Photoinitiated Marangoni flow morphing in a liquid crystalline polymer film directed by super-inkjet printing patterns

Abstract

Slight contaminations existing in a material lead to substantial defects in applied paint. Herein, we propose a strategy to convert this nuisance to a technologically useful process by using an azobenzene-containing side chain liquid crystalline (SCLCP) polymer. This method allows for a developer-free phototriggered surface fabrication. The mass migration is initiated by UV-light irradiation and directed by super-inkjet printed patterns using another polymer on the SCLCP film surface. UV irradiation results in a liquid crystal-to-isotropic phase transition, and this phase change immediately initiates a mass migration to form crater or trench structures due to the surface tension instability known as Marangoni flow. The transferred volume of the film reaches approximately 440-fold that of the polymer ink, and therefore, the printed ink pattern acts as a latent image towards the amplification of surface morphing. This printing-aided photoprocess for surface inscription is expected to provide a new platform of polymer microfabrication.

Photo-triggered large mass transport driven only by a photoresponsive surface skin layer

“…Thus, PAz in the cis-rich state has a higher surface tension than that in the trans state. These results agree with the reports by Ellison et al 36 for the surface fabrication by photopatterning onto an Az polymer and our observations in inkjet printed system 40 . The effect of linear UV light polarisation was examined.…”

“…Roughly 20 times larger thickness of PCPBz is affected from the PAz surface layer at each thickness. Our previous inkjet-printing study 40 revealed that a larger amount of surface ink results in a larger flow motion. The observed thickness dependence herein could be explained in the same manner.…”

“…Figure S1 shows the DSC curves. The thermal phase transition behaviour of PAz is reported elsewhere 40,42 . PCPBz exhibited a nematic phase between 23-114 °C (Fig.…”

“…To prevent mass transfer motion, one monolayer coverage is sufficient regardless of the initial film thickness. The minor motions leading to 30 nm undulations may be attributed to the effect of the large viscosity alternation formed at the boundary between the smectic A and isotropic phases 40 . In this UV irradiation condition, photoisomerisation to the cis-rich photostationary state fully proceeded.…”

Rate of Entropy Production in Evolving Interfaces and Membranes under Astigmatic Kinematics: Shape Evolution in Geometric-Dissipation Landscapes

“…Shape and curvedness affect membrane elasticity [ 13 ], the rate of growth of cell tissues [ 14 ] and particle behaviours [ 15 ]. For example, the shape and curvedness of liquid crystals are sensitive to external stimuli such as electromagnetic field [ 16 ], light stimulation [ 17 , 18 ], force field [ 19 ], surface anchoring [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ] and surfactants [ 28 , 29 ]. They can be applied in superhydrophobic materials [ 30 ] and optical lenses [ 31 , 32 ].…”