Name: depolymerizable olefinic polymers based on fused-ring cyclooctene monomers
Uploaded: 2022-12-16T13:10:00
Description: Watch this Scientific Journal Video about Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers at JoVE.com

We acknowledge funding support from the University of Akron and the National Science Foundation under grant DMR-2042494.

NOTE: The protocols outlined below are detailed forms of experimental procedures reported previously15,18,19. Characterization of the small molecules and polymers has been reported previously15,18. Additionally, syntheses of monomers and polymers and depolymerization of polymers should be performed inside a fume hood with appropriate personal protective equipment (PPE), ...

<ol>
	<li>Geyer, R., Jambeck, J. R., Law, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production,+use,+and+fate+of+all+plastics+ever+made.">Production, use, and fate of all plastics ever made.</a> Science Advances. 3 (7), 1700782 (2017).</li><li>Barnes, D. K. A., Galgani, F., Thompson, R. C., Barlaz, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accumulation+and+fragmentation+of+plastic+debris+in+global+environments.">Accumulation and fragmentation of plastic debris in global environments.</a> Philosophical Transactions of the Royal Society B: Biological Sciences. 364 (1526), 1985-1998 (2009).</li><li>Zheng, J., Suh, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strategies+to+reduce+the+global+carbon+footprint+of+plastics.">Strategies to reduce the global carbon footprint of plastics.</a> Nature Climate Change. 9 (5), 374-378 (2019).</li><li>Coates, G. W., Getzler, Y. D. Y. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+recycling+to+monomer+for+an+ideal,+circular+polymer+economy.">Chemical recycling to monomer for an ideal, circular polymer economy.</a> Nature Reviews Materials. 5 (7), 501-516 (2020).</li><li>Odian, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ring-opening+Polymerization.">Ring-opening Polymerization.</a> Principles of Polymerization. , 544-618 (2004).</li><li>Zhu, J. B., Watson, E. M., Tang, J., Chen, E. Y. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+synthetic+polymer+system+with+repeatable+chemical+recyclability.">A synthetic polymer system with repeatable chemical recyclability.</a> Science. 360 (6387), 398-403 (2018).</li><li>Xiong, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Geminal+dimethyl+substitution+enables+controlled+polymerization+of+penicillamine-derived+&#946;-thiolactones+and+reversed+depolymerization.">Geminal dimethyl substitution enables controlled polymerization of penicillamine-derived &#946;-thiolactones and reversed depolymerization.</a> Chem. 6 (7), 1831-1843 (2020).</li><li>Abel, B. A., Snyder, R. L., Coates, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemically+recyclable+thermoplastics+from+reversible-deactivation+polymerization+of+cyclic+acetals.">Chemically recyclable thermoplastics from reversible-deactivation polymerization of cyclic acetals.</a> Science. 373 (6556), 783-789 (2021).</li><li>Neary, W. J., Isais, T. A., Kennemur, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Depolymerization+of+bottlebrush+polypentenamers+and+their+macromolecular+metamorphosis.">Depolymerization of bottlebrush polypentenamers and their macromolecular metamorphosis.</a> Journal of the American Chemical Society. 141 (36), 14220-14229 (2019).</li><li>Feist, J. D., Xia, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enol+ethers+are+effective+monomers+for+ring-opening+metathesis+polymerization:+Synthesis+of+degradable+and+depolymerizable+poly(2,3-dihydrofuran).">Enol ethers are effective monomers for ring-opening metathesis polymerization: Synthesis of degradable and depolymerizable poly(2,3-dihydrofuran).</a> Journal of the American Chemical Society. 142 (3), 1186-1189 (2020).</li><li>Hong, M., Chen, E. Y. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Completely+recyclable+biopolymers+with+linear+and+cyclic+topologies+via+ring-opening+polymerization+of+&#947;-butyrolactone.">Completely recyclable biopolymers with linear and cyclic topologies via ring-opening polymerization of &#947;-butyrolactone.