Preparation of micron-sized, monodispersed, "onion-like" multilayered poly(methyl methacrylate)/polysterene composite particles by reconstruction of morphology with the solvent-absorbing /releasing method

Okubo, Masayoshi; Takekoh, Ryu; Izumi, Jin

doi:10.1007/s003960100489

Cited by 21 publications

(23 citation statements)

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“…Overall, this multilayered morphology demonstrated is an impressive result that shows how both the number and the composition of each layer of the nano-engineered particles can be readily controlled via a judicious choice of monomers in each step of the sequential RAFT emulsion polymerization. Although particles of similar onion-layered structures have been reported using other approaches, − the present work represents (to the best of our knowledge) the first time that the number of layers of nano-engineered particles can be accurately controlled. Furthermore, on the basis of the previous strategies reported, − a multilayered particle with versatile control of the composition of each layer would not be readily accessibleor close to impossible to achieveas self-assembly approaches based on diblock copolymers (i.e., only two monomer types) were employed.…”

Section: Resultsmentioning

confidence: 89%

“…Although particles of similar onion-layered structures have been reported using other approaches, − the present work represents (to the best of our knowledge) the first time that the number of layers of nano-engineered particles can be accurately controlled. Furthermore, on the basis of the previous strategies reported, − a multilayered particle with versatile control of the composition of each layer would not be readily accessibleor close to impossible to achieveas self-assembly approaches based on diblock copolymers (i.e., only two monomer types) were employed. Our strategy can, in principle, be extended to multiple monomer types.…”

Section: Resultsmentioning

confidence: 89%

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Nano-Engineered Multiblock Copolymer Nanoparticles via Reversible Addition–Fragmentation Chain Transfer Emulsion Polymerization

et al. 2019

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Block copolymers composed of polymer segments of sufficiently high molecular weight such that microphase separation and self-assembly into complex nanostructured materials can occur provide a pathway to a myriad of nano-engineered materials with applications ranging from nanomedicine to materials science and microelectronics. In the present work, we have developed a methodology based on reversible addition−fragmentation chain transfer polymerization that allows the synthesis of multiblock copolymers based on sequential aqueous emulsion polymerization using the three most common industrially employed monomer families in emulsion polymerization systems: methacrylates, acrylates, and styrene. By exploiting the segregation effect (compartmentalization) resulting from polymerization within polymeric nanoparticles, a high molecular weight multiblock copolymer (up to 140,000 g•mol −1 ) is obtained in a relative short time period of 3 h for each cycle of polymerization. The concept of nano-engineering of polymer nanoparticle morphology is demonstrated by exploiting the ability to covalently link numerous polymer blocks that are chemically incompatible, resulting in microphase separation and the formation of a well-defined multilayered structure within the nanoparticles. The method developed is environmentally friendly (use of water as solvent) and fulfills all requirements for scale up to an industrial process using existing industrial equipment such as no intermediate purification steps, relatively high solid content, good colloidal stability with no flocculation/coagulation, and near full monomer conversion.

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 89%

Nano-Engineered Multiblock Copolymer Nanoparticles via Reversible Addition–Fragmentation Chain Transfer Emulsion Polymerization

et al. 2019

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“…Here, we emphasize that in this article the spaced concentric vesicles (SCVs) refer to the concentric vesicles with uniform spacing between the walls, which is different from another type of concentric vesicle in which there is no spacing between the walls. The latter is relatively easy to fabricate and has been successfully prepared via self-assembling strategy, also directly from polymerization . However, fabrication of the SCVs via PISR strategy has not been reported.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Spaced Concentric Vesicles and Polymerizations in RAFT Dispersion Polymerization

