Novel Polymerization Methodologies
The ongoing development of new methods for the synthesis of polymers of complex architecture has led to a continuing interest in controlled/living polymerization. Inspired by rapid progress in photoredox catalysis, a few research groups (e.g., Fors, Hawker, Boyer, Boydston) have recently begun to explore the application of these systems for controlled polymerization.
In a collaboration with Prof. Dave Nicewicz (UNC Chapel Hill), we carried out initial studies into the methanol-controlled visible light photoinitiated polymerization of 4-methoxystyrene using pyrylium salts. First order kinetic behavior, linear Mn growth with respect to monomer consumption, narrow Ð, and continued polymerization upon monomer addition all indicate the controlled/living nature of the polymerization. The accumulated data suggest methanol plays a role as a reversible chain transfer agent, analogous to that of dithiocarbamates in RAFT polymerization. This is a completely new mechanism for living cationic polymerization. Our most recent work further proved that it was the alcohol, rather than the photoredox catalyst, that dictates this controlled cationic polymerization.
We are actively further developing this new polymerization methodology, including scope of monomers, scope of chain transfer agents, among other. We are also exploring how to use this new polymerization methodology to create novel materials. Furthmore, we can apply our expertise in polymer chemistry to create novel polymeric materials for a variety of applications. One such example is developing micelle forming copolymers which can transport and generate singlet oxygen, which can be used in photodynamic therapy for cancer treatment. Further examples include the development of various biocomposites which can be used in many applications, such as dental and bone scaffolds.
Below are selected publications from our efforts in these areas.
Photoinitiated, Living Cationic Polymerization:
J. Am. Chem. Soc. 2015, 137, 7580−7583
Polym. Chem., 2019, 10, 4126-4133
Perfluorocarbon-based O2 nanocarrier for efficient photodynamic therapy:
J. Mater. Chem. B, 2019, 7, 1116-1123
Development of Biocomposites for Biomedical Applications:
J. Mater. Chem., 2012, 22, 22888-22898
J. Mater. Chem. B, 2014, 2, 7704–7711
Langmuir 2016, 32, 9873−9882.