The authors are grateful for the financial support from the Netherlands Organization for Scientific Research (NWO) (grant 023.007.020 awarded to Jack van Schijndel).

1. Green Knoevenagel condensation of syringaldehyde towards sinapinic acid with 5 mol% ammonium bicarbonate
<ol>
	<li>Add malonic acid (20.81 g, 200.0 mmol) together with syringaldehyde (36.4 g, 200.0 mmol) to a 250 mL round-bottom flask. Dissolve both constituents in 20.0 mL of ethyl acetate and add ammonium bicarbonate (790 mg, 10.0 mmol) to the flask. 
	NOTE: To ensure full completion of the condensation reaction, the rotary evaporator can be used to distill the ethyl acetate and concentrate the reaction mixture, resulting in a solvent-less reaction.</li>
	<li>Keep the reaction mixture for 2 hours at 90 &#176;C in the open flask without stirring for complete conversion to sinapinic acid. 
	NOTE: During this reaction, several morphological changes are observed. The reaction mixture changes from a dense grey mixture to a dissolved yellow mix due to the formation of water during the condensation step of the reaction. After evaporation of the condensate, the reaction mixture solidifies again, indicating full conversion.</li>
	<li>In the work-up of the sinapinic acid product, dissolve the residue in 100 mL of a saturated aqueous NaHCO3-solution. Transfer the solution to a beaker and subsequently acidify it to a pH of 2 using 6 M HCl. 
	NOTE: While adding the saturated aqueous NaHCO3-solution, the crude product dissolves slowly and requires some time and manual scraping to dissolve fully. Once wholly dissolved and transferred to the beaker, the acidic solution of 6 M HCl is added drop-wise. Sinapinic acid will precipitate quickly, and the release of CO2 gas will cause the product to foam.</li>
	<li>Separate the resulting residue by vacuum filtration and wash it with demineralized water. 
	NOTE: At this point, the purity of the product can be analyzed by HPLC. If the product appears contaminated, the next purification step (e.g., recrystallization) must be applied.</li>
	<li>After recrystallization in a mixture of water-ethanol (4:1, v/v), separate the crystals by vacuum filtration. Dry the residue at 60 &#176;C in a vacuum oven, resulting in 42.56 g of pure sinapinic acid. 
	NOTE: The purity of sinapinic acid is measured by melting point analysis and HPLC.</li>
</ol>
2. Hydrogenation of sinapinic acid towards dihydrosinapinic acid with RaneyTM nickel.
<ol>
	<li>Charge a 450 mL flask (using a hydrogenation apparatus) with sinapinic acid (33.6 g, 150 mmol). Dissolve the sinapinic acid in 300 mL of 2 M NaOH solution and add 1.5 g of nickel slurry (see Table of Materials) before fitting the flask to the apparatus. 
	NOTE: The color of the reaction mixture changes due to the addition of the alkaline solution. Sinapinic acid will be yellow in its crystalline form, but when deprotonated by the base, the color of the solution will change to red. The addition of nickel will turn the color black.</li>
	<li>Pressurize the reactor with three bar of hydrogen gas and mechanically shake the reaction at 80 &#176;C for three hours.</li>
	<li>Cool the reactor to room temperature and depressurized slowly. Recover most of the nickel catalyst with a magnet and subsequently filter the solution under reduced pressure. 
	NOTE: The reaction mixture should change from red to green color, visible after filtration. The notable color change is because the conjugated system is interrupted by hydrogenation of the double bond.</li>
	<li>Acidify the solution with a 4 M HCl solution towards a pH of 2. Subsequently, perform an extraction with ethyl acetate (4 times 50 mL). Remove the solvent under reduced pressure after drying over MgSO4. Dry the solid product dihydrosinapinic acid at 60 &#176;C in a vacuum oven. 
	NOTE: Theoretically, the polycondensation reaction can be processed on dihydrosinapinic acid, but there are some practical drawbacks. Due to the molecular structure, dihydrosinapinic acid sublimates above the melting point. An acetylation reaction can be performed to prevent sublimation and increase reactivity.</li>
</ol>
3. Acetylation of dihydrosinapinic acid towards acetylated monomers and oligomers (prepolymer).
<ol>
	<li>Add dihydrosinapinic acid (22.6 g, 100 mmol) to a 250 mL round-bottom flask, followed by acetic anhydride (14.2 mL, 150 mmol) and sodium acetate (0.82 g, 10 mmol). 
	NOTE: The dihydrosinapinic acid does not fully dissolve in the acetic anhydride at room temperature.</li>
	<li>Heat the solution to 90 &#176;C while stirring for one hour for complete conversion of dihydrosinapinic acid towards 4-acetoxy-dihydrosinapinic acid and its acetylated oligomers. 
	NOTE: All the products remain dissolved in acetic anhydride. To increase the total precipitation of 4-acetoxy-dihydrosinapinic acid, add a small amount of water-soluble solvent in the next step.</li>
