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Synthesis of Phthalonitrile-Containing Siloxane Polymers for use in

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Synthesis of Phthalonitrile-Containing Siloxane Polymers for use in

  1. 1. Synthesis of Phthalonitrile-Containing Siloxane Polymers for Semiconductor Power Modules NOAH GRIGGS1, JACOB MONZEL2, AND DR. GORDON YEE1 1 VIRGINIA TECH DEPARTMENT OF CHEMISTRY 2 VIRGINIA TECH DEPARTMENT OF MATERIAL SCIENCE & ENGINEERING 1
  2. 2. Phthalonitriles  Candidates for high-temperature polymers  Strong up to 500 ˚C, easily processed, and nearly fireproof  Replacement for metal in sections of turbine engines  Encapsulation compound for semiconductor power modules 2
  3. 3. Current state of Phthalonitriles  Similar properties to polyetheretherketone (PEEK) polymers  Brittle once the thermosetting is complete  Insoluble in most organic solvents 3
  4. 4. Improving Phthalonitriles  Incorporating thermally stable, flexible linkages in backbone of polymer  Lowers softening point  Improves solubility  Does not sacrifice the properties of the cured material  Recent interest in incorporating silicon-based linkages  Siloxane polymers are both thermally stable and flexible 4
  5. 5. Objectives  Design synthesis route for 1,3-Bis(p-hydroxyphenyl)1,1,3,3- tetraphenyldisiloxane  Form the phthalontrile linkages  Polymerize the disiloxane to synthesize the polymer 5
  6. 6. Preparation of Disiloxane  Reaction of dichlorodiphenylsilane with 4-benzyloxybromobenzene  Formation of reactive Grignard  1:1 stoichiometry  Prevention of unwanted side reactions via a benzyl protecting group 6 A) n-BuLi B) Mg, THF
  7. 7. Preparation of Disiloxane  The chlorosilane product is air sensitive, and when exposed to moisture forms the disiloxane 7 A) H2O, RT B) NaOH, H2O, Heat C) DMF
  8. 8. Cleavage of Protecting groups  The protecting groups were cleaved via acid to produce the target disiloxane 8 A) Pd/C, H2 B) Pd/C, Ph2S, H2 C) H+ , EtOH
  9. 9. Polymer Synthesis  Determination of optimal reaction conditions via reaction of disiloxane with nitrophthalonitrile 9 K2CO3, DMF
  10. 10. Polymer Synthesis  Extending the length of the monomer 10 NaOH, K2CO3, DMF
  11. 11. Polymer Synthesis  Synthesize the final polymer via reacting the disiloxane with dichlorobenzene and 4-(4-hydroxyphenoxy)phthalonitrile under basic conditions in DMF 11 NaOH, K2CO3, DMF
  12. 12. Results  Characterization conducted via H1 NMR and ESI TOF Mass Spectrometry  Low yields with Grignard synthesis of disiloxane  Side products formed in greater yield than desired product  Isolation of desired product difficult due to the chemical similarity of side products 12
  13. 13. NMR Results 13 Starting Material Product
  14. 14. Mass Spectrometry Results 14
  15. 15. Conclusion  Most likely high purity reagents and extremely low moisture environments are required to achieve viable yields using the Grignard method  Low yields may be due to compromised glove box 15
  16. 16. Future Work  Use of halogen-lithium exchange to form the reagent instead of magnesium  Testing the properties of the phthalonitrile- linked siloxane polymer  Formation of phthalocyanine rings via reacting the phthalonitrile end groups with Lithium metal 16
  17. 17. Acknowledgements  National Science Foundation  Virginia Polytechnic Institute and State University, Macromolecules Innovation Institute, and Department of Chemistry  Dr. Gordon Yee, Jacob Monzel, and Chris Houser 17

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