Novel fused ring semiconducting polymers

ring

Benzodithiophene with phenylethynyl substituents and thieno[3,2-b:4,5-bí]dipyrrole have been selected as monomers due to the following considerations:

  1. Both monomers contain three fused rings which will confer increased planarity to the polymer backbone.
  2. Benzodithiophene monomers contain a star-like structure with phenylethynyl electron withdrawing substituents attached to the rigid benzodithiophene core that should render the polymer a lower LUMO energy.
  3. By contrast, thieno[3,2-b:4,5-bí]dipyrrole monomers have increased donor ability due to the presence of the pyrrole heterocycle, which in turn should generate polymers with a higher energy LUMO.
  4. Copolymerization of thieno[3,2-b:4,5-bí]dipyrrole with benzodithiophene with phenylethynyl substituents is expected to generate an intermediate LUMO level.
  5. Both selected monomers should have increased ability to self-assemble through p stacking interactions.
  6. The attachment of alkyl substituents to both monomers is necessary for making the polymer soluble.

Collaborators

  • Dr. Michael Biewer, University of Texas at Dallas

Supramolecular Organization in Electronic Polymers: Block-Copolymers Containing Regioregular Polythiophenes and Liquid Crystalline Polymers

Well-defined rod-rod block copolymers containing regioregular polythiophene and helical liquid crystalline segments will be generated by a combination of living polymerization techniques. Poly(N-hexylisocyanate), poly[(R)-2,6-dimethylheptyl isocyanate], poly(N,N-di-n-hexylguanidine) and poly(g-benzyl-L-glutamate) will be incorporated in block copolymers with regioregular poly(3-hexylthiophene). These novel materials are expected to generate well-ordered supramolecular assemblies with tunable optoelectronic properties. The proposed rod-rod copolymers will be used in organic electronics applications, such as thin film transistors and chemical sensors.

Conjugated Polymer-quantum Dot Networks for Hybrid Solar Cell Applications

Extensive research is currently directed towards conjugated polymer-quantum dot bulk heterojunction solar cells, an alternative to crystalline silicon inorganic counterparts.  To increase the performance of these solar cells, quantum dots must be efficiently blended into the conjugated polymer matrix.  Additionally the charge transport through the conjugated polymer quantum dot interface must be improved. Here conjugated polymer-quantum dot networks will be generated using the interaction between quantum dots and polythiophene with alkenyl and thiol side chains. The interaction of thiol and olefin functional groups with the quantum dots is expected to create both an increased interfacial contact and a more effective dispersion of the inorganic phase into the organic matrix.

Collaborators

  • Dr. Anvar Zakhidov, University of Texas at Dallas

Active Neodymium Catalysts for Polymerization of Dienes and Vinyl Monomers and Ring Polymerization of Cyclic Esters

Ziegler-Natta type catalytic systems have attracted heavy industrial attention for the polymerization of olefins and dienes, yet posing a problem for the polymerization of polar vinyl monomers. A unique solution to the problem is the proposed neodymium based binary catalytic system which encompasses not only the polymerization of polar vinyl monomers but also stereospecific polymerization of dienes with high cis content. This catalytic system is a truly industrially feasible due to the small quantities of the catalyst used for the polymerizations; making the system inexpensive, hence a true replacement for the industrial application of the traditional Ziegler-Natta catalytic systems. The synthesis of systems composed of neodymium trichloride (NdCl3) with different phosphate ligands. The concept is to demonstrate the effect of the ligand environment, around the metal center, on the catalytic activity. The NdCl3-3TEP and NdCl3-3TBP catalysts together with triisobutylaluminum (TIBA) co-catalyst promotes the stereospecific polymerization of dienes, myrcene and isoprene, to generate polymers with >97% cis incorporation with high molecular weights. The systematic variation of the ligands, co-catalysts, Nd/Al ratio, and monomers is expected to generate an improved system which will promote the living stereospecific polymerization of dienes and as well as polar vinyl monomers.

Functional aliphatic polyesters for drug delivery

Novel γ-substituted lactone monomers will be synthesized and employed in ring opening polymerization. Octyloxy and tri(ethylene glycol) monomethyl ether substituted caprolactone will be homopolymerized and copolymerized by thin mediated ring-opening polymerization. The ring-opening polymerization of the functional lactones will generate biocompatible aliphatic polyesters. Hydrophylicity, biodegradation, and bioadeshion of the functional aliphatic polyesters will be correlated with their molecular structure.

Collaborators:

  • Dr. Michael Biewer, University of Texas at Dallas
  • Dr. Daniel Seigwart, UT Southwestern
  • Dr. David Oupicky, Nebraska Medical Center