The Johnson laboratory seeks creative, macromolecular solutions to problems at the interface of chemistry, medicine, biology, and materials science. Materials synthesis is approached in an analogous manner to natural-products synthesis; an interesting target structure is chosen and a synthetic scheme is designed to access that structure as efficiently as possible. The targets are designed de novo from careful consideration of the specific needs of a given application and with a particular emphasis on function. The tools of traditional organic and organometallic synthesis, synthetic polymer chemistry, photochemistry, surface science, and biopolymer engineering are combined to realize the designs.

Just as natural-products chemists must often invent new reaction methodologies to access complex structures and their corresponding derivatives, the Johnson lab will seek to develop new methodologies for the construction and modification of complex material libraries. Iterative library synthesis, function-based screening, and design optimization will ultimately yield basic knowledge, such as structure-function relationships for materials in specific applications, and new materials-based technologies that outperform current alternatives. Some examples of target material platforms and their associated applications are: (1) novel, nanoscopic branched-arm star polymer architectures for in vivo drug delivery and supported catalysis, (2) hybrid synthetic-natural hydrogels for correlation of the effects of network microstructure on cell response, and (3) new types of semiconducting organometallic polymers and polymer films for sensing, supported catalysis, and energy conversion.

“Photo-controlled growth of telechelic polymers and end-linked polymer gels.” Zhou, H.; Johnson, J. A. Angew. Chem. Int. Ed. 2013, DOI: 10.1002/anie.201207966.

“Counting Primary Loops in Polymer Gels.” Zhou, H.; Woo, J.; Cok, A. M.; Wang, M.; Olsen, B.D.; Johnson, J. A. Proc. Natl. Acad. Sci. U.S.A. 2012, 109, 19119-19124.

“‘Brush-first’ method for the parallel synthesis of photocleavable, nitroxide-labeled poly(ethylene glycol) star polymers.” Liu, J.; Burts, A. O.; Li, Y.; Zhukhovitskiy, A.; Ottaviani, M. F.; Turro, N. J.; Johnson, J. A. J. Am. Chem. Soc. 2012, 134, 16337-16344.

“Using EPR to compare PEG-branch-nitroxide bivalent-brush polymers and traditional PEG bottle-brush polymers: branching makes a difference.” Burts, A. O.; Li, Y.; Zhukhovitskiy, A.; Patel, P. R.; Grubbs, R. H.; Ottaviani, M. F.; Turro, N. J.; Johnson, J. A. Macromolecules 2012, 45, 8310-8318.

“Application of 1H DOSY for facile measurement of polymer molecular weights.” Li, W.; Chung, H.; Daeffler, C.; Johnson, J. A.; Grubbs, R. H. Macromolecules 2012, 45, 9595-9603.

“EPR study of spin labeled brush polymers in organic solvents.” Xia, Y.; Li, Y.; Burts, A. O.; Ottaviani, M. F.; Tirrell, D. A.; Johnson, J. A.; Turro, N. J.; Grubbs, R. H. J. Am. Chem. Soc. 2011, 133, 19953-19959.