, and much more.³

The twelve principles outlined in this text are:
  1. Prevention - prevent waste by designing different chemical syntheses, rather than treat or clean up waste.
  2. Design safer chemicals/products - reduce toxicity while maintaining effectiveness of chemicals and products.
  3. Less hazardous chemical syntheses - design syntheses to use, and produce, substances that have little or no toxicity to both humans and the environment.
  4. Use renewable feedstock - use feedstocks that are renewable {tough to paraphrase that one} , such as agriculture products or wastes from other processes, rather than nonrenewable feedstocks, such as fossil fuels.
  5. Use catalysts instead of stoichiometric reagents - use catalysts, which are reusable and used in small amounts, as opposed to stoichiometric reagents, which can be used only once and are used in excess to drive the reaction.
  6. Reduction of chemical derivatives - avoid use of unnecessary derivatization, such as use of blocking groups, temporary modification of physical and/or chemical processes, and protecting/deproctecting, as such steps require additional reagents and generate waste.
Principles 7-12

Awards Won in Green Chemistry


Presidential Green Chemistry Challenge Awards Program
This is an annual challenge that is an opportunity for individuals, groups, and organizations to compete for recognition of their innovations in cleaner, cheaper, and smarter chemistry. This program started in 1995, and has five categories; Academic, Small Business, Greener Synthetic Pathways, Greener Reaction Conditions, and Designing Greener Chemicals. One award is given in each category every year, and the winners are chosen by a panel of chemists from the American Chemical Society.⁴

uv-car.jpg
UV-cure primer on car door at I-CAR training event http://www.radtech.org/Industry/automotive/I_Car_Event.html


Past Recipients: {I think I'd say "Highlights of Past Recipients" to be more descriptive}

  • Greener Reaction Conditions 2005 - BASF Corporation won this award for its development of a automobile paint primer that is curable by Ultraviolet (UV) light. This UV-cured primer contains less than one half the amount of volatile organic compounds (VOCs) than the traditional alternative (1.7 lbs/gal compared to 3.5-4.8 lbs/gal). This new coating uses an urethane acrylate oligomer primer system. The primer cures in minutes by light from inexpensive UV-A lamps, or even sunlight. This UV-cured primer eliminates the need for ovens that are used to cure the current primers; this greatly reduces the energy consumption of curing primers. This product not only required less energy consumption and uses safer chemicals, but it actually performs better than the current conventional primers. Compared to the conventional primers, these UV-cured primers cure ten times faster, require less preparation, have a lower application rate, {Not sure what that means- can you explain?} are more durable, control corrosion better, have an unlimited shelf life, and reduce waste from 20% to almost zero.⁵·⁶

  • Small Business Award 2007 - NovaSterilis Inc. won this award for their environmental benign process of sterilizing biological tissue for medical purposes. The process this company designed uses supercritical carbon dioxide and peroxide that cycles moderate pressure at low temperatures to sterilize delicate biological material that is used for transplants, grafts and vaccinces, among other uses. This {This what? how about "innovation"} revolutionized the standard sterilization process, which was limited to problematic techniques involving ethylene oxide or gamma radiation. Ethylene oxide is a mutangenic and carcinogenic gas that actually can remain on the biological tissue after sterilization. This {This what? how about "property"} increases the chance of toxic side effects of the biological material. The gamma radiation is lethal to human cells, so it can either compromise the tissues being harvested, or the person performing the sterilization. This new method {See? This "This" is much clearer because it is being followed by a noun} involving carbon dioxide and peroxide has neither hazardous wastes, or potential cell damage. This {This what? No, I'm not going to let up} means, not only is this process more favorable for the environment, but also those patients that {who} are receiving the biological tissues. ⁵{The sentence kind of lost it at the end.}
biorez.jpg
  • Greener Synthetic Pathways Award 2008 - This award was given to Battelle for their development and commercialization of biobased toner. This new soy-based toner performs as well as the traditional petroleum-based toner, but is much easier to remove from waste paper. Traditional toner tends to fuse more permanently to paper and does not allow for great {Define "great"}recycling of waste paper. This means that not only is the production of the toner using much less hazardous materials, but it also allows for improved recycling of waste paper. ⁵

