Epitaxial growth of light-responsive azobenzene molecular crystal actuators on oriented polyethylene films

Abstract

We report on the epitaxial growth of photoresponsive alkyl-substituted azobenzene fibres on top of uniaxially oriented polyethylene (PE) films.

NIR–vis–UV Light‐Responsive High Stress‐Generating Polymer Actuators with a Reduced Creep Rate

“…The stress-generating actuators based on PE-BZT-GN-QR films are compared with other actuators using the specific actuation stress, defined as the actuation stress divided by the material density (Figure S13a, Supporting Information). [2,11,29,[46][47][48][49] The multi-wavelength responsive actuators in this work exhibit almost 100 times higher specific actuation stresses than natural muscle, and also outperform dielectric elastomers, liquid crystalline actuators and piezo polymers. On the other hand, the current actuators display a fast and stable actuation with a low baseline drift-to-stress ratio (Figure S13b, Supporting Information) and similar or higher actuation stresses in comparison to oriented PE/azobenzene composites actuators, [29,30] which are only driven by UV and blue light.…”

“…Recently, ultradrawn, ultrahigh molecular weight polyethylene (UHMWPE) films [28] containing light-responsive azobenzene dyes with long aliphatic tails were reported. [29,30] It was shown that fast responding (<1 s) photoactuators with maximal actuation stresses up to 60 MPa can be produced at low strain (<0.1 %). [29][30][31] Moreover, it was shown that photoactuators containing UV stabilizers such as 2-(2Hbenzotriazol-2-yl)-4,6-ditertpentylphenol (BZT) have a similar performance.…”

“…[29,30] It was shown that fast responding (<1 s) photoactuators with maximal actuation stresses up to 60 MPa can be produced at low strain (<0.1 %). [29][30][31] Moreover, it was shown that photoactuators containing UV stabilizers such as 2-(2Hbenzotriazol-2-yl)-4,6-ditertpentylphenol (BZT) have a similar performance. [31] The operating mechanism of these UV lightresponsive actuators is the photothermal effect in combination with a negative thermal expansion coefficient of the oriented and chain extended polymer.…”

“…[31] The operating mechanism of these UV lightresponsive actuators is the photothermal effect in combination with a negative thermal expansion coefficient of the oriented and chain extended polymer. [29][30][31] However, there is continuous and rapid stress decay in these stress-generating actuators due to the innate stress relaxation.…”

Stimuli-Responsive Shape Changing Commodity Polymer Composites and Bilayers

“…In stress relaxation experiments, the adsorbed chromophores allowed for repeated stress generation in response to UV-light exposure. Adapted from ref ( 73 ) with permission from The Royal Society of Chemistry. (B) A flexible LDPE substrate is locally coated with carbon nanotube doped poly( N -isopropylacrylamide) to form bilayer, hinged actuators.…”