In
the development of organic electronics, polyimide (PI)-based
materials have drawn significant research attention due to their remarkable
features, including a simple synthesis, solution processability, outstanding
thermal stability, and respectable mechanical strength. Despite the
good electronic performance of PI-based materials, a high elastic
modulus over 1 GPa and a modest elongation at break of the conventional
PIs have restricted their applications in stretchable electronics.
To address this issue, poly(siloxane imide) (PSI) with a soft siloxane
chain has been proposed to achieve a significantly reduced modulus
and an increased stretchability. However, previous works revealed
the weak mechanical strength of PSI, in which the latest reported
stretchable device comprising PSI thin film could only sustain a tensile
strain below 40%. Herein, in the present study, we developed a thermally
stable and mechanically durable PSI network through the polyaddition–condensation
reaction between 4,4′-oxidiphthalic anhydride, aminopropyl-terminated
polydimethylsiloxane, and varied amounts of 1,3,5-triaminophenoxybenzene
(TAB) as a cross-linker. An optimal PSI network with 11.1% TAB exhibited
a high decomposition temperature at 426 °C, a softening temperature
over 200 °C, an elongation at break over 400%, a superior toughness
at 13.29 MJ m–3, and low strain hysteresis. Owing
to the improved solubility of PSI, the polymer elastomer can be processed
as a substrate material or thin-film active layer with good mechanical
properties. Finally, all-solution-processed, stretchable, and durable
electronic devices including resistive memory and organic field-effect
transistors were fabricated using the designed PSI with an affordable
and feasible solution process. This work underlines the importance
of network design on soft polymers to create mechanically tough and
durable elastomers for next-generation stretchable electronics.