Preparation and co-catalytic properties of amphiphilic diblock copolymers consisting of polystyrene and ionene

Well-defined amphiphilic diblock copolymers, consisting of an oligomeric quaternary ammonium block and a polystyrene (I) block, were synthesized. The route started with the prepn. of monofunctionalized I by anionic polymn., using 3-(dimethylamino)propyllithium as initiator. I was obtained with relatively narrow mol. wt. distributions (.hivin.Mw/.hivin.Mn = 1.2-1.4). This I was coupled stepwise with a no. of different monodisperse oligomer units of 2,4-ionene, having reactive end-groups, resulting in a monodisperse 2,4-ionene block. End-group titrn., size exclusion chromatog., thin-layer chromatog., and IR spectroscopy were utilized to characterize the polymers. Addnl. the block copolymer in combination with tetrasodium phthalocyaninatocobalt(II)tetrasulfonate was tested as co-catalyst in the phase-transfer-catalyzed autoxidn. of 1-dodecanethiol. Very high catalytic activities (775 mol O2/(mol Co.s)) were achieved, 40 times higher as compared with the polymer-free system, due to a combination of the formation of the most active species and hydrophobic interaction with the hydrophobic thiol. This hydrophobic interaction resulted in an enhancement of the autoxidn. rate by a factor 2.5, compared with the analogous hydrophilic homopolymer 2,4-ionene