Completely Alternating Copolymerization of CO 2 and Epoxides to Polycarbonates

Transcription

1 Completely Alternating Copolymerization of C 2 and Epoxides to Polycarbonates Donald J. Darensbourg Texas A&M University, Department of Chemistry djdarens@mail.chem.tamu.edu + + n

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3 Greener Synthesis of Polycarbonates R + R ' C catalyst n R R ' R R ' m + R R ' o extraneous solvent required 100% atom economy polycarbonate ether linkages cyclic carbonate Constructive use of abundant waste C1 feedstock Living polymerization Typical Catalytic System: (salen)m(iii) with onium salt cocatalyst R 1 M R 3 Robust, tetradentate* ligand Activity/Selectivity tunable by altering R 1, R 2, R 3, M, R 2 R 2 R 1 P P Typical System: PP M = Cr, Co Darensbourg, D. J. Chem. Rev. 2007, 107, Darensbourg, D. J., Wilson, S. J. Green Chem. 2012, 14, nbu 4 R 1 = R 2 = t Bu R 3 = -C 2 H 4 -, cyclohexyl 3

4 Monitoring Polymerization Kinetics in situ ATR FT-IR 1810 cm cm -1 C 2 inlet reactants inlet jacketed heating mantle 1750 cm -1 ASI ReactIR 1000 // // argon, vacuum crystal ReactIR ic10 C 2 inlet reactants inlet Solution becomes too viscous at this point. 0.6 Excellent for reactions run with at least 12 ml at temperatures 25 o C. 0.5 Small high-pressure reactor 0.4 designed in-house. Absorbance Absorbence Manages well with small scale reactions (< 5 ml). probe Polymer Cyclic argon, vacuum Wavenumbers(cm Attenuated Total Reflectance -1 ) Infrared Spectroscopy System can be heated or cooled to any practical temperature. Time (h) Time (hours) 4

5 Coupling Mechanism M M ' - ' M M - M - M ' See review: Darensbourg, D. J.; Yeung, A. D. Polymer Chemistry 2014, 5, ' 5

6 Routes to Cyclic Carbonates [M] P a b P [M] P c d P [M] e f P growing polymer chain Metal free pathway has much lower kinetic barrier. [M] - metal catalyst anionic initiator 6

7 Copolymerization of Styrene xide and Carbon Dioxide + C 2 Catalyst * * + Thermal stability up to 300 o C and Tg = 80 o C PSC SC t Bu t Bu Co t Bu = 2, 4 - dinitrophenoxy PP as cocatalyst t Bu 25 o C, TF = 75 h 2.0 Mpa C 2 Selectivity PSC:SC of 99:1 M n (kg mol -1 ) PDI RI (mv) Conversion (%) Wu, G.-P.; Wei, S.-H.; Lu,.-B.; Ren, W.-M.; Darensbourg, D. J. Macromolecules 2010, 43, Wu, G.-P.; Wei, S.-H.; Ren, W.-M.; Lu,.-B.; Li, B.; Zu, Y.-P.; Darensbourg, D. J. Energy & Environmental Sci. 2011, 4, Retention Volume (ml) 7

8 Rapid and Reversible Chain Transfer Processes M [M] (0 equiv H 2 ) (5 equiv H 2 ) (10 equiv H 2 ) (20 equiv H 2 ) Mn (g/mol) an d C 2 M [M] H chain transfer [M] P H 2 H H an d C 2 copolymer isolated from acidic methanol copolymer isolated from acidic methanol H H H Bimodal Distribution of Molecular Weights 8

9 Polyether Polyols Polyols currently used derived 100% from petroleum resources (polyethers). Automotive Adhesives, Sealants & Binders Replaced with polycarbonate polyols derived in part (~50%) from C 2. Coatings & Elastomers Feedstocks Appliances Footwear Building & Construction 9

10 Desired Properties? BPA Polycarbonate Lexan Industrial standard polycarbonate T g 150 o C Amorphous, robust polymer High M n s achievable Chain entanglement at low MW What conditions can we use to produce polymers similar to that of BPA polycarbonate? poly(cyclohexene carbonate) T g 115 o C easy to polymerize brittle polymer poly(styrene carbonate) T g 80 o C sensitive polymerization poly(propylene carbonate) T g 40 o C excellent mechanical properties industrially produced ur Focus: high glass transition temperature (T g ) poly(1-hexene carbonate) T g -15 o C Wu, G.-P.; Wei, S.-H.; Lu,.-B.; Ren, W.-M.; Darensbourg, D.J. Macromolecules 2010, 43, Seong, J.E.; a, S.J.; Cyriac, A.; Kim, B.-W.; Lee, B.Y. Macromolecules. 2010, 43,

