RAFT Chemistry and Huisgen 1,3-Dipolar Cycloaddition: A Route to Block Copolymers of Vinyl Acetate and 6-O-Methacryloyl Mannose?

Abstract

The present communication explores a novel avenue to glycopolymer-block-poly(vinyl acetate) polymers by a combination of reversible addition fragmentation chain transfer (RAFT) chemistry and Huisgen 1,3-dipolar cycloaddition (i.e., so-called ‘click’ chemistry) under mild reaction conditions. Such block copolymers are—because of the strongly disparate reactivity of the two monomers—otherwise not obtainable. Poly(vinyl acetate) that has an azide end group (Mn 6800 g mol–1, PDI 1.15) was treated with poly(6-O-methacryloyl mannose) (Mn 7600 g mol–1, PDI 1.11) in the presence of 1,8-diaza[5,4,0]bicycloundec-7-ene and copper(i) iodide. The resulting poly(vinyl acetate)-block-poly(6-O-methacryloyl mannose) had a number-average molecular weight of 15400 g mol–1 and a PDI of 1.48, which indicates that while the cycloaddition had occurred the resulting polymer distribution featured a considerable width. The resulting slightly amphiphilic block copolymer was subsequently investigated with regard to its self-assembly in aqueous solution. Dynamic light scattering studies indicated a hydrodynamic diameter of close to 200 nm. Transmission electron microscopy studies indicate the formation of rods as well as spheres with transitions between these two phases. However, the segregation between core and shell in the spheres is not pronounced; such behaviour is expected for weakly amphiphilic block copolymers.

RAFT Polymerization of Vinyl Esters: Synthesis and Applications

“…In between these extremes, a wide range of R-groups may be employed to good effect, including esters of 1-acetyl [86][87][88][89][90]108,[110][111][112][113], 2-propionyl [3][4][5][6][7][8][9]30,31,34,66,69,70,[80][81][82]85,89,91,107,[114][115][116][117][118][119][120][121][122][123] and 2-methyl-2-propionyl [67,91], 2-acetic acid [124], 2-propionic acid [106,114,125], t-butyl [106], cyanomethyl [67,102], benzyl …”

“…Well-defined block copolymer, PS-b-PVAc was prepared via "click" chemistry between these two homopolymers (Scheme 21a). Later they used a similar approach to prepare well-controlled amphiphilic glycopolymer poly(VAc)-block-poly(6-O-methacryloyl mannose) [112] as well as PVAc comb polymers [117] (Scheme 21b).…”

Click Chemistry, A Powerful Tool for Pharmaceutical Sciences

“…Following TIPS deprotection, the heterotelechelic homopolymers were joined together via HDC reactions. When RAFT polymerization was employed to obtain the homopolymer blocks, however, specially functionalized chain transfer agents had to be synthesized to allow the introduction of terminal azides or acetylenes (44,45). Additionally, this modular strategy of clicking different homopolymer blocks together has also been exploited by numerous other research teams (46)(47)(48)(49).…”

Living Radical Polymerization by the RAFT Process - A Second Update

“…St [169] 287 [170] S O N 3 O S CN 27 [171] St [169,171,172] DMAM [171] St-b-DMAM [171] DMAM-b-St [171] [173] DEGMA [173] LMA [89,173] MMA [173] PEGMA [89,173] NIPMAM [173] 29 [174] O N 3 O S S CN St [174] (Continued) [176] 33* [180] PEO macro-RAFT agent [180] 34 [181] PEO macro-RAFT agent [182] G1 dendron RAFT agent D (ar-3,5-substitution)…”