Synthesis and aqueous solution properties of near-monodisperse tertiary amine methacrylate homopolymers and diblock copolymers

Group transfer polymerisation (GTP) of four tertiary amine methacrylates, 2 -(dimethylamino)ethyl methacrylate (DMA), 2-(diethylamino)ethyl methacrylat e (DEA), 2-(diisopropylamino)ethyl methacrylate (DPA) and 2-(N-morpholino)e thyl methacrylate (MEMA) produced a series of near-monodisperse homopolymer s (Mw/Mn < 1.15). Molecular weights were controlled by varying the monomer/ initiator ratio. The DMA and MEMA homopolymers were both water-soluble at 2 0<degrees>C in acidic or neutral media. Inverse temperature solubility beha viour was observed at higher temperatures, with cloud-points ranging from 3 2 to 53 degreesC at pH 8. The Cloud-points decreased monotonically with inc reasing degrees of polymerisation, as expected. The MEMA homopolymers were particularly sensitive to the added electrolyte, with 'salting out' occurri ng at 20 degreesC on addition of 0.2-0.3 M Na2SO4. The more hydrophobic DEA and DPA homopolymers were both insoluble at 20 degreesC and neutral pH but readily dissolved as cationic polyelectrolytes in acidic media due to prot onation of the tertiary amine residues. In addition, DNA was block copolyme rized in turn with each of the other three tertiary amine methacrylate como nomers. These diblock copolymers could be dissolved molecularly without co- solvents in aqueous media at 20 degreesC, with micellization occurring reve rsibly on judicious adjustment of the solution pH, temperature or electroly te concentration. In all three cases, stable block copolymer micelles were formed with DMA coronas and hydrodynamic diameters of 20-60 nm. (C) 2001 El sevier Science Ltd. All rights reserved.