	<li>Dissolve the solid in 25 mL of acetone, precipitate (solvent-non solvent) into 250 mL of 0.1 M HCl while stirring vigorously&#160;and filter under vacuum. 
	NOTE: The best result shows an entirely precipitated white, sticky solid. If the product solution is added to the HCl solution too quickly, the product remains as a brown liquid at the bottom of the acidic solution. In this situation, extract the entire product solution with ethyl acetate (4 times 50 mL). After drying over MgSO4, remove the ethyl acetate under reduced pressure. The product is 4-acetoxy-dihydrosinapinic acid and prepolymer.</li>
</ol>
4. Polymerization of acetylated monomers and oligomers.
<ol>
	<li>Add the monomers, 4-acetoxy-dihydrosinapinic acid (20.8 g, 100 mmol), and prepolymer to a 100 mL round-bottom flask and add finely powdered NaOH (400 mg, 10.0 mmol). Heat the reaction mixture for three hours at a set temperature of 140 &#176;C in the open flask while stirring at 100 rpm. 
	NOTE: During this reaction, water and acetic acid condense from the open flask. The pH of the vapor can be measured to confirm the condensation of acetic acid. The morphology of the reaction product changes from a molten state to a compact, light-brown product. The setup is subjected to a nitrogen flow to promote the evaporation of the condensate and prevent oxidation. Such reactions are usually stirred with a mechanical stirrer due to the high viscosity of the mixture. However, the use of a magnetical stirrer is sufficient, and the difference is negligible on this scale.</li>
	<li>Set up a solvent assisted polymerization by adding zinc(II)acetate (180 mg, 1 mmol) and 25.0 mL of 1,2-xylene to the flask. Raise the set temperature to 160 &#176;C. 
	NOTE: Raise the set temperature to 160 &#176;C to ensure the reflux of 1,2-xylene and full reactivity of the polymerization. The temperature of the reaction itself remains at 144 &#176;C, due to the boiling point of the 1,2-xylene.</li>
	<li>Reflux the mixture at 144 &#176;C for three hours with constant water and acetic acid removal using a Dean-Stark head. 
	NOTE: After adding the 1,2-xylene and heating the reaction flask to the required temperature, the reagents form a brown slurry with a lower viscosity. This lower viscosity is presumed to benefit the mobility of the end-groups of the polymer, promoting reactivity.</li>
	<li>Cool the reaction mixture down and remove the 1,2-xylene by applying a vacuum (&#60;10 mbar). 
	NOTE: The reaction mixture solidifies while evaporating the solvent and turns into an off-white solid.</li>
	<li>Raise the temperature to 240 &#176;C during the final stage of the polymerization and apply a high vacuum &#60;1 mbar for thirty minutes. 
	NOTE: Only a slight amount of condensate evaporates during this step because only a small amount of condensation is needed to boost the chain length substantially at this stage of polymerization.</li>
	<li>Cool the polymer poly-S to room temperature and wash with methanol to eliminate 4-acetoxy-dihydrosinapinic acid and prepolymers. The obtained product is a light-brown solid. 
	NOTE: After the process, the chain length and thermal properties of the polyester are investigated by GPC and DSC.</li>
</ol>
5. Representative procedure for the depolymerization of poly-S in 1 M NaOH:
<ol>
	<li>Finely grind and sieve poly-S into particles smaller than 180 &#956;m to measure hydrolytic degradation. 
	NOTE: To grind the particles to the required size, use a mortar and pestle with liquid nitrogen-cooled poly-S, followed by a mechanical sieving step.</li>
	<li>Load several test tubes with 20 mg of poly-S and add 1.0 mL of 1 M NaOH solution. Incubate the tubes at three different temperatures (RT, 50, and 80 &#176;C), with an agitation of 500 rpm using a controlled environment incubator shaker. 
	NOTE: Use a heating-block/shaker with multiple entries for this reaction to ensure all the reactions take place in precisely the same (thermal) conditions.</li>
	<li>Neutralize a test tube at regular time intervals with 1.0 mL of 0.5 M H2SO4 and add 2.0 mL of methanol after cooling. 
	NOTE: Small amounts of poly-S and only 1.0 mL of 1 M NaOH are used because these concentrations can, after the addition of methanol, be directly injected in HPLC and do not require any further dilution.</li>
	<li>Filter all samples using 0.45 &#956;m PTFE syringe filters and inject (20 &#956;L) on HPLC using an autosampler. Monitor the absorbance at &#955; = 254 nm, and calculate the concentrations from a calibration curve of known dihydrosinapinic acid standard solutions. 
	NOTE: The standard solutions of the calibration curve should be made in the same solvent mixture as the work-up after the depolymerization.</li>
</ol>

