Advanced Materials by Atom Transfer Radical Polymerization

Matyjaszewski, Krzysztof

doi:10.1002/adma.201706441

Cited by 534 publications

(388 citation statements)

References 298 publications

(343 reference statements)

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“…[68] Therefore, another important parameter affecting the network shear modulus is the crosslink density, [7,24,33,34,69] or the DP of the bottlebrush backbone between crosslinks, n x . These elastomers have intrinsic supersoft and superelastic properties without additional solvents and are promising candidates for synthetic substitutes of biological tissues.…”

Section: Diluted Plateau Shear Modulusmentioning

confidence: 99%

Comb and Bottlebrush Polymers with Superior Rheological and Mechanical Properties

2019

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combined with the grafting-to method [1,10] results in comb polystyrenes (PSs) with well-entangled monodisperse backbone and side chains; however, branch points along the backbone are randomly distributed. This random distribution of branch points has no distinct effect on the rheological properties of dense comb topologies; however, it will broaden the backbone relaxation time of loose comb topologies even though the molecular weight distribution is narrow enough. [11] A controlled branching point spacing can be achieved through the coupling of living macroanions; [12] however, this method is prone to slightly high molecular weight distribution, Ð > 1.5. Synthesis of welldefined densely grafted bottlebrushes using ROMP and grafting-through method guarantees the presence of one side chain per repeating unit on the backbone. Bottlebrushes with more than one branch per backbone repeating unit can also be synthesized using ROMP and macromonomers with more bulky groups referred as wedge polymers. [13] These bottlebrushes are similar to that of the dendronized polymer with only one layer of grafting. Loosely grafted bottlebrushes with longer distance between the branching points can be achieved using ROMP technique through copolymerization of macromonomer and a diluent molecule, e.g., racemic endo,exo-norbornenyl diesters, with different ratios. However, different reactivity of macromonomer and diluent leads to a gradient of branching point spacing along the backbone, [14] where the conformations of side chains along the backbone are affected by this gradient. [15] It should be mentioned that the bottlebrushes synthesized with ROMP technique have different repeating units in the backbone than the side chains which might cause microphase separation. However this issue could be ignorable in dense bottlebrushes where the volume fraction of backbone is less than 1 wt%. In order to avoid any microphase separation, Sheiko and co-workers [16] synthesized a series of dense combs and loose bottlebrushes homo poly(n-butyl acrylates) (PBA) with similar side chains and systematically varied grafting density through copolymerization of nonfunctional n-butyl acrylates with trimethylsilyl-protected acrylates by ATRP. However, in order to achieve high degree of polymerization (DP) of backbone (entangled system) for dense bottlebrushes, they had to use slightly different backbones, i.e., poly(n-butyl methacrylate). An organometallic coordinative insertion polymerization of α-olefins results in entangled densely grafted bottlebrushes with rod-like side chains where both backbone and side chains have alkane groups. However the dispersity index of such homopolymer bottlebrushes would Comb and bottlebrush polymers present a wide range of rheological and mechanical properties that can be controlled through their molecular characteristics, such as the backbone and side chain lengths as well as the number of branches per molecule or the grafting density. This review investigates the impact of these characteristics specifically on the zero sh...

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Section: Diluted Plateau Shear Modulusmentioning

confidence: 99%

Comb and Bottlebrush Polymers with Superior Rheological and Mechanical Properties

2019

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“…

Molecular weight distribution of polymers,t ermed dispersity ( = M w /M n ), is afundamental parameter in determining polymer properties such as processability,viscoelasticity,and self-assembly behaviors,w here M w and M n are the weightand number-average molecular weights,r espectively.

