Dispersion Polymerization of Methyl Acrylate in Nonpolar Solvent Stabilized by Block Copolymers Formed In situ via the RAFT Process

Abstract

The free-radical dispersion polymerization of methyl acrylate (MA) in isododecane was carried out in the presence of a poly(2-ethylhexyl acrylate) macromolecular RAFT (reversible addition-fragmentation chain transfer) agent bearing a trithiocarbonate reactive group in the middle of the chain (P2EHA-TTC). The presence of the trithiocarbonate function was crucial for the synthesis of monodisperse colloidal poly(methyl acrylate) (PMA) particles stabilized by the P2EHA segments. The hydrodynamic diameters ranged from 100 to 300 nm, using particularly low amounts of the macro(RAFT agent) (1-6 wt % vs. MA) in dispersion polymerizations carried out at 20 wt % solids content. As shown by 2D liquid chromatography, P2EHA-b-PMA or P2EHA-b-PMA-b-P2EHA block copolymers formed in situ at the early stage of the dispersion polymerization due to the reversible transfer process and played the role of particle stabilizer. The glass-transition temperature of the derived polymer films was not affected by the low amount of the chosen macromolecular stabilizer and the mechanical properties were mainly those of PMA, which makes the technique very attractive for coating applications.

Living Radical Polymerization by the RAFT Process – A Third Update

“…[267] Pressley et al [611] have reported on an improved methodology for conducting click reactions to form block and cyclic polymers. [227] PFPMA/LMA Ph AIBN 25 70 100 [225] BA Ph AIBN 30 80 ,25 [194] HA Ph ACPA 5 70 100 [240] HA Ph AHPN 5 70 100 [240] BA/NA Ph AIBN 20 80 100 [202] BA C 4 H 9 S AIBN 30 80 ,25 [194] BA C 4 H 9 S AIBN þ BPO 20 þ 2 E 80 100 [194] HPA [596] tBA Poly(tBA)S AIBN -80 100 [597] NIPAm Poly(tBA-b-NIPAm)S AIBN -80 100 [597] tBA/TBBPMA Ph AIBN (20) (80) 100 [598] DAMEA/TFEA C 12 H 25 S AIBN 20 65 100 [599] HADA [194] St Ph AIBN þ BPO 20 þ 2 E 80 100 [194] St C 4 H 9 S AIBN 30 À 100 80 ,60 [194] St C 12 H 25 S AIBN 10 95 92 [393] A Monomer unit adjacent to thiocarbonylthio group. The process makes use of commercially available copper nanoparticles and is performed with microwave irradiation.…”

Polymerization-induced self-assembly of block copolymer nanoparticles via RAFT non-aqueous dispersion polymerization

“…Compared to RAFT alcoholic dispersion polymerization, there are relatively few reports of RAFT dispersion polymerization being conducted in non-polar solvents [92][93][94][95][96][97][98][99]. Charleux and co-workers [92][93][94] reported an all-acrylic RAFT non-polar dispersion polymerization formulation that produced poly(2-ethylhexyl acrylate)-poly(methyl acrylate) (PEHA-PMA) diblock copolymer nanoparticles in iso-dodecane.…”

“…Charleux and co-workers [92][93][94] reported an all-acrylic RAFT non-polar dispersion polymerization formulation that produced poly(2-ethylhexyl acrylate)-poly(methyl acrylate) (PEHA-PMA) diblock copolymer nanoparticles in iso-dodecane. However, it is emphasized that only spherical nanoparticles could be accessed in this study.…”

Dispersion polymerization in non-polar solvent: Evolution toward emerging applications

“…These authors demonstrated that presence of the RAFT agent on the stabilizer chain was crucial to allow for covalent grafting and thus efficient colloidal particle stabilization; the non-reactive P2EHA was unable to absorb onto the particle surface. [78] In addition, a kinetic study of the free radical polymerization in the presence of P2EHA-TTC and P2EHA-DTB showed that only the P2EHA-TTC stabilizer was able to control the polymerization leading to welldefined triblock copolymers forming small monodisperse core-shell colloidal particles (120 to 320 nm). [77,78] The use of P2EHA-DTB macro-RAFT agent as stabilizer at the lowest concentration did not provide control over the polymer structure (PDI =18) but led to the formation of small monodisperse particles (39 to 93 nm).…”

“…[78] In addition, a kinetic study of the free radical polymerization in the presence of P2EHA-TTC and P2EHA-DTB showed that only the P2EHA-TTC stabilizer was able to control the polymerization leading to welldefined triblock copolymers forming small monodisperse core-shell colloidal particles (120 to 320 nm). [77,78] The use of P2EHA-DTB macro-RAFT agent as stabilizer at the lowest concentration did not provide control over the polymer structure (PDI =18) but led to the formation of small monodisperse particles (39 to 93 nm). However, the monomer conversion stayed low compared to the other macro-RAFT agent and an important retardation phenomenon was observed.…”