</a> Nature Chemistry. 8 (1), 42-49 (2016).</li><li>Shi, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+principles+for+intrinsically+circular+polymers+with+tunable+properties.">Design principles for intrinsically circular polymers with tunable properties.</a> Chem. 7 (11), 2896-2912 (2021).</li><li>Neary, W. J., Kennemur, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polypentenamer+renaissance:+Challenges+and+opportunities.">Polypentenamer renaissance: Challenges and opportunities.</a> ACS Macro Letters. 8 (1), 46-56 (2019).</li><li>Ols&#233;n, P., Odelius, K., Albertsson, A. -. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermodynamic+presynthetic+considerations+for+ring-opening+polymerization.">Thermodynamic presynthetic considerations for ring-opening polymerization.</a> Biomacromolecules. 17 (3), 699-709 (2016).</li><li>Sathe, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Olefin+metathesis-based+chemically+recyclable+polymers+enabled+by+fused-ring+monomers.">Olefin metathesis-based chemically recyclable polymers enabled by fused-ring monomers.</a> Nature Chemistry. 13 (8), 743-750 (2021).</li><li>Scherman, O. A., Walker, R., Grubbs, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+characterization+of+stereoregular+ethylene-vinyl+alcohol+copolymers+made+by+ring-opening+metathesis+polymerization.">Synthesis and characterization of stereoregular ethylene-vinyl alcohol copolymers made by ring-opening metathesis polymerization.</a> Macromolecules. 38 (22), 9009-9014 (2005).</li><li>You, W., Hugar, K. M., Coates, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+alkaline+anion+exchange+membranes+with+chemically+stable+imidazolium+cations:+Unexpected+cross-linked+macrocycles+from+ring-fused+ROMP+monomers.">Synthesis of alkaline anion exchange membranes with chemically stable imidazolium cations: Unexpected cross-linked macrocycles from ring-fused ROMP monomers.</a> Macromolecules. 51 (8), 3212-3218 (2018).</li><li>Chen, H., Shi, Z., Hsu, T. G., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overcoming+the+low+driving+force+in+forming+depolymerizable+polymers+through+monomer+isomerization.">Overcoming the low driving force in forming depolymerizable polymers through monomer isomerization.</a> Angewandte Chemie International Edition. 60 (48), 25493-25498 (2021).</li><li>Sathe, D., Chen, H., Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulating+the+thermodynamics+and+thermal+properties+of+depolymerizable+polycyclooctenes+through+substituent+effects.">Regulating the thermodynamics and thermal properties of depolymerizable polycyclooctenes through substituent effects.</a> Macromolecular Rapid Communications. , (2022).</li><li>Vogel, A. I., Furniss, B. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Vogel's Textbook of Practical Organic Chemistry. , (2003).</li><li>Pirrung, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Following+the+Reaction.">Following the Reaction.</a> The Synthetic Organic Chemist's Companion. , 93-105 (2007).</li><li>Royzen, M., Yap, G. P. A., Fox, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Photochemical+synthesis+of+functionalized+trans-cyclooctenes+driven+by+metal+complexation.">A Photochemical synthesis of functionalized trans-cyclooctenes driven by metal complexation.</a> Journal of the American Chemical Society. 130 (12), 3760-3761 (2008).</li><li>Chiang, Y., Kresge, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+of+hydration+of+simple+olefins+in+aqueous+solution.+cis-+and+trans-Cyclooctene.">Mechanism of hydration of simple olefins in aqueous solution. cis- and trans-Cyclooctene.</a> Journal of the American Chemical Society. 107 (22), 6363-6367 (1985).</li><li>Fang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+the+stability+and+stabilization+of+trans-cyclooctenes+through+radical+inhibition+and+silver+(I)+metal+complexation.">Studies on the stability and stabilization of trans-cyclooctenes through radical inhibition and silver (I) metal complexation.</a> Tetrahedron. 75 (32), 4307-4317 (2019).</li></ol>

