Synthesis of asymmetric difunctional initiators and their use in the preparation of block copolymers via ATRP and SFRP

Microphase‐Separated Poly(vinylpyridine) Block Copolymer Prepared with a Novel Bifunctional Initiator

“…It has been previously reported that 2-phenyl-2-[(2,2,6,6-tetramethylpiperidino)oxy]ethyl 2-bromo propanoate 4 was synthesized as a bifunctional initiator for stepwise polymerization using 1-hydroxy-2-phenyl-2-(2 0 ,2 0 ,6 0 ,6 0 -tetramethyl-1 0 -piperidinyloxy)ethane 3 and was obtained by reacting TEMPO, styrene, and several grams of benzoyl peroxide (Scheme 1(b)); but it resulted in a low total yield of the reaction to obtain 4(15%) and used a large amount of the explosive peroxide. [20,24] We have succeeded in synthesizing the alkoxyamine 2 via the route shown in Scheme 1(a). The hydroxylated alkoxyamine precursor was prepared by simply heating a mixture of 4-hydroxy TEMPO and p-xylene.…”

“…Tunca et al reported a bifunctinoal initiator applicable to ATRP and NMRP in the preparation of PMMA-b-P4VP. [20] However, the synthetic route of the bifunctional initiator (shown in Scheme 1(b)) required tedious synthetic steps and the use of an explosive peroxide.…”

Syntheses and Characterizations of Block Copolymers Prepared via Controlled Radical Polymerization Methods

“…Many monomers with different structures can be polymerized to yield block copolymers with novel properties. In addition to the transformation methods discussed above, other transformation polymerizations, such as the combination of coordination or photoinduced polymerization with controlled radical polymerizations, or the combination of two different controlled radical polymerizations have been reported [145][146][147][148][149][150]. One method involves the application of a bifunctional initiator, in which the two functional groups are stimulated either in sequence or concurrently to initiate the polymerization of two kinds of monomers via different polymerization mechanisms.…”

“…The polymerization ability of the monomer with functional groups is related to the type of controlled radical polymerization. Block copolymers with desired structures can be prepared by the combination of two controlled radical polymerizations, such as combinations of photoinduced polymerization and ATRP [146], or ATRP and SFRP [147,148]. In most cases, the initiators carrying two different radical initiating sites were used in the preparation of block copolymers.…”

“…Using novel asymmetric difunctional initiators containing TEMPO and 2bromopropanoate or 2-bromo-2-methylpropanoate groups, block copolymers can be prepared via combination of ATRP and STRP [147,148]. For example, asymmetric difunctional initiator, CLI-25 was used in the ATRP of MMA with CuCl/N, N, N', N',N''-pentamethyldiethylene-triamine (PMDETA) as catalyst.…”