In Situ and Time-Resolved Small-Angle Neutron Scattering Observation of Star Polymer Formation via Arm-Linking Reaction in Ruthenium-Catalyzed Living Radical Polymerization

Terashima, Takaya; Motokawa, Ryuhei; Koizumi, Satoshi; Sawamoto, Mitsuo; Kamigaito, Masami; Ando, Tetsu; Hashimoto, Takeji

doi:10.1021/ma101235j

Cited by 46 publications

(47 citation statements)

References 83 publications

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“…Finally, TR-SANS has been applied to observe structural changes during miniemulsion polymerisation 144 and a living radical polymerization to form a microgel-core star polymer. 145 Again, the application of TR-SANS is appropriate given the wealth of knowledge on the modelling of SANS data from polymer solutions. 35 For the formation of microgel-core star polymers, two stages were followed: (a) the process to form the poly(methyl methacrylate), PMMA arms and (b) their linking to form stars.…”

Section: Time-resolved Sans (Tr-sans)mentioning

confidence: 99%

Practical applications of small-angle neutron scattering

Hollamby

2013

Phys. Chem. Chem. Phys.

120

116

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Recent improvements in beam-line accessibility and technology have led to small-angle neutron scattering (SANS) becoming more frequently applied to materials problems. SANS has been used to study the assembly, dispersion, alignment and mixing of nanoscale condensed matter, as well as to characterise the internal structure of organic thin films, porous structures and inclusions within steel.Using time-resolved SANS, growth mechanisms in materials systems and soft matter phase transitions can also be explored. This review is intended for newcomers to SANS as well as experts. Therefore, the basic knowledge required for its use is first summarised. After this introduction, various examples are given of the types of soft and hard matter that have been studied by SANS. The information that can be extracted from the data is highlighted, alongside the methods used to obtain it. In addition to presenting the findings, explanations are provided on how the SANS measurements were optimised, such as the use of contrast variation to highlight specific parts of a structure. Emphasis is placed on the use of complementary techniques to improve data quality (e.g. using other scattering methods) and the accuracy of data analysis (e.g. using microscopy to separately determine shape and size). This is done with a view to providing guidance on how best to design and analyse future SANS measurements on materials not listed below.

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Section: Time-resolved Sans (Tr-sans)mentioning

confidence: 99%

Practical applications of small-angle neutron scattering

Hollamby

2013

Phys. Chem. Chem. Phys.

120

116

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“…Recently, Terashima et al [18] determined, via in situ smallangle neutron scattering experiments, that three distinct and sequential processes occur during the core cross-linking step: (1) reactive block copolymer formation, (2) polymer linking to form CCS polymers, and (3) growth of CCS polymers. During these processes, termination reactions lead to the formation of ''dead'' polymers and ''dead'' block copolymers, [19]b i.e., polymers without carbon-halide functionality.…”

Section: Resultsmentioning

confidence: 99%

Highly Efficient Synthesis of Low Polydispersity Core Cross‐Linked Star Polymers by Ru‐Catalyzed Living Radical Polymerization

Goh

Yamashita

Satoh

et al. 2011

Macromol. Rapid Commun.

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The efficient formation of low polydispersity core cross-linked star (CCS) polymers via controlled/living radical polymerization (LRP) and the arm-first approach was found to be dependent on the mediating catalyst system. The Ru catalyst, Ru(Ind)Cl(PPh₃)₂ Cat. 1, and tertiary amine co-catalyst were used to synthesize highly living poly(methyl methacrylate) (PMMA) macroinitiators, which were then linked together with ethylene glycol dimethacrylate (EGDMA) to form PMMA(arm)PEGDMA(core) CCS polymers. The quantitative and near-quantitative synthesis of CCS polymers were observed for low to moderate molecular weight macroinitiators (M(n) = 8 and 20 kDa), respectively. Lower conversions were observed for high-molecular weight macroinitiators (M(n) ≥ 60 kDa). Overall, an improvement of between 10 and 20% was observed when comparing the Cat. 1 system to a conventional Cu-catalyzed system. This significant improvement in macroinitiator-to-star conversion is explained in the context of catalyst system selection and CCS polymer formation.

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“…Local crosslinking of polymer chains and their aggregates is a key technology to build soluble functional macromolecules of stable three-dimensional architecture in various solvents and environments. [1][2][3][4][5] Microgel-core star polymers [1][2][3][4][6][7][8][9][10][11][12] are representative core-shell macromolecules carrying a microgel core that is covered by multiple linear arm polymers. The crosslinked core not only serves to maintain the star-branched structure in various environments but also provides unique nano compartments for catalysis [8][9][10][11] and molecular encapsulation and release.…”

Section: Introductionmentioning

confidence: 99%

Single-chain crosslinked star polymers via intramolecular crosslinking of self-folding amphiphilic copolymers in water

Terashima

Sugita

Sawamoto

2015

Polym J

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Single-chain crosslinked star polymers with hydrophilic multiple short arms and a hydrophobic core were created as novel microgel star polymers of single polymer chains. The synthetic process involves the intramolecular crosslinking of self-folding amphiphilic random copolymers in water. For this, amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic olefin pendants were synthesized by ruthenium-catalyzed living radical copolymerization of PEG methyl ether methacrylate, dodecyl methacrylate, and hydroxyl-functionalized methacrylates, and the in-situ or post esterification of the hydroxyl pendants of the resulting copolymers with methacryloyl chloride. The olefin-bearing copolymers with 20-40 mol% hydrophobic units efficiently self-folded with hydrophobic interaction in water and were crosslinked intramolecularly using a free radical initiator or a ruthenium catalyst to selectively provide single-chain crosslinked star polymers, while a counterpart with 50 mol% hydrophobic units induced bimolecular aggregation in water to give double-chain crosslinked star polymers. Primary structure of the star polymers can be precisely controlled with random copolymer precursors. Owing to PEG arm units, the star polymers further showed thermosensitive solubility in water.

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In Situ and Time-Resolved Small-Angle Neutron Scattering Observation of Star Polymer Formation via Arm-Linking Reaction in Ruthenium-Catalyzed Living Radical Polymerization

Cited by 46 publications

References 83 publications

Practical applications of small-angle neutron scattering

Practical applications of small-angle neutron scattering

Highly Efficient Synthesis of Low Polydispersity Core Cross‐Linked Star Polymers by Ru‐Catalyzed Living Radical Polymerization

Single-chain crosslinked star polymers via intramolecular crosslinking of self-folding amphiphilic copolymers in water

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