The tCBCO monomers can be prepared from a common precursor: the [2+2] photocycloadduct of maleic anhydride and 1,5-cyclooctadiene, anhydride 1. Since the crude anhydride 1 is difficult to purify but can be hydrolyzed readily, the crude photoreaction mixture is subjected to methanolysis conditions to yield the readily isolable methyl ester-acid 2. The recrystallization of 2 after column chromatography is key to obtaining the pure trans-c...

The versatile and robust nature of synthetic polymers has made them a ubiquitous fixture of modern human existence. On the flip side, the same robust and environmentally resistant properties make polymer waste exceedingly persistent. This, together with the fact that a large fraction of all synthetic polymers ever made has ended up in landfills1, has raised legitimate concerns about their environmental effects2. Additionally, the open-loop nature of the traditional polymer economy has caused a steady consumption of petrochemical resources and a mounting carbon footprint3. Promising routes to a closed-loop polymer economy are, thus, highly sought after.
Chemical recycling to monomer (CRM) is one such route. The advantage of CRM over traditional recycling is that it leads to the regeneration of monomers that can be used to manufacture pristine polymers, as opposed to mechanical recycling of materials with deteriorating properties over multiple processing cycles. Polymers based on ring-opening polymerizations have appeared as especially attractive routes to CRM materials4. The thermodynamics of polymerization is typically an interplay between two opposing factors: the enthalpy of polymerization (&#916;Hp, which is typically negative and favors polymerization) and the entropy of polymerization (&#916;Sp, which is also typically negative but disfavors polymerization), with the ceiling temperature (Tc)&#160;being the temperature at which these two factors balance each other out5. For a polymer to be capable of CRM under practical and economically beneficial conditions, the right balance of &#916;Hp and &#916;Sp must be achieved. Cyclic monomers allow a convenient means to tune these factors via the selection of the appropriate ring size and geometry, since here, &#916;Hp is primarily determined by the ring strain of the cyclic monomers4,5. As a result, CRM polymers with a wide variety of monomers have been reported of late6,7,8,9,10,11. Out of these systems, ROMP polymers prepared from cyclopentenes are particularly promising due to the rather cheap starting material required and the hydrolytic and thermal stability of the polymers. Additionally, in the absence of a metathesis catalyst, the depolymerization is kinetically unfeasible, affording high thermal stability despite a low Tc12. However, cyclopentenes (and other monomers based on small cyclic structures) pose a key challenge-they cannot be readily functionalized, as the presence of functional groups on the backbone can affect the thermodynamics of polymerization in drastic, and sometimes unpredictable, ways13,14.
Recently, we reported a system that overcomes some of these challenges15. Inspired by examples of low-strain fused ring cyclooctenes in the literature16,17, a new CRM system was designed based on ROMP polymers of trans-cyclobutane fused cyclooctenes (tCBCO) (Figure 1A). The tCBCO monomers could be prepared at a gram scale from the [2+2] photo cycloadduct of maleic anhydride and 1,5-cyclooctadiene, which could be readily functionalized to achieve a diverse set of substituents (Figure 1B). The resulting monomers had ring strains comparable to cyclopentene (~5 kcal&#183;mol&#8722;1, as calculated using DFT). Thermodynamic studies revealed a low &#916;Hp (&#8722;1.7 kcal&#183;mol&#8722;1 to &#8722;2.8 kcal&#183;mol&#8722;1), which was offset by a low &#916;Sp (&#8722;3.6 kcal&#183;mol&#8722;1&#183;K&#8722;1 to &#8722;4.9 kcal&#183;mol&#8722;1&#183;K&#8722;1), allowing the preparation of high molecular weight polymers (at high monomer concentrations) and near quantitative depolymerization (&#62;90%, under dilute conditions) at ambient temperatures in the presence of Grubbs II catalyst (G2). It was also demonstrated that materials with diverse thermomechanical properties could be obtained while preserving the ease of polymerization/depolymerization. This ability was further exploited to prepare a soft elastomeric network (which could also be readily depolymerized), as well as a rigid thermoplastic (with tensile properties comparable to polystyrene).
One drawback with this system was the need for high monomer concentrations to access high molecular weight polymers. At the same time, due to extensive chain transfer and cyclization reactions, the polymerization was uncontrolled in nature. This was addressed in a subsequent work via photochemical isomerization of the Z-alkene in the tCBCO monomers to prepare highly strained E-alkene tCBCO monomers18. These monomers could be rapidly polymerized in a living manner at low initial monomer concentrations (&#8805;25 mM) in the presence of Grubbs I catalyst (G1) and excess triphenylphosphine (PPh3). The polymers could then be depolymerized to yield the Z-alkene form of the monomers. This has created opportunities to access new depolymerizable polymer architectures, including block copolymers and graft/bottlebrush copolymers.
In this work, detailed protocols are outlined for the synthesis of tCBCO monomers with different functional groups and their polymerization, as well as the depolymerization of the resulting polymers. Additionally, protocols for the preparation of dogbone samples of a soft elastomeric network and their depolymerization, as well as compression molding of the N-phenylimide substituted rigid thermoplastic polymer, are also described. Finally, protocols for the photoisomerization of a tCBCO monomer to its strained E-alkene tCBCO form and its subsequent living ROMP are also discussed.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1 and 3 dram vials</td>
