Functional Liquid Crystal Polymer Surfaces with Switchable Topographies

Abstract

Surface coatings, as interfaces between functional devices and targeted objects, are critical in the performance of functional devices. Switchable topographies bring opportunities to regulate the functionality of surfaces, ranging from morphing and controllable friction to object lifting and debris removal. Various responsive materials have been investigated to develop switchable surfaces, among which liquid crystal (LC) polymers are attractive candidates due to their anisotropic properties. Herein, focus is put on recent reports of switchable surfaces made of LC polymers. The principle of actuation of LC polymer–based switchable surfaces is introduced, with following exemplary applications derived from these responsive surfaces in the field of surface morphing, switchable surface friction, and moving/lifting of objects. Finally, future possible applications of and challenges in using dynamic coatings with switchable surface topographies are discussed.

Regulating Surface Topography of Liquid‐Crystalline Polymers by External Stimuli

“…where 𝜃 is the angle between the mesogenic molecule and the director. [33] Therefore, mesogenic molecules are usually anisotropic in many aspects including mechanical properties, thermal properties, dielectric properties and so on. This provides Reproduced with permission.…”

“…[32] As for SMP, it is an intriguing material which can memorize and recover its surface structures, [25] but programming is first needed. Compared to these two materials, the most prominent advantage of LCP is that mesogens can be oriented along preferred direction, [33] which leads to the physical anisotropy of materials, enabling the surface topography to change under external stimuli. Therefore, LCP is a potential material in terms of stimuli-responsive surface topographical control.…”

“…Therefore, LCP is a potential material in terms of stimuli-responsive surface topographical control. Recently, Feng et al reviewed the research progress in functional switchable surfaces, [33] and the key point is to introduce some exemplary applications using dynamic coatings, while other types of deformation are excluded. In our latest paper, a wider variety of surface topographies have been reviewed, but only limited to photocontrolled surfaces.…”

Biodegradable, Breathable Leaf Vein‐Based Tactile Sensors with Tunable Sensitivity and Sensing Range

“…[1][2][3] Considerable researches have been conducted to develop bioinspired e-skins by mimicking perceiving capability and features of breathable characteristics have been gradually integrated to obtain a comprehensive performance of e-skin to accommodate the practical applications. [23][24][25][26][27][28] Especially, breathability is an essential approach to enhance the comfortability of wearable devices by balancing thermal-moisture between the human body and external environment. Bio-degradability allows the implanted devices degraded and resorbed in the body without any harm, so no subsequent operation will be required to remove them when used in medical therapy.…”

Azobenzene‐Based Photomechanical Biomaterials

“…Stimuli‐responsive biomaterials are a class of materials that exhibit smart behavior: their physicochemical properties respond to changes in the external environment, such as light, temperature, ultrasound, electricity, magnetic field, and pH. [ 1–11 ] These tailorable systems have promising biomedical applications in the fields of drug delivery, [ 12–16 ] sensors, [ 17,18 ] artificial muscles, [ 19–24 ] actuators, [ 25–28 ] and tissue engineering. [ 29–31 ] Among these materials, light‐responsive biomaterials are an emerging class of materials promising for biomedical applications.…”