<ol>
	<li>Rahimi, A., Garc&#237;a, 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=Chemical+recycling+of+waste+plastics+for+new+materials+production.">Chemical recycling of waste plastics for new materials production.</a> Nature Reviews Chemistry. 1 (6), 41570 (2017).</li><li>Sardon, H., Dove, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plastics+recycling+with+a+difference.">Plastics recycling with a difference.</a> Science. 360 (6387), 380-381 (2018).</li><li>Jones, G. O., Yuen, A., Wojtecki, R. J., Hedrick, J. L., Garc&#237;a, 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=Computational+and+experimental+investigations+of+one-step+conversion+of+poly(carbonate)s+into+value-added+poly(aryl+ether+sulfone)s.">Computational and experimental investigations of one-step conversion of poly(carbonate)s into value-added poly(aryl ether sulfone)s.</a> Proceedings of the National Academy of Sciences of the United States of America. 113 (28), 7722-7726 (2016).</li><li>Garc&#237;a, J. M., 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=Recyclable,+Strong+Thermosets+and+Organogels+via+Paraformaldehyde+Condensation+with+Diamines.">Recyclable, Strong Thermosets and Organogels via Paraformaldehyde Condensation with Diamines.</a> Science. 344 (6185), 1251484 (2014).</li><li>Brutman, J. P., De Hoe, G. X., Schneiderman, D. K., Le, T. N., Hillmyer, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Renewable,+Degradable,+Chemically+Recyclable+Cross-Linked+Elastomers.">Renewable, Degradable, Chemically Recyclable Cross-Linked Elastomers.</a> Industrial &amp; Engineering Chemistry Research. 55 (42), 11097-11106 (2016).</li><li>Hong, M., Chen, E. Y. <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>Lochab, B., Shukla, S., Varma, I. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Naturally+occurring+phenolic+sources:+monomers+and+polymers.">Naturally occurring phenolic sources: monomers and polymers.</a> RSC Advances. 4 (42), 21712 (2014).</li><li>Fache, M., Boutevin, B., Caillol, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vanillin,+a+key-intermediate+of+biobased+polymers.">Vanillin, a key-intermediate of biobased polymers.</a> European Polymer Journal. 68, 488-502 (2015).</li><li>Pinto, P. C. R., Costa, C. E., Rodrigues, A. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidation+of+Lignin+from+Eucalyptus+globulus+Pulping+Liquors+to+Produce+Syringaldehyde+and+Vanillin.">Oxidation of Lignin from Eucalyptus globulus Pulping Liquors to Produce Syringaldehyde and Vanillin.</a> Industrial &amp; Engineering Chemistry Research. 52 (12), 4421-4428 (2013).</li><li>Llevot, A., Grau, E., Carlotti, S., Grelier, S., Cramail, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+Lignin-derived+Aromatic+Compounds+to+Novel+Biobased+Polymers.">From Lignin-derived Aromatic Compounds to Novel Biobased Polymers.</a> Macromolecular Rapid Communications. 37 (1), (2016).</li><li>Hern&#225;ndez, N., Williams, R. C., Cochran, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+battle+for+the+"green"+polymer.+Different+approaches+for+biopolymer+synthesis:+bioadvantaged+vs.+bioreplacement.">The battle for the "green" polymer. Different approaches for biopolymer synthesis: bioadvantaged vs. bioreplacement.</a> Organic &amp; Biomolecular Chemistry. 12 (18), 2834-2849 (2014).</li><li>Kricheldorf, H. R., Stukenbrock, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+polymer+syntheses+85.+Telechelic,+star-shaped+and+hyperbranched+polyesters+of+&#946;-(4-hydroxyphenyl)+propionic+acid.">New polymer syntheses 85. Telechelic, star-shaped and hyperbranched polyesters of &#946;-(4-hydroxyphenyl) propionic acid.</a> Polymer. 38 (13), 3373-3383 (1997).</li><li>Gilding, D. K., Reed, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodegradable+polymers+for+use+in+surgery-poly(ethylene+oxide)+poly(ethylene+terephthalate)+(PEO/PET)+copolymers:+1.">Biodegradable polymers for use in surgery-poly(ethylene oxide) poly(ethylene terephthalate) (PEO/PET) copolymers: 1.</a> Polymer. 20 (12), 1454-1458 (1979).</li><li>Jiang, Y., Loos, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enzymatic+Synthesis+of+Biobased+Polyesters+and+Polyamides.">Enzymatic Synthesis of Biobased Polyesters and Polyamides.</a> Polymers. 8 (7), 243 (2016).</li><li>Kricheldorf, H. R., Stukenbrock, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+polymer+syntheses,+92.+Biodegradable,+thermotropic+copolyesters+derived+from+&#946;-(4-hydroxyphenyl)propionic+acid.">New polymer syntheses, 92. Biodegradable, thermotropic copolyesters derived from &#946;-(4-hydroxyphenyl)propionic acid.</a> Macromolecular Chemistry and Physics. 198 (11), 3753-3767 (1997).</li><li>Kreye, O., Oelmann, S., Meier, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Renewable+Aromatic-Aliphatic+Copolyesters+Derived+from+Rapeseed.">Renewable Aromatic-Aliphatic Copolyesters Derived from Rapeseed.</a> Macromolecular Chemistry and Physics. 214 (13), 1452-1464 (2013).</li><li>Mialon, L., Pemba, A. G., Miller, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biorenewable+polyethylene+terephthalate+mimics+derived+from+lignin+and+acetic+acid.">Biorenewable polyethylene terephthalate mimics derived from lignin and acetic acid.