			<td>VWR</td>
			<td>66011-041, 66011-100</td>
			<td></td>
		</tr>
		<tr>
			<td>1,4-butanediol</td>
			<td>Sigma-Aldrich</td>
			<td>240559-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>1,5-cyclooctadiene</td>
			<td>ACROS</td>
			<td>AC297120010</td>
			<td></td>
		</tr>
		<tr>
			<td>1-butanol</td>
			<td>Fisher</td>
			<td>A399-1</td>
			<td></td>
		</tr>
		<tr>
			<td>20 mL scintillation vials</td>
			<td>VWR</td>
			<td>66022-081</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic Anhydride</td>
			<td>Alfa-Aesar</td>
			<td>AAL042950B</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>Fisher</td>
			<td>A18-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Aluminum backed TLC plates</td>
			<td>Silicycle</td>
			<td>TLA-R10011B-323</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium hydroxide</td>
			<td>Fisher</td>
			<td>A669-212</td>
			<td></td>
		</tr>
		<tr>
			<td>Aniline</td>
			<td>TCI</td>
			<td>A0463500G</td>
			<td></td>
		</tr>
		<tr>
			<td>BD precisionglide (18 G)</td>
			<td>Fisher</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>Fisher</td>
			<td>C298-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Column for circulation (to be packed with silver nitrate treated silica gel)</td>
			<td></td>
			<td></td>
			<td>Approximately 1 cm radius and 25 cm long, with inner thread on either end</td>
		</tr>
		<tr>
			<td>d-Chloroform</td>
			<td>Cambridge Isotopes</td>
			<td>DLM-7-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Dichloromethane</td>
			<td>VWR</td>
			<td>BDH1113-19L</td>
			<td></td>
		</tr>
		<tr>
			<td>EDC.HCl; 3-(3-dimethylaminopropyl)-1-ethyl-carbodiimide hydrochloride</td>
			<td>Chemimpex</td>
			<td>00050</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl Acetate</td>
			<td>Fisher</td>
			<td>E145-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl Vinyl Ether</td>
			<td>Sigma-Aldrich</td>
			<td>422177-250ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass chromatography columns</td>
			<td>Fabricated in-house</td>
			<td>D = 20 mm, L= 450 mm and D = 40 mm, L = 450 mm</td>
			<td>The columns are fitted with a teflon stopcock at one end and a 24/40 ground glass joint to accommodate a solvent reservoir if needed.</td>
		</tr>
		<tr>
			<td>Grubbs Catalyst 1st Generation (M102)</td>
			<td>Sigma-Aldrich</td>
			<td>579726-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Grubbs Catalyst 2nd Generation (M204)</td>
			<td>Sigma-Aldrich</td>
			<td>569747-100MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexanes</td>
			<td>Fisher</td>
			<td>H292-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydraulic press</td>
			<td>Carver Instruments</td>
			<td>#3912</td>
			<td>Coupled with temperature control modules (see below)</td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Fisher</td>
			<td>AA87617K4</td>
			<td></td>
		</tr>
		<tr>
			<td>Maleic Anhydride</td>
			<td>ACROS</td>
			<td>AC125240010</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Fisher</td>
			<td>A412-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro essential Hydrion pH paper (1-13 pH)</td>
			<td>Fisher</td>
			<td>14-850-120</td>
			<td></td>
		</tr>
		<tr>
			<td>Normject Luer Lock syringes (1, 3 and 10 mL)</td>
			<td>VWR</td>
			<td>89174-491, 53547-014 and 53547-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Photoreactor chamber</td>
			<td>Rayonet</td>
			<td>RPR-100</td>
			<td></td>
		</tr>
		<tr>
			<td>QuadraPure TU (catalyst scavenger)</td>
			<td>Sigma-Aldrich</td>
			<td>655422-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Quartz tubes</td>
			<td>Favricated in-house</td>
			<td>D=2&#34;, L=12.5&#34; and D=1.5&#34;, L=10.5&#34;</td>
			<td></td>
		</tr>
		<tr>
			<td>Rotavap</td>
			<td>Buchi</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SciLog Accu Digital Metering Pump MP- 40</td>
			<td>Parker</td>
			<td></td>
			<td>500 mL capacity</td>
		</tr>
		<tr>
			<td>Siliaflash Irregular Silica, F60</td>
			<td>Silicycle</td>
			<td>R10030B-25KG</td>
			<td></td>
		</tr>
		<tr>
			<td>Silver Nitrate</td>
			<td>ACROS</td>
			<td>AC197680050</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>VWR</td>
			<td>BDH9292-2.5KG</td>
			<td></td>
		</tr>
		<tr>
			<td>Steel Mold</td>
			<td>Fabricated in-house</td>
			<td>Overall dimensions of mold cavity: length 20 mm, width 7 mm and depth 1 mm; gauge dimensions: length 10 mm, width 3 mm)</td>
			<td></td>
		</tr>
		<tr>
			<td>Steel Plates</td>
			<td>Fabricated in-house</td>
			<td>100 mm x 150 mm x 1 mm</td>
			<td></td>
		</tr>
		<tr>
			<td>Teflon Mold (6-cavities)</td>
			<td>Fabricated in-house</td>
			<td>Overall cavity dimensions: length 25 mm, width 8.35 mm and depth 0.8 mm; gauge dimensions: length 5 mm, width 2 mm)</td>
			<td></td>
		</tr>
		<tr>
			<td>Teflon Sheets (0.005&#34; thick)</td>
			<td>McMaster-Carr</td>
			<td>8569K61</td>
			<td></td>
		</tr>
		<tr>
			<td>Temperature Control Modules</td>
			<td>Omega</td>
			<td>C9000A and C9000</td>
			<td>&#176;C units (two modules, one for top and one for bottom)</td>
		</tr>
		<tr>
			<td>Triphenyl Phosphine</td>
			<td>TCI</td>
			<td>T0519500G</td>
			<td></td>
		</tr>
		<tr>
			<td>UV lamps</td>
			<td>Rayonet</td>
			<td>RPR2537A and RPR3000A</td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum pump</td>
			<td>Welch Duoseal</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Whatman Filter Paper (grade 2)</td>
			<td>VWR</td>
			<td>09-810F</td>
			<td>filter paper</td>
		</tr>
	</tbody>
</table>

