Study of the Dynamic Process of Enhancing the Stability of Conjugated Polymer Solutions and Films Induced by an External Electric Field

Abstract

Taking the classic red light conjugated polymer MEH-PPV material as a representative, aiming at the common problem, that is, its degradation over time in the natural environment, which leads to unstability of the solution and film, a new idea and method based on the self-assembly of molecular chains in solution induced by an external electric field are proposed to manipulate the condensed-state structure of molecular chains in solution and enhance the dynamic stability of its solution. Then, the stability of the film was enhanced by transferring the condensed-state structure of the solution to the film in the dynamic evolution process from the solution to the film. First, the molecular mechanism of the unstability of the MEH-PPV precursor solution with time change was explored. Then, the self-built external electric field equipment was used for enhancing the dynamic stability of the conjugated polymer MEH-PPV solution and film by induction of an external electric field. Surprisingly, it was found that the precursor solutions with different concentrations all responded significantly to the induction of an external electric field during the 30 day storage period, forming large-scale, close-packed, chain-aggregated structures. More importantly, this structure can stably exist in the process of dynamic evolution with time change, thereby enhancing the stability of the solution. Through a series of studies on the films, it was found that the chain-aggregated structure formed in the solution could be stably transferred to the film in the process of dynamic transition from the solution to the film. Under the induction of the external electric field, a large-area, compact arrangement and ordered chain structures also appeared in the films, which not only enhanced the stability of the film but also revealed that there was an internal and intrinsic physical connection between the condensed-state structures of the solution and film in the dynamic evolution process. The study also revealed the molecular mechanism of the stability enhancement for the conjugated polymer MEH-PPV solution and film induced by the external electric field.

Liquid–Solid Transfer Process of Ordered Structures in Efficient Polymer Photovoltaic Materials

“…In SLS measurement, when 1 < qR agg < 10, the I ( q ) of aggregation is dependent on the scattering vector q , as I ( q ) ∝ q – d f . The larger the value of d f , the more compact the polymer chain packing in the aggregation Figure c shows that the d f values increased from 1.99 to 2.78 as the temperature increased from 25 to 40 °C, which indicated that PBDT-TTz changed from loose to relatively compact aggregation.…”

“…The larger the value of d f , the more compact the polymer chain packing in the aggregation. 56 Figure 3c shows that the d f values increased from 1.99 to 2.78 as the temperature increased from 25 to 40 °C, which indicated that PBDT-TTz changed from loose to relatively compact aggregation. A suitable temperature increase improved the solubility of the polymer, causing a more extended chain conformation, which reduced the steric hindrance of side chains between molecular chains.…”

Hybrid Monomer Design Synergizing Property Trade‐offs in Developing Polymers for Circularity and Performance

“…Chemically recyclable polyethylene‐like materials have been achieved through the incorporation of a labile or reactively cleavable bond in the polyethylene main chain structure [61, 62] . Likewise, the chemical recycling of polycarbonates back to epoxides or cyclic carbonate monomers is an interesting and very active area searching solutions to existing challenges [63, 64] . Specifically, the recycled cyclic carbonate monomer is often too thermodynamically stable to repolymerize, which impedes the realization of the closed‐loop circularity [63] .…”

Concentration effect on the chain structure and photoelectric properties of conjugated polymer precursor solutions and thin films: A mini review

“…For solutions with higher concentrations, the time required for maximum conformational disorder to occur was shorter. Our group 93 prepared MEH‐PPV solutions of different concentrations (0.1–3.0 mg mL −1 ) under the influence of an external electric field. A significant increase could be observed in the size of chain aggregation within the studied concentration range.…”