Research
Thiol-ene Chemistry • Degradable Polymers • Polyarylenes • 3D Printing
Thiol-ene and Thiol-Michael Chemistry
Thiol-ene and thiol-Michael reactions involve the addition of a S-H bond across a double or triple bond by either a free radical (thiol-ene) or ionic (thiol-Michael) mechanism. These reactions are essentially the sulfur version of the hydrosilylation reaction.
Because the reactions are efficient, high yielding, and tolerant of various solvents and functional groups, many researchers now consider these reactions to be “click” reactions.
We have found the thiol-ene reaction to be an excellent method for derivatizing unsaturated organosilicon and organic compounds. We reported the synthesis of a variety of functional organosilicon compounds from thiol-ene reactions of tetravinylsilane with commercially available thiols. Dendrimers can also be prepared via alternating thiol-ene and Grignard reaction sequences.
- Rissing, C.; Son, D. Y. “The Thiol-ene Reaction for the Synthesis of Multifunctional Branched Organosilanes”, Organometallics 2008, 27, 5394-5397. Link
- Rissing, C.; Son, D. Y. “Application of Thiol-ene Chemistry to the Preparation of Carbosilane-thioether Dendrimers”, Organometallics 2009, 28, 3167-3172. Link
Using thiol-Michael chemistry, we derivatized 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAT) in high yields and short reaction times. Very little purification of the products was necessary.
- Rim, C.; Lahey, L. J.; Patel, V. G.; Zhang, H.; Son, D. Y. “Thiol-ene reactions of 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAT): facile access to functional tripodal thioethers”, Tetrahedron Letters 2009, 50, 745-747. Link
- Rim, C.; Son, D. Y. “Facile and efficient synthesis of star-shaped oligomers from a triazine core”, Tetrahedron Letters 2009, 50, 4161-4163. Link
Degradable Polymers
We have prepared degradable polymers and plastics through the incorporation of silyl ether bonds. Silyl ethers possess a Si–OR linkage and are moisture-sensitive. The degree of moisture-sensitivity is affected by the other groups attached to silicon, and can therefore be controlled at the molecular level.
Based on our interest in thiol-ene and thiol-Michael chemistry, we reported a route to multifunctional silyl ether thiols through the selective reaction of mercaptoalcohols with chlorosilanes. Yields were good to excellent.
- Jennings, A. R.; Son, D. Y. “Multifunctional thiols from the highly selective reaction of mercaptoalcohols with chlorosilanes”, Chemical Communications 2013,49, 3467-3469. Link
- Son, D. Y.; Jennings, A. R. US 9,243,006 (issued 1/26/16): “Multi-thiol mercaptoalkoxysilane compositions.”
- Son, D. Y.; Jennings, A. R. US 9,447,124 (issued 9/20/16): “Multi-thiol mercaptoalkoxysilane compositions.”
Through a collaboration with Professor Walter Voit at the University of Texas at Dallas, some of these multi-thiols were used in the preparation of degradable thiol-ene substrates for implantable neural electronics.
- Ware, T.; Jennings, A. R.; Bassampour, Z. S.; Simon, D.; Son, D. Y.; Voit, W. “Degradable, silyl ether thiol-ene networks for implantable electronics”, RSC Advances 2014, 4, 39991-40002. Link
Through a collaboration with the Retina Foundation of the Southwest (Dallas, TX) and other academic laboratories at SMU and UT-Dallas, we prepared a series of degradable thiol-acrylate networks designed for controlled release of ocular drugs.
- Bunton, C. M.; Bassampour, Z. M.; Boothby, J. M.; Smith, A. N.; Rose, J. V.; Nguyen, D. M.; Ware, T. H.; Csaky, K. G.; Lippert, A. R.; Tsarevsky, N. V.; Son, D. Y. “Degradable silyl-ether networks from tri-functional thiols and acrylates”, Macromolecules, 2020, 53, 9890-9900. Link
We have explored other chemistry for the preparation of degradable silyl ether networks, including amine-epoxy and Diels-Alder chemistry.