depolymerizable olefinic polymers based on fused-ring cyclooctene monomers

The growing consumption of synthetic polymers and the accumulation of polymer waste have led to a pressing need for new routes to sustainable materials. Achieving a closed-loop polymer economy via chemical recycling to monomer (CRM) is one such promising route. Our group recently reported a new CRM system based on polymers prepared by ring-opening metathesis polymerization (ROMP) of trans-cyclobutane fused cyclooctene (tCBCO) monomers. This system offers several key advantages, including the ease of polymerization at ambient temperatures, quantitative depolymerization to monomers under mild conditions, and a broad range of functionalities and thermomechanical properties. Here, we outline detailed protocols for the preparation of tCBCO-based monomers and their corresponding polymers, including the preparation of elastic polymer networks and compression molding of linear thermoplastic polymers. We also outline the preparation of high ring strain E-alkene tCBCO monomers and their living polymerization. Finally, the procedures for the depolymerization of linear polymers and polymer networks are also demonstrated.

Discussed here are representative results previously published15,18,19. Figure 5 shows the GPC traces for polymer P1 prepared by conventional ROMP with G2 (red curve)15 and living ROMP of EM1&#160;with G1/PPh3 (black)18</...

Watch this Scientific Journal Video about Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers at JoVE.com

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers

Here, we describe protocols for the preparation of trans-cyclobutane fused cyclooctenes (tCBCO),&#160;their polymerization to prepare depolymerizable olefinic polymers, and the depolymerization of these polymers under mild conditions. Additionally, protocols for the preparation of depolymerizable networks and compression molding of rigid linear plastics based on this system are described.

The growing consumption of synthetic polymers and the accumulation of polymer waste have led to a pressing need for new routes to sustainable materials. ...

