Reversibly and Irreversibly Humidity‐Responsive Motion of Liquid Crystalline Network Gated by SO₂ Gas

Abstract

Manipulating functional liquid crystalline networks (LCNs) by multiple stimuli has been a hot topic in the research of smart actuators and fabrication of biomimetic robots. Here, a single-layer LCN film showing dual responsiveness to humidity and SO 2 gas is prepared. Interestingly, the humidity sensitivity of the LCN film can be gated by exposing the film to SO 2 . At the same time, the SO 2 sensitivity is strongly affected by the ambient relative humidity (RH) and the response time is able to be tuned by changing the RH over a wide range. The mechanism of this dual response of the LCN film is ascribed to the neutralization of carboxylic acid and in situ acidification of the carboxylic salt. The reversibly and irreversibly humidity-induced motion gated by SO 2 renders the LCN film valuable in the design and preparation of multifunctional devices.

Humidity‐Responsive Blue Phase Liquid‐Crystalline Film with Reconfigurable and Tailored Visual Signals

“…[ 17 ] Usually, a polymer film from the system composed of acrylate monomers without fluoro‐substitution has a small CA. [ 18 ] Therefore, CAs of all the film from system S 0 are far less than 90° at the three different states, since they are always hydrophilic. However, CA of the film from system S 1 is less than 90° at the K‐salt state, but larger than 90° at the acidified state (Figure 2e).…”

“…This distinct response of the color change can be easily distinguished by naked‐eye detection, which is able to apply for acidic gas or liquid detection such as SO 2 , Cl 2 , and acid rain. [ 18 ] When the K‐salt film was immersed in a solution of PH ≈ 1, the response completely disappeared because the film was hydrophobic (CA = 102°). Utilizing this unique property, a patterned signal for antifake model is demonstrated in Figure 5b.…”

Associative Learning by Classical Conditioning in Liquid Crystal Network Actuators

“…Potential approaches could include the use of absorbing molecules or particles with dynamic properties, 32 responsive-material-based logic gates, or more complex intelligent responses. 59 In Figure S17, we show that it is possible to externally manipulate the artificial memory using chemicals. The absorbance of a conditioned sample drops by 80% by bathing in isopropanol for 15 min at 70 C. Note that this process only mimics the apparent forgetting-like behavior using chemical compounds and significantly differs from its biological counterpart, in which no chemical additives are required to drive the forgetting.…”

Self-healing and shape memory functions exhibited by supramolecular liquid-crystalline networks formed by combination of hydrogen bonding interactions and coordination bonding

“…Nanostructured liquid crystals have attracted attention because of great potential as new functional materials. [1][2][3][4][5][6][7][8][9][10] In particular, combination of nano-science and supramolecular chemistry in liquid-crystalline (LC) assemblies is expected to provide new so materials with dynamic and anisotropic functions. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] For example, development of supramolecular LC polymers has resulted in the induction of their stimuli-responsive and selfhealing properties as well as facile and simple formation processes.…”