</a> Green Chemistry. 12 (10), 1704 (2010).</li><li>Nguyen, H. T. H., Reis, M. H., Qi, P., Miller, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyethylene+ferulate+(PEF)+and+congeners:+polystyrene+mimics+derived+from+biorenewable+aromatics.">Polyethylene ferulate (PEF) and congeners: polystyrene mimics derived from biorenewable aromatics.</a> Green Chemistry. 17 (9), 4512-4517 (2015).</li><li>van Schijndel, J., Canalle, L. A., Molendijk, D., Meuldijk, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Green+Knoevenagel+Condensation:+Solvent-free+Condensation+of+Benzaldehydes.">The Green Knoevenagel Condensation: Solvent-free Condensation of Benzaldehydes.</a> Green Chemistry Letters and Reviews. 10 (4), 404-411 (2017).</li><li>van Schijndel, J., Molendijk, D., Spakman, H., Knaven, E., Canalle, L. A., Meuldijk, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanistic+considerations+and+characterization+of+ammonia-based+catalytic+active+intermediates+of+the+Green+Knoevenagel+reaction+of+various+benzaldehydes.">Mechanistic considerations and characterization of ammonia-based catalytic active intermediates of the Green Knoevenagel reaction of various benzaldehydes.</a> Green Chemistry Letters and Reviews. 12 (3), 323-331 (2019).</li><li>Sheldon, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fundamentals+of+green+chemistry:+efficiency+in+reaction+design.">Fundamentals of green chemistry: efficiency in reaction design.</a> Chemical Society Reviews. 41 (4), 1437-1451 (2012).</li><li>van Schijndel, J., Molendijk, D., Canalle, L. A., Rump, E. T., Meuldijk, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature+Dependent+Green+Synthesis+of+3-Carboxycoumarins+and+3,4-unsubstituted+Coumarins.">Temperature Dependent Green Synthesis of 3-Carboxycoumarins and 3,4-unsubstituted Coumarins.</a> Current Organic Synthesis. 16 (1), 130-135 (2019).</li><li>Bloom, M. E., Vicentin, J., Honeycutt, D. S., Marsico, J. M., Geraci, T. S., Miri, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+renewable,+thermoplastic+tetrapolyesters+based+on+hydroquinone,+p-hydroxybenzoic+acid+or+its+derivatives,+phloretic+acid,+and+dodecanedioic+acid.">Highly renewable, thermoplastic tetrapolyesters based on hydroquinone, p-hydroxybenzoic acid or its derivatives, phloretic acid, and dodecanedioic acid.</a> Journal of Polymer Science Part A: Polymer Chemistry. 56 (14), 1498-1507 (2018).</li><li>Padias, A. B., Hall, H. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+Studies+of+LCP+Synthesis.">Mechanism Studies of LCP Synthesis.</a> Polymers. 3 (2), 833-845 (2011).</li><li>Moon, S., Lee, C., Taniguchi, I., Miyamoto, M., Kimura, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Melt/solid+polycondensation+of+l-lactic+acid:+an+alternative+route+to+poly(l-lactic+acid)+with+high+molecular+weight.">Melt/solid polycondensation of l-lactic acid: an alternative route to poly(l-lactic acid) with high molecular weight.</a> Polymer. 42 (11), 5059-5062 (2001).</li><li>Wellen, R. M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+polystyrene+on+poly(ethylene+terephthalate)+crystallization.">Effect of polystyrene on poly(ethylene terephthalate) crystallization.</a> Materials Research. 17 (6), 1620-1627 (2014).</li><li>Kricheldorf, H. R., Conradi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+polymer+syntheses+16.+LC-copolyesters+of+3-(4-hydroxyphenyl)+propionic+acid+and+4-hydroxy+benzoic+acids.">New polymer syntheses 16. LC-copolyesters of 3-(4-hydroxyphenyl) propionic acid and 4-hydroxy benzoic acids.</a> Journal of Polymer Science Part A: Polymer Chemistry. 25 (2), 489-504 (1987).</li><li>Chen, Y., Tan, L., Chen, L., Yang, Y., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+on+biodegradable+aromatic/aliphatic+copolyesters.">Study on biodegradable aromatic/aliphatic copolyesters.</a> Brazilian Journal of Chemical Engineering. 25 (2), 321-335 (2008).</li><li>Han, X., 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=A+Change+in+Mechanism+from+Acidolysis+to+Phenolysis+in+the+Bulk+Copolymerization+of+4-Acetoxybenzoic+Acid+and+6-Acetoxy-2-naphthoic+Acid.">A Change in Mechanism from Acidolysis to Phenolysis in the Bulk Copolymerization of 4-Acetoxybenzoic Acid and 6-Acetoxy-2-naphthoic Acid.</a> Macromolecules. 29 (26), 8313-8320 (1996).</li><li>Lu, X. F., Hay, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isothermal+crystallization+kinetics+and+melting+behaviour+of+poly(ethylene+terephthalate).">Isothermal crystallization kinetics and melting behaviour of poly(ethylene terephthalate).</a> Polymer. 42 (23), 9423-9431 (2001).</li><li>S&#225;nchez, M. E., Mor&#225;n, A., Escapa, A., Calvo, L. F., Mart&#237;nez, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+thermogravimetric+and+mass+spectrometric+analysis+of+the+pyrolysis+of+municipal+solid+wastes+and+polyethylene+terephthalate.">Simultaneous thermogravimetric and mass spectrometric analysis of the pyrolysis of municipal solid wastes and polyethylene terephthalate.</a> Journal of Thermal Analysis and Calorimetry. 90 (1), 209-215 (2007).</li></ol>

