Controlled RAFT Cyclopolymerization of Oriented Styrenic Difunctional Monomers

Abstract

We describe the first example of controlled free radical cyclopolymerization of difunctional styrenic monomers. The newly designed monomers are obtained from the introduction of two 4‐vinylbenzyl moieties as malonate or dialkylated malonate esters. The more sterically hindered monomer is particularly efficient in the cyclization and propagation processes, giving cyclopolymers, in diluted solvent conditions, with good yields and degrees of polymerization. In the presence of a suitable RAFT mediator, and, upon careful optimization of the solvent, temperature and monomer concentration, a linear increase in the number average molecular weight with conversion and low polydispersity indexes can be achieved.

A Mild Oxidative Aryl Radical Addition into Alkenes by Aerobic Oxidation of Arylhydrazines

“…In the case of polymers 10 and 11 , the narrow PDIs and the close correspondence between theoretical and observed molecular weights (Table 1) indicate the efficiency of the protocols used for RAFT polymerization and NMP. Furthermore, the incorporation of fragments of the initiators end‐capping the polymer chains, as expected from the well‐established mechanisms of these controlled polymerizations,34–38 is evidenced in the 1 H NMR spectra of the purified, precipitated polymers (peaks labelled e in Fig. 2 (centre) and d (Aamer and Tew38) in Fig.…”

“…If the polymeric supports are to be applied in a recyclable, repeatable scheme, a polymer post‐modification approach is certainly more attractive and was therefore actively pursued. In order to optimize the macromolecular architecture, in terms of achievable molecular weights and of narrow polydispersity indexes (PDIs), we approached the synthesis of precursor copolymers 9, 10 and 11 using either conventional free radical polymerization or controlled methodologies such as RAFT polymerization34–36 or nitroxide‐mediated polymerization (NMP) 37, 38. Benzyl dithiobenzoate 7 as the mediator, or alkoxyamine 8 as the initiator and mediator were used, respectively.…”

Cyclopolymerization of a bisacrylate through selective formation of a 19-membered ring

“…However, the low concentration often limits the yields of polymers. 4,9 Effective strategies for improvement of the cyclization tendency involve conformational orientation of two polymerization groups with cyclic structures [10][11][12][13][14][15][16][17][18][19][20][21] or templates such as metal cations 22,23 and selective alternating copolymerization. 24,25 In the most common method, namely, the design of oriented monomers, additional constraints by steric hindrance 12,13,19 and hydrogen bonding 17 are effective in improving the cyclization tendency.…”

Synthesis and characterization of rigid functional anionic polyelectrolytes: Block copolymers and star homopolymers

“…In recent years, controlled radical polymerizations have been used for the formation of rigid cyclolinear polymers of well‐defined size and interesting structural properties 8–13. For example, some of the cyclolinear polymers bore particularly large cycles of 10‐ to 19‐membered rings 11–13.…”

“…In recent years, controlled radical polymerizations have been used for the formation of rigid cyclolinear polymers of well‐defined size and interesting structural properties 8–13. For example, some of the cyclolinear polymers bore particularly large cycles of 10‐ to 19‐membered rings 11–13. In another case, the polymers prepared bore positive charge; this was the work by Agarwal and coworkers8 who reported the use of reversible addition–fragmentation chain transfer (RAFT) cyclopolymerization of alkyl ammonium dienes to synthesize cyclolinear polymers with five‐membered heterocyclic monomer repeating units.…”