Toward Sulfur-Free RAFT Polymerization Induced Self-Assembly

Abstract

Polymerization induced self-assembly (PISA) using methacrylate-based macromonomers as RAFT agents is an unexplored, attractive route to make self-assembled colloidal objects. The use of this class of RAFT-agents in heterogeneous polymerizations is however not trivial, because of their inherent low reactivity. In this work we demonstrate that two obstacles need to be overcome, one being control of chain-growth (propagation), the other monomer partitioning. Batch dispersion polymerizations of hydroxypropyl methacrylate in presence of poly(glycerol methacrylate) macromonomers in water showed limited control of chain-growth. Semi-continuous experiments whereby monomer was fed improved results only to some extent. Control of propagation is essential for PISA to allow for dynamic rearrangement of colloidal structures. We tackled the problem of monomer partitioning (caused by uncontrolled particle nucleation) by starting the polymerization with an amphiphilic thermoresponsive diblock copolymer, already "phase-separated" from solution. TEM analysis showed that PISA was successful and that different particle morphologies were obtained throughout the polymerization. gy, with the big advantage that conventional organosulfur based RAFT agents can be omitted. ASSOCIATED CONTENTSupporting Information. Materials and methods. Reaction schemes for the macromonomer synthesis and its chain extension via RDRP polymerization. 1 H-NMR traces of the PGMA and PGlyMA macromonomers. Additional GPC traces and DLS data for HPMA chain-extensions. This material is available free of charge via the Internet at

Synthesis of Janus and Patchy Particles Using Nanogels as Stabilizers in Emulsion Polymerization

“…The nanogels adopted in this work were made by corecrosslinking of ω-end unsaturated poly(methyl methacrylate-methacrylic acid)-block-poly(n-butyl methacrylate) P(MMA-MAA)-PBMA copolymer micelles synthetized via sulfur-free reversible addition-fragmentation chain transfer (RAFT) (Scheme 1a). [38][39][40][41] Initially, cobalt-mediated catalytic chain transfer polymerization (CCTP) 42,43 using a mixture of MMA and MAA (1.8:1.0 molar ratio) was carried out as a semi-batch emulsion polymerization process to make polymer latexes in which the particles consist predominantly of ω-end unsaturated poly(methyl methacrylate-co-methacrylic acid) P(MMA-MAA) macromonomers. CCTP relies on the use of certain low-spin Co(II) complexes as efficient chain-transfer agents in the polymerization of methacrylate monomers 44 (Scheme S1), and commonly yields a-hydrogen w-unsaturated telechelic functional polymers.…”

Polymerization‐Induced Self‐Assembly under Compressed CO2: Control of Morphology Using a CO2‐Responsive MacroRAFT Agent

“…Polymerization‐induced self‐assembly (PISA), most commonly based on reversible addition‐fragmentation chain transfer (RAFT) polymerization, has emerged as a useful method for synthesis of a wide range of nanoparticle morphologies. More recently, PISA has been expanded to approaches based on nonliving radical polymerization (addition‐fragmentation chain transfer polymerization), photo‐induced CLRP, as well as ring‐opening metathesis polymerization . PISA is typically implemented as a dispersion polymerization, although emulsion polymerization can also be employed.…”

“…[1,2] Polymerization-induced self-assembly (PISA), [3][4][5][6][7][8][9] most commonly based on reversible addition-fragmentation chain transfer (RAFT) polymerization, has emerged as a useful method for synthesis of a wide range of nanoparticle morphologies. More recently, PISA has been expanded to approaches based on nonliving radical polymerization (addition-fragmentation chain transfer poly merization), [10,11] photo-induced CLRP, [12] pressure. Scheme 1 illustrates how nanoparticles with tuned morphology can be reproducibly prepared using this approach.…”

Automatic peak assignment and visualisation of copolymer mass spectrometry data using the ‘genetic algorithm’

“…[7][8][9][10][11] Copolymers of vinyl monomers may be synthesised by a wide variety of polymerisation methods, including catalytic chain transfer polymerisation (CCTP), [12][13][14] atom transfer radical polymerisation (ATRP), [15][16][17] ionic polymerisation, 18,19 reversible addition-transfer chain-transfer polymerisation (RAFT), [20][21][22] and sulphur-free RAFT. [23][24][25][26] These polymerisation methods can lead to different challenges in mass spectrometry, from examination of labile end groups [27][28][29][30] (e.g., ATRP and RAFT) to higher dispersities leading to a wide m/z range to be covered [31][32][33][34] (e.g., in CCTP). These challenges become even more complex, often to the point of becoming intractable and unsolvable, in the case of copolymers due to the enormous number of different molecular species present in a material.…”