2014

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Different from concentric vesicles without spacing between the walls, the concentric vesicles with uniform spacing between the walls were rarely fabricated. We successfully fabricate the spaced concentric vesicles (SCVs) via RAFT dispersion polymerization, and continuous propagation of the residual polymer chains inside the large vesicles induces self-assembling to form SCVs. Concentration of the residual polymer chains in the solution of the nascent-formed vesicles is the determining factor for formation of SCVs, and continuous propagation of less or too more residual polymer chains will not form SCVs but form other morphologies. Generally, the concentration of the residual polymer chains after formation of vesicles is too low to self-assemble, so formation of SCVs is impossible. By adjusting the ratio of St/methanol or macro-RAFT agent P4VP-b-PS/P4VP, the concentration of residual polymer chains can be controlled, and further control of the morphologies is achieved. Formation of the inner vesicles by self-assembling inside the large vesicles requires high molecular weight of the polymer chains due to their very low concentration. The polymers of inner vesicles possess very high molecular weight (×10 6 g/mol) in comparison with the polymer of outmost vesicles (×10 5 g/mol). Polymerization kinetic study reveals very high increasing rate of the molecular weight inside the vesicles probably owing to long duration of the chain radicals, and the polymerization rate (R p ) inside the vesicles is faster than the R p in the outmost vesicles, but both rates are in the same order. ■ INTRODUCTIONAs one of the efficient strategies for fabrication of nanostructural materials, the polymerization-induced self-assembly and reorganization (PISR) has been used to create a broad range of intricate polymeric nanomaterials. 1,2 The polymerizations used for this purpose include living anionic and living radical polymerizations, especially reversible addition−fragmentation transfer (RAFT) dispersion polymerization. 3 The factors influencing the polymer aggregates involve recipe, nature of starting materials, and reaction conditions. When the precipitator of one block chain is used as media of the RAFT dispersion polymerization, only spherical micelles are formed because a significant decrease of the polymerization rate in the spheres formed by microphase separation leads to transition of the spherical micelles to other morphologies impossible. 4,5 One feasible method for solving this problem is to minimize decrease of the polymerization rate after phase separation because one determining factor of morphologies formed via self-assembling strategy is chain length ratio of two blocks in the diblock copolymers, 6 which can be achieved by increasing concentration of the monomers in the cores of micelles. Consider monomer distribution between two phases formed by phase separation, two methods, enhancing initial monomer concentration and lowering solubility of the monomer in the reaction media, can be used for this purpose. Polymerization w...

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“…An alternative and entirely different synthetic route to multilayered particles entails the initial preparation of micron-sized, monodisperse poly(methyl methacrylate) (PMMA)/polystyrene (PS) core-shell particles by seeded dispersion polymerization (SDP) of styrene (S) with PMMA seed particles in ethanol/water. These core-shell particles had a thermodynamically unstable morphology (kinetic as opposed to thermodynamic morphology control) [20,21]. Swelling of the particles with a good solvent allowed formation of the thermodynamically stable morphology, a multilayered "onion-like" structure, which was "fixed" by subsequent evaporation of the solvent [22].…”

Section: Introductionmentioning

confidence: 99%

Preparation of onion-like multilayered particles comprising mainly poly(iso-butyl methacrylate)-block-polystyrene by two-step AGET ATRP

Kitayama

Yorizane

Kagawa

et al. 2009

Polymer

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Synthesis of multilayered composite polymer particles comprising mainly poly(iso-butyl methacrylate)-block-polystyrene (PiBMA-b-PS) has been carried out by use of two-step activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) in aqueous microsuspension. PiBMA-Br macroinitiator seed particles were prepared in the first step, followed by swelling with styrene and subsequent second step (seeded) polymerization. The blocking efficiency in the second step was found to be crucial with regards to the resulting particle morphology. A disordered sea-island morphology was obtained when the blocking efficiency was 47% (73% conversion), whereas a blocking efficiency of 61% (71% conversion) resulted in formation of multilayered particles. High blocking efficiency can be achieved by careful adjustment of the activation rate by proper choice of polymerization temperature and amount of reducing agent (ascorbic acid).

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Preparation of micron-sized, monodispersed, "onion-like" multilayered poly(methyl methacrylate)/polysterene composite particles by reconstruction of morphology with the solvent-absorbing /releasing method

Cited by 21 publications

References 0 publications

Nano-Engineered Multiblock Copolymer Nanoparticles via Reversible Addition–Fragmentation Chain Transfer Emulsion Polymerization

Nano-Engineered Multiblock Copolymer Nanoparticles via Reversible Addition–Fragmentation Chain Transfer Emulsion Polymerization

Fabrication of Spaced Concentric Vesicles and Polymerizations in RAFT Dispersion Polymerization

Preparation of onion-like multilayered particles comprising mainly poly(iso-butyl methacrylate)-block-polystyrene by two-step AGET ATRP

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