{Nice job of wrapping the text around the images.}


Nobel Prize

Starting in 1901 the Nobel Foundation in Stockholm, Sweden administers awards for achievements in physics, chemistry, medicine, literature and for peace. This foundation was founded by the wishes of Alfred Nobel, who left a large portion of his estate in 1895 to the establishment of this program. The prize consists of a medal, diploma, and a cash award. ⁷
richard_r._schrock.jpg
Richard R. Schrock, 1/3 Winner of 2005 Nobel Prize in Chemistry http://nobelprize.org/nobel_prizes/chemistry/laureates/2005/index.html

In 2005, the Noble Prize in chemistry was awarded to Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock for their development of metathesis {metathesis in organic synthesis- this is not inorganic metathesis} . In this organic chemistry reaction double bonds are broken and then made between carbon atoms in such a way that is {it} causes atom groups to change places. This {This what?} happens with the assistance of a catalyst. The catalysts were worked on separately by each man, and what compounds worked, and didn't, {a little awkward} were determined first by Yves Chauvin. In 1990 Richard Schrock found a metal complex that worked very efficently as a catalyst, and in 1992 Robert Grubbs found an even better catalyst that was air stable. The method of metathesis has since been developed even further to the point where this method is strongly thought of {strong thoguhts?} as green chemistry. The process is now more efficient, with fewer steps, used resourced {typo?} , and waste, simpilier {that's definitely a typo} to use, it is air stable {the process is air stable?} and has normal temperatures and pressures, as well as using less hazardous solvents, which leads to less hazardous wastes. ⁸

Green Laws


In the United States:
  • Connecticut, 2009: Manufacturers of TV’s, laptops, desktops and computer monitors have to pay for the recycling process of their products. ⁹
  • Missouri, 2008: All computer electronic equipment manufacturers have to develop and implement recycling plans for their products. ⁹
  • New York City, 2008: Manufacturers have to submit plans for the collection, transportation and recycling of computers, monitors, printers and TVs.⁹
  • California, 2008: California Green Chemistry Initiative - requires California's Department of Toxic Substances Control to prioritize chemicals of concern. ¹⁰
In the UK:
  • REACH - 2006: Registration, Evaluation, Authorisation and Restriction of Chemical substances. This law aims to protect human health and the environment through better, and earlier, identification of the properties of chemical substances¹¹
In China:
  • Beijing, 2008: This new law mandates that the government improves monitoring of carbon-intensive industries (I.E. steel, power generation, oil refinery, construction and printing). Industries will now be required to introduce water-saving technologies, and encouraged to switch to cleaner forms of energy, such as natural gas and renewables (tax breaks will be introduced on energy efficient and clean technologies).¹²

{This wiki has very interesting information, and I can understand that it had to be stretched to reach the required page length, but the text should still make transitions from one section to the next. Otherwise it comes across as "fun facts." Generally the writing is very solid- you just need to look at the big picture as well.}

References

1-"Green Chemistry." Environmental Protection Agency, http://www.epa.gov/greenchemistry/ (February 11, 2009)
2-"Green Chemistry Institute." American Chemistry Society, http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_TRANSITIONMAIN&node_id=830&use_sec=false&sec_url_var=region1&__uuid=67919408-3890-4c56-ab6f-2cd8b12fe5d5 (February 11, 2009)
3-"12 Principles of Green Chemistry." Environmental Protection Agency, http://www.epa.gov/greenchemistry/pubs/principles.html (February 11, 2009)
4-"Presidential Green Chemistry Challenge." Environmental Protection Agency, http://www.epa.gov/greenchemistry/pubs/pgcc/presgcc.html (February 11, 2009)
5-"Award Winners." Environmental Protection Agency, http://www.epa.gov/greenchemistry/pubs/pgcc/past.html (February 11, 2009)

