Biodegradable Polymers

 

1. Polycarbonates

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Carbon dioxide, is a highly abundant,  nontoxic, nonflammable,  C1 feedstock which can be copolymerized with epoxides to generate polycarbonates. These materials have a wide range of potential applications including use in polyurethanes and specialty products. Our group  studies highly active β-diiminate zinc  ([BDI]ZnOAc) catalysts  which have allowed us to access a plethora of different polycarbonates, including isotactic polymers via meso desymmeterization, and  poly(limonene carbonate) which shows a unique example of stereocomplexation.

Selected References:
  1.  For a review of  catalyst development in the field of polycarbonate synthesis see: Coates, G.W.; Moore, D.R. Discrete Metal-based Catalysts for the Copolymerization of CO2 and Epoxides: Discovery, Reactivity, Optimization, and Mechanism. Angew. Chem., Int. Ed. 2004, 43, 6618-6639. doi:10.1002/anie.200460442
  2. Ellis, W. Chadwick; Jung, Yukyung; Mulzer, Michael; Di Girolamo, Rocco; Lobkovsky, Emil B.; Coates, Geoffrey W. Copolymerization of CO2 and meso epoxides using enantioselective β-diiminate catalysts: a route to highly isotactic polycarbonates. Chem. Sci., 2014, 5, 4004-4011. doi: 10.1039/C4SC01686F
  3. Auriemma, F.; De Rosa, C.; Di Caprio, M. R.; Di Girolamo, R.; Ellis, W. C.; Coates, G. W.Stereocomplexed Poly(Limonene Carbonate): A Unique Example of the Cocrystallization of Amorphous Enantiomeric Polymers. Angew. Chem. Int. Ed., 2015, 54, 1215–1218. doi: 10.1002/anie.201410211

 

2. Polyesters

epox-anhyd

Our group has developed zinc, chromium, cobalt, and aluminum catalysts for the alternating copolymerization of epoxides and cyclic anhydrides. This chain-growth synthesis offers an attractive alternative to  traditional step-growth methods for polyester synthesis. We can synthesize an array of diverse structures with widely varying properties, ranging from semi-crystalline stereocomplexed poly(propylene succinate), to completely amorphous high-Tg terpene based materials, to polyester-b-polycarbonate block copolymers via a one-pot terpolymerization.

Selected Reference:
  1.  Jeske, R. C.; Rowley, J. M.; Coates, G. W. Pre-rate-determining Selectivity in the Terpolymerization of Epoxides, Cyclic Anhydrides, and CO2: a One-step Route to Diblock Copolymers. Angew. Chem., Int. Ed. 200847, 6041-6044, S6041/6041-S6041/6016. doi: 10.1002/anie.200801415
  2. Longo, J. M.; DiCiccio, A. M.; Coates, G. W. Poly(propylene succinate): A New Polymer Stereocomplex. J. Am. Chem. Soc., 2014136, 15897–15900. doi:10.1021/ja509440g
  3. Van Zee, N. J.; Coates, G.W. Alternating Copolymerization of Propylene Oxide with Biorenewable Terpene-Based Cyclic Anhydrides: A Sustainable Route to Aliphatic Polyesters with High Glass Transition Temperatures. Angew. Chem., Int. Ed. 2015, 54, 2665-2668. DOI: 10.1002/anie.201410641
  4. Van Zee, N. J.; Sanford, M. J.; Coates, G.W. Electronic Effects of Aluminum Complexes in the Copolymerization of Propylene Oxide with Tricyclic Anhydrides: Access to Well-Defined, Functionalizable Aliphatic Polyesters. J. Am. Chem. Soc. 2016, 138, 2755–2761.doi: 10.1021/jacs.5b12888

3. Poly(hydroxyalkanoates)

PHAs

Poly(hydroxyalkanoate)s (PHA)s are naturally-occurring biodegradable polyesters made by bacterial fermentation. Our goal is to develop an alternative synthetic route that consists of carbonylation of epoxides to beta-lactones, followed by ring-opening polymerization to yield PHAs. Recently, we reported a one-pot carbonylative polymerization method that makes poly(3-hydroxybutyrate) (PHB) from propylene oxide and carbon monoxide.

Selected Reference:
  1. Dunn, E. W.; Coates, G. W. J. Am. Chem. Soc. 2010132, 11412. doi: 10.1021/ja1049862

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