  Porous and flexible actuating materials are important in the development of
smart systems. We report here a facile method to prepare scalable, flexible
actuating porous membranes based on a poly(ionic liquid)-modified tissue paper.
The targeted membrane property profile was based on a synergy of a gradient
porous structure of poly(ionic liquid) network and the flexibility of tissue
paper. The gradient porous structure was built up through ammonia-triggered
electrostatic complexation of a poly(ionic liquid) with poly(acrylic acid)
(PAA) that were previously impregnated inside the tissue paper. As a result,
these porous membranes undergo bending deformation in response to organic
solvents in vapor or liquid phase and can recover their shape back in air,
which was demonstrated to be able to serve as solvent sensors. Besides, they
show enhanced mechanical properties due to the introduction of mechanically
flexible tissue paper that allows the membranes to be designed as new
responsive textiles and contractile actuators.
