Research Interest Areas

Polymer Surface Engineering

1) Post-polymerization of Polymer Brush Surfaces

An ultimate goal of polymer surface engineering is the ability to deliberately tailor the composition, distribution, and spatial arrangement of functional groups on a surface using facile and efficient chemistries.  Advances in controlled surface-initiated polymerization (SIP) techniques provide a powerful toolset to tailor these parameters given knowledge of reaction conditions, reactivity ratios, and order of monomer addition, but challenges remain particularly regarding direct polymerization of monomers with complex pendent functionality. In this regard, post-polymerization modification (PPM) of polymer surfaces, when combined with SIP, has evolved as a powerful approach to engineer polymer surfaces with complex functionality. PPM circumvents limitations associated with direct polymerization of functional monomers due to intolerance of many functional groups with the polymerization mechanism and/or reaction conditions (i.e. reactivity, steric hindrance, temperature/light sensitivity).  The Patton Group has demonstrated modular PPM methodologies using thiol-click chemistry for rapid fabrication of highly functional, multicomponent polymer surfaces.
Schematic for synthesis of dual-functional polymer brushes by sequential and orthogonal and thiol-based click reactions. 

Related publications:

  • Arnold, R.; Patton, D.; Popik, V.; Locklin, J.* "A Dynamic Duo: Pairing Click Chemistry and Postpolymerization Modification to Design Complex Surfaces" Acc. Chem. Res. 2014, ASAP.  [Read More]
  • Rahane, S.; Hensarling, R.; Sparks, B.; Stafford, C.; Patton, D.* "Synthesis of multifunctional polymer brush surfaces via sequential and orthogonal thiol-click reactions" J. Mater. Chem. 2012, 22, 932-943.  [Read more]
  • Hensarling, R.; Rahane, S.; LeBlanc, A.; Sparks, B.; White, E.; Locklin, J.; Patton, D.* "Thiol-Isocyanate “Click” Reactions: Rapid Development of Functional Polymeric Surfaces" Polym. Chem. 2011, 2, 88-90.  [Read more]  
  • Sparks, B.; Ray, J.; Savin, D.; Stafford, C. Patton, D.* “Synthesis of Thiol-Clickable and Block Copolypeptide Brushes via Nickel-Mediated Surface Initiated Polymerization of α-Amino Acid N-Carboxyanhydrides (NCAs)” Chem.Commun. 2011, 47, 6245-6247. [Read more]
  • Hensarling, R.; Doughty, V.; Chan, J.; Patton, D.* "Clicking Polymer Brushes with Thiol-Yne Chemistry: Inside and Out" J. Am. Chem. Soc. 2009, 131, 14673-14675. [Read more]

Photopolymerization and Functional Polymer Networks

High speed video of water droplets bouncing off a thiol-ene coated glass substrate.

1) Superantiwetting Surfaces

Light-induced polymerization is an industrially viable process that offers numerous economic and technical advantages over conventional thermal polymerization, particularly toward the fabrication of crosslinked thermoset thin films.  These advantages include rapid through cure, low energy requirements, ambient temperature processing, solvent-free resin compositions, and spatial and temporal control over the polymerization process.  This presentation will focus on our group’s recent efforts to use thiol-ene photopolymerizations to fabricate thin, crosslinked polymer networks containing functionality aimed at tailoring the surface chemical functionality and morphology of the films.  For example, the spray-deposition of nanoparticle-laden thiol-ene resins provides surfaces with hierarchical morphologies exhibiting both micro- and nanoscale roughness. The wetting behavior of such films can be tailored toward superhydrophobicity (anti-wetting with water) or superamphiphobicity (anti-wetting with water and oils) by judicious choice of monomer constituents.  Beyond the simplicity offered by thiol-ene photopolymerizations, the cross-linked thiol-ene coatings are solvent resistant, stable at low and high pH, and maintain antiwetting behavior after extended exposure to elevated temperatures.  These surfaces exhibit a low propensity toward contamination, and as a result, are of great interest for potential applications in self-cleaning, antifouling, separation processes, and drag reduction coatings.

Related Publications:

  • Xiong, L.; Kendrick, L.; Heusser, H.; Webb, J.; Sparks, B.; Goetz, J.; Guo, W.; Stafford, C.; Blanton, M.; Nazarenko, S.; Patton, D.* "Spray-Deposition and Photopolymerization of Organic–Inorganic Thiol–ene Resins for Fabrication of Superamphiphobic Surfaces" ACS Appl. Mater. Interfaces 2014, 6, 10763-10774.  [Read More] 

  • Sparks, B; Hoff, E.F.T.; Xiong, L.; Goetz, J.; Patton, D.* "Superhydrophobic Hybrid Inorganic-Organic Thiol-ene Surfaces Fabricated via Spray -Deposition and Photopolymerization" ACS Appl. Mater. Interfaces 2013, 5, 1811-1817. [Read More]

