Pegylated thermally responsive block copolymer micelles and nanogels via in situ RAFT aqueous dispersion polymerization

Abstract

A very straightforward approach was developed to synthesize pegylated thermoresponsive core-shell nanoparticles in a minimum of steps, directly in water. It is based on RAFT-controlled radical crosslinking copolymerization of N,N-diethylacrylamide (DEAAm) and N,N 0 -methylene bisacrylamide (MBA) in aqueous dispersion polymerization. Because DEAAm is water-soluble and poly(N,N-diethylacrylamide) (PDEAAm) exhibits a lower critical solution temperature at 32 C, the initial medium was homogeneous, whereas the polymer formed a separate phase at the reaction temperature. The first macroRAFT agent was a surface-active trithiocarbonate based on a hydrophilic poly(ethylene oxide) block and a hydrophobic dodecyl chain. It was further extented with N,N-dimethylacrylamide (DMAAm) to target macroRAFT agents with increasing chain length. All macroRAFT agents provided excellent control over the aqueous dispersion homopolymerization of DEAAm. When they were used in the radical crosslinking copolymerization of DEAAm and MBA, the stability and size of the resulting gel particles were found to depend strongly on the chain length of the macro-RAFT agent, on the concentrations of both the monomer and the crosslinker, and on the process (one step or two steps). The best-suited experimental conditions to reach thermosensitive hydrogels with nanometric size and well-defined surface properties were determined.

Living Radical Polymerization by the RAFT Process - A Second Update

“…DEAM [333] DMAM [333] DMAM-b-DEAM [333] St [325] (Continued) NIPAM [324] 140 [324] BMA [334] BA [334] EHA [334] LA [334] St [334] St-b-BA [334] BA-b-EHA [334] BA-b-LA [334] 142 [334] S…”

“…St [325] 134 [326,327] MA [328] MA-b-tBA [328] 136 [ BA [330] St [171] DMAM [171] NIPAM [331] St-b-DMAM [171] DMAM-b-St [171] NIPAM-b-DMAM [332] 138 [333] PEO macro-RAFT agent…”

“…Hexanediol diacrylate [352] AA 211 Methylene-bis-acrylamide [397] BA 22 407 [105] St 39 Divinylbenzene/4VP [184] St 109 Divinylbenzene [284] St 133 Divinylbenzene [325] St St-b-NIPAM 61 Divinylbenzene [518] PEO 38 Divinylbenzene/S [180] PEO-b-DMAM PEO-b-DEAM PEO-b-DMAM-b-DEAM 138 Methylene-bis-acrylamide/DEAM [333] VAc 211 Divinyl adipate [388] A See footnote A of Table 3. B See footnote B of Table 3.…”

RAFT dispersion polymerization in non-polar solvents: facile production of block copolymer spheres, worms and vesicles in n-alkanes

“…For example, RAFT aqueous dispersion polymerization has been utilized to grow a waterinsoluble core-forming block from a water-soluble stabilizer block in order to prepare a range of sterically-stabilized diblock copolymer nanoparticles. [9][10][11][12][13][14] Spherical morphologies are most 35 commonly obtained, [9][10][11][12][13] but systematic variation of the block copolymer composition coupled with a detailed knowledge of the block copolymer phase diagram also allows access to higher order morphologies such as worms [14][15][16] and vesicles. [17][18][19][20][21][22][23][24][25][26] In most cases good blocking efficiencies and reasonably low final 40 polydispersities (e.g.…”

Characterization of Diblock Copolymer Order-Order Transitions in Semidilute Aqueous Solution Using Fluorescence Correlation Spectroscopy

“…[ 9 ] One promising candidate for such applications is a diblock copolymer comprising poly(glycerol monomethacrylate) (PGMA) and poly(2-hydroxypropyl methacrylate) (PHPMA), which are conveniently prepared via polymerization-induced self-assembly [9][10][11][12][13] using reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization. [14][15][16] This versatile approach has enabled spherical, worm-like or vesicular copolymer morphologies to be generated in concentrated solution.…”