Cycloalkenyl-Functionalized Polymers and Block Copolymers: Syntheses via Selective RAFT Polymerizations and Demonstration of Their Versatile Reactivity

Abstract

A facile synthetic strategy for the preparation of well-defined polymers bearing cycloalkenyl side groups has been established via selective reversible addition-fragmentation chain transfer (RAFT) polymerization of cycloalkene-functionalized asymmetrical divinyl monomers. Two representative monomers, 4-(6′-methylcyclohex-3′-enylmethoxy)-2,3,5,6-tetrafluorostyrene and 4-(cyclohex-3′-enylmethoxy)-2,3,5,6-tetrafluorostyrene, were synthesized. RAFT polymerizations of these bifunctional monomers, using S-1-dodecyl-S′-(R,R′-dimethyl-R′′-acetic acid)trithiocarbonate as the chain transfer agent and 2,2′-azobis(isobutyronitrile) (AIBN) as the thermal initiator, exhibited superb selectivity toward the substituted styrenyl vinylic unit relative to the cyclohexenyl unit, even at high monomer conversions (>80%). The resulting polymers retained quantitative cyclohexenyl groups, while having predetermined molecular weights and narrow molecular weight distributions (PDI ) 1.09-1.15). Well-defined block copolymers with pendent cyclohexenyl groups were also prepared by sequential RAFT chain extension polymerizations. A variety of functional polymers were further obtained by functional group transformations using the cyclohexene-functionalized polymers as precursors.

Living Radical Polymerization by the RAFT Process - A Second Update

“…MMA [296] St [296] 128* [283] S S C 12 H 25 S CO 2 H AA [91] CA [297] tBA [298] MA [299] (BMA) [300] (BMA) [300] CMA [301] MMA [122,283] (MMA) [122] BAM [302] DEAM [302,303] DMAM [302,303] EMAM [302,303] NIPAM [302][303][304][305][306] PAM [302,306] MVK [307] PVK [307] 297 [308] tBS [276] CMS [309] HMS [309] St [91,300,309] (St) [300] 4VP [310] Ip [311] 320 [312] 325 [100] 327 [309] 331 [313] 332 [313] NVP [103] 331-b-St [313] tBA-b-Ip [298] tBA-b-St [298] tBA-b-IP-b-St …”

“…Styrene derivatives subjected to RAFT polymerization 348 [100,199] O 349 [138] O N N N 350 [158,309] N VBTAC 351 [159] Cl Ϫ Nϩ 352 [459] HN O 353 [321] O F F F F 354 [313] O F F F F 355 [313] [244] VBTPC 359 [34] Cl Ϫ P ϩ 360 [244] 361 [250] O N O 362 [207] O O O 363 [134] O O O Fe 364 [102] N 365 [102] N Table 23. Vinyl derivatives subjected to RAFT polymerization 366 [380] N 367 [380] N 368 [380] N 369 [390] N O O G. Moad, E. Rizzardo, and S. H. Thang [111,135] 370 [135,146] 375 [136] 376 [195] 377 [150] 378 [410] O O (H 3 C) 3 Si 372 [338,346,347] 373 [201] 374 [459] O [466] NAS 380 [160,299,317,345,347] 381 [178] 382 [222] [149,…”

The Power of RAFT for Creating Polymers Having Imbedded Side-Chain Functionalities: Norbornenyl-Functionalized Polymers and their Transformations via ROMP and Thiol-ene Reactions

“…Especially, the developments of living radical polymerizations (LRP) [20][21][22][23][24] and ring-opening metathesis polymerization (ROMP), [25] which possess good functional group tolerance and do not require stringent reaction conditions, have resulted in facile methods to incorporate chemoselective handles into polymer architectures. Alkene-functionalized polymers could be converted to polymer materials with new or improved properties through diverse functionalization strategies such as radical cross-linking and polymerization, [5,8,[26][27][28][29][30][31] electrophilic addition, [32,33] cross-metathesis reaction, [34] osmylation, [35,36] and aldehyde-alkene photoreaction. [37] Recently, thiol-ene radical addition has emerged as a robust and orthogonal method for macromolecular synthesis and functionalization.…”

“…As demonstrated by us [57] and Patton et al, [58] because of the low reactivity of Nb relative to typical vinyl monomers, Nb-functionalized macromonomers could be prepared by ATRP and RAFT polymerization, employing Nb-functionalized initiators or chaintransfer agents (CTAs). Recently, we have also reported a facile approach to synthesize (co)polymers with pendent openchain [59] or cyclic alkenyl groups [36] via selective RAFT polymerization of alkene-functionalized vinyl monomers. Based on these results, we hypothesized that LRP of monomers containing both an Nb group and a reactive vinyl functionality may also proceed selectively, and that the resulting polymers with Structural design and comparison of three bifunctional monomers, each containing a styrenyl and an alkenyl moiety; A: 4-(3 -buten-1 -oxy)-2,3,5,6-tetrafluorostyrene; [59] B: 4-(cyclohexe-3 -enylmethoxy)-2,3,5,6-tetrafluorostyrene; [36] 1: 4-(5 -norbornene-2 -methoxy)-2,3,5,6-tetrafluorostyrene.…”

“…A broad variety of polymers and polymeric nanostructures has been synthesized. [40,[60][61][62][63][64][65][66] Recently, our research group has conducted RAFT polymerizations to afford linear functional polymers, [36,59,67] and also various complex macromolecular architectures with nanoscopic features, such as molecular brushes, [68] nanoparticles, [69,70] vesicles, [71] and nanoporous materials. [72] In the present article, we report our study on the design, preparation, and characterization of well-defined polymers having pendent Nb functionalities by selective RAFT polymerization, as well as their transformations into star polymers by ROMP and their chemical modifications by thiol-ene reactions.…”