Interrogating the Effect of Block Sequence on Cocrystallization, Microphase Separation, and Charge Transport in All-Conjugated Triblock Copolymers

Li, Lixin; Zhan, Hao; Chen, Shuwen; Zhao, Qingqing; Peng, Juan

doi:10.1021/acs.macromol.2c00406

Cited by 9 publications

(8 citation statements)

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“…The block sequence is a particular parameter peculiar to triblock copolymers compared with diblock copolymers. ,, Finally, the influence of block sequence was studied by designing series C (P3OT- b -P3BT- b -P3EHT and P3BT- b -P3OT- b -P3EHT) around the block ratio of 1:1:1. Both P3OT- b -P3BT- b -P3EHT and P3BT- b -P3OT- b -P3EHT showed only one (100) peak at q z of 3.78 ( d 100 = 1.66 nm) and 3.85 nm –1 ( d 100 = 1.63 nm), respectively, indicating the formation of cocrystallization in their as-cast state (Figure a,b).…”

Section: Resultssupporting

confidence: 76%

Tuning Cocrystallization, Microphase Separation, and Optical Property of All-Conjugated Triblock Copolymers by Molecular Engineering

Liu

Peng

2022

ACS Appl. Polym. Mater.

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Compared to the widely studied classical coil−coil block copolymers (BCPs) with well-established phase diagram and recent advances achieved in all-conjugated diblock copolymers, the investigation into the phase behavior of all-conjugated triblock copolymers is rather limited. In this work, we prepare a series of triblock copolymers containing various poly(3-alkylthiophene)s (P3ATs), interrogate their phase transition between cocrystallization and microphase separation adjusted by a set of molecular parameters (alkyl side chains, block ratios, and block sequences), and correlate these different structures strongly to their optical properties. Poly(3-butylthiophene) (P3BT), poly(3-hexylthiophene) (P3HT), poly(3-(2′-ethyl)hexylthiophene) (P3EHT), poly(3octylthiophene) (P3OT), and poly(3-dodecylthiophene) (P3DDT) are selected, in which P3EHT has a much less crystalline capability than the other four components. Interestingly, when the P3EHT block is situated in the BCP middle position (P3BT-b-P3EHT-b-P3AT), a smaller side chain difference between the two outer P3BT and P3AT blocks and the P3EHT with a shorter main chain length favor cocrystallization in the triblock copolymers over microphase separation. Moreover, when changing the block sequence to place the P3EHT block at two terminals (P3OT-b-P3BT-b-P3EHT and P3BT-b-P3OT-b-P3EHT), they display stronger cocrystalline capability than P3BT-b-P3EHT-b-P3OT with the P3EHT in the central. At last, these various crystalline structures are related to their optical properties. This work demonstrates the tuning of the phase transition between cocrystalline and microphase-separated structures in conjugated triblock copolymers via molecular engineering, which correlate closely to their optical properties and may underpin their applications in optoelectronic devices.

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Section: Resultssupporting

confidence: 76%

Tuning Cocrystallization, Microphase Separation, and Optical Property of All-Conjugated Triblock Copolymers by Molecular Engineering

Liu

Peng

2022

ACS Appl. Polym. Mater.

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“…It should be pointed out that no such variation was observed in the 2-D GIXRD images of the samples of l -T-OPE 4 -DPP-OPE 4 under similar conditions (Figure S11). Previous results showed that the H-aggregate packing mode of π-conjugated segments would lead to a more pronounced crowding effect of their alkyl side chains and results in a larger d -spacing of alkyl side chains. , On the basis of these results, it was supposed that the d -spacing of about 1.85 and 1.46 nm was assigned to the domains of a crystalline π-conjugated backbone along with ordered packing alkyl side chains of l -T-OPE 4 -DPP-OPE 4 units adopted H- and J-aggregate packing modes, respectively (Figure E), and numerous l -T-OPE 4 -DPP-OPE 4 units of l -T-OPE 4 -DPP-OPE 4 - b -P2VP 44 transferred from the H-aggregate packing mode to a more slipping J-aggregate mode after the aging, leading to the decrease of d -spacing from 1.85 to 1.46 nm.…”

Section: Results and Discussionmentioning

confidence: 81%

Crystallization-Driven Self-Assembly toward Uniform Nanofibers Containing a Donor–Acceptor Core with Near-Infrared Absorption/Emission, Photodynamic, and Photothermal Activities: A Small Variation on the Structure of Donor–Acceptor Segment Matters

