Bradford B. Wayland
A.B. Western Reserve University (1961)
Ph.D. University of Illinois (1964)
Beury Hall 352
Department of Chemistry
Beury Hall R. 130
1901 N. 13th Street
Philadelphia, PA 19122
Inorganic / Materials
A unifying theme of my research program is to utilize metallo-radical and organo-metal substrate reactions to obtain both energy relevant small molecule organometallic transformations and living radical polymerization for applications in block copolymer materials. These two current focal areas of research are briefly described below.
A broad based program in polymer chemistry sponsored by NSF spans areas from transition metal catalyst development and block copolymer synthesis to technological applications of self assembled nano-structured polymer arrays. Reactivity of metal-centered radical species and organometallic derivatives are used in the control of radical polymerization through both catalytic chain transfer and living radical polymerization. Organo-cobalt porphyrin complexes mediate a highly precise living radical polymerization of vinyl monomers such as acrylates and vinyl esters to form low polydispersity homopolymers and block co-polymer materials. This pathway to obtain living radical polymerization is a transition metal form of degenerative transfer that we refer to as radical interchange polymerization (RIP). Living radical polymerization provides access to a vast array of new classes of block copolymers. Self assembly of amphiphilic block copolymers into micelles and nano-structured arrays have many technological applications in nano-reactors, gene and drug delivery, dispersants, metal nanoparticle synthesis, water and fuel cell membranes, sensors, and solar cells which are being developed through collaborations with materials scientists and engineers. New materials design strategies are determined for each of the central topics along with the requisite approaches for polymer synthesis, morphology, and property evaluation.
Our energy related catalysis research supported by DOE is focused on developing new strategies to accomplish thermodynamically and kinetically challenging substrate reactions such as methane activation and carbon monoxide reductive coupling. Ligands are designed to achieve high selectivity through steric and electronic constraints on forming the transition states for substrate reactions. The primary focus is on group nine (Co, Rh, Ir) metal complexes where the importance of metallo-radicals is a recurring theme. Metallo-porphyrins, chlorophylls, and related macrocyclic complexes are prominent thermal and photocatalysts in biological systems and emerging as important catalyst materials for chemical manufacturing processes. The unique chemical and physical properties of metallo-porphyrins and macrocyclic complexes are used in producing thermal and photocatalytic cycles for small molecule reactions.Several important examples include hydrogenation of CO and CO2, activation of methane, oxidation of alkenes, photoreductions, and alkene polymerization. Tethered diporphyrin ligands have been designed and synthesized that are used in forming bimetalloradical complexes of Rh(II). Bimetalloradicals provide preorganization of transition states that involve two metalloradicals and give rapid highly selective substrate reactions. Structural, kinetic-mechanistic, thermodynamic, and reactivity studies are used in characterizing intermediates, anticipating new types of reactions, and guiding the design of strategies to produce selective catalyst materials.