6- Richards, B. "EPA Announces Green Chemistry Award for UV Primer." http://www.radtech.org/documents/epaannouncesgreen.pdf (February 11, 2009)
7- "The Nobel Prize." Nobel Foundation, http://nobelprize.org/nobel_prizes/ (February 11, 2009)
8- "The Nobel Prize in Chemistry 2005." Nobel Foundation, http://nobelprize.org/nobel_prizes/chemistry/laureates/2005/press.html (February 11, 2009)
9- Brown, L."'Green' Laws Ranked in 2009 Legal Trends." Earth 911, http://earth911.com/blog/2009/01/23/green-laws-ranked-in-2009-top-legal-trends/ (February 11, 2009)
10-"California Green Chemistry Initiative." California Department of Toxic Substances Control, http://www.dtsc.ca.gov/PollutionPrevention/GreenChemistryInitiative/ (February 11, 2009)
11-"What is REACH?." Europa, http://ec.europa.eu/environment/chemicals/reach/reach_intro.htm (February 11, 2009)
12- "China Passes New Green Laws Aimed at Businesses." Business Green, http://www.greenbiz.com/news/2008/09/03/china-passes-new-green-laws (February 11, 2009)

{THIS IS THE CORRECT FORMAT FOR REFERENCES!}

Chris Levesque
CH 519 Environmental Chemistry
Wiki Project #1

12 Principles of Green Chemistry and UV Technology

In this page, the contents will focus on the last 6 principles of Green Chemical relating to current green chemistry practices and when applicable the use of UV technology. The 12 principles of green chemistry defined by the founders of green chemistry Paul Anastas and John Warner are as follows:

{Nice job of framing the information on the page}

(Principles 1-6 and the Definition of Green Chemistry)

{I'm a little confused here. You have a link to Principles 1-6, but you have repeated them here? Or are these actually 7-12?}
  1. A raw material feedstock should be renewable rather than depleting whenever technically and economically practical.
  2. Unnecessary derivatization (blocking group, protection/deprotection, and temporary modification of physical/chemical processes) should be avoided whenever possible.
  3. Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
  4. Chemical products should be designed so that at the end of their function they do not persist in the environment and ultimately break down into innocuous degradation products.
  5. Analytical methodologies need to be further developed to allow for real-time in-process monitoring and control prior to the function of hazardous substances.
  6. Substances and the form of a substance used in a chemical process should be chosen so as to minimize the potential for chemical accidents, including releases, explosions, and fires.

Principle #7

Ultra Violet Light has been the major source of energy for all vegetation growth.{I thought it was visible light, not UV} All vegetation is essentially renewable for the means of feedstock, shelter, fuels, clothing and other resources, but one plant in particular has out performed the others for renewable and sustainable products in today’s world. The plant is bamboo and it is classified as a grass. Bamboo grows at a much higher rate than trees but has similar characteristics as trees. Although UV is the greatest source of energy for bamboo, fabrics made from bamboo fibers when chemically treated with bactericide can also absorb UV light which can lead to skin cancer and cataracts in humans and animals. {I'll say that that seems odd. You put a bacteria-killing agent on the fabric and it automatically absorbs UV light?} The treated bamboo also has great antibacterial qualities. Bamboo shoots are consumed by humans and animals for food.

Although bamboo has been historically plant grown in the Eastern Hemisphere, Western Culture is beginning to notice the unique and beneficial qualities of the plant. Western sustainable building designs incorporate the use of bamboo as a major construction material similar to the methods used by the inhabitants in it’s indigenous areas for centuries. {Very nice link to one of the other wikis}
Bamboo.jpg
http://forestry.about.com/b/2007/07/06/is-bamboo-the-answer-to-our-worlds-environmental-problems.htm