This protocol describes the synthesis, characterization, and the chemical recycling of a chemical recyclable polymer system developing our lamp, which we think have the potential to address the challenges associated with the sustainable use of plastics. Compared with chemically recyclable polymers developed so far, the advantage of our system is that it enables the chemical recycling of polymers with hydrocarbon backbone, which has excellent hydrolytic stability. Demonstrating the procedure will be Devavrat Sathe and Hanlin Chen, graduate students from my laboratory.To begin, add maleic anhydride, cyclooctadiene, and 150 milliliters of dry acetone to a quartz tube. Seal the quartz flask with a rubber septum and insert a 6-inch needle connected to the nitrogen on a Schlenk line and a smaller bleed needle. Stir the solution on a magnetic stir plate while bubbling with nitrogen for around 30 minutes.After that, remove the needles. Equip the photoreactor with 300-nanometer lamps, and place the flask in it, clamped to a vertical support. Make sure to cover the top of the photoreactor loosely and turn on the cooling fan and UV lamps.After irradiating overnight, concentrate the mixture on a rotavap until most of the solvent is removed. Add cotton and silver nitrate-impregnated silica gel to a circulation column, and fill the rest of the column with untreated silica gel. Add another another piece of cotton, wrap the column with aluminum foil, and connect with tubing on either end.Connect one end of the column to a metering pump for circulation, with another piece of tubing coming out of the metering pump. Put either end of the tubing into a flask with 200 millimeters diethyl ether/hexane solvent mixture and circulate for 2 hours to pack the column tight. Check any possible leaking.Next, dissolve dimethyl ester monomer, or M1, and methyl benzoate in diethyl ether/hexane solvent mixture in a quartz tube. Equip the photoreaction chamber with 254-nanometer wavelength lamps. Replace the flask with the quartz tube, place it in the photoreaction chamber, and continue circulation under irradiation for 16 hours.After turning off the photoreactor, pull the tubing up above the solution level and circulate for an additional 1 hour to dry the column. Pack another column with a silica gel layer at the bottom and silver nitrate-impregnated silica gel at the top. After emptying the circulation column, load its contents to the normal column.Collect the solution from the quartz tube and concentrate. Add this concentrated solution to the silica column. Wash the column with diethyl ether/hexane solvent mixture to collect methyl benzoate and M1, followed by washing with acetone to collect EM1 silver complex.After acetone is removed on a rotavap, add a mixture of 200 milliliters of DCM and 200 milliliters of concentrated aqueous ammonia to the residue and stir for 15 minutes. Add trans-cyclobutane fused cyclooctene monomer M2 and crosslinker XL to a 4-dram glass vial. Then, add 500 microliters of dichloromethane to this and dissolve using a vortex mixer.Add Grubbs II catalyst, or G2, to this and agitate manually to ensure dissolution. Add the solution to a polytetrafluoroethylene, or PTFE, mold with six cavities using a glass pipette. Allow the network to cure at room temperature for 24 hours and then at 6 degrees Celsius for 24 hours.Carefully remove the sample from the mold and submerge the sample in a 20-milliliter vial with around 5 milliliter of ethyl vinyl ether for 4 hous. Place the prepared sample in a cellulose thimble and then place it in a Soxhlet extraction apparatus. Affix the Soxhlet extractor onto a 500-milliliter round-bottom flask with 250 milliliter of chloroform and place it in an oil bath.Attach a condenser to the top of the Soxhlet extractor and allow the solvent to reflux for almost 14 hours. Remove the sample from the thimble, place it on a piece of paper towel placed on a clean surface, cover it, and allow the solvent to evaporate under ambient conditions for almost 6 hours. Place the sample in a 20-milliliter vial and place it under a vacuum to dry completely, weighing periodically until no weight loss is detectable.Place the polymer P1 in a 3-dram glass vial and dissolve it in 4706 microliters of deuterated chloroform. Weigh G2 in a 1-dram glass vial and add 148.6 microliters of deuterated chloroform to dissolve it. Next, add 50 microliters of the solution of G2 to the solution of P1.The total concentration of olefinic groups is therefore 25 millimolar.Split the vial's contents into three different vials and place the vials in a water bath at 30 degrees Celsius for almost 16 hours. Then, add 50 microliters of ethyl vinyl ether to this to quench G2.Follow the same procedure for the depolymerization of the polymer network PN1. Structures of trans-cyclobutane fused cyclooctene monomers for chemically recyclable polymers are shown here.Photochemical 2 2 cycloaddition of 1, 5-cyclooctadiene and maleic anhydride affords the anhydride 1, which can be readily converted to M1 and XL, M2, and M3.Reaction schemes for the synthesis of trans-cyclobutane fused cyclooctene small molecules and monomers and the synthesis of P1 by conventional and by living ring-opening metathesis polymerization are shown here. The representative image shows the GPC traces for polymer P1 prepared by living ROMP in the presence of G1 and triphenyl phosphine and conventional ROMP in the presence of G2.The depolymerization reaction scheme of trans-CBCO polymers is presented in this image. The stacked partial proton NMR spectra of polymer P1 after depolymerization and before depolymerization, monomer M1 are shown here.1H NMR spectra of network PN1 after depolymerization, crosslinker XL, and monomer M2 are presented in this figure. The representative images show the stress vs. strain curves of polymer network PN1 and polymer P3.When setting up the photocycloaddition reaction, it's important to remember to spark the reaction mixture with nitrogen.It's also important to quench the catalyst right after polymerization or depolymerization before workup. Finally, after Soxhlet extraction of the network P1, it should be dried gradually to avoid the evaporation-induced fraction. These methods can be adapted to make tCBCO polymers with many different functional groups and to prepare depolymerizable polymers with diverse material properties and to understand the substituent effect on polymerization behavior.

