Revealing the Influences of Solvent Boiling Point and Alkyl Chains on the Adlayer Crystallinity of Furan-Diketopyrrolopyrrole-Thienylene Copolymer at Molecular Level

Abstract

Crystallinity of the polymer poly­(3,6-difuran-2-yl-2,5-di­(2-octyldodecyl)-pyrrolo­[3,4-c]­pyrrole-1,4-dione-altthieylenevinylene) (PDVF) adlayers casted from low-boiling-point (L-bp), medium-bp (M-bp), and high-bp (H-bp) solvents was investigated through scanning tunneling microscopy (STM) and analyzed by the assistance of Hansen solubility parameter (HSP) theory and molecular dynamics (MD) simulations. Crystallinity of the PDVF adlayers increases evidently from the L- to H-bp solvents. Also, the solvent with an alkyl chain such as ethylbenzene (EB) facilitates in improving the crystallinity than the one without an alkyl chain such as chlorobenzene (CB) if the solvent bp is present in the same group. The HSP space discloses that EB is a marginal solvent for PDVF in contrast to CB. Quasi-isolate PDVF in the EB solution revealed by MD simulations facilitates the formation of crystallized domains through surface assembling mechanism. However, in CB, interconnected PDVF molecules through intermolecular overlapping tend to generate amorphous structures through direct deposition of the preformed structures in solution.

Noncovalent wedging effect catalyzed the cis to syn transformation of a surface-adsorbed polymer backbone toward an unusual thermodynamically stable supramolecular product

“…It is well known in STM studies that alkyl chains are usually imaged as lowestcontrast trenches because of their much lower electron density in comparison to that of aromatic backbones. [21][22][23][24][25] The alkyl chains in the trenches can be recognized in the high-resolution image in Fig. 3b (indicted by an arrow).…”

“…Scanning tunneling microscopy (STM) has unique advantages in investigating surface structures and processes at a molecular level. [16][17][18][19][20][21][22][23][24][25][26][27][28][29] Meanwhile, theoretical research based on density functional theory (DFT) provides a deep understanding of the interaction mechanisms, structural transformations, optoelectronic properties and functions of organic-organic and organicsubstrate systems. 25,[30][31][32][33] By combining these two powerful tools, the silver substrate is suggested to be able to reduce the energy barrier of bowl-to-bowl inversion of aromatic compounds as well.…”

In Situ Monitoring of Polaron Localization and Cell Activity with Charge Accumulation Spectroscopy

“…To investigate the sensitivity of the CAS signal to the local molecular ordering of charge-occupied regions, we fabricated highordering and low-ordering pBTTT films, respectively. Since employing a high boiling point solvent and thermal annealing have been shown to improve crystallinity and structural ordering of polymeric films, [25,26] the highly ordered pBTTT film was obtained by using 1,2-dichlorobenzene as the solvent followed by thermal annealing, while the low-ordering sample was spun from a chloroform solution without annealing (see the Experimental Section for details). Note that the experimental results presented in the other parts of this work were obtained with the high-ordering pBTTT film unless specified.…”

Effect of solvent quality and sidechain architecture on conjugated polymer chain conformation in solution

“…15 These solvents possess diverse characteristics including solubility, toxicity, boiling point, viscosity, and polarity. 16,17 Newbloom et al investigated the gelation of poly(3-alkylthiophene)s (P3ATs) in a mixture of good and poor solvents. 18 They found that for P3HT in dichlorobenzene, more poor-solvent n-dodecane results in smaller, abundant fiber formation and better electrical conductivity.…”