Next Article in Journal
Fluorescent and Mechanical Properties of Silicon Quantum Dots Modified Sodium Alginate-Carboxymethylcellulose Sodium Nanocomposite Bio-Polymer Films
Previous Article in Journal
In Search of a Green Process: Polymeric Films with Ordered Arrays via a Water Droplet Technique
Previous Article in Special Issue
Synthesis of Highly Thermally Stable Daidzein-Based Main-Chain-Type Benzoxazine Resins
Open AccessArticle

Phase Diagrams of n-Type Low Bandgap Naphthalenediimide-Bithiophene Copolymer Solutions and Blends

1
Institute of Engineering Materials and Biomaterials, Faculty of Mechanical Engineering, Silesian University of Technology, 44-100 Gliwice, Poland
2
School of Materials Science and Engineering, Jimma Institute of Technology, Jimma University, Post Office Box 378 Jimma, Ethiopia
3
Center of Polymer and Carbon Materials to the Polish Academy of Sciences, M. Curie-Skłodowska 34 Street, 41-819 Zabrze, Poland
4
School of Chemical Engineering, Jimma Institute of Technology, Jimma University, Post Office Box 378 Jimma, Ethiopia
*
Author to whom correspondence should be addressed.
Polymers 2019, 11(9), 1474; https://doi.org/10.3390/polym11091474
Received: 9 August 2019 / Revised: 26 August 2019 / Accepted: 26 August 2019 / Published: 9 September 2019
(This article belongs to the Collection Sustainable Polymeric Materials from Renewable Resources)
Phase diagrams of n-type low bandgap poly{(N,N′-bis(2-octyldodecyl)naphthalene -1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-5,5′,-(2,2′-bithiophene)} (P(NDI2OD-T2)) solutions and blends were constructed. To this end, we employed the Flory–Huggins (FH) lattice theory for qualitatively understanding the phase behavior of P(NDI2OD-T2) solutions as a function of solvent, chlorobenzene, chloroform, and p-xylene. Herein, the polymer–solvent interaction parameter (χ) was obtained from a water contact angle measurement, leading to the solubility parameter. The phase behavior of these P(NDI2OD-T2) solutions showed both liquid–liquid (L–L) and liquid–solid (L–S) phase transitions. However, depending on the solvent, the relative position of the liquid–liquid phase equilibria (LLE) and solid–liquid phase equilibria (SLE) (i.e., two-phase co-existence curves) could be changed drastically, i.e., LLE > SLE, LLE ≈ SLE, and SLE > LLE. Finally, we studied the phase behavior of the polymer–polymer mixture composed of P(NDI2OD-T2) and regioregular poly(3-hexylthiophene-2,5-dyil) (r-reg P3HT), in which the melting transition curve was compared with the theory of melting point depression combined with the FH model. The FH theory describes excellently the melting temperature of the r-reg P3HT/P(NDI2OD-T2) mixture when the entropic contribution to the polymer–polymer interaction parameter (χ = 116.8 K/T − 0.185, dimensionless) was properly accounted for, indicating an increase of entropy by forming a new contact between two different polymer segments. Understanding the phase behavior of the polymer solutions and blends affecting morphologies plays an integral role towards developing polymer optoelectronic devices. View Full-Text
Keywords: phase diagram; Flory–Huggins theory; n-type polymer; low bandgap polymer; conjugated polymer; polymer solution; polymer blend; all polymer solar cells phase diagram; Flory–Huggins theory; n-type polymer; low bandgap polymer; conjugated polymer; polymer solution; polymer blend; all polymer solar cells
Show Figures

Graphical abstract

MDPI and ACS Style

Fanta, G.M.; Jarka, P.; Szeluga, U.; Tański, T.; Kim, J.Y. Phase Diagrams of n-Type Low Bandgap Naphthalenediimide-Bithiophene Copolymer Solutions and Blends. Polymers 2019, 11, 1474.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map

1
Back to TopTop