title: Morphology and thermodynamic properties of a copolymer with an electronically conducting block: poly(3-ethylhexylthiophene)-block-poly(ethylene oxide).
abstract: We report on the synthesis and morphology of a block copolymer, poly(3-(2'-ethylhexyl)thiophene)-b-poly(ethylene oxide) (P3EHT-b-PEO), that conducts both electrons and ions. We show that in the melt state the P3EHT-b-PEO chains self-assemble to produce traditional nanoscale morphologies such as lamellae and gyroid. This is in contrast to a majority of previous studies on copolymers with electronically conducting blocks wherein a nanofibrillar morphology is obtained. Our approach enables estimation of the Flory-Huggins interaction parameter, χ. The segregation strength between the two blocks is controlled through the addition of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). For the salt-free sample, the gyroid morphology, obtained in the melt state, is transformed into lamellae below the melting temperature of the P3EHT block. This is due to the "breaking out" of the crystalline phase. For the salt-containing sample, P3EHT-b-PEO has a lamellar morphology in both melt and crystalline states (confined crystallization).
authors: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, United States.
authors: Shrayesh N
authors: SN
authors: Patel
authors: Anna E
authors: AE
authors: Javier
authors: Keith M
authors: KM
authors: Beers
authors: John A
authors: JA
authors: Pople
authors: Victor
authors: V
authors: Ho
authors: Rachel A
authors: RA
authors: Segalman
authors: Nitash P
authors: NP
authors: Balsara
mesh_terms: D004553:Electric Conductivity; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000737:chemistry*; D013499:Surface Properties; D013814:Thermal Conductivity; D013816:Thermodynamics; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D046911:Macromolecular Substances; D013876:Thiophenes; D011092:Polyethylene Glycols