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

Abstract

application of stimuli-responsive materials still remains as a great challenge since it is very difficult to develop smart stimuli-responsive materials with the well-balanced performance of stimuliresponsive speed, mechanical strength, multi-functionality, and deformation diversity as well. [14] Designing the asymmetric layer structure is regarded as a conventional strategy to achieve stimuli-responsive materials, which can be divided into two categories: One is built through the covalent or non-covalent interaction, that is, van der Waals force, hydrogen bonds, electrostatic attraction, and supramolecular assembly, between two functional layers. [4c,7h,15] These strategies enabled the manipulation of the thickness and microstructure of each functionalized layer. However, complicated synthetic procedures are generally required. Furthermore, the adhesive interaction between the functional layers might be weak, so they tend to be delaminated after repeated stimulus-response bending. The other one is gradient distribution of certain components prepared from the in situ polymerization under external magnetic or electric field [16] or polymers with gradient change of cross-linking density produced by flash welding, ionoprinting, or electrostatic complexation. [4e,17] This method is simple but required the external fields or special techniques. Besides, the asymmetry film prepared from the gradient distribution or the cross-linking alteration of a certain component sometimes exhibited the relatively single stimuli responsive functionality or deformation bending direction. Therefore, there is still a high demand to develop a simple method to fabricate smart actuator materials with stimuliresponsive multifunctionality/deformation bending diversity and reversibility. In 2018, Yang's group reported a one-pot and one-step polymerization strategy to prepare bilayer hydrogels showing response to both salt and heat. [18] Later, they employed this method to further fabricate the salt-responsive bilayer hydrogels with 2D and 3D shape transformations. [19] These results inspired more research efforts on the development of more facile synthetic strategies for fabricating asymmetric films with multi-stimuli responses and adaptive deformations to complex environment. It is challenging to synthesize stimuli-responsive materials with the wellbalanced 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, P 60 B 40-HPI film is fabricated on hydrophilic subst...

Fabrication and Applications of Pentaerythritol Tetrakis(3-Mercaptopropionate) Addition to N-Phenylacrylamide Based on Thiol-Ene Click Reaction

“…The NPP was prepared according to the following procedure, referring to the previous kinds of literature [2,3,7]. Photoinitiator (1173, 1% of total mass), the molar ratio of PETMP: NPA (thiol:ene) was 1:4, and the above mixture was dissolved in a mixed solvent of acetone and ethanol (volume ratio of 2:1) of 20 ml.…”

“…Acrylamides are well-known for their ability to undergo thiol-ene reactions, whose mechanisms include nucleophilic addition and free-radical reactions [1][2][3]. Thiol/ene free-radical reactions are light-activated in the presence of a photoinitiator, the reaction is also called the thiol-ene click reaction [2][3][4][5][6][7]. The click reaction has become a popular method for synthesis and modification in organic chemistry due to its high selectivity and efficiency.…”

“…Pentaerythritol tetra(3-mercaptopropionate) (PETMP) has been researched as a thiol monomer for the fabrication of water/acetone vapor-responsive hierarchical films through one-step thiol-ene click reaction [3]. PETMP is also selected as the hardener for epoxy coatings due to its polyfunctionality, which is crucial for achieving desirable mechanical and physical properties of the coating [13].…”

Self‐healing polymers for soft actuators and robots

“…Via a light‐mechanical energy conversation, the actuation mechanisms of photomechanical actuators discussed in this review are general two groups: photochemical and photothermal actuation. Photochemical actuation relies on photochemical reactions in polymers, like the isomerization of typical molecular photo‐switches including azobenzene (Azo), 31–34 spiropyrans (SPs) and hexaarylbiimidazoles (HABI's), 35–40 thiol‐ene click chemistry and allyl thiol exchange chemistry 41–46 . The photochemical changes at the molecular scale could transformed into the visible macroscopic deformation of bulk materials, producing the photochemical actuators.…”

Magnetic-field-controlled counterion migration within polyionic liquid micropores enables nano-energy harvest

“…The magnetic PLM is then synthesized through a thiol-ene click reaction [29][30][31] between the remaining CQC bonds on PLM and the thiol-functionalized magnetic ionic liquid (1-10-mercaptodecyl-3-methylimidazolium dysprosium tetranitrate, [HS-C 10 mim] [Dy(NO 3 ) 4 ]). The details of the synthesis of [HS-C 10 mim] [Dy(NO 3 ) 4 ] can be found in the Experimental section.…”