Effect of Stabilizer on Formation of “Onionlike” Multilayered Polystyrene-<i>block</i>-poly(methyl Methacrylate) Particles

Saito, Naohiko; Takekoh, Ryu; Nakatsuru, Reiko; Okubo, Masayoshi

doi:10.1021/la063654f

Cited by 59 publications

(63 citation statements)

References 54 publications

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“…In this context, controlled radical polymerization, including the three different methods (nitroxide-mediated radical polymerization (NMP) [1], atom transfer radical polymerization (ATRP) [2] and reversible addition fragmentation chain-transfer polymerization (RAFT) [3]), has in the past years emerged as a technique of choice to prepare block, graft or comb copolymers of precise molecular and chemical structure. These types of polymers are increasingly involved in traditional structural materials [4] as well as in higher added value applications such as core-shell functional nanoparticles [5], organic/inorganic nanoparticles [6] or block copolymer lithography [7,8]. For the development of materials with unique combinations of properties, the self-assembling capability of block copolymers and the resulting regular nanostructures are indeed highly appreciated.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, Okubo et al reported two main approaches to prepare nanostructured polymer particles [6,10,11,12]. In the first approach, multilayered polystyrene/poly(methyl methacrylate) composite microparticles were prepared by the so-called solvent-absorbing/releasing method [6,10,11], using either graft copolymers (polystyrene- g -polymethyl methacrylate) or block copolymers (polystyrene- b -polymethyl methacrylate) as compatibilizers. In the second approach, they used two-step ATRP miniemulsion polymerization process to prepare poly( i -butyl methacrylate)- b -polystyrene nanostructured latex particles [12].…”

Section: Introductionmentioning

confidence: 99%

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Mechanical and Morphological Properties of Waterborne ABA Hard-Soft-Hard Block Copolymers Synthesized by Means of RAFT Miniemulsion Polymerization

et al. 2019

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High molecular weight waterborne ABA block copolymers of styrene (St) and 2-ethylhexyl acrylate (2EHA) containing hard and soft domains were synthesized by means of RAFT (mini)emulsion polymerization using a bifunctional symmetric S,S-dibenzyl trithiocarbonate (DBTTC) RAFT agent. Miniemulsion polymerization was initially used for the synthesis of the A-block, which forms hard domains, followed by 2EHA pre-emulsion feeding to build the B-block soft domains. Polymerization kinetics and the evolution of the Molecular Weight Distribution (MWD) were followed during the synthesis of different ABA block copolymers. The thermal properties of the final symmetric block copolymers were studied on dried films by means of DSC. It was found that the block copolymers have two glass transitions, which indicates the presence of a two-phase system. Phase separation was investigated by means of microscopic techniques (AFM and TEM) and SAXS, both of the particles in the latex form, as well as after film formation at room temperature and after different post-treatments. Films were annealed at temperatures well above the glass transition temperature (Tg) of the hard phase to study the bulk morphology of the films after complete particle coalescence. Moreover, for comparison purposes, the films were re-dissolved in THF, and films were again cast directly from the homogeneous THF solutions. As THF is a good solvent for both blocks, such films serve as a reference for the equilibrium morphology. Finally, DMTA studies of the films annealed at different temperatures were performed to correlate the morphology changes with the mechanical properties of the block copolymers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanical and Morphological Properties of Waterborne ABA Hard-Soft-Hard Block Copolymers Synthesized by Means of RAFT Miniemulsion Polymerization

et al. 2019

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“…However, because methods for modifying the surfaces of such confining geometries have not been well-developed, many studies have not considered wall effects. [20][21][22] This is especially true of confining geometries with a mobile interfacial boundary, in which the dynamics of the interface may affect the shape of the confining geometry as well as the internal phase morphology. Here, we explored the interface-driven morphological evolution of a symmetric diblock copolymer of polystyreneblock-polybutadiene (PS-b-PB) confined in oil-in-water emulsion droplets.…”

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confidence: 99%

Cooperative Assembly of Block Copolymers with Deformable Interfaces: Toward Nanostructured Particles

