Brenton Hammer

EDUCATION

Ph. D. (Polymer Science and Engineering), University of Massachusetts, Amherst, 2013
M. Sc. (Polymer Science and Engineering), University of Massachusetts, Amherst, 2008
B. S. (Chemistry), Colorado School of Mines, 2007

POSTDOCTORAL APPOINTMENT

Max-Planck Institute for Polymer Research, Mainz, Germany, 2013-2016

COURSES TAUGHT

Chemistry 101, General Chemistry I 
Chemistry 334, Organic Chemistry II 

RESEARCH INTERESTS

Synthetic polymer chemistry
Dr. Hammer’s research focuses on using synthetic chemistry to produce novel polymeric materials for real world applications involving gas filtration/sensing, water purification, renewable energy, and robust polymer composites. Currently, the lab is investigating two primary fields:

1)  Synthesis and assembly of molecularly defined graphene materials
Graphene-based materials have garnered a tremendous amount of attention due to their remarkable optical, electronic, and mechanical properties. However, to date most research has utilized graphene that is undefined in terms of its functionality and dimensions, where defects in the structure can significantly diminish the properties of the materials. Thus, this research focuses on the synthesis of well-defined graphene-derivatives to control their molecular uniformity, dimensions, and heteroatom functionalization. These macromolecules are being studied as a) porous membranes for gas sensing and filtration and b) as additives to improve the thermal and mechanical properties of polymer composites.

2)  Surface-bound polymers for stimuli-responsive membranes
Polymers covalently attached to substrates have been widely used to manipulate the surface properties. Yet controlling the surface density of polymer chains in films and their hydrophilicity are two challenging fields that still attract significant interest from the scientific community. This project is looking at the synthesis of hyperbranched, phosphoryl choline-based polymers tethered to silicon substrates in an effort to control a) the wettability and stimuli-responsive nature of the surface and b) tailor the surface density of the polymer in comparison to linear analogues. These surface-bound polymer films are being studied in lithographic and water filtration applications.

Students joining the lab will gain experience in an array of chemistry disciplines such as the synthesis and purification of small molecules, different polymerization and post-polymerization functionalization techniques, as well as with a variety of characterization methods such as nuclear magnetic resonance (NMR) and Infrared (IR) spectroscopies, size-exclusion chromatography (SEC), mass spectrometry, gas chromatography, and atomic force microscopy (AFM).

REPRESENTATIVE PUBLICATIONS 

1. Hammer, B. A. G.; Müllen, K., Dimensional Evolution of Polyphenylenes: Expanding in All Directions. Chem. Rev. 2015, 116(4), 2103-2140.
2. Hammer, B. A. G.; Moritz, R.; Stangenberg, R.; Baumgarten, M.; Müllen, K., The Polar Side of Polyphenylene Dendrimers. Chem. Soc. Rev. 2015, 44, 4072-4090.
3. Hammer, B. A. G.; Reyes-Martinez, M. A.; Bokel, F. A.; Liu, F.; Russell, T. P.; Hayward, R. C.; Briseno, A. L.; Emrick, T., Robust Polythiophene Nanowires Cross-linked with Functional Fullerenes. Journal of Materials Chemistry C 2014, 2(45), 9674-9682.
4. Hammer, B. A. G.; Reyes-Martinez, M. A.; Bokel, F. A.; Liu, F.; Russell, T. P.; Hayward, R. C.; Briseno, A. L.; Emrick, T., Reversible, Self Cross-Linking Nanowires from Thiol-Functionalized Polythiophene Diblock Copolymers. ACS Applied Materials & Interfaces 2014, 6(10), 7705-7711.
5. Hammer, B. A. G.; Baumgarten, M.; Müllen, K., Covalent Attachment and Release of Small Molecules from Functional Polyphenylene Dendrimers. Chem. Commun. 2014, 50(16), 2034-2036.
6. Baghgar, M.; Barnes, A. M.; Pentzer, E.; Wise, A. J.; Hammer, B. A. G.; Emrick, T.; Dinsmore, A. D.; Barnes, M. D., Morphology-Dependent Electronic Properties in Cross-Linked (P3HT-b-P3MT) Block Copolymer Nanostructures. ACS Nano 2014, 8(8), 8344-8349.
7. Hammer, B. A. G.; Bokel, F. A.; Hayward, R. C.; Emrick, T., Cross-Linked Conjugated Polymer Fibrils: Robust Nanowires from Functional Polythiophene Diblock Copolymers. Chem. Mater. 2011, 23(18), 4250-4256.
8. Lee, E.; Hammer, B.A.G.; Kim, J.-K.; Page, Z.; Emrick, T.; Hayward, R. C., Hierarchical Helical Assembly of Conjugated Poly(3-hexylthiophene)-block-poly(3-triethylene glycol thiophene) Diblock Copolymers. J. Am. Chem. Soc. 2011, 133 (27), 10390-10393.
9. Rowe, M. D.; Hammer, B. A. G.; Boyes, S. G., Synthesis of Surface-Initiated Stimuli-Responsive Diblock Copolymer Brushes Utilizing a Combination of ATRP and RAFT Polymerization Techniques. Macromolecules 2008, 41(12), 4147-4157.