The authors have nothing to disclose.

When dihydrosinapinic acid was heated in a reaction vessel, sublimation of the starting material occurred, and this effect was enhanced when a vacuum was applied. Acetylation has been performed on dihydrosinapinic acid to avoid sublimation. Kricheldorf et al.12,27 recognized that not only acetylation but similarly di- and oligomerization occurred. However, these esterified monomers and oligomers no longer sublimate and are suitable as monomers for the melt polyco...

In contrast to the incineration of polymeric waste, chemical recycling offers the possibility to recover the monomers. Chemical recycling is a logical choice at the end of the technical life of polymeric materials since these polymeric materials are produced chemically1. There are two ways to recycle the polymeric material chemically, pyrolysis and molecular recycling2. With pyrolysis, the polymeric material is transformed into products of higher value by using extreme conditions3,4. Molecular recycling is an efficient method for recovering the starting materials using depolymerization. After depolymerization, the monomeric units can be repolymerized into virgin polymeric materials5. The availability of suitable monomers to apply molecular recycling on a larger scale is wanting. The current plastic problem dictates that society demands sturdy and robust polymeric materials. At the same time, it is also preferred that the same polymeric materials are easily recyclable and do not endure in the environment. Current polymeric materials with good thermal and mechanical properties do not depolymerize easily6.
Lignin, commonly found in vascular plants, is responsible for 30% of the world&#39;s natural carbon content and is the second most abundant biopolymer after cellulose. Lignin has a complex amorphous structure and appears to be a suitable alternative to replace aromatics extracted from fossil materials. The three-dimensional structure of lignin provides strength and stiffness to wood, as well as resistance to degradation. Chemically speaking, lignin is a very complex polyphenolic thermoset. It consists of varying composition of three different methoxylated phenylpropane structures. Syringyl, guaiacyl, and p-hydroxyphenyl (often abbreviated as S, G, and H, respectively) are derived from the monolignols sinapyl alcohol, coniferyl alcohol, and p-coumaryl alcohol7. The distribution of these units differs per biomass type, with softwood, for instance, consisting of mostly guaiacyl units and hardwood of guaiacyl and syringyl units8,9. Renewable natural sources, such as trees and plants, are desirable for the production of redesigned monomers for innovative polymeric materials10. These monomers, isolated and synthesized from natural sources, are polymerized to so-called biobased polymers11.
Aromatic carboxylic acids are several orders of magnitude less electrophilic than the equivalent aliphatic carboxylic acids for electronic reasons12. Various commercial polyesters use aromatic carboxylic acids instead of aliphatic carboxylic acids. As a result, the fibers in polyester textiles made from poly(ethylene terephthalate) (PET) fibers are almost insensitive to hydrolysis during washing or, for example, rain13. When the molecular recycling of polyesters is wanted, it is advisable to use aliphatic esters in the build-up of the polymer.
For the reasons mentioned, we have investigated the possibilities of making polyesters from 4-hydroxy-3,5-dimethoxy-dihydrocinnamic acids14. Previous studies by Kricheldorf15, Meier16, and Miller17,18 show that it is challenging to build polymers using 4-hydroxy-3,5-dimethoxy-dihydrocinnamic acid. Decarboxylation and crosslinking hindered the polymerizations, and so limiting the success of these syntheses. Also, the mechanism of the polycondensation remained unclear. The presented paper describes the conditions in which the polyester poly(dihydrosinapinic acid) can be synthesized regularly and in high yield, thus paving the way for using semi-aromatic polyesters that are molecularly recyclable.
We have developed a green and efficient way to synthesize sinapinic acid using a condensation reaction between syringaldehyde and malonic acid19,20. After this Green Knoevenagel, hydrogenation produces dihydrosinapinic acid, which is suitable for reversible polycondensation. This publication visualizes the synthetic steps to the molecularly recyclable polymer poly(dihydrosinapinic acid), referring to the base units of lignin, called poly-S. After analyzing the polymeric material, poly-S is depolymerized to the monomer dihydrosinapinic acid under relatively favorable conditions and repolymerized over and over again.

