Unexpected Consequences of Block Polydispersity on the Self-Assembly of ABA Triblock Copolymers

Widin, Joan M.; Schmitt, Adam K.; Schmitt, Andrew L.; Im, Kyuhyun; Mahanthappa, Mahesh K.

doi:10.1021/ja210548e

Cited by 199 publications

(274 citation statements)

References 71 publications

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“…While the molecular weight distributions are not as narrow as can be obtained for the individual homopolymers using other RAFT agents, the dispersity may in fact lead to improved stabilization and/or new phases. [43,[46][47][48][49] Thus we believe that this particular approach and RAFT agent may be useful for the production of other block copolymers consisting of monomers with different reactivities. Table 2 for polymer details).…”

Section: Discussionmentioning

confidence: 94%

RAFT Polymerization of Monomers with Highly Disparate Reactivities: Use of a Single RAFT Agent and the Synthesis of Poly(styrene-block-vinyl acetate)

2013

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A single reversible addition-fragmentation chain transfer (RAFT) agent, malonate N,N-diphenyldithiocarbamate (MDP-DTC) is shown to successfully mediate the polymerization of several monomers with greatly differing reactivities in radical/RAFT polymerizations, including both vinyl acetate and styrene. The chain transfer constants (C tr ) for MDP-DTC for both these monomers were evaluated; these were found to be ,2.7 in styrene and ,26 in vinyl acetate, indicating moderate control over styrene polymerization and good control of vinyl acetate polymerization. In particular, the MDP-DTC RAFT agent allowed for the synthesis of block copolymers of these two monomers without the need for protonation/ deprotonation switching, as has been previously developed with N-(4-pyridinyl)-N-methyldithiocarbamate RAFT agents, or other end-group transformations. The thermal properties of the block copolymers were studied using differential scanning calorimetry, and those with sufficiently high molecular weight and styrene composition appear to undergo phase separation. Thus, MDP-DTC may be useful for the production of other block copolymers consisting of monomers with highly dissimilar reactivities.

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Section: Discussionmentioning

confidence: 94%

RAFT Polymerization of Monomers with Highly Disparate Reactivities: Use of a Single RAFT Agent and the Synthesis of Poly(styrene-block-vinyl acetate)

2013

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“…Because of its lower surface energy compared with that of PDMS, the fluorine block migrated easier to the air-side during the drying process [2,32]. According to references, different aggregations could happen, showing layered, cylindrical, and spherical structures when the block length in a block copolymer changed [20,33,34]. The PDMS block in an "ABA" structured sample S4 was relatively short (f PDMS = 9.5%), while the fluorine block was longer.…”

Section: Surface Propertiesmentioning

confidence: 99%

Synthesis of POSS-containing fluorosilicone block copolymers via RAFT polymerization for application as non-wetting coating materials

Zhang

et al. 2015

Progress in Organic Coatings

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“…Although long time the idea was set that ordered microphases in block copolymers can be achieved only by a narrow dispersity, [68] some studies have demonstrated their self-assembly into well-ordered structures even presenting a broader molecular weight distribution (MWD). [69][70][71][72][73] Our starting materials for the blends exhibit, with values of 1.16 and 1.19 for neat SIM and ISM, by themselves relatively broad MWDs and as both terpolymers have unequal molecular weights the combination in a blend provides both a polydispersity in molecular weight and composition. The repulsive segmental interactions between the copolymer blocks is the driving force for microphase separation and leads them to stretch in order to adopt a minimum of interfacial contact area.…”

Section: Resultsmentioning

confidence: 97%

Four‐Phase Morphologies in Blends of ABC and BAC Triblock Terpolymers

Haenelt

Abetz

2017

Macro Chemistry & Physics

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considerably more complex compared to diblock copolymers due to an increased number of variables. Thus, the morphology of linear ABC triblock terpolymers is controlled mainly by three interaction parameters (χ AB , χ AC , χ BC ,) and two independent volume fractions (f A , f B , f C = 1 -f A -f B ), as well as the block sequence. Among the morphologies are lamellae, lamellae with spheres or cylinders, knitting pattern, spheres on sphere, alternating and core-shell double gyroids, cylinder in cylinder, undulated/perforated cylinder in cylinder, cylinder at cylinder, spheres on cylinder, helices on cylinder. [12][13][14][15][16][17][18] The helices on cylinder represents a special case in between these morphologies. On the one hand, it is rare because it can be achieved only in a rather narrow composition window, but what is even more peculiar, it is the self-assembly of a nonchiral block copolymer into a chiral structure. [19] In order to develop functional materials with special electrical, optical, or magnetic properties, multiblock copolymers are promising, because of their capability to self-assemble into complex ordered morphologies, with symmetries like crystalline structures known from low molecular weight inorganic salts. [20] Lee et al. [21,22] were the first to identify a Frank-Kasper σ phase, which is a large tetragonal unit cell with P4 2 /mnm symmetry and 30 spheres, [23,24] in linear block copolymers. From then on numerous studies about novel sphere-forming morphologies in AB diblock [25][26][27] copolymers and ABAC tetrablock terpolymers [28] have been published. Especially linear ABAC tetrablock terpolymers are promising for the investigation of new structures. [29] Chanpuriya et al. [30] have presented nine different spherical phases for tetrablock terpolymers.Controlling the morphology for a given block copolymer by changing the volume fractions of the corresponding blocks implies the synthesis of one block copolymer for each morphology. There are other, more readily available methods to achieve different morphologies starting from one block copolymer. One method implicates chemical postmodification, like complexation or hydrogenation. Bronstein et al. [31] have modified the polybutadiene block (PB) of a polystyreneblock-polybutadiene-block-poly(methyl methacrylate) (SBM) triblock terpolymer by complexation with transition metal complexes, like Fe-complex and Pd-complex. They were able to observe a change from a lamellar morphology before modification to a cylindrical or gyroid morphology after the Blends It is investigated how binary blends of two asymmetric triblock terpolymers with the same type of monomers but different block sequences (ABC, BAC) and different block lengths lead to three new ABAC tetrablock terpolymer like morphologies. This study ascribes the formation of four microphases to a parallel chain orientation during the blend process. Because of the resultant spatial superposition, the B-blocks of both block copolymers can mix into each other as well as both C-blocks, whereas bot...

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Unexpected Consequences of Block Polydispersity on the Self-Assembly of ABA Triblock Copolymers

Cited by 199 publications

References 71 publications

RAFT Polymerization of Monomers with Highly Disparate Reactivities: Use of a Single RAFT Agent and the Synthesis of Poly(styrene-block-vinyl acetate)

RAFT Polymerization of Monomers with Highly Disparate Reactivities: Use of a Single RAFT Agent and the Synthesis of Poly(styrene-block-vinyl acetate)

Synthesis of POSS-containing fluorosilicone block copolymers via RAFT polymerization for application as non-wetting coating materials

Four‐Phase Morphologies in Blends of ABC and BAC Triblock Terpolymers

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