Organocatalyzed Photo-Atom Transfer Radical Polymerization of Methacrylic Acid in Continuous Flow and Surface Grafting.

The organocatalyzed photo-atom transfer radical polymerization (photoATRP) using 10-phenylphenothiazine as catalyst is studied toward its use in methacrylic acid (MAA) polymerization and surface grafting. The organocatalyzed photoATRP of methyl methacrylate (MMA) is first optimized for continuous flow synthesis in order to assess the livingness of the polymerization. MMA can be polymerized in batch and in flow; however, conversions are limited by the loss of bromine functionality and hence high conversions have to be traded in with increasing dispersities. Also, MAA is polymerized successfully in continuous flow with similar limitations. Flow conditions are transferred to surface grafting from silanized silicon wafers. The presence of ATRP initiators after silanization is confirmed by secondary ion mass spectrometry and X-ray photoelectron spectroscopy. Dense polymethacrylic acid brush films are successfully produced, which is not directly accessible via classical copper-mediated ATRP techniques.