Abstract
A series of ABA triblock copolymers, consisting of double-bond-containing poly(phenoxyallene) (PPOA), poly(methyl methacrylate) (PMMA), or poly(butyl acrylate) (PBA) segments, were synthesized by sequential free radical polymerization and atom transfer radical polymerization (ATRP). A new bifunctional initiator bearing azo and halogen-containing ATRP initiating groups was first prepared followed by initiating conventional free radical homopolymerization of phenoxyallene with cumulated double bond to give a PPOA-based macroinitiator with ATRP initiating groups at both ends. Next, PMMA-b-PPOA-b-PMMA and PBA-b-PPOA-b-PBA triblock copolymers were synthesized by ATRP of methyl methacrylate and n-butyl acrylate initiated by the PPOA-based macroinitiator through the site transformation strategy. These double-bond-containing triblock copolymers are stable under UV irradiation and free radical circumstances.
Highlights
We reported the first example of triblock copolymers containing phenoxyallene andacrylate repeated units prepared by a combination of conventional azo-initiated free radical polymerization and ATRP, which showed high stability under free radical and UV irradiation surroundings
It was difficult to prepare block copolymers of allene derivatives and vinyl monomers by single polymerization mechanism, i.e. sequential feeding, because nickel-catalyzed living coordination polymerization is only suitable for allene derivatives[3–9], diene[12], isocyanide[13], and thiophene[14,15], not suitable for common vinyl monomers
We have displayed the detailed synthesis of PMMA-b-PPOA-b-PMMA and PBA-b-PPOA-b-PBA triblock copolymers by the combination of free radical polymerization, ATRP and the site transformation strategy, employing a bifunctional initiator possessing azo and Br-containing ATRP initiating groups as starting material
Summary
Synthesis and characterization of azo-ATRP bifunctional initiator. As mentioned above, it was difficult to prepare block copolymers of allene derivatives and vinyl monomers by single polymerization mechanism, i.e. sequential feeding, because nickel-catalyzed living coordination polymerization is only suitable for allene derivatives[3–9], diene[12], isocyanide[13], and thiophene[14,15], not suitable for common vinyl monomers. The signals between 4.50 ppm and 5.50 ppm attributed to the protons of the double bonds in POA repeated unit evidenced that the double bonds of PPOA block kept inert during ATRP of MMA It can be concluded from the above-mentioned results that double-bond-containing PMMA-b-PPOA-b-PMMA 3 triblock copolymers were successfully synthesized through ATRP of MMA initiated by Br-PPOA-Br 2 macroinitiator. This point implied that double bonds in polyallene-based copolymer are stable under common radical surrounding, which may faciliate the potential further application
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