<table>
	<tbody>
		<tr>
			<td>Reaction 1: Green Knoevenagel condensation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium bicarbonate</td>
			<td>Sigma Aldrich</td>
			<td>&#62;99%</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Boom</td>
			<td>Technical grade</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl acetate</td>
			<td>Macron</td>
			<td>99.8%</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid</td>
			<td>Boom</td>
			<td>37%</td>
			<td></td>
		</tr>
		<tr>
			<td>Malonic acid</td>
			<td>Sigma Aldrich</td>
			<td>99%</td>
			<td>used as received</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate</td>
			<td>Sigma Aldrich</td>
			<td>&#62;99.7%</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringaldehyde</td>
			<td>Sigma Aldrich</td>
			<td>98%</td>
			<td>used as received</td>
		</tr>
		<tr>
			<td>Reaction 2: Hydrogenation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium sulfate</td>
			<td>Macron</td>
			<td>99%</td>
			<td>dried</td>
		</tr>
		<tr>
			<td>Raney&#8482; nickel</td>
			<td>Sigma Aldrich</td>
			<td>&#62;89%</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Boom</td>
			<td>Technical grade</td>
			<td>dissolved</td>
		</tr>
		<tr>
			<td>Reaction 3: Acetylation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic anhydride</td>
			<td>Macron</td>
			<td>&#62;98%</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>Macron</td>
			<td>&#62;99.5%</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium acetate</td>
			<td>Sigma Aldrich</td>
			<td>&#62;99%</td>
			<td></td>
		</tr>
		<tr>
			<td>Reaction 4A: Polymerisation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1,2-xylene</td>
			<td>Macron</td>
			<td>&#62;98%</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Boom</td>
			<td>Technical grade</td>
			<td>finely powdered</td>
		</tr>
		<tr>
			<td>Zinc(II)acetate</td>
			<td>Sigma Aldrich</td>
			<td>99.99%</td>
			<td></td>
		</tr>
		<tr>
			<td>Reaction 4B: Depolymerisation</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Boom</td>
			<td>Technical grade</td>
			<td>dissolved</td>
		</tr>
		<tr>
			<td>Sulfuric acid</td>
			<td>Macron</td>
			<td>100%</td>
			<td></td>
		</tr>
		<tr>
			<td>Analysis</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CDCl3</td>
			<td>Cambride Isotope Laboratories, Inc.</td>
			<td>99.5%</td>
			<td></td>
		</tr>
		<tr>
			<td>CF3COOD</td>
			<td>Cambride Isotope Laboratories, Inc.</td>
			<td>98%</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethylformamide</td>
			<td>Macron</td>
			<td>&#62;99.9%</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexafluoro-2-propanol</td>
			<td>TCI Chemicals</td>
			<td>&#62;99%</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Macron</td>
			<td>&#62;99.8%</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrahydrofuran</td>
			<td>Macron</td>
			<td>&#62;99.9%</td>
			<td></td>
		</tr>
	</tbody>
</table>

designed for molecular recycling: a lignin-derived semi-aromatic biobased polymer

The development of chemically recyclable biopolymers offers opportunities within the pursuit of a circular economy. Chemically recyclable biopolymers make a positive effort to solve the issue of polymer materials in the disposal phase after the use phase. In this paper, the production of biobased semi-aromatic polyesters, which can be extracted entirely from biomass such as lignin, is described and visualized. The polymer poly-S described in this paper has thermal properties similar to certain commonly used plastics, such as PET. We developed a Green Knoevenagel reaction, which can efficiently produce monomers from aromatic aldehydes and malonic acid. This reaction has been proven to be scalable and has a remarkably low calculated E-factor. These polyesters with ligno-phytochemicals as a starting point show an efficient molecular recycling with minimal losses. The polyester poly(dihydrosinapinic acid) (poly-S) is presented as an example of these semi-aromatic polyesters, and the polymerization, depolymerization, and re-polymerization are described.