2) Hybrid Thiol-ene Polymer Networks

Light-induced polymerization provides numerous economic and technical advantages over conventional thermal polymerization processes for fabrication of cross-linked thermosets, including rapid through cure, low energy requirements, ambient temperature processing, solvent-free resin compositions and spatial and temporal control over the polymerization.  UV photopolymerization is a viable industrial process for applications ranging from polymeric coatings and composites to inks and adhesives.  Recently, cross-linked polymer networks derived from light-induced radical-mediated thiol-ene “click” reactions have garnered significant interest for many of the aforementioned applications. Thiol-ene cross-linked polymer networks form via a free-radical step-growth process facilitated by a rapid, highly efficient chain-transfer reaction between multifunctional enes and thiols. Thus, thiol-ene photopolymerizations proceed very rapidly, but reach the gel-point only at relatively high functional group conversions yielding uniform networks with reduced shrinkage and stress.  However, as thiol-ene networks are comprised of flexible sulfide bonds, applications that require improved thermal (i.e. glass transition temperature) and mechanical properties (i.e. modulus/cross-link density) are not readily accessible using traditional thiol-ene combinations.  To address the shortcomings of traditional thiol-ene networks, we are interested in hybrid organic/inorganic design strategies – where attributes of thiol/ene functionalized organic and inorganic materials are synergistically combined to improve properties such as rubbery modulus, abrasion resistance and thermal stability. 

Related publications:

  • Sparks, B.; Kuchera, T.; Jungman, M.; Richardson, A.; Savin, D.; Hait, S.; Lichtenhan, J.; Striegel, M.; Patton, D.* "Cyclic Tetravinylsiloxanetetraols as Hybrid Inorganic-Organic Thiol-ene Networks" J. Mater. Chem. 2012, 22,3817-3824.  [Read more]
  • Sparks, B.; Kuchera, T.; Richardson, A.; Savin, D.; Hait, S.; Lichtenhan, J.; Striegel, M.; Patton, D. “Cyclic Tetravinlysiloxanetetraol Hybrid Thiol-Ene Networks: A kinetic and Thermomechanical Study” RadTech Report 2012, 2, 39-42. 

3) Biomimetic Thiol-ene Polymer Networks

This project exploits the biomimetic adhesive and hydrogen-bonding properties of dopamine-functionalized polymer networks to improve interfacial interactions.  Dopamine is a catecholamine that serves dual functions in natural adhesives as cross-linking agents and as adsorptive moieties.  Catechols have been shown to adsorb strongly to many different surfaces, including polymer, metal, and inorganic materials.  Here, we demonstrate the ability to tailor the thermal and mechanical properties of thiol-ene photopolymer networks by incorporating varying amounts of dopamine acrylamide in the network structure.  These materials show improved adhesion to a broad variety of substrate surfaces.

Related publications:

  • Sparks, B.; Hoff, E. F.; Hayes, L.; Patton, D.* “Mussel-inspired Thiol-ene Polymer Networks: Influencing Network Properties and Adhesion with Catechol Functionality” Chem. Mater. 2012, 24, 3633–3642.  [Read more]

4) Dual Cure Polymer Networks

The development of high glass transition networks offers potential to expand the scope of thiol-ene photopolymerization and open the door to new application opportunities.  In this direction, we are interested in the application of dual chemistries for synthesizing multicomponent networks that exhibit properties unachievable with traditional thiol-ene systems.

Related publications:

  • Narayanan, J.; Jungman, M.; Patton, D.* "Hybrid dual-cure polymer networks via sequential thiol-ene photopolymerization and thermal ring-opening polymerization of benzoxazines" 2012, React. Funct. Polym. 72, 799-806. [Read More]

Polybenzoxazines 

1) Design of Flexible Polybenzoxazine Thermosets

Thermoset resins derived from heterocyclic bis-1,3-benzoxazines have been vigorously investigated in recent years as attractive alternatives to traditional phenolic resins for a variety of high performance applications.Thermoset resins derived from heterocyclic bis-1,3-benzoxazines have been vigorously investigated in recent years as attractive alternatives to traditional phenolic resins for a variety of high performance applications.  The Patton Group is interested in the synthetic design of polybenzoxazine networks with improved thermomechanical properties and tailored functionality. 

Related publications:

  • Jungman, M.; Cobb, J.; Lawler, D.; Sholar, J.; Johnson, C.; Patton, D.* "Exploring the Effect of Maximum Cure Temperature on the Thermal and Thermomechanical Properties of Polybenzoxazine Networks" Macromolecular Symposia 2013, 329, 133-141. [Read More]
  • Baranek, A.; Kendrick, L.; Narayanan, J.; Tyson, G.; Wand, S.; Patton, D.* “Flexible aliphatic-bridged bisphenol-based polybenzoxazines” Polym. Chem. 2012, 3, 2892-2900. [Read more]