Researcher(s)
- Gizelle Lamptey, Chemistry, University of Maryland Baltimore County
Faculty Mentor(s)
- Brock Hunter, Chemcial and Biomolecular engineering, University of Delaware
- Christian Pester, Materials and Science of Engineering, University of Delaware
Abstract
The growing demand for advanced polymeric materials has created a need for more controlled and sustainable polymerization methods. Photoinduced electron/energy transfer reversible addition–fragmentation chain transfer (PET-RAFT) polymerization offers precise control over polymer growth under visible light; however, conventional systems typically rely on homogeneous photocatalysts that are difficult to recover and reuse. This contribution reports on reusable polymeric photocatalytic beads that serve as heterogeneous photocatalysts for PET-RAFT polymerization.
A porphyrin-based photocatalyst, tetrakis(4-allyloxyphenyl)porphyrin (TAOPP), was incorporated into polymeric beads through suspension co-polymerization with styrene and divinylbenzene. Using optical microscopy, the average diameter was measured at 200 µm. Bead solvent swelling behavior was predicted by Hansen Relative Energy Difference (RED) analysis, and increased crosslinker content led to reduced swelling.
The photocatalytic performance of the beads were evaluated through PET-RAFT polymerization of methyl methacrylate (MMA) under blue light. Polymer formation was confirmed by ¹H NMR spectroscopy and gel permeation chromatography (GPC). Number-average molecular weight (Mn) increased linearly with monomer conversion, and low dispersity (Ð < 1.2) was observed, indicating controlled polymerization even when open to air. Studies are ongoing to determine the role of photoiniferter polymerization as a competing mechanism.
A packed bed reactor was utilized to evaluate photocatalytic bead performance for PET-RAFT in continuous flow. A steady-state number-average molecular weight (Mn) of approximately 5,500 g mol⁻¹ was obtained with six hours residence time in agreement with batch kinetics.These results demonstrate that polymeric photocatalytic beads can enable a more scalable and sustainable approach to controlled polymer synthesis.