Sinapinic acid was synthesized in high purity and high yield (&#62; 95%) from syringaldehyde using the Green Knoevenagel condensation. (Supporting Information: Figure S1) The E-factor is an indication of waste production where a higher number indicates more waste. The E-factor is calculated by taking the total material input, subtracting the amount of the desired end product, and dividing the whole by the amount of the end product. This Green Knoevenagel condensation has an E-factor of 1.0, which can be ...

Watch this Scientific Journal Video about Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer at JoVE.com

Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer

An example of a closed-loop approach towards a circular materials economy is described here. A whole sustainable cycle is presented where biobased semi-aromatic polyesters are designed by polymerization, depolymerization, and then re-polymerized with only slight changes in their yields or final properties.

The development of chemically recyclable biopolymers offers opportunities within the pursuit of a circular economy. Chemically recyclable biopolymers make ...

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&alpha;-Carbon Chemistry: Enols, Enolates, and Enamines

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3.4K Views.  Avans University of Applied Science. An example of a closed-loop approach towards a circular materials economy is described here. A whole sustainable cycle is presented where biobased semi-aromatic polyesters are designed by polymerization, depolymerization, and then re-polymerized with only slight changes in their yields or final properties.

Video: Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer

Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template&#39;s channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology.

This article describes the preparation of well-ordered nickel nanofoams via electroless metal deposition onto nanoporous templates obtained from self-assembled diblock copolymer based supramolecules.

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, ...

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Photodynamic Therapy with Blended Conducting Polymer/Fullerene Nanoparticle Photosensitizers

In this article a method for the fabrication and reproducible in-vitro evaluation of conducting polymer nanoparticles blended with fullerene as the next generation photosensitizers for Photodynamic Therapy (PDT) is reported. The nanoparticles are formed by hydrophobic interaction of the semiconducting polymer MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]) with the fullerene PCBM (phenyl-C61-butyric acid methyl ester) in the presence of a non-compatible solvent. MEH-PPV has a high extinction coefficient that leads to high rates of triplet formation, and efficient charge and energy transfer to the fullerene PCBM. The latter processes enhance the efficiency of the PDT system through fullerene assisted triplet and radical formation, and ultrafast deactivation of MEH-PPV excited stated. The results reported here show that this nanoparticle PDT sensitizing system is highly effective and shows unexpected specificity to cancer cell lines.

This protocol describes a method for the fabrication of conducting polymer nanoparticles blended with fullerene. These nanoparticles were investigated for their potential use as a next generation photosensitizers for Photodynamic Therapy (PDT).

In this article a method for the fabrication and reproducible in-vitro evaluation of conducting polymer nanoparticles blended with fullerene as the next ...

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous solution. In a carbon nanotube/PEO105-PPO70-PEO105 (poloxamer 407) aqueous solution, the amphiphilic poloxamer 407 adsorbs onto the carbon nanotube surfaces and self-assembles into continuous layers, driven by intermolecular interactions between constituent molecules. The addition of 5-methylsalicylic acid changes the self-assembled structure from spherical-micellar to a cylindrical morphology. The fabricated poloxamer 407/carbon nanotube hybrid particles exhibit thermo-responsive structural features so that the density and thickness of poloxamer 407 layers are also reversibly controllable by varying temperature. The detailed structural properties of the poloxamer 407/carbon nanotube particles in suspension can be characterized by small-angle neutron scattering experiments and model fit analyses. The distinct curve shapes of the scattering intensities depending on temperature control or addition of aromatic additives are well described by a modified core-shell cylinder model consisting of a carbon nanotube core cylinder, a hydrophobic shell, and a hydrated polymer layer. This method can provide a simple but efficient way for the fabrication and in-situ characterization of carbon nanotube-based nano particles with a structure-tunable encapsulation.

A method for the functionalization of carbon nanotubes with structure-tunable polymeric encapsulation layers and structural characterization using small-angle neutron scattering is presented.

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous ...

The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ethylene-propylene rubber, grafted with maleic anhydride, is thermo-reversibly cross-linked in two steps. The pending anhydride moieties are first modified with furfurylamine to graft furan groups to the rubber backbone. These pendant furan groups are then cross-linked with a bis-maleimide via a Diels-Alder coupling reaction. Both reactions can be performed under a broad range of experimental conditions and can easily be applied on a large scale. The material properties of the resulting Diels-Alder cross-linked rubbers are similar to a peroxide-cured ethylene/propylene/diene rubber (EPDM) reference. The cross-links break at elevated temperatures (&#62; 150 &#176;C) via the retro-Diels-Alder reaction and can be reformed by thermal annealing at lower temperatures (50-70 &#176;C). Reversibility of the system was proven with infrared spectroscopy, solubility tests and mechanical properties. Recyclability of the material was also shown in a practical way, i.e., by cutting a cross-linked sample into small parts and compression molding them into new samples displaying comparable mechanical properties, which is not possible for conventionally cross-linked rubbers.

