The dispersion RAFT polymerizations mediated with monofunctional and bifunctional macro-RAFT agents were comparatively studied, in which different block copolymer morphologies were detected.

A new multi-stimuli-responsive homopolymer of poly [N-[2-(diethylamino)ethyl]acrylamide] (PDEAEAM), which combines the thermoresponsive and pH/CO 2 -responsive moieties of the diethylamino and acrylamide groups, was proposed and synthesized by RAFT polymerization. Well-defined PDEAEAM was synthesized by solution RAFT polymerization as indicated by the linear increase in the polymer molecular weight with the monomer conversion and the narrow molecular weight distribution. The appending diethylamino group in the polymer backbone was found to be crucial to determine the thermoresponse of PDEAEAM in water. The parameters including the polymerization degree, the polymer concentration, the deuterated solvent, the terminal attached on the polymer backbone, the additives of salt and urea, and pH and bubbling CO 2 affecting the thermoresponse of PDEAEAM in aqueous solution at the lower critical solution temperature (LCST) were investigated. The temperature-variable 1 H NMR analysis suggests that the dehydration of PDEAEAM at temperature above LCST is ascribed to the weakened hydrogen bonding between the CONHCH 2 and/or (CH 2 N(CH 2 CH 3 ) 2 ) moieties with the solvent of water. The proposed multi-stimuli-responsive homopolymer of PDEAEAM has two advantages of (1) the convenient and controllable RAFT synthesis and (2) the pH/CO 2 tunable LCST at ∼36 °C being very close to body temperature.

Doubly thermo-responsive triblock copolymer nanoparticles are prepared by a dispersion RAFT polymerization and the nanoparticles exhibit a two-step phase-transition with increasing temperature.

Synthesis of ingenious nanoassemblies is pursued in materials science. Herein, the in situ synthesis of the self-assembled blends of AB/BAB block copolymers of poly(ethylene glycol)-block-polystyrene/polystyrene-blockpoly(ethylene glycol)-block-polystyrene (PEG-b-PS/PS-b-PEG-b-PS) via two-macro-RAFT agent comediated dispersion polymerization is reported. The synthesis strategy combines the advantages of polymer blending and polymerizationinduced self-assembly. Following this strategy, various nanoassemblies of PEG-b-PS/PS-b-PEG-b-PS blends such as high-genus compartmentalized vesicles, multilayer and bicontinuous nanoassemblies, and porous nanospheres are prepared. The parameters, such as PEG-b-PS/PS-b-PEG-b-PS molar ratio, polymerization degree of the PS block, and fed monomer concentration, affecting morphology/structure of PEG-b-PS/PS-b-PEG-b-PS self-assembled blends are revealed.Computer simulations of self-assembly of the AB/BAB blends are performed, and nanoassemblies similar to those observed in our experiments are obtained, indicating that these morphologies are close to thermodynamical equilibrium. The formation mechanism of compartmentalized vesicles is investigated. The proposed strategy of two-macro-RAFT agent comediated dispersion polymerization is considered to be an efficient approach to construct selfassembled blends of block copolymers.

A new formulation of polymerization-induced self-assembly in poly(ethylene glycol) (PEG) named PEG-PISA to synthesize diblock copolymer nanoassemblies via macromolecular RAFT agent mediated dispersion polymerization is reported. In PEG-PISA, the viscous PEG with molecular weight ranging from 200 to 1000 Da is used as polymerization medium. The utilization of the viscous PEG as the polymerization medium affords the advantages including fast polymerization rate, good control over the synthesis of diblock copolymers, and in situ synthesis of both amphiphilic and doubly hydrophobic diblock copolymer nanoassemblies at polymer concentration of up to 50%. Also ascribed to the viscous polymerization medium of PEG, two new and/or interesting diblock copolymer nanoassemblies of ellipsoidal vesicles and nanotubes are formed via PEG-PISA, and the reason on formation of ellipsoidal vesicles and nanotubes is discussed. The proposed PEG-PISA is anticipated to be an effective method to synthesize block copolymer nanoassemblies combining the advantages of alcoholic/aqueous PISA and versatility of poly(ethylene glycol).

Flower-like triblock copolymer nanoparticles containing a central looped solvophilic block and two outer solvophobic blocks are prepared by seeded dispersion RAFT polymerization.

The micellar macro-RAFT agent-mediated dispersion polymerization of styrene in the methanol/water mixture is performed and synthesis of temperature-sensitive ABC triblock copolymer nanoparticles is investigated. The thermoresponsive diblock copolymer of poly(N,N-dimethylacrylamide)block-poly[N-(4-vinylbenzyl)-N,N-diethylamine] trithiocarbonate forms micelles in the polymerization solvent at the polymerization temperature and, therefore, the dispersion RAFT polymerization undergoes as similarly as seeded dispersion polymerization with accelerated polymerization rate. With the progress of the RAFT polymerization, the molecular weight of the synthesized triblock copolymer of poly(N,N-dimethylacrylamide)-block-poly[N-(4-vinylbenzyl)-N,N-diethylamine]-b-polystyrene linearly increases with the monomer conversion, and the PDI values of the triblock copolymers are below 1.2. The disper-sion RAFT polymerization affords the in situ synthesis of the triblock copolymer nanoparticles, and the mean diameter of the triblock copolymer nanoparticles increases with the polymerization degree of the polystyrene block. The triblock copolymer nanoparticles contain a central thermoresponsive poly [N-(4-vinylbenzyl)-N,N-diethylamine] block, and the soluble-toinsoluble phase-transition temperature is dependent on the methanol content in the methanol/water mixture.

This review focuses on the synthesis of multicompartment block copolymer nanoparticles (MBCNs) via solution self-assembly and polymerization-induced self-assembly (PISA).