Crystallization Modes of Poly(3-dodecylthiophene)-Based Block Copolymers Depend on Regioregularity and Morphology
Conjugated block copolymers (BCPs) can self-assemble into highly ordered nanostructures in a melt state. Yet, when cooled below the melting temperature, crystal growth can disrupt the self-assembled structure and produce a poorly ordered fibrillar texture. We determine that crystallization modes of conjugated BCPs based on poly(3-dodecylthiophene) (P3DDT) and poly(2-vinylpyridine) (P2VP) can be tuned through P3DDT regioregularity (RR), as this attribute controls the melting temperature and crystallization rates of P3DDT. When RR is low (7080%), crystallization is observed at temperatures near or below the glass transition of P2VP, so crystal growth is largely confined by the glassy cylindrical or lamellar BCP structure. When RR is high (94%), crystallization occurs at 40 K above the glass transition of P2VP, so there is no longer a restriction of glassy domains. Importantly, crystal growth remains confined by the rubbery P2VP lamellae, but breaks through the rubbery P2VP cylinders. This morphology-dependent behavior is attributed to geometric compatibility of P3DDT crystal growth and the self-assembled symmetry. In a lamellar phase, the P3DDT chain orientations at the P3DDT-block-P2VP interface are compatible with crystal growth, and both the alkyl-stacking and $$\pi\pi$$ growth directions are unrestricted within a lamellar sheet. In a cylindrical phase, the radial orientation of P3DDT chains at the P3DDT-block-P2VP interface is not compatible with crystal growth, and the hexagonal close-packed symmetry only allows for one direction of unrestricted crystal growth. Significantly, these studies demonstrate that tuning RR of polyalkylthiophenes can open up multiple crystallization modes with the same monomer chemistries and block lengths, thereby decoupling the parameters that govern classical BCP self-assembly and crystal growth.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); Korea Advanced Inst. Science and Technology (KAIST), Daejeon (Korea); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1504470
- Journal Information:
- Macromolecules, Vol. 51, Issue 22; ISSN 0024-9297
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Rapid solvo-microwave annealing for optimizing ordered nanostructures and crystallization of regioregular polythiophene-based block copolymers
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journal | January 2019 |
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