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11/20/19
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Friday, Green Materials & Design for DegradationFollow-up on some suggested topics, NESSE/Beyond
Benign/IUPAC, e-posters
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Why is design for degradation needed?• Degradation and surfactants — A simple
change to a functional group on the compound that is accumulating in the environment can allow it to degrade far faster (easier for bacteria to break down)
• Degradation and pesticides — In many ways DDT was the ideal pesticide BUT it was persistent and it wasn’t until after several years of use that they noticed its adverse effects (i.e. accumulating in fatty tissues of animals, resulting in reproductive effects)… Silent Spring, Rachel Carson (1962)
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SO3H
SO3H
High degradation rate
Low degradationrate
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Polymer degradation
• With plastics in order for it to break down in the environment we have to design them with functional groups that bacteria are already good at degrading or include other chemicals to enhance the rate of photo- or chemical-degradation
e.g. starch is sometimes included in the polymer backbone but this comes with drawbacks at levels over 9% starch as the strength of the polymer is severely reduced, limiting its use to film-type applications
• Alternatives to current plastics are needed: either more readily recycled (incl. back to monomers) or more readily degradable or switchable degradation behaviour
• ACU Blue Charter76
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What functional groups help? Rules?1. Natural products are usually biodegradable; structures closely resembling natural materials are likely to
be more degradable.
2. Catechol is an intermediate in the degradation of aromatics, therefore aromatic products that do not
contain two adjacent unsubstituted (or hydroxy-substituted) carbons will degrade more slowly.
3. Highly electronegative groups such as nitro decrease the rate of degradation of substituted aromatics.
4. Many heterocyclic species are slow to biodegrade.
5. Highly branched aliphatic chains degrade more slowly than linear chains.
6. Aliphatic ether- (long carbon chains on either side of the oxygen) containing molecules degrade slowly.
7. Materials containing strong C-Cl or C-F generally do not undergo rapid degradation.
8. Materials which are very water insoluble are unlikely to be readily biodegradable.
9. Biodegradation rates normally decrease with increasing molecular weight 77
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Discussion - Degradation• Which of these ionic liquids (ILs) would degrade more easily in the
environment? (Assume that they are all water-soluble)
• Choline chloride can be used to prepare ILs. In your opinion, would they be less toxic and more easily degradable than the imidazolium examples shown above?
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Are ‘natural substances’ – Less harmful? More readily degradable?
• Poly(limonene carbonate) has been shown to be less readily degradable than poly(propylene carbonate) even though it comes from a ‘natural’ polymer.
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• Degradation depends on the conditions. Paper, food etc. often don’t biodegrade in landfill sites because they are too compressed/crowded, i.e. anaerobic, so microorganisms cannot function effectively.
• There are many toxic compounds/materials produced in nature e.g. snake venom.
• Just because something is natural doesn’t mean it is harmless
Mummified carrot
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Packaging
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Degradable polymers• Polyesters (good and bad); UCSB has shown
that in each wash, a synthetic fleece released an average of 1.7g of microfibres; UK National Trust “a warm green alternative is being sought”
• PET vs. PLA vs. P(e-Cl)• Commodity vs. medical• 3D-printable• Degradation environment
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How are these degradable polyesters prepared?• Condensation of lactic acid prepared via fermentation
• Only low molecular weight polymers can be obtained• Ring-opening polymerization of cyclic esters (lactones)
• Polyhydroxyalkanoates are prepared by fermentation incl. PHB shown here
• PHB is similar in its material properties to polypropylene 82
RO MLnδ-
δ+
poly(lactide) challenge in controlling
stereoselectivity
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Behaviour of some of our polymers after environmental exposure (via SEM analysis)
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CONTROL
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A new approach to degradable polymers?• J. Am. Chem. Soc. 2019, 141, 31, 12207-12211
• How are the monomers made?• Under what conditions do they degrade?• Are the degradation products benign? 84
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‘Green’ Surfactants• Surfactant market in Europe is 3 million tonnes per year!• Renewable hydrophobes (…renewable hydrophiles are also
accessible usually from starches/sugar)
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Chemical Society Reviews2012, 41, 1499-1518.
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Varying the head group
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Chemical Society Reviews2012, 41, 1499-1518.
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BiosurfactantsChemical Society Reviews2012, 41, 1499-1518.
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‘Green’ Purification/Separation• No ‘simple’ alternative to column chromatography in a research lab …• Key is selectivity in reactions (e.g. use of selective catalysts) and/or extractions (e.g.
use of selective solvent such as scCO2)• Ionic liquids can be tailored to help selectivity, see for example “Ionic-Liquid-
Mediated Extraction and Separation Processes for Bioactive Compounds: Past, Present, and Future Trends” Chem. Rev. 2017, 117, 6984-7052 e.g.