depolymerizable-olefinic-polymers-based-on-fused-ring-cyclooctene

Research

JoVE Journal

Chemistry

Particles without a Box: Brush-first Synthesis of Photodegradable PEG Star Polymers under Ambient Conditions

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug delivery, biological imaging, and supported catalysis. In this report, we demonstrate parallel synthesis of brush-arm star polymer (BASP) nanoparticles by the &#34;brush-first&#34; method. In this method, a norbornene-terminated poly(ethylene glycol) (PEG) macromonomer (PEG-MM) is first polymerized via ring-opening metathesis polymerization (ROMP) to generate a living brush macroinitiator. Aliquots of this initiator stock solution are added to vials that contain varied amounts of a photodegradable bis-norbornene crosslinker. Exposure to crosslinker initiates a series of kinetically-controlled brush+brush and star+star coupling reactions that ultimately yields BASPs with cores comprised of the crosslinker and coronas comprised of PEG. The final BASP size depends on the amount of crosslinker added. We carry out the synthesis of three BASPs on the benchtop with no special precautions to remove air and moisture. The samples are characterized by gel permeation chromatography (GPC); results agreed closely with our previous report that utilized inert (glovebox) conditions. Key practical features, advantages, and potential disadvantages of the brush-first method are discussed.

Poly(ethylene glycol) (PEG) brush-arm star polymers (BASPs) with narrow mass distributions and tunable nanoscopic sizes are synthesized in via ring opening metathesis polymerization (ROMP) of a PEG-norbornene macromonomer followed by transfer of portions of the resulting living brush initiator to vials containing varied amounts of a rigid, photo-cleavable bis-norbornene crosslinker.

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug ...

Manufacturing of Three-dimensionally Microstructured Nanocomposites through Microfluidic Infiltration

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite in&#64257;ltration of 3D interconnected microfluidic networks. The manufacturing of the reinforced beams begins with the fabrication of microfluidic networks, which involves layer-by-layer deposition of fugitive ink filaments using a dispensing robot, filling the empty space between filaments using a low viscosity resin, curing the resin and finally removing the ink.&#160;Self-supported 3D structures with other geometries and many layers (e.g.&#160;a few hundreds layers) could be built using this method. The resulting tubular micro&#64258;uidic networks are then infiltrated with thermosetting nanocomposite suspensions containing nanofillers (e.g.&#160;single-walled carbon nanotubes), and subsequently cured. The infiltration is done by applying a pressure gradient between two ends of the empty network (either by applying a vacuum or vacuum-assisted microinjection). Prior to the infiltration, the nanocomposite suspensions are prepared by dispersing nanofillers into polymer matrices using ultrasonication and three-roll mixing methods. The nanocomposites (i.e.&#160;materials infiltrated) are then solidified under UV exposure/heat cure, resulting in a 3D-reinforced composite structure. The technique presented here enables the design of functional nanocomposite macroscopic products for microengineering applications such as actuators and sensors.

Three-dimensional (3D) microstructured composite beams are fabricated through the directed and localized infiltration of nanocomposites into 3D porous microfluidic networks. The flexibility of this manufacturing method enables the utilization of different thermosetting materials and nanofillers in order to achieve a variety of functional 3D reinforced nanocomposite macroscopic products.

Microstructured composite beams reinforced with complex three-dimensionally (3D) patterned nanocomposite microfilaments are fabricated via nanocomposite ...

Using Polystyrene-block-poly(acrylic acid)-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are encapsulated in polystyrene-block-poly(acrylic acid) (PSPAA) shells and then used as monomers for their self-assembly. Spherical PSPAA micelles upon acid treatment are known to assemble into cylindrical micelles. Exploiting this tendency, the core-shell nanoparticles are induced to aggregate, coalesce, and then transform into long chains. When more than one type of nanoparticles are used, random and block &#8220;copolymers&#8221; of nanoparticles can be obtained. Detailed procedures are reported for the PSPAA encapsulation of nanoparticles, homo- and co-polymerization of the core-shell nanoparticles, separation and purification of the resulting nanoparticle chains. Transformations of single-line chains into double- and triple-line chains are also presented. The synergy between the polymer shell and the embedded nanoparticles leads to an unusual chain-growth polymerization mode, giving long nanoparticle chains that are distinct from the products of the traditional step-growth aggregation process.

Using Polystyrene-block-polyacrylic acid-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We report protocols for &#8220;polymerizing&#8221; various types of polymer-encapsulated metal nanoparticles into long chains of &#8220;homo-&#8220; and &#8220;co-polymers&#8221;.

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are ...