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confidence: 99%

Polymer Dispersity Control by Organocatalyzed Living Radical Polymerization

2019

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Molecular weight distribution of polymers,t ermed dispersity (), is af undamental parameter for determining polymer material properties.T his paper reports an ovel approach for controlling by exploiting at emperatureselective radical generation in organocatalyzed living radical polymerization. The polymers with tailored were synthesized in ab atch system without the assistance of an external pump.Aunique aspect of this approach is that was tuneable from 1.11 to 1.50 in any segment in diblock, triblock, and multiblock copolymers and in any form of star and brush polymer without segmental or topological restriction. This approach is amenable to various monomers and free from metals and thus attractive for applications.T he approach also generated polymer brushes on surfaces with tailored .A n interesting finding was that the polymer brushes exhibited unique interaction with external molecules,d epending on the value.Molecular weight distribution of polymers,t ermed dispersity ( = M w /M n ), is afundamental parameter in determining polymer properties such as processability,viscoelasticity,and self-assembly behaviors,w here M w and M n are the weightand number-average molecular weights,r espectively. [1][2][3][4][5][6] Living radical polymerization (LRP) facilitates the synthesis of polymers with small values,a sw ell as pre-determined molecular weights and sophisticated architectures. [7][8][9][10][11][12] However,p olymers with large values are occasionally desired for improved physical properties such as miscibility and processability,a nd the manipulation of in LRP is an important topic but still challenging. Several approaches have been developed to manipulate values.Blending polymers with different molecular weights is often applied. [13][14][15] Thep olymers need to be prepared in multiple independent runs,a nd the blended polymers often have multimodal molecular weight distribution. By optimizing the polymerization conditions such as catalyst loadings, initiators,temperatures,and additional chain-transfer agents, the was modulated at 1.1-2.0 in LRP. [16][17][18] However,t he attained large usually arose from inefficient control in LRP. Thus,t he obtained polymers hardly undergo further chain extension. Recently,F ors et al. elegantly varied and molecular weight distribution "shapes" by metering the addition of an initiator using af eeding pump in anionic and nitroxide-mediated polymerizations. [19][20][21][22] This approach was applied to homopolymers and the first segment of block copolymers but not to the other segments of block copolymers.B oyer et al. recently metered the addition of the polymeric initiator (macro-initiator) in ap hotocontrolled LRP and successfully obtained block copolymers with tailored in the second segment. [23,24] However, the pumpassisted method is always inapplicable to heterogeneous systems,s uch as polymer brush synthesis from solid substrates,a nd thus limits applications.We have developed an organocatalyzed LRP,t hat is, reversible complexation mediated polymerization (RCMP) t...

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“…Living radical polymerization (LRP)30–34 (also termed reversible deactivation radical polymerization) is a robust and versatile tool to synthesize well‐defined polymers and has been utilized in the synthesis of ABC‐type miktoarm stars. Different LRP techniques such as nitroxide‐mediated radical polymerization, atom transfer radical polymerization, and reversible addition‐fragmentation chain transfer polymerization, were combined to synthesize stars bearing three different arms through the “coupling‐onto” and “combinatorial” approaches 35,36.…”

Section: Synthesis Of Abc Miktoarm Star Copolymersmentioning

confidence: 99%

Synthesis of ABC Miktoarm Star Copolymers via Organocatalyzed Living Radical Polymerization

Chen

Sim

et al. 2020

Macromol. Rapid Commun.

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ABC‐type miktoarm star copolymers are synthesized using a single living radical polymerization (organocatalyzed living radical polymerization) via a “combinatorial” approach. The arm A is poly(butyl acrylate), the arm B is poly(methyl methacrylate), and the arm C encompasses hydrophobic and hydrophilic polyacrylates. A poly(butyl acrylate) with a vinyl chain end (macromonomer) is synthesized. A poly(methyl methacrylate) is subsequently connected to the reactive vinyl group to generate diblock copolymer. From the junction of the diblock copolymer, polymer C grew to yield star copolymers. An amphiphilic star copolymer is also synthesized, and its self‐assembly structure is studied in an aqueous solution.

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Advanced Materials by Atom Transfer Radical Polymerization

Cited by 534 publications

References 298 publications

Comb and Bottlebrush Polymers with Superior Rheological and Mechanical Properties

Comb and Bottlebrush Polymers with Superior Rheological and Mechanical Properties

Polymer Dispersity Control by Organocatalyzed Living Radical Polymerization

Synthesis of ABC Miktoarm Star Copolymers via Organocatalyzed Living Radical Polymerization

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