Ma,

Huang,

Zhang

et al. 2023

Macromolecules

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Although living crystallization-driven self-assembly (CDSA) has emerged as a facile approach to generate uniform πconjugated-polymer-based fiber-like micelles, the extension of living CDSA to prepare uniform donor−acceptor (D−A) fiber-like micelles of controlled length with attractive near-infrared (NIR) absorption/emission, photodynamic (PD), and photothermal (PT) properties is virtually unexplored. Herein, three block copolymers composed of the same corona-forming P2VP 44 (P2VP = poly(2vinylpyridine), the subscript is the degree of polymerization) but different D−A π-conjugated core-forming co-oligomers of OPE 4 -DPP-OPE 4 (OPE 4 = oligo(p-phenylene ethynylene), DPP = diketopyrrolopyrrole) are designed and synthesized to probe the steric and electronic effect of co-oligomers of OPE 4 -DPP-OPE 4 on their CDSA behaviors and photophysical properties. One cooligomer contains a DPP with two 2-ethylhexyl side chains flanked by two thiophene-OPE 4 segments (b-T-OPE 4 -DPP-OPE 4 ). The variation of the second one is the replacement of 2-ethylhexyl side chains with linear octyls (l-T-OPE 4 -DPP-OPE 4 ). The last one is composed of a DPP with two linear octyl side chains flanked by two phenylene-OPE 4 segments (l-P-OPE 4 -DPP-OPE 4 ). Uniform fiber-like micelles can be generated by a self-seeding approach for b-T-OPE 4 -DPP-OPE 4 -b-P2VP 44 and l-P-OPE 4 -DPP-OPE 4 -b-P2VP 44 , whereas polydisperse fiber-like micelles only can be obtained for l-T-OPE 4 -DPP-OPE 4 -b-P2VP 44 likely due to the multiple packing modes of l-T-OPE 4 -DPP-OPE 4 . Intriguingly, the aging of micelles of l-T-OPE 4 -DPP-OPE 4 -b-P2VP 44 can promote the conversion of the packing mode of l-T-OPE 4 -DPP-OPE 4 units to their most thermodynamically stable packing mode, and thus, selfseeding of aged seed micelles of l-T-OPE 4 -DPP-OPE 4 -b-P2VP 44 gave uniform fiber-like micelles of controlled length. More interestingly, micellar solution of b-T-OPE 4 -DPP-OPE 4 -b-P2VP 44 exhibits NIR absorption/emission, PT, and PD activities upon the light irradiation at 660 nm. Although micellar solution of l-T-OPE 4 -DPP-OPE 4 -b-P2VP 44 also shows NIR absorption/emission and PT activity, its PD activity is much lower relative to that of b-T-OPE 4 -DPP a -OPE 4 -b-P2VP 44 . The micellar solution of l-P-OPE 4 -DPP-OPE 4 -b-P2VP 44 exhibits neither NIR absorption/emission nor PT/PD activities upon the light irradiation at 660 nm. All these results showed that a small variation of structure of OPE 4 -DPP-OPE 4 can lead to distinct CDSA behaviors and absorption/emission/ PD/PT properties.

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“…), which can be readily extended to conjugated rod–rod BCPs. Recently, the co-crystallization of two conjugated blocks is found to enhance the charge transport of conjugated rod–rod BCPs. − Nonetheless, the scrutiny of co-crystallization in the literature has been comparatively few owing to the difficulty in achieving conjugated polymer co-crystals. − More importantly, the co-crystallization kinetics in conjugated rod–rod BCPs has been rarely explored. Clearly, the ability to process conjugated rod–rod BCPs for accessing co-crystallization and subsequently reveal the influence of processing strategies on the two competing phase behaviors (co-crystallization versus microphase separation) represents a significant endeavor toward not only providing fundamental insight into their phase behaviors but also capitalizing on the conjugated polymer co-crystals for high-performance optoelectronics.…”

Section: Introductionmentioning

confidence: 99%

Tailoring Co-crystallization over Microphase Separation in Conjugated Block Copolymers via Rational Film Processing for Field-Effect Transistors

et al. 2022

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In sharp contrast to widely studied coil–coil block copolymers (BCPs), investigation into conjugated rod–rod BCPs is relatively few and limited in scope. Moreover, the ability to exquisitely tailor microphase separation (i.e., forming two dissimilar crystals from two blocks, respectively) and co-crystallization (i.e., co-crystals of two blocks) in conjugated rod–rod BCPs offers a robust route to scrutinize their processing–structure–property relationship. Herein, we report the tailoring of co-crystalline and microphase-separated structures in a family of poly(3-butylthiophene)-block-poly(3-hexylselenophene) (denoted P3BT-b-P3HS) with different molecular weights via three processing strategies (i.e., drop-casting, meniscus-assisted solution-shearing (MASS), and post solvent annealing) and the subsequent exploration of the correlation between their different structures (i.e., microphase separation and co-crystallization) and charge transport properties for use in organic field-effect transistors (OFETs). In the case of drop-casting, a larger molecular weight of P3BT-b-P3HS and a faster rate of solvent evaporation are found to favor their co-crystallization over the microphase separation of P3BT and P3HS. Interestingly, the MASS process effectively enables a phase transition from initial microphase-separated P3BT-b-P3HS to their co-crystallization. By contrast, the co-crystalline structure of P3BT-b-P3HS in a certain molecular weight range originally attained from drop-casting could be transformed into a microphase-separated structure upon post solvent annealing. Afterward, the correlation between the crystalline structures yielded from the three processing strategies and charge mobilities of P3BT-b-P3HS is established. This study highlights the effectiveness of the three strategies in regulating co-crystallization and microphase separation in conjugated rod–rod BCPs, which in turn strengthens the fundamental understanding of phase behavior in conjugated BCPs that underpins future developments in organic optoelectronic materials and devices.

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Interrogating the Effect of Block Sequence on Cocrystallization, Microphase Separation, and Charge Transport in All-Conjugated Triblock Copolymers

Cited by 9 publications

References 58 publications

Tuning Cocrystallization, Microphase Separation, and Optical Property of All-Conjugated Triblock Copolymers by Molecular Engineering

Tuning Cocrystallization, Microphase Separation, and Optical Property of All-Conjugated Triblock Copolymers by Molecular Engineering

Crystallization-Driven Self-Assembly toward Uniform Nanofibers Containing a Donor–Acceptor Core with Near-Infrared Absorption/Emission, Photodynamic, and Photothermal Activities: A Small Variation on the Structure of Donor–Acceptor Segment Matters

Tailoring Co-crystallization over Microphase Separation in Conjugated Block Copolymers via Rational Film Processing for Field-Effect Transistors

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