Synthesis and aqueous solution properties of near-monodisperse tertiary amine methacrylate homopolymers and diblock copolymers V. Bu Ètu Èn b , S.P. Armes a, * , N.C. Billingham a a School of Chemistry, Physics and Environmental Science, University of Sussex, Falmer, Brighton BN1 9QJ, UK b Department of Chemistry, Faculty of Arts and Science, Osmangazi University, Eskisehir 26480, Turkey Received 13 December 2000 Abstract Group transfer polymerisation GTP) of four tertiary amine methacrylates, 2-dimethylamino)ethyl methacrylate DMA), 2-diethylami- no)ethylmethacrylateDEA),2-diisopropylamino)ethylmethacrylateDPA)and2-N-morpholino)ethylmethacrylateMEMA)produceda seriesofnear-monodispersehomopolymersM w /M n , 1.15).Molecularweightswerecontrolledbyvaryingthemonomer/initiatorratio.The DMA and MEMA homopolymers were both water-soluble at 208C in acidic or neutral media. Inverse temperature solubility behaviour was observed at higher temperatures, with cloud-points ranging from 32 to 538C at pH 8. The Cloud-points decreased monotonically with increasing degrees of polymerisation, as expected. The MEMA homopolymers were particularly sensitive to the added electrolyte, with `saltingout'occurringat208Conadditionof0.2±0.3MNa 2 SO 4 .ThemorehydrophobicDEAandDPAhomopolymerswerebothinsoluble at208CandneutralpHbutreadilydissolvedascationicpolyelectrolytesinacidicmediaduetoprotonationofthetertiaryamineresidues.In addition, DMA was block copolymerized in turn with each of the other three tertiary amine methacrylate comonomers. These diblock copolymers could be dissolved molecularly without co-solvents in aqueous media at 208C, with micellization occurring reversibly on judicious adjustment of the solution pH, temperature or electrolyte concentration. In all three cases, stable block copolymer micelles were formed with DMA coronas and hydrodynamic diameters of 20±60 nm. q 2001 Elsevier Science Ltd. All rights reserved. Keywords: Homopolymers; Copolymers; DMA 1. Introduction Poly[2-dimethylamino)ethyl methacrylate] is a weak polybase, which is water-soluble both at neutral pH and in acidicmediaduetoprotonationofthetertiaryaminegroups. Recently several research groups have described the synth- esis of well-de®ned, near-monodisperse copolymers based on 2-dimethylamino)ethyl methacrylate DMA) via living polymerisation techniques. For example, Hoogeveen et al. described the synthesis and adsorption behaviour of a range of diblock copolymers comprising DMA and 2,3-dihydrox- ypropyl methacrylate DHPM) [1]. These copolymers were prepared via classical anionic polymerisation using protect- ing group chemistry for the DHPM residues. It was found that these copolymers adsorbed onto silica particles via the basic DMA residues. Subsequent ¯occulation of the silica sol was explained in terms of charge neutralization of the anionic silica by the cationic DMA residues and the unex- pectedly poor steric stabilization properties imparted by the DHPM block. The same workers also reported the use of such copolymers as stabilizers and ¯occulants for oxide particles [2] and compared the adsorption of DMA and quaternized DMA homopolymers onto colloidal silica and titania particles [3]. Creutz et al. described the controlled polymerisation of three basic monomers using classical anionic techniques: DMA [4], 4-vinylpyridine [5,6] and t-butylaminoethyl methacrylate [7]. Zwitterionic diblock and triblock copolymers comprising DMA and sodium methacrylatewerealsoprepared,usingt-butylmethacrylate as a protected monomer for the sodium methacrylate resi- dues. The kinetics of unimer-micelle exchange of these naphthalene-labelled block copolymers, and also a series of related analogues, were studied by ¯uoresence spectro- scopyusingapyreneprobe[8,9].TherelatedDMA±ammo- nium methacrylate diblock copolymers were claimed to have some potential as universal pigment dispersants since arangeofinorganicoxidesandorganicdyescouldberead- ily dispersed in aqueous media over a wide pH range [10]. This was attributed to the ubiquitous adsorption character- istics imparted by the DMA residues. Polymer 42 2001) 5993±6008 0032-3861/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved. PII:S0032-386101)00066-0 www.elsevier.nl/locate/polymer * Correspondingauthor.Tel.: 144-01273-6067552043;fax: 144-01273- 677196. E-mail address: s.p.armes@sussex.ac.uk S.P. Armes).