11 Coupling of C 2 and Indene xide Stephanie Wilson Poly(indene carbonate) T g around 140 o C T d ~ 249 o C Highest reported T g for C 2 /epoxides coupling! Darensbourg, D.J.; Wilson, S. J. J. Am. Chem. Soc. 2011, 133,

12 Binary vs Bifunctional Catalyst Systems (1) (2) versus Selectivity for Polymer Darensbourg, D.J.; Wilson, S. J. Macromolecules 2013, 46, (1) (2) polymer cyclic 12

13 Bifunctional Catalyst System How They Work polymer detaches backbiting to cyclic commences C 2, polymer attracted to ammonium cation backbiting prevented 13

14 Design of ew Polymeric Materials Terpolymerization, addition of a second epoxide monomer. Postfunctionalization of copolymers. Diblock polymers incorporating RP of other cyclic monomers, e.g., polycarbonate-polylactide (TE: polylactides are among the few biodegradable polymers with FDA approval for human clinical use. Controlled drug delivery and tissue engineering scaffolds.) 14

15 Terpolymerization with Postpolymerization Functionalization + catalyst C 2 n m Using free-radical initiator (AIB), add S n m HS-CH 2 CH 2 H (2-mercaptoethanol) HS CH 2 C (thioglycolic acid) H H Deprotonate latter water-soluble H 4 polymer 15

16 Postfunctionalization of Copolymers Hybrid Polymers HC H 3 Cl H 3 Cl H CH C 2 H H H HC H 3 Cl H 4 C H 3 Cl CH HC CH CH 4 HC CH H 4 C CH 4 hydrophobic amphiphilic water-soluble Darensbourg, D. J.; Tsai, F.-T., Macromolecules, 2014, 47,

17 Functionalization of Polycarbonate Films or + + C 2 cat. terpolymerization HS SH uv crosslinking HS uv surface functionalization 17

18 Tandem Synthesis of Poly(styrene carbonate-block-lactide) Absorption Reaction Time (min) Absorption cm -1 Cyclic styrene carbonate Cyclic styrene carbonate 1760 cm -1 Poly(styrene Poly(Styrene carbonate) P PSC-block-PLA PSC-block-PLA at 1760 cm Lactide Lactide at 1771 cm cyclic Cyclic styrene styrene carbonate carbonate at 1820 cm Reaction Time (min) Lactide + DBU P Back - biting n - 1 P H Wu, G.-P.; Darensbourg, D. J.; Lu,.-B. J. Am. Chem. Soc., 2012, 134, P P n H n H n Back - biting n P H n DBU H m n Poly( s tyrene carbonate - block - lactide ) H 18

19 A ne-pot Synthesis of a Triblock Copolymer from P/C 2 and Lactides C H 2 H 2 2/PPY x H LA DBU x y poly(lactide-b-propylene carbonate-b-lactide) z Co H 2 H-(PPC)-H PLA-b-PPC-b-PLA 2 = CF 3 C - C 2 Darensbourg, D. J.; Wu, G.-P. Angew. Chem. Int. Ed. 2013, 52,

20 ABA Triblock Polymers H H n DBU/LA ABA block copolymer lactide at 1772 cm -1 block copolymer at 1757 cm -1 Absorbtion Time (min) 20

21 Darensbourg, D. J.; Chung, W.-C.; Wang, K.; Zhou, H.-C. ACS Catalysis, 2014, 4,

22 DJD Group Members: Wan-Chun Chung Samuel Kyran Andrew Yeung Yanyan Wang Dr. Fu-Te Tsai Dr. Rongjiao Zhu Dr. Hamidreza Samouei Acknowledgements Former DJD Group Members: Dr. Sheng-Hsuan Wei Dr. Stephanie Wilson Dr. Ross Poland Dr. sit Karroonnirun Dr. Adriana Moncada Dr. Wonsook Choi Dr. Eric Frantz Dr. Shawn Fitch Dr. Jeremy Andreatta Dr. Carla Rodarte Dr. Adolfo Horn Jr. Dr. Binyuan Liu Dr. Bo Li Dr. Guangpeng Wu 22