Molecular Weight Distribution Shape as a Versatile Approach to Tailoring Block Copolymer Phase Behavior

Gentekos, Dillon T.; Fors, Brett P.

doi:10.1021/acsmacrolett.8b00295

Cited by 61 publications

(65 citation statements)

References 42 publications

(56 reference statements)

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“…[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. [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. Several approaches have been developed to manipulate values.Blending polymers with different molecular weights is often applied.…”

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confidence: 99%

“…Several approaches have been developed to manipulate values.Blending polymers with different molecular weights is often applied. [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. 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.…”

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confidence: 99%

“…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) that uses alkyl iodides (RÀI) as dormant species and organic catalysts such as Bu 4 N + I À (BNI;s ee Scheme S1 in the Supporting Information).…”

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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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Polymer Dispersity Control by Organocatalyzed Living Radical Polymerization

2019

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“…Recently, Fors et al. elegantly varied Đ and molecular weight distribution “shapes” by metering the addition of an initiator using a feeding pump in anionic and nitroxide‐mediated polymerizations . This approach was applied to homopolymers and the first segment of block copolymers but not to the other segments of block copolymers.…”

Section: Figurementioning

confidence: 99%

Polymer Dispersity Control by Organocatalyzed Living Radical Polymerization

2019

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Molecular weight distribution of polymers, termed dispersity (Đ), is a fundamental parameter for determining polymer material properties. This paper reports a novel approach for controlling Đ by exploiting a temperature‐selective radical generation in organocatalyzed living radical polymerization. The polymers with tailored Đ were synthesized in a batch system without the assistance of an external pump. A unique aspect of this approach is that Đ 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. The approach also generated polymer brushes on surfaces with tailored Đ. An interesting finding was that the polymer brushes exhibited unique interaction with external molecules, depending on the Đ value.

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“…12,13 Furthermore, there have been various reports on the inuence of block length and Đ on polymer microphase behaviour, which has a direct inuence on bulk properties. [14][15][16][17][18][19] While these reports provide important information regarding the inuence of block size and midblock MWD breadth on elastomeric properties, there remains an opportunity to use the entire endblock MWD shape as a means to ne-tune TPE properties.…”

Section: Introductionmentioning

confidence: 99%