A simple two-step approach involving rubber modification and cross-linking yields fully reworkable, elastic rubber products.

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ...

Direct Imaging of Laser-driven Ultrafast Molecular Rotation

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb explosion imaging setup in which a hitherto-impractical camera angle is realized. In our imaging technique, diatomic molecules are irradiated with a circularly polarized strong laser pulse. The ejected atomic ions are accelerated perpendicularly to the laser propagation. The ions lying in the laser polarization plane are selected through the use of a mechanical slit and imaged with a high-throughput, 2-dimensional detector installed parallel to the polarization plane. Because a circularly polarized (isotropic) Coulomb exploding pulse is used, the observed angular distribution of the ejected ions directly corresponds to the squared rotational wave function at the time of the pulse irradiation. To create a real-time movie of molecular rotation, the present imaging technique is combined with a femtosecond pump-probe optical setup in which the pump pulses create unidirectionally rotating molecular ensembles. Due to the high image throughput of our detection system, the pump-probe experimental condition can be easily optimized by monitoring a real-time snapshot. As a result, the quality of the observed movie is sufficiently high for visualizing the detailed wave nature of motion. We also note that the present technique can be implemented in existing standard ion imaging setups, offering a new camera angle or viewpoint for the molecular systems without the need for extensive modification.

We present a protocol for creating a real-time movie of a molecular rotational wave packet using a high-resolution Coulomb explosion imaging setup.

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb ...

Microfluidic Dry-spinning and Characterization of Regenerated Silk Fibroin Fibers

The protocol demonstrates a method for mimicking the spinning process of silkworm. In the native spinning process, the contracting spinning duct enables the silk proteins to be compact and ordered by shearing and elongation forces. Here, a biomimetic microfluidic channel was designed to mimic the specific geometry of the spinning duct of the silkworm. Regenerated silk fibroin (RSF) spinning doped with high concentration, was extruded through the microchannel to dry-spin fibers at ambient temperature and pressure. In the post-treated process, the as-spun fibers were drawn and stored in ethanol aqueous solution. Synchrotron radiation wide-angle X-ray diffraction (SR-WAXD) technology was used to investigate the microstructure of single RSF fibers, which were fixed to a sample holder with the RSF fiber axis normal to the microbeam of the X-ray. The crystallinity, crystallite size, and crystalline orientation of the fiber were calculated from the WAXD data. The diffraction arcs near the equator of the two-dimensional WAXD pattern indicate that the post-treated RSF fiber has a high orientation degree.

A protocol for the microfluidic spinning and microstructure characterization of regenerated silk fibroin monofilament is presented.

The protocol demonstrates a method for mimicking the spinning process of silkworm. In the native spinning process, the contracting spinning duct enables ...

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). ...

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces are demonstrated. This work requires careful design, considerable synthetic effort, and proper analysis. The rotary motion of the molecular motor in solution is shown by 1H NMR and UV-vis absorption spectroscopy techniques. In addition, the method to graft the motor onto an amine-coated quartz is described. This method helps to gain more insight into molecular machines.

The manuscript describes how to synthesize and graft a molecular motor on surfaces for single molecular imaging.

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces ...

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids

Rational design of disordered molecular aggregates and solids for optoelectronic applications relies on our ability to predict the properties of such materials using theoretical and computational methods. However, large molecular systems where disorder is too significant to be considered in the perturbative limit cannot be described using either first principles quantum chemistry or band theory. Multiscale modeling is a promising approach to understanding and optimizing the optoelectronic properties of such systems. It uses first-principles quantum chemical methods to calculate the properties of individual molecules, then constructs model Hamiltonians of molecular aggregates or bulk materials based on these calculations. In this paper, we present a protocol for constructing a tight-binding Hamiltonian that represents the excited states of a molecular material in the basis of Frenckel excitons: electron-hole pairs that are localized on individual molecules that make up the material. The Hamiltonian parametrization proposed here accounts for excitonic couplings between molecules, as well as for electrostatic polarization of the electron density on a molecule by the charge distribution on surrounding molecules. Such model Hamiltonians can be used to calculate optical absorption spectra and other optoelectronic properties of molecular aggregates and solids.

Here, we present a protocol for parametrizing a tight-binding excitonic Hamiltonian for calculating optical absorption spectra and optoelectronic properties of molecular materials from first-principles quantum chemical calculations.

Rational design of disordered molecular aggregates and solids for optoelectronic applications relies on our ability to predict the properties of such ...