Principle #8

Principle 8 looks to investigate methods in which the use of safer solvents and safer reaction conditions are the means to obtaining our products.
UV curing technology has had great success in curing of paints, inks and other coating materials. UV light compared to previous and more traditional technologies reduce the amount of Volatile Organic Compounds (VOCs) released into the earths {Earth gets capitalized, and in this case gets an appostrophe} atmosphere. Companies using this technology have also been able to reduce energy costs for operating preceding equipment such as gas fired ovens, afterburners and chill rollers and increase productivity with shorter curing periods and the availability of the previous equipment’s operating space.
UV-CURING.jpg
http://www.profileprints.com/uv-curing.html

Principle #9 {It would probably make sense to do links within the wiki if possible between your list above and these detailed descriptions}

Catalytic reagents are chemicals that increase the rate of a chemical reaction, but are not consumed or altered by the chemical reaction
[1]. UV light treatment has been used as a catalyst {I'm not sure that it's technically a catalyst} to help humans with skin conditions, mode and sleep disorders, Parkinson’s disease and other ailments and diseases. In the case of psoriasis, a non-contagious autoimmune disease that rapidly produces skin cells and causes inflammation, UV treatment is used to suppress the immune system through chemical reactions, which slows down the regeneration of cell growth. Ultraviolet light is a catalyst, which temporarily provides low levels of energy to the growing cells and disrupts the growth. To have beneficial results of UV treatment people with psoriasis may need to receive daily to weekly treatments.

Principle #10

Chemical products have been designed and are still being designed to withstand environmental conditions and when their design life has past the environment is unable to degrade these products easily.
Polychlorinated Biphenyl (PCBs) are an example of a product that persists in the environment after it has served its design life. PCBs were used in many functions including lubricants, hydraulic fluids, sealants, flame retardants and others. They have been identified as a toxicant and can produce severe health effects to humans and animals and the environment.

UV technology is used in a few processes to degrade PCBs to a non-harmful form. One such technology uses UV technology with microorganisms that are able to degrade biphenyl. UV light is used to degrade and remove the chlorine atoms from the PCBs molecules. This process is preferred over other chemical treatments because of cost savings and the absence of harmful byproducts. Once the chlorine atoms are separated from the biphenyl, the microorganisms can degrade the chlorine free biphenyl into water, carbon dioxide and chlorine.
[2] {Good citation format}

Principle #11 {It might be helpful to restate the principle again before you do the details example}

In most water treatment and wastewater treatment facilities Supervisory Control And Data Acquisition (SCADA) systems are installed to monitor and operate the facility’s functions. One such system in each plant is the disinfection system. Facilities typically use one or more of three typical disinfection processes, which are chlorination, ozone and ultraviolet. Each has their advantages and disadvantages. An advantage for chlorine in a water treatment plant is that chlorine has residual disinfection effectiveness throughout the transmission from the facility to the costumer; the disadvantage is that chlorine byproducts such as TTHMs {this is one of the few abbreviations that you didn't define} are suspected carcinogens. Ultraviolet technology to disinfect bacteria, viruses and microorganisms in wastewater has more advantages than chlorine in treating wastewater because chlorine has the potential to kill healthy organisms downstream in the discharge stream. The method used by engineers and chemists to effectively disinfect wastewater leaving a plant is by monitoring flows throughout the plant by the use of Programmable Logic Controllers (PLC), a SCADA component used to collect and transmit real-time data from measurement points. The real-time data is then forwarded to the Human Machine Interface (HMI), which through preset programming will output data to another PLC, which may control the intensity or number of UV lamps used for disinfection.
Water_Treatment.jpg
http://www.hanovia.com/applications/drinkingwater.aspx

Principle #12

The greatest resource used by industry in the last century has been fossil fuels and especially diesel. Products such as ethanol and biodiesel are being introduced as replacements of petroleum fuel sources. Biodiesel in particular is available for use in many markets including transportation. Biodiesel is formed by vegetable oils and animal fats. The use of biodiesel will significantly lower the risk of environmental impact when accidents occur which could amount to releases or explosions. Ultraviolet light is a degrader of biodiesel greatly reducing any negative impacts to the environment when released. Biodiesel has its challenges in the future with modified diesel engines, effects of biodiesel on petroleum based seals and gaskets in engines and its use in cold temperatures.
biodiesel_cycle.png
http://community.middlebury.edu/~cri/Biodiesel/why_biodiesel.htm
biodiesel-flow-chart.gif
http://www.learnbiodiesel.com/making-biodiesel/flow_chart.html


