Synthesis by RAFT and Ionic Responsiveness of Double Hydrophilic Block Copolymers Based on Ionic Liquid Monomer Units

Abstract

Three imidazolium-based ionic liquid (IL) monomers, namely, 3-(1-ethyl imidazolium-3yl)propylmethacrylamido bromide (IL-1), 2-(1-methylimidazolium-3-yl)ethyl methacrylate bromide (IL-2), and 2-(1-ethylimidazolium-3-yl)ethyl methacrylate bromide (IL-3), and methacrylic acid (MAA) were polymerized by the reversible addition fragmentation chain transfer (RAFT) process in methanolic solutions at 70 °C, using either 2-cyanopropyl dithiobenzoate (CTA-1) or (4-cyanopentanoic acid)-4-dithiobenzoate (CTA-2) as chain transfer agents (CTAs). Under these conditions, polymers exhibited molar masses predetermined by the initial molar ratio of the monomers to the dithioester precursor, as evidenced by 1 H NMR spectroscopy from chain ends analysis. These hydrophilic polymers were subsequently used as macro-CTAs in chain extension experiments in aqueous or in alcoholic solutions, affording IL-based double hydrophilic block copolymers (DHBCs) of the type PIL-1-b-PAm, PMAA-b-PIL-2 and PMAA-b-PIL-3, where PAm and PIL stand for polyacrylamide and polymeric ionic liquid. These DHBCs could be further manipulated and made to self-assemble in micelle-like structures in water by exchanging the bromide (Br -) counteranion of IL blocks for -N(SO 2 CF 3 ) 2 . This anion exchange indeed turned the solution properties of the PIL blocks from hydrophilic to hydrophobic, as verified on the corresponding IL-based homopolymers which were immiscible with water after the anion switch. Investigations by 1 H NMR evidenced that the diblock copolymers exhibited salt-responsive behavior in aqueous solutions: anion exchange induced the formation of water-soluble micellar aggregates consisting of hydrophobic -N(SO 2 CF 3 ) 2 -based IL blocks at the core stabilized by water-soluble PAm or PMAA at the shell.

Living Radical Polymerization by the RAFT Process - A Second Update

“…BMA [139] MAA [140] MMA [64,141] AEMA [90,142] DEGMA [141] DMAEMA [143] DPAEMA [144] MAA [145] PEGMA [144,[146][147][148] 383 [149] DMAM [150] NIPAM [151] 274 [152,153] 325 [154] 326 [154] APMAM-b-NIPAM [89,152] AEMAM [153] St [155] 274 [153] 275 [153] 285 [156] 286 [156] 289 [157] 292 [158] 304 [140] 305 [140] 331 [159] 329 [140] 327 [157] 380 [160] 391 [161,162] 389 [104] (390) [104] 416 [163,164] MAA-b-280 [145] BMA-b-MPC [139] PEGMA/ 320 [165] PEGMA/344 [165] DEGMA-b-384 [141] MMA-b-384 …”

“…[96] N O O 278 [96] O O N N O O MMBL 279 [258] O [124,145] 281 [124] O [197] O F 3 C F 3 C CONH 2 CONH 2 284 [197] [158] 294 [125] N O O N N CN 295 [126] O O O N OH 296 [127] [436] O O O O 299 [317] O O O O O OH 300 [455] [456] TPMMA 302 [92] O O 303 [203] O O S 304 [140] …”

“…305 [140] O O N N 306 [128] O O N N 307 [128] O O N N N 308 [128] [295,301] 310 [382] O O (CH 2 ) 6 O N N N 311 [382] (CH 2 312 [210] O O O [308] O O C 8 F 17…”

“…Methacrylamide derivatives subjected to RAFT polymerization 325 [154] 326 [154] 327 [157] OH [278] 329 [140] HN Table 20. Amino acid-derived acrylamides subjected to RAFT polymerization (R )-2-acrylamidopropanoic acid 330 [318,457] (S )-2-acrylamidopropanoic acid 331 [159,318,401,457] O NH HO 2 C O NH HO 2 C 332 [221,457] O NH HO 2 C 333 [457] 334 [458] 335 [458] [221,458] 337 [458] 338 [221,235,401,457] O…”

Temperature-responsive self-assembly of star block copolymers with poly(ionic liquid) segments

“…14,15 For example, Waymouth et al 16,17 demonstrated the synthesis of a series of block copolymers containing polystyrene and imidazolium-functionalized polystyrene by nitroxide-mediated polymerization, followed by post-synthetic modification of the chloromethyl groups. Recently, Gnanou et al 18 reported the synthesis of double hydrophilic block copolymers with ionic responsive properties by the reversible addition-fragmentation chain transfer (RAFT) polymerization of methacrylate-type ionic liquids. RAFT polymerization was also employed for the synthesis of block copolymers containing imidazolium and thiazole groups, which showed characteristic magnetic properties.…”