Macroscopic Structural Compositions of pi-Conjugated Polymers: Combined Insights from Solid-State NMR and Molecular Dynamics Simulations

作者：Melnyk Anton; Junk Matthias J N; McGehee Michael D; Chmelka Bradley F; Hansen Michael Ryan^*; Andrienko Denis^*

来源：Journal of Physical Chemistry Letters, 2017, 8(17): 4155-4160.

DOI：10.1021/acs.jpclett.7b01443

Molecular dynamics simulations are combined with solid-state NMR measurements to gain insight into the macroscopic structural composition of the pi-conjugated polymer poly(2,5-bis(3-tetradecyl-thiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT). The structural and dynamical properties, as established by the NMR analyses, were used to test the local structure of three constitutient mesophases with (i) crystalline backbones and side chains, (ii) lamellar backbones and disordered side chains, or (iii) amorphous backbones and side chains. The relative compositions of these mesophases were then determined from the deconvolution of the H-1 and C-13 solid-state NMR spectra and dynamic order parameters. Surprisingly, on the basis of molecular dynamics simulations, the powder composition consisted of only 28% of the completely crystalline mesophase, while 23% was lamellar with disordered side chains and 49% amorphous. The protocol presented in this work is a general approach and can be used for elucidating the relative compositions of mesophases in pi-conjugated polymers.

• 出版日期2017-9-7