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The procedure is performed under an inert atmosphere using air- and water-exclusion techniques. The outcome of the polymerization is affected by the ratios of monomer, initiator, and catalyst used as well as the reaction concentration, solvent, and nature of the light source. Temporal control over the polymerization can be exercised by turning the visible light source off and on. Low dispersities of the resultant polymers as well as the ability to chain-extend to form block copolymers suggest control over the polymerization, while chain end-group analysis provides evidence supporting an atom-transfer radical polymerization mechanism.

A method for the atom transfer radical polymerization of functionalized vinyl monomers using perylene as a visible-light photocatalyst is described.

A standardized technique for atom transfer radical polymerization of vinyl monomers using perylene as a visible-light photocatalyst is presented. The ...

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

A protocol for the synthesis and characterization of diffusive motion of cyclic polymers at the single molecule level is presented.

We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single ...

Scale-up Chemical Synthesis of Thermally-activated Delayed Fluorescence Emitters Based on the Dibenzothiophene-S,S-Dioxide Core

We report a procedure to linearly scale-up the synthesis of 2,8-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)dibenzothiophene-S,S-dioxide (compound 4) and 2,8-bis(10H-phenothiazin-10-yl)dibenzothiophene-S,S-dioxide (compound 5) using Buchwald-Hartwig cross-coupling reaction conditions. In addition, we demonstrate a scaled-up synthesis of all non-commercially available starting materials that are required for the amination cross-coupling reaction. In the present article, we provide the detailed synthetic procedures for all of the described compounds, alongside their spectral characterization. This work shows the possibility to produce organic molecules for optoelectronic applications on a large scale, which facilitates their implementation into real world devices.

Scale-up synthesis of highly efficient thermally activated delayed fluorescence emitters is described in the presented article.

We report a procedure to linearly scale-up the synthesis of 2,8-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)dibenzothiophene-S,S-dioxide (compound 4) and ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Raman and IR Spectroelectrochemical Methods as Tools to Analyze Conjugated Organic Compounds

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule on the vibrational level of energy. Raman and IR spectroelectrochemistry can be used for advanced characterization of the structural changes in the organic electroactive compounds. Here, the step-by-step analysis by means of Raman and IR spectroelectrochemistry is shown. Raman and IR spectroelectrochemical techniques provide complementary information about structural changes occurring during an electrochemical process, i.e. allows for the investigation of redox processes and their products. The examples of IR and Raman spectroelectrochemical analysis are presented, in which the products of the redox reactions, both in solution and solid state, are identified.

A protocol of step-by-step Raman and IR spectroelectrochemical analysis is presented.

In the presented work, two spectroelectrochemical techniques are discussed as tools for the analysis of the structural changes occurring in the molecule ...

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds

Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance (EPR) or ultraviolet-visible and near-infrared (UV-Vis-NIR) spectroscopies, we obtain useful information such as electron affinity, ionization potential, band-gap energies, the type of charge carriers, and degradation information that can be used to synthesize stable organic electronic devices. In this study, we present electrochemical and spectroelectrochemical methods to analyze the processes occurring in active layers of an organic device as well as the generated charge carriers.

In this article, we describe electrochemical, electron paramagnetic resonance, and ultraviolet-visible and near-infrared spectroelectrochemical methods to analyze organic compounds for application in organic electronics.

Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance ...

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) Mass Spectrometry

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group analysis as matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). This tutorial demonstrates methods for optimization of the sample preparation, spectral acquisition, and data analysis of synthetic polymers using MALDI-TOF MS. Critical parameters during sample preparation include the selection of the matrix, identification of an appropriate cationization salt, and tuning the relative proportions of the matrix, cation, and analyte. The acquisition parameters, such as mode (linear or reflector), polarization (positive or negative), acceleration voltage, and delay time, are also important. Given some knowledge of the chemistry involved to synthesize the polymer and optimizing both the data acquisition parameters and the sample preparation conditions, spectra should be obtained with sufficient resolution and mass accuracy to enable the unambiguous determination of the end groups of most homopolymers (masses below 10,000) in addition to the repeat unit mass and the overall molecular weight distribution. Though demonstrated on a limited set of polymers, these general techniques are applicable to a much wider range of synthetic polymers for determining mass distributions, though end group determination is only possible for homopolymers with narrow dispersity.

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

A protocol for the matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) characterization of synthetic polymers is described including the optimization of sample preparation, spectral acquisition, and data analysis.

There are many techniques that can be employed in the characterization of synthetic homopolymers, but few provide as useful of information for end group ...