After a brief history that positions polymerization‐induced self‐assembly (PISA) in the field of polymer chemistry, this Review will cover the fundamentals of the PISA mechanism. Furthermore, this Review will also give an overview of some of the features and limitations of RAFT‐mediated PISA in terms of the choice of the components involved, the nature of the nanoobjects that can be obtained and how the syntheses can be controlled, as well as some potential applications.

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In simulations and experiments, we study the drying of films containing mixtures of large and small colloidal particles in water. During drying, the mixture stratifies into a layer of the larger particles at the bottom with a layer of the smaller particles on top. We developed a model to show that a gradient in osmotic pressure, which develops dynamically during drying, is responsible for the segregation mechanism behind stratification.

The present paper describes the successful onepot synthesis of self-stabilized particles composed of amphiphilic block copolymers based on poly(methacrylic acid) (PMAA) obtained by polymerization-induced selfassembly. First, controlled radical polymerization of MAA is performed in water using the RAFT process by taking advantage of our recent results showing the successful RAFT polymerization of MAA in water [Chaduc et al. Macromolecules 2012, 45, 1241−1247. The so-formed hydrophilic macro-RAFT agents are then chain-extended in situ with a hydrophobic monomer to form amphiphilic block copolymer chains of controlled molar mass that self-assemble into stable nanoparticles. Various parameters such as the pH, the molar mass and the concentration of the PMAA segments or the nature of the hydrophobic block have been investigated.

International audienceThe reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylic acid (AA) in water was studied in detail at different pHs using 4-cyano-4-thiothiopropylsulfanyl pentanoic add (CTPPA) as a control agent and 4,4'-azobis(4-cyanopentanoic acid) (ACPA) as an initiator. Well-defined hydrophilic macromolecular RAFT agents (PAA-CTPPA) were obtained and further used directly in water for the polymerization of styrene. The corresponding polymerization-induced self-assembly (PISA) process was evaluated at different pHs and it was shown that working in acidic conditions (pH = 2.5) led to well-defined amphiphilic block copolymer particles (D < 1.4) of small size (below 50 nm). When the pH increased, the control over the growth of the polystyrene (PS) block was gradually lost. Chain extension experiments of PAA-CTPPA with N-acryloylmorpholine (NAM), a hydrosoluble and non-pH sensitive monomer, performed at different pHs showed that the very first addition-fragmentation steps that occurred in water were impeded when PAA was ionized leading to partial consumption of PAA-CTPPA and thus to PS molar masses higher than expected. Varying the PAA-CTPPA concentration at pH = 2.5 led in all cases to stable particles composed of well-defined block copolymers with PS segments of different molar masses

Water-borne phosphine-functionalized core-cross-linked micelles (CCM) consisting of a hydrophobic core and a hydrophilic shell were obtained as stable latexes by reversible addition-fragmentation chain transfer (RAFT) in water in a one-pot, three-step process. Initial homogeneous aqueous-phase copolymerization of methacrylic acid (MAA) and poly(ethylene oxide) methyl ether methacrylate (PEOMA) is followed by copolymerization of styrene (S) and 4-diphenylphosphinostyrene (DPPS), yielding P(MAA-co-PEOMA)-b-P(S-co-DPPS) amphiphilic block copolymer micelles (M) by polymerization-induced self-assembly (PISA), and final micellar cross-linking with a mixture of S and diethylene glycol dimethacrylate. The CCM were characterized by dynamic light scattering and NMR spectroscopy to evaluate size, dispersity, stability, and the swelling ability of various organic substrates. Coordination of [Rh(acac)(CO)2 ] (acac=acetylacetonate) to the core-confined phosphine groups was rapid and quantitative. The CCM and M latexes were then used, in combination with [Rh(acac)(CO)2 ], to catalyze the aqueous biphasic hydroformylation of 1-octene, in which they showed high activity, recyclability, protection of the activated Rh center by the polymer scaffold, and low Rh leaching. The CCM latex gave slightly lower catalytic activity but significantly less Rh leaching than the M latex. A control experiment conducted in the presence of the sulfoxantphos ligand pointed to the action of the CCM as catalytic nanoreactors with substrate and product transport into and out of the polymer core, rather than as a surfactant in interfacial catalysis.

Reversible addition-fragmentation chain transfer polymerization (RAFT) of styrene has been successfully performed in miniemulsion, mediated by a very efficient RAFT agent: 1-phenylethyl phenyldithioacetate (PEPDTA). To gain a better understanding of this system, we compared the performance of this RAFT agent with those of cumyl dithiobenzoate (CDB) and 1-phenylethyl dithiobenzoate (PEDB) in bulk and found a superior performance for PEPDTA. This result is consistent with a more efficient reversible radical sink in this system. Miniemulsion polymerizations mediated by PEPDTA (initiated by potassium persulfate at 75 °C) were also found to proceed at a considerably higher rate than those mediated by CDB or PEDB mediated ones; however, all three systems showed a significant decrease in polymerization rate as compared to a conventional miniemulsion polymerization. This latter observation is conceivably related to entry and exit events, as a prepolymerized PEPDTA RAFT agent displayed rates close to the conventional nonliving miniemulsion system. All systems were found to produce polymers with relatively broad molar mass distributions, which is fully explained by consideration of initiator-derived chains.

The syntheses of amphiphilic block copolymers are successfully performed in water by chain extension of hydrophilic macromolecules with styrene at 80 °C. The employed strategy is a one-pot procedure in which poly(acrylic acid), poly(methacrylic acid) or poly(methacrylic acid-co-poly(ethylene oxide) methyl ether methacrylate) macroRAFTs are first formed in water using 4-cyano-4-thiothiopropylsulfanyl pentanoic acid (CTPPA) as a chain transfer agent. The resulting macroRAFTs are then directly used without further purification for the RAFT polymerization of styrene in water in the same reactor. This simple and straightforward strategy leads to a very good control of the resulting amphiphilic block copolymers.