The widespread use of toxic halogenated solvents in processing high-performance conjugated polymers raises environmental concerns and hinders large-scale organic electronics production. While the terpolymer approach has improved the donor–acceptor polymer performance, it remains unexplored in quinoidal systems. This study pioneers a terpolymer strategy for quinoidal polymers to enable eco-friendly processing by fine-tuning interchain aggregation and film crystallinity, leading to improved charge mobility and stability in organic field-effect transistors (OFETs). A series of para-azaquinodimethane-based random terpolymers with varied ratios of terthiophene (3T) and quaterthiophene (4T) units are developed, demonstrating that higher 4T content enhances interchain aggregation but reduces solubility, dramatically affecting molecular packing and OFET performance. When processed from chlorobenzene, all terpolymers outperformed reference alternating copolymers, with PA-3T25-4T75 containing 75% 4T achieving the highest hole mobility of 2.26 cm2 V–1 s–1 due to its most ordered microstructure. Notably, PA-3T75-4T25 with 25% 4T achieves an impressive hole mobility of 2.09 cm2 V–1 s–1 with tetrahydrofuran as the solvent, marking a record high value for quinoidal polymers processed from eco-friendly solvents. This work underscores the potential of terpolymer design in enhancing both OFET performance and environmental sustainability of quinoidal polymers, contributing to the development of eco-friendly organic electronics.
Many industrial applications require a quick method to determine the chain length-dependent phase diagram of a given polymer solution, such as converting a solution polymerization into a precipitation polymerization, to greatly save the cost. However, it is rather difficult and time-consuming to precisely map phase diagrams of polymer solutions with different chain lengths, so that good phase diagrams are scarcely documented in the literature. The difficulties come from two facts: (1) one has to prepare polymer solutions with different concentrations and chain lengths first, and then (2) measure the temperature dependent on each solution carefully, normally taking months if not years. In this study, the chain length and temperature-dependent scaling laws for linear polymer phase diagrams were established as and for concentrations (Φl and Φh) lower and higher than the critical concentration (ΦC), where TC is the critical temperature; and Φ0, Φ1, and Φ2 are the chain-length independent parameters. Armed with these scaling laws, we have developed a quick optical method to map the coexistence curve of the phase diagram of each kind of polymer solution by measuring the phase transition temperatures of five or more polymer solutions with a given chain length but different concentrations to determine the five parameters ΦC, TC, Φ0, Φ1, and Φ2.
Despite the solution of the recycling difficulty of traditional thermosetting polymers including polydimethylsiloxane (PDMS) with the development of vitrimers, addressing the trade-off among the mechanical, reprocessing, and thermal properties of PDMS remains a scientific challenge. Herein, a novel “one-stone-for-three-birds” structural design strategy based on the triple effects of Fe3+ including coordination cross-linking for reinforcement and toughening, catalytic effect on silyl ether exchange for reprocessing, and free radical quenching for thermal stabilization is reported, realizing the integration of mechanical robustness, reprocessability, and unprecedentedly high thermal stability in PDMS for the first time. The PDMS vitrimer in this work exhibits the highest thermal stability among the reported PDMS vitrimers, comparable to commercial PDMS. To elucidate the intrinsic mechanisms of the triple effects of Fe3+ in PDMS, multiple characterizations have been performed from the microscopic structure to the macroscopic mechanical, reprocessing, and thermal performances both theoretically and experimentally.
We apply molecular dynamics simulations to quantify the effects of free surfaces and interfacial regions on crystallization in freestanding and bilayer polymer films. We show that enhanced crystal nucleation in polymer thin films is quantitatively correlated to faster local segmental dynamics induced by free surfaces. When a second layer is deposited onto a semicrystalline film, we observe rapid primary nucleation near the free surface, secondary nucleation near the semicrystalline interface, and slower primary nucleation near the center of the fresh polymer layer, which can result in enhanced crystallization in the interlayer region and impact the interfacial strength. We expect molecular insight into thin-film and bilayer polymer crystallization to help optimize polymer products manufactured by layer-by-layer processes.
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