- Bassampour, Z.; Budy, S.; Son, D. Y. “Degradable epoxy resins based on bisphenol A diglycidyl ether and silyl ether amine curing agents”, Journal of Applied Polymer Science, 2017, 134(12). Link
- Bunton, C. M.; Rose, J. V.; Hall, Jamie D.; Wey, A.; Kennedy, A. K.; Al Khazalah, R.; Son, D. Y., manuscript in preparation.
We are also collaborating with Professor Paul Krueger in the SMU Department of Mechanical Engineering on the characterization of Diels-Alder and related degradable plastics for commercial applications. This work is supported by the Global Development Laboratory in the Hunt Institute at SMU.
Polyarylenes
Polyarylenes are aromatic polymers with a high concentration of phenyl groups that are both pendant and in the main chain of the repeat unit. Polyarylenes are thermally stable and highly processable, which make them excellent candidates for a number of advanced applications.
We recently reported the microwave Diels-Alder synthesis of organic and fluorinated polyarylenes. Using microwaves dramatically reduces the time required to synthesize the polyarylenes.
- Budy, S. M.; Khan, M.; Chang, X.; Iacono, S. T.; Son, D. Y. “Semi-fluorinated Polyarylenes: Microwave-assisted Synthesis and Structure-Property Relationships”, Journal of Polymer Science, 2020, 58(19), 2774-2783. Link
Similar Diels-Alder chemistry was used to prepare a novel polyarylene diamine, which can be used to synthesize polyimides or epoxy networks.
- Budy, S. M.; Hall, J. K.; Son, D. Y. “Polyarylene polyimides with hydrocarbon and semi‐fluorinated backbones: Synthesis, characterization, and properties”, Polymer Chemistry, 2020, 11, 6273-6280. Link
- Budy, S. M,; Rose, J. V.; Gibson, C.; Son, D. Y. “Synthesis, characterization, and nanoparticle formation of polyarylene poly(amic acid)s and polyimides containing fluorescent dye moieties”, Polymer International, 2021, 70, 759-767. Link
- Budy, S. M.; Wey, A.; Wu, A.; Son, D. Y. “Synthesis and characterization of phenylated phenylenediamine and bisphenol a diglycidyl ether epoxy networks“, Journal of Applied Polymer Science, 2022, 139(11), 51808. Link
We also used polyarylenes to prepared boron nitride nanotube (BNNT) nanocomposites.
- Budy, S. M.; Son, D. Y. “Ethynyl-functionalized BNNT and Preparation of Polyarylene-BNNT Nanocomposites”, Polymer, accepted, in press. Link
3D-Printing (additive manufacturing)
We are collaborating with Professor Paul Krueger in the SMU Department of Mechanical Engineering to develop 3D-printable polymers for controlled release applications or as degradable plastics.
We have examined a variety of printable silicones that can be cured by ultraviolet irradiation or heat. Various printing parameters have been optimized for maximum cure and to minimize encapsulant degradation.
- Porter, D. A.; Cohen, A. L.; Krueger, P. S.; Son, D. Y. “Additive manufacturing with ultraviolet curable silicones containing carbon black”, 3D Printing and Additive Manufacturing, 2018, 5(1), 73-86. Link
- Porter, D.; Davis, N.; Krueger, P.; Son, D. Y.; Cohen, A. “Additive Manufacturing by Material Extrusion with Medical Grade Silicone Elastomers and IR Laser Curing”, Rapid Prototyping Journal, 2020, 26, 145-155. Link
- Porter, D. A.; Davis, N. E.; Hejny, T.; Takacs, A.; Bunton, C. M.; Krueger, P. S.; Son, D.; Csaky, K. “Particle Loading Effects on Additively Manufactured and Laser Cured Medical Grade Silicone”, submitted.
We are also interested in developing degradable 3D-printable plastics in which degradation rate and mechanical properties can be controlled.
Interested in sharing ideas, collaborating on a project, joining our group, or just want to chat?
We would love to hear from you!