Figure 7.

Stimuli-responsive shape changing PE. (A) Epitaxially grown crystals of light-sensitive azobenzene dopants bearing C20 aliphatic side chains adsorbed onto oriented PE as seen with optical microscopy. 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. The hinges change shape when being heated above the lower critical solution temperature enabling bending. Reprinted with permission from ref (74). Copyright 2011 American Chemical Society. (C) A light-driven plastic motor is prepared by connecting the ends of a photoinert LDPE substrate coated with an azobenzene-containing liquid crystal elastomer. The bilayer actuator continuously rotates using simultaneous UV and visible light illumination driving cooperative azobenzene isomerization. Reproduced with permission from ref (76). Copyright 2008 Wiley-VCH.