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[BMPyrrol][Tf2N](hydrophobic IL) used in extraction of erythromycin from an aqueous solution
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Best practice in disposal of chemical waste• Tips include: Proper Labeling of Hazardous Waste, Developing a
Hazardous Waste Contingency Plan (a program designed to minimize hazards to human health and the environment from fires, explosions or an unplanned sudden release of a hazardous waste), Regular Inspections, Regular Training
• U.S. EPA has advice for small businesses on chemical disposal (see some of the key points the next slide)
• To reduce waste management costs “Consider any reuse opportunities for chemicals. Another option for reuse is to provide it to someone else who may have a use for it–such as a school or other business”
• Green Chemistry targets mitigation of waste by preventing it being generated in the first place. Environmental remediation is a related but entirely different field some popular ‘new’ approaches include growing crops which will take up toxic metals and then the harvested crops are ‘burnt’ to produce a biochar from which the metal can be isolated.
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Beyond Benign, https://www.beyondbenign.org
• #ChemistsInventGreen• Social Media Campaign
• John Warner, Warner Babcock Institute for Green Chemistry“Do not fear failure! Fear not trying in the first place or following blindly the footsteps of others. Be creative and original; You never know where your unique path might lead you!”
2. Lizz Michael-Sapia, Ph.D., Eastman Chemical Company“I knew I wanted to make a difference in people’s lives, and like everybody, I wanted to do something that would be fun, something I was passionate about, and something that would be really different and exciting every day”
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Beyond Benign, https://www.beyondbenign.org
3. Tony Bova, PhD student and Co-founder of Mobius“For us, it is not enough to just invent something, we want it to be impactful. So, we look for partners that can help us bring our products and processes to the market. The invention process is about who can help you bring it (your invention) into reality.”https://www.mobius.co/
4. The next inventor will be announced on Dec. 392
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NESSEwww.sustainablescientists.org
• Network of Early-Career Sustainable Scientists & Engineers
• Details are available on their website• Lots of volunteering and networking
opportunities• “Our values are driven by the desire to
empower early-career scientists to tackle today’s environmental and energy challenges, and move towards a sustainable future.”
• Range of events including “Randomised coffee trials”
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A D VA N C I N G C H E M I S T R Y W O R L D W I D E
International Union of Pure and Applied ChemistryDevelopment of the Language of Chemistry
• Nomenclature, Symbols, TerminologyStandardization of Chemistry Methods
• Data Presentation• Study of Analytical Methods
Critical Evaluation of Physico-Chemical Data• Atomic Weights• Thermodynamic Data• Kinetic Data
IUPAC - Primary Activities
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A D VA N C I N G C H E M I S T R Y W O R L D W I D E
• Data Exchange Standards for Computers and Instruments• Endorsement of International Conferences
• Biennial IUPAC Congress• San Juan, Puerto Rico (2011), Istanbul, Turkey (2013), Busan, Korea (2015), Sao
Paulo, Brazil (2017), Paris, France (2019), Montreal, Canada (2021)• More than 30 Specialized Symposia each Year
• Chemistry Education• Industrial Safety and Environmental Programs• CHEMRAWN Conferences addressing Chemistry and World
Needs
Primary IUPAC Activities (Cont.)
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A D VA N C I N G C H E M I S T R Y W O R L D W I D E
IUPAC Membership Programs• National Adhering Organizations-Are the Governing bodies (Council) of IUPAC (Jamaica and
Puerto Rico are NAOs)• Associate National Adhering Organizations
• Observer Status-Chemical councils, Chemical Societies, National Academies and institutions representing national chemical interests
• Associated Organizations• International organizations that share common goals and interest with IUPAC.
• Company Associates• Industrial companies, research and development institutions can associate through
the program• Individual Members
• Membership for individuals, coordinated by NAOs, Societies or directly with IUPAC
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A D VA N C I N G C H E M I S T R Y W O R L D W I D E
• Post-Graduate Summer School Program• Focus on Younger Chemists (<35)
• ChemRAWN VII Prize in Green Chemistry• International Conference on Green Chemistry (every two years
– it was in conjunction with the ACS Annual Green Chemistry Conference this year, so the next one will be in 2021)
• Interdivisional Committee on Green Chemistry for Sustainable Development (ICGCSD) &
• From Jan 2020– I will be chair• We are on social media
Green Chemistry & Related: Education, Outreach and Conference Series
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A D VA N C I N G C H E M I S T R Y W O R L D W I D E
and background, recruited by transparent and well-understood processes.
Encourage and Mentor the Best and Brightest for the Future and Collaboration on Global Scale
Young Chemists
IYCNYoung Observers
The next World Chemistry Congress and General Assembly will be in Montreal, August 2021
https://www.iycnglobal.com/
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….final thoughts• Any questions about green chemistry? Or any other ideas that were
presented?• Any questions/concerns about the e-posters?• We will send some gifts from Newfoundland to anyone who participates
(….but because of Christmas they will likely not arrive until the new year, one parcel will be sent to Dr. Jalsa).
• You can contact us by e-mail ([email protected], [email protected]) or on Twitter (@ChemMouse, @kozycanuck)
• If you want us to tweet your e-poster, e-mail us your jpg file and we will• If you tweet your e-poster yourself, please include us @ChemMouse,
@kozycanuck in your tweet and we can re-tweet your e-poster• Also, include #GreenChemUWI so that we can use this hashtag to find all the
posters too and promote green chemistry at UWI100
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Thankyou!
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