Room-temperature phosphorescence (RTP) polymers have attracted much attention due to their advantages, such as easy processing, low cost, and good biocompatibility. Herein, we present a new strategy for the design...
Polymerization-induced self-assembly (PISA) is a robust strategy for the syntheses of block copolymer nano-objects with various morphologies. Although PISA has been extensively studied, the use of cyclic macromolecular chain transfer agents (macroCTAs) as the hydrophilic block has not been reported. We explored the effects of macroCTA topology on the polymerization kinetics and morphologies of block copolymer assemblies during reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization. To this end, linear and cyclic poly (ethylene oxide) (PEO) with 4-(4-cyanopentanoic acid) dithiobenzoate (CPADB) groups were synthesized and used as CTAs to mediate the RAFT polymerization of benzyl methacrylate (BzMA) and 2,3,4,5,6-pentafluorostyrene (PFSt) under PISA formulation. Interestingly, the nucleation period of the linear PEO is slightly shorter than that of its cyclic analog, and the cyclic hydrophilic segment leads to a delayed morphological transition during PISA.
Polymerization-induced self-assembly (PISA) has been demonstrated as a robust method for the preparation of polymeric nanoparticles with various morphologies in high solid content. Developing efficient methods for the direct recognition of the morphologies of copolymer nanoparticles during PISA in a low-cost and simple manner is of practical significance. Herein, we proposed a fluorescent chroma method that enabled the direct recognition of the morphologies of copolymer nano-objects in the PISA process. Methacrylate monomer bearing pyrene fluorophore (PyAMA) with a broad emission region was first synthesized, which exhibited blue monomeric fluorescence and produced green excimer emission when stacked together in a dimer state. PyAMA was then used as a comonomer during the RAFT dispersion polymerization of benzyl methacrylate (BzMA) using 4-cyano-4-(2phenylethanesulfanyl-thiocarbonyl)sulfanylpentanoic acid (PETTC) capped poly(ethylene oxide) (PEO-PETTC) as a macromolecular chain transfer agent (macroCTA). Accompanying with the morphological transformation from micelles to nanowires to vesicles, the fluorescent color of the copolymer nanoparticles underwent the variation from blue to cyan to green due to the increased emission ratio of pyrene excimer to monomer (I excimer /I monomer ), and the direct observation of the nanostructural changes during PISA by naked eyes was realized. Furthermore, an easy-to-use smartphone program was elaborately designed to simplify the morphological recognition based on the fluorescent colors for different morphologies. This strategy provides a facile platform to monitor the morphological evolutions during PISA and realizes the preassessment of the morphologies of PISA-generated nanoparticles.
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