Effect of polymer branching on degradation during inkjet printing

In this paper we demonstrate the potential of high molecular weight hyperbranched methacrylate polymers for inkjet printing. Using the Strathclyde method, a series of hyperbranched poly (methylmethacrylate) polymers of increasing branch density were prepared. All hyperbranched polymers show both a significantly greater maximum printable concentration compared to equivalent linear polymers with implications for faster print speed. Increasing chain branching above a critical value across the molecular weight distribution was found to result in suppression of molecular weight degradation. This resistance to molecular degradation is because the longest chain segment being much smaller, such that upon jetting the polymer rapidly retains its thermodynamically stable Gaussian coil conformation and the full force of the constrictional flow in the print head is not passed on to the polymer and degradation is supressed. We further go on to show using Electron Paramagnetic Resonance that degradation occurs via a free radical chain scission mechanism.