2008

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Block copolymers, which consist of chemically distinct polymer blocks, exhibit a variety of self-assembled ordered nanophases such as spheres, cylinders, and lamellae depending on their compositions, volume fractions, and molecular weights.[1] These block copolymer self-assemblies have great potential as templates for fabricating functional devices with nanoscopic periodicities. [2] In particular, recent studies have demonstrated that block copolymers confined in two-and three-dimensional geometries self-assemble into ordered phase-separated domains that are observed in the bulk or anomalous microscopic phases such as helices and tori with improved directional order, [3][4][5][6][7][8][9][10][11][12][13][14] which is based on pioneering works on block copolymer self-assembly in one-dimensional confined geometries. [15][16][17][18][19] These previous studies have focused mainly on the commensurability between the characteristic length of the confining geometry and the block copolymer domain spacing. However, because methods for modifying the surfaces of such confining geometries have not been well-developed, many studies have not considered wall effects. [20][21][22] This is especially true of confining geometries with a mobile interfacial boundary, in which the dynamics of the interface may affect the shape of the confining geometry as well as the internal phase morphology. Here, we explored the interface-driven morphological evolution of a symmetric diblock copolymer of polystyreneblock-polybutadiene (PS-b-PB) confined in oil-in-water emulsion droplets. To control the surface preferences of the constituent PS and PB blocks at the emulsion interface, a mixture of two designed amphiphilic diblock copolymers, polystyrene-block-poly(ethylene oxide) (PS-b-PEO) and polybutadiene-block-poly(ethylene oxide) (PB-b-PEO), was used as a surfactant. In addition, we added PS homopolymer (hPS) in the emulsion phase to modify the nanoscopic features of the self-assembled morphologies. The emulsion drops with deformable interface-driven internal morphologies were solidified by evaporating the solvent, yielding blend particles of PS-b-PB and hPS with unique external shapes and internal morphologies (as illustrated schematically in Scheme 1). These colloidal particles with nanoscopic internal structures are potentially applicable to various particle-based technologies such as photonic bandgap materials, [23,24] conductive particles for anisotropic conductive films based on block copolymer/ metal nanoparticle composites, [25,26] porous particles, [27] optical actuation in microfluidic chips, [28] optochemical sensing devices, [29] and catalytic supports. [22,30] To the best of our knowledge, this is the first report on the structural evolution of a block copolymer driven by controlling the dynamics of the mobile interface and the commensurability of the block copolymer confined in emulsion droplets. In the present system, there are two compositional parameters: the volume fraction (F) of hPS out of the total volume of hPS and PS-b-...

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“…Half-spherical structures are accessible by removing the liquid in acorn structures formed with a polymer and a liquid [40,61]. Onion-like structures are created from block copolymers, for which the phase separation into lamellae causes layered structures that follows the curvature of the particle where they are confined [37,40,62]. The diameter of the particle is in this case also very important.…”

Section: Colloidal Structuresmentioning

confidence: 99%

Recent Advances in the Emulsion Solvent Evaporation Technique for the Preparation of Nanoparticles and Nanocapsules

Staff

Landfester

Crespy

2013

Hierarchical Macromolecular Structures: 60 Years After the Staudinger Nobel Prize II

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The emulsion solvent evaporation technique is a method for preparing nanoparticles and nanocapsules that are particularly adapted for applications requiring materials with high purity and low toxicity, such as for biomedicine or electronics. We discuss here new important advances concerning the elucidation of the mechanism of nanoparticle formation, and the synthesis of nanoparticles with new structures or from new polymers.

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Effect of Stabilizer on Formation of “Onionlike” Multilayered Polystyrene-block-poly(methyl Methacrylate) Particles

Cited by 59 publications

References 54 publications

Mechanical and Morphological Properties of Waterborne ABA Hard-Soft-Hard Block Copolymers Synthesized by Means of RAFT Miniemulsion Polymerization

Mechanical and Morphological Properties of Waterborne ABA Hard-Soft-Hard Block Copolymers Synthesized by Means of RAFT Miniemulsion Polymerization

Cooperative Assembly of Block Copolymers with Deformable Interfaces: Toward Nanostructured Particles

Recent Advances in the Emulsion Solvent Evaporation Technique for the Preparation of Nanoparticles and Nanocapsules

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