Cationic End-Functional Polyethylene via Catalyzed Chain Growth: Synthesis, Mass Spectrometry, and Applications

We report the controlled synthesis of polyethylene (PE) via catalyzed chain growth (CCG) carrying a cationic end-group. CCG and subsequent iodine treatment give rise to both low dispersed PE and a high degree of end-group functionalization. The end-group can be further substituted by 3-dimethylamino-1-propanol leading to a well-defined cationic functionality, as validated by NMR spectroscopy. The positive charge enables matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and electrospray ionization mass spectrometry (ESI-MS) of these PE chains with an excellent signal-to-noise ratio. Moreover, the charged PE acts as a phase transfer catalyst (PTC) in a nucleophilic substitution with excellent yields even in comparison to well-established conventional PTCs. This new PE-based catalyst is completely recoverable by simple filtration due to its temperature-dependent solubility. On the basis of this powerful phase-transfer ability, we prepared charged PE loaded by an anionic dye via the extraction of the dye from aqueous to organic phase. Atom transfer radical polymerization (ATRP) initiator and acrylate-based end-groups were also introduced to the polymer system resulting in a positively charged PE-based macroinitiator/macromonomer, expanding the array of applications of this new type of polymer. Further block copolymerization of the ATRP functionalized PE with n-butyl acrylate was conducted successfully.