Controllable, Bidirectional Water/Organic Vapors Responsive Actuators Fabricated by One-Step Thiol-Ene Click Polymerization.

It is challenging to synthesize stimuli-responsive materials with the well-balanced performance of fast stimulus-response speed, good mechanical strength, multi-functionality, and deformation diversity as well. This work reports a facile, one-step thiol-ene click polymerization strategy for preparation of water/acetone vapor-responsive hierarchical films, by using diallyl terephthalate (P) as hydrophobic ene-monomer, 1,4-diallyl-1,4-diazabicyclo [2.2.2]octane-1,4-diium bromide (B) as hydrophilic ene-monomer, and pentaerythritol tetra(3-mercaptopropionate) (PETMP) as thiol monomer. Besides, by taking advantage of the specific hydrophilic/hydrophobic induction effect of substrate and adjusting the molar ratio of P to B, P60 B40 -HPI film is fabricated on hydrophilic substrate "with plasma treatment" whereas P80 B20 -HPO film is obtained on hydrophobic substrate "without plasma treatment". Their "upper-dense and lower-porous" structural feature ensured the excellent combination of fast stimuli-response speed endowed by the porous structure and good mechanical strength enhanced by the upper dense surface. Both films are bidirectional water/acetone vapor-responsive materials, but their bending directions responding to the stimuli factors are completely opposite. This strategy showed great potential in the development of smart stimuli-responsive materials.