Enhanced miscibility and strain resistance of blended elastomer/π‐conjugated polymer composites through side chain functionalization towards stretchable electronics

Abstract

This work presents improved compatibility in an elastomer/π‐conjugated polymer blend through side chain functionalization of the electronic polymer. Poly[(3‐(6‐bromohexyl)thiophene)‐ran‐(3‐hexylthiophene)] (P3BrxHT, x = 0%–100%) was synthesized (i) to improve miscibility with polybutadiene (PB) elastomer through altered π–π interactions and (ii) to covalently bond across phase‐segregated interfaces. Functionalization led to morphology with reduced domain sizes to improve crack onset strain from 7% to 40%. Furthermore, UV‐activated crosslinking reinforced mechanically weak interfaces and yielded at least an additional 40% increase in crack onset strain. Charge mobility in PB/P3BrxHT organic field‐effect transistors showed minimal dependence on bromide concentration and no negative effects from crosslinking. Functionalization was an effective method to reduce brittleness in PB/P3BrxHT blends through morphology modification and crosslinking to improve stability towards strain for potential stretchable electronic applications. © 2019 Society of Chemical Industry

Synergistic Manipulation of Phase Transition between Cocrystallization and Microphase Segregation in Conjugated Triblock Copolymers for Organic Field-Effect Transistors

“…49,50 Whereas the BCP (1:0.2:0.9) absorbed at 521 nm, the main peak of BCP (1:2.6:1.3) exhibited a marked blue-shift to 508 nm, indicating a less ordered structure due to disruptions in the packing caused by the longest P3BrHT block. 51 After heating at 150 °C, these three BCPs exhibited an increased intensity of vibronic peaks, suggesting that they produced stronger π−π interactions, as low-temperature heating improved their crystalline ordering. However, all samples annealed at 240 °C produced stronger main peaks and weaker vibronic peaks compared to those of their as-cast samples.…”

“…Three absorption peaks appeared at 508–523, 553–554, and 599–605 nm in the results for the three as-cast P3HT- b -P3BrHT- b -P3DT samples. The main peak at 508–523 nm was ascribed to a polythiophene intrachain π–π* transition and the other two vibronic peaks were attributed to interchain π–π interactions. , Whereas the BCP (1:0.2:0.9) absorbed at 521 nm, the main peak of BCP (1:2.6:1.3) exhibited a marked blue-shift to 508 nm, indicating a less ordered structure due to disruptions in the packing caused by the longest P3BrHT block . After heating at 150 °C, these three BCPs exhibited an increased intensity of vibronic peaks, suggesting that they produced stronger π–π interactions, as low-temperature heating improved their crystalline ordering.…”

A molecular design approach towards elastic and multifunctional polymer electronics

“…In summary, previous semiconductor/small molecule crosslinked systems fell short in simultaneously realizing high covalent crosslinking density (essential for elasticity) and maintaining decent charge carrier mobility 20,21,32 . While in our system, this challenging obstacle was overcome by leveraging the reactivity difference between azide/C-H insertion and azide/C=C cycloaddition, and selecting the appropriate rubber precursor structure to induce desired morphology for facilitated charge transport.…”

Quantitative comparison of the copolymerisation kinetics in catalyst-transfer copolymerisation to synthesise polythiophenes

“…The chosen comonomers vary by the side chains at their 3 positions and have been shown to be compatible with KCTP in either homopolymerisation or copolymerisation. 17,[24][25][26] In addition to the reactivity ratios commonly applied to describe the relative kinetics of comonomers, 21,27,28 we further calculated the four rate constants, k 11 , k 12 , k 22 , and k 21 that define the ratios. The more specific kinetic information will help determine the kinetic difference related to the order of monomer addition, which is helpful in the synthesis of more complex copolymer architectures such as triblock copolymers.…”