{It's very frustrating when just the right figure doesn't have the resolution you need to have it be clear, but the resolution here is starting to break up.}
----

[1] http://wiki.answers.com/Q/What_is_a_catalyst
[2] http://www.jrtr.net/jrtr17/f17_environment.html
{need to work on the correct reference format}
{I liked the strategy of going into depth on how each Principle had been applied in different situations. That worked nicely.}

Page 3: The Life of a Urethane Acrylate Oligomer {The connection to the other pages would be clearer if you explained that this was a case study of how Green Chemistry Principles could be applied to a system}




In 2005, BASF Corporation won the Presidential Green Chemistry Challenge Award in the Greener Reaction Conditions category for their urethane acrylate oligomer primer system. Among many others, this system has the notable environmental advantages of low energy consumption and low VOC emissions. The purpose of this page is to summarize the “life” of a typical urethane acrylate oligomer, like the one produced by BASF, from start to finish in order to better understand how “green” the system actually is.



Part I. My Parents (a.k.a. Raw Materials)
(Principles Implicated: 2 & 4)



IMG_0059.jpg


As with most things on the planet Earth, my life begins with my parents; the stuff that went into my creation. In my simplest form, I am made up of three main components: a di- or tri- functional polyol, a difunctional isocyanate, and another hydroxy containing{hyphenated} compound which also has the reactive acrylate functionality. This third component is sometimes called a capping agent.

Polyols
are rather innocuous, non-hazardous starting materials some of which occur in nature, such as castor oil and sucrose, or can be derived from renewable vegetable oils. They can be aliphatic, aromatic, linear, cyclic, polyester based or polyether based, or any combination of the above. These various polyol characteristics that are inherited by urethane acrylate oligomers leading to enormous versatility in physical properties.

My polyol parent is 1,4 butanediol. Here's a picture.

800px-1,4-butanediol.png


Unlike polyols, isocyanates are quite a hazardous bunch causing asthma in humans due to the high reactivity of the NCO group. Indeed, it was methyl isocyanate (CH3NCO) {Need to figure out how to do subscripts} that was responsible for the deaths of thousands in Bhopal, India in 1984.[[#_ftn3|[3]]] However, if appropriate precautions are taken the use of diisocyanates is quite safe and lead to a non-hazardous product like me.

My parent diisocyanate is Isophorone Diisocyanate {Shouldn't be capitalized} (IPDI). Here is a picture of it.[[#_ftn4|[4]]]


635px-Isophorone-diisocyanate-2D-skeletal.png


Capping agents are what give urethane acrylate oligomers their UV-reactivity and what makes them different from other polyurethanes. The acrylate group is a C = C double bond adjacent to a carbonyl which undergoes photo-polymerization {I like the definition of the functional group here. It should be added above}. Some {referring to the acrylate group or the oligomers?}can be corrosive and irritating to the skin, but they are not nearly as harmful as the isocyanates.

My parent capping agent {need a comma here} 2-hydroxyethyl acrylate, which is the most common of the capping agents used. {Sentence fragment} Of course, here is a picture.[[#_ftn5|[5]]]


HEA.gif


Part II. My Conception (a.k.a Reaction Mechanism and Conditions)
(Principles {You're a little far away from these references- need a stronger link to the Green Chemistry Principles} Implicated: 1, 2, 3, 5, 6, 7, 8, 9 & 11)



IMG_0053.jpg


Now that I have introduced my parents, it is time to move to where most of the magic happens; the actual making of me.

I am fundamentally the product of a urethane reaction: a reaction between an alcohol and an isocyanate group generalized as [[#_ftn6|[6]]]


800px-Generalizedpolyurethanereaction.png


In the case of urethane acrylate oligomers, the idealized reaction is one end of the diisocyanate reacting with each hydroxyl of the polyol and the other end reacting with the hydroxyl of the capping agent, like so:
CA-DI-P-DI-CA {need to define these abbreviations}
This reaction has several environmental advantages. First, as the reaction is essentially just a rearrangement of atoms, it has an atom economy of 100 percent.{No one went into atom economy, so you either need to define it or link to a definition.}Nothing goes to waste and even unintended byproducts, such as a CA-DI-CA adduct, will eventually become a part of my adult form.

Second, {not clear whether this is the second step or the second environmental advantage. I think it's the latter, but since it's a different paragraph, the connection should be stronger.} the harmful NCO groups are removed and replaced with the extremely strong urethane linkage making me less toxic than my starting raw material parents. This can easily be assured through the in-process monitoring of the isocyanate absorbance peak on my FTIR spectra {spectrum. It's singular} . This peak absorbs at ~2400 cm-1 {superscript} which is literally out in the middle of nowhere and cannot really be missed. {This just went over the edge into too informal. You can't mix the sophisticated chemistry above in which you are assuming that people know quite a bit of chemistry with "I'm clueless" language of describing a region of the IR as "in the middle of nowhere.}. When the peak {band is the correct term} disappears, the reaction is complete.

IMG_0051.jpg
FTIR Spectra of Oligomer Containing Free NCO

{Nice idea to include the figure.}
Third, {here again, since you've got a big distance between your items, you need to explain "third" in what series?} the urethane reaction is also a very efficient reaction. It is exothermic and, depending on the isocyanate used, goes to completion in a relatively short amount of time. It proceeds at room temperature even without any catalyst. If the reaction time does need to be shortened, the reaction can be catalyzed with amines or organometallic-complexes. The most common catalyst is Dibutyltin Dilaurate {lowercase} (DBTDL), however bismuth or zinc catalysts can also be used and have the advantage of being less toxic than their tin based counterparts.{Nice point}

Finally, even the trace chemicals can be ecofriendly. Small amounts of antioxidants are added to prevent my premature and unintended polymerization. One such antioxidant commonly used is Butylated hydroxytoluene {capitalization is getting random} (BHT), an FDA approved food additive.

IMG_0054.jpg
Infant Macro-Me






image002.gif
Molecular Me (formula: C38H62N4O12)


Let's do a double check of my atom economy. {formula? Reference? this really isn't user-friendly} I have one molecule of 1,4-butandiol at 90.1 g/mol, two molecules of IPDI at 222.3 g.mol each, and two molecules of HEA at 116.1 g/mol each. My molecular formula is C38H62N4O12 which calculates out to 766.9. So:

[1(90.1)+2(222.3)+2(116.1)]/766.9 = 766.9/766.9 = 1.00 Perfect ;)

My FTIR spectra {spectrum} also shows none of the hazardous free NCO present either.

IMG_0052.jpg
Final Product FTIR without Free NCO




Part III. All Grown Up (The UV cure of an Urethane Acrylate Oligomer) {What happened to the font size?}
(Principles Implicated: 1, 2, 3, 5, 7 & 9)

IMG_0056.jpg

The final stage in my life is my metamorphosis from a liquid to a solid via free radical polymerization. The reaction is typically catalyzed by a photoinitiator, such as a peroxide, which decomposes into a highly reactive free radical when exposed to UV light in the range of 254-400 nm. These radicals then react with my acrylate functionality to produce more radicals {comma} and the polymerization proceeds in the usual way for unsaturated compounds: chain initiation, chain propagation, and finally chain termination. Like the urethane reaction that produced me, this reaction is exothermic and very fast, sometimes taking less than one minute of UV exposure to complete. It also has a near perfect atom economy as it is merely a rearrangement of bonds between the same atoms.

Polymers produced in this way have physical properties that are quite diverse due to the diversity in starting raw materials. Long linear chains with low acrylate functionality tend to give soft, flexible polymers. Short chains and higher acrylate functionality produce more highly branched and cross-linked networks resulting in hard, brittle polymers.

